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This paper proposes a coordinated voltage control scheme for transmission systems based on linearized power flow functions to determine the set points of local control voltage devices. The scheme considers models and interactions between different devices to attain the appropriate performance (non-optimal or optimal) of the whole power system. The sensitivity analysis is used to formulate a partly linearized model that relates the voltage variations of buses to the reactive power variation of synchronous machines, settings of static VAr compensators (SVCs), shunt capacitors susceptance, and tap position of load tap changers (LTCs) to determine the set of the settings of the voltage control devices. Two formulations are proposed by considering the susceptance of SVCs or the slope and reference voltage of characteristics of SVCs as control variables. The developed formulation based on the linearized power flow functions provides the possibility of the practical implementation of the coordinated voltage control scheme, especially the optimal one, by reducing the model complexity and solving time. The performance of the proposed formulations is investigated by some studies of voltage control and an optimally coordinated problem on the IEEE 30-bus and IEEE 118-bus test systems. • Coordinated voltage control of a wide variety of voltage control devices dispersed on the transmission network. • Formulating a partly linearized model based on a sensitivity analysis of nonlinear power flow functions. • Formulations by considering two different models for SVC. • Applicable to both non-optimal coordinated or optimal coordinated problems. • Considering a complete set of objectives, including operation indices of the network and fast and slow voltage control devices. [ABSTRACT FROM AUTHOR]

The depletion of conventional fuel reserves and the high carbon emissions have alarmed the energy sector drivers. The integration of renewable energy resources (RERs) towards power system transformation is an obvious approach for a new-zero future. However, this integration also brings challenges in terms of voltage stability and power losses due to the variable output of RERs. To address these challenges, this work proposes a novel approach utilizing photovoltaic (PV) inverters and static var compensators (SVCs) for reactive power control in power distribution networks (PDNs). It enhances voltage stability and minimizes power losses. The proposed study deploys a proximal policy optimization (PPO) algorithm for real-time communication and control between reactive power devices. Performance evaluation was made on an IEEE-33 Bus system to demonstrate the effectiveness of the proposed scheme in integrating RER-based distributed generators (DGs). The proposed system achieved 68 % voltage control, keeping the voltage within a certain range of ±5 % while minimizing power losses. The proposed system also reduced the voltage out-of-control ratio to 0.044, which indicates minimum voltage deviation from the standard value. The proposed study provides a promising solution for controlling the voltage of DGs integrated PDN, which can potentially enhance the efficiency and reliability of the power system. • This paper introduces PV inverters and SVC-based reactive power voltage regulation for renewable DG-integrated systems. • Reactive power control in the DG-integrated system is adopted using Reinforcement Learning-Driven PPO. • The validation of the proposed method uses the IEEE-33 bus system to integrate RERs-based DGs and achieve PPO-based control. • The proposed method achieved 68% voltage control, reduced power loss, and reduced the voltage out-of-control ratio to 0.044. • This research compares the suggested approach to different methodologies to demonstrate its validity and applicability. [ABSTRACT FROM AUTHOR]

With the expansion of distributed power systems and renewable energy worldwide, the use of synchronous condensers (SC) has been gradually increasing to maintain the power quality of an electric grid. Because SC generates fewer harmonics and has the advantage of strengthening system inertia, it is considered as a primary option in Korea over other options such as Static Var Compensator (SVC) and STATic synchronous COMpensator (STATCOM). If superconductor synchronous condenser (SSC) is applied instead of SC, it brings more advantages: (1) it can minimize the adverse impact on the power system due to lower synchronous reactance, and (2) the higher power density can lead to many advantages in a limited area of substation. With these backgrounds, we report a design study on 40 MVAr SSC with no-insulation high-temperature superconductor (NI-HTS) field coil. Firstly, design criteria and procedures for electromagnetic design were set. Secondly, with the design procedure, the electromagnetic design having the minimum HTS conductor usage was obtained among the designs satisfying design criteria. Based on the final design, key characteristics of SSC including no-load voltage, the maximum flux density under the rated-load condition, V-curve characteristic, synchronous reactance, zero sequence reactance, negative sequence reactance, critical current, and NI-HTS characteristics were calculated by using finite element method. Lastly, the design comparison between SSC and SC was presented. • The use of synchronous condensers has been gradually increasing. • Superconductor synchronous condenser is a promising alternative option. • It has not only a much lower synchronous reactance but also a higher power density. • The advantages were confirmed through the electromagnetic design study. [ABSTRACT FROM AUTHOR]

• Reactive power management. • Point estimation method. • Hony Badger algorithm. • Two-stage stochastic programming. • Inverter reactive power capability. In order to reduce the Static Var Compensators' (SVCs') initial investment costs and their anticipated yearly running costs, this paper offers a two-layer methodology for the allocation and sizing of the SVCs in radial distribution systems. First, the Power Loss (PLI) is used to choose the best candidate buses for allocating SVCs. A two-stage stochastic programming algorithm is then proposed to solve the sizing problem, with the Point Estimate Method (PEM) being used to account for the uncertainties in the PV and load powers. Analysis is also done on the advantages of combining the SVCs and the PV inverter's ability to provide reactive power. The optimization problem is solved using Honey Badger Algorithm (HBA) and compared to Archimedes Optimization Algorithm (AOA), Beetle antenna based Grey Wolf Optimization (BGWO), Particle Swarm Optimization (PSO) and Genetic Algorithm (GA). The IEEE 33 and 69 radial bus systems have been used to validate the suggested methodology. The findings demonstrate that, HBA models delivered the best outcomes in terms of convergence characteristics and computation time. When considering the PV inverter's capability to provide reactive power, estimated yearly operating costs are reduced by 17.44 % and 36.36 % for compensations of 600 kVAR and 1,000 kVAR, respectively. [ABSTRACT FROM AUTHOR]

In order to effectively compensate negative sequence current (NSC) of the V/v traction system and reduce the capacity and cost of railway power conditioner (RPC), a low-cost hybrid railway power conditioner (HRPC) technology scheme considering regenerative braking energy is proposed in this paper. The proposed HRPC consists of an RPC with a modular multilevel converter structure (MMC-RPC) and a railway static var compensator (RSVC). First, the circuit topology of the proposed scheme and the principle of NSC compensation considering regenerative braking energy are given. Then, the capacity configurations of MMC-RPC and RSVC are presented to reduce the capacity of active equipment and further lower the investment cost of HRPC. On this basis, the HRPC with energy storage units (ESU-HRPC) is studied to recycle the remaining regenerative braking energy, and the difference from the proposed HRPC is further analyzed. Subsequently, the capacities of HRPC and ESU-HRPC are designed based on the measured power data from a heavy-haul railway in China as an example. Besides, the system control strategy is given. Finally, the proposed technical schemes are verified by the hardware in loop (HIL) experiments. [ABSTRACT FROM AUTHOR]

A local load connected with the grid-interfaced photovoltaic (GIPV) system demands reactive power compensation at the distribution level. The compensation either fulfilled by the PV inverter or grid side arrangements such as capacitor bank, static VAR compensator or tap-changing transformers. Amongst both, the inverter has merit to compensate reactive power without using an additional compensator or oversizing the inverter rating. However, it always depends upon the availability of irradiance and especially when the inverter transfers power with full capacity has no margin to generate the reactive power. Therefore, to make the system flexible according to the demand of the local loads and to create a margin to generate the reactive power at any time instant, a GIPV system with modified perturb & observe (MP&O) maximum power point tracking (MPPT) technique has been proposed. This proposed technique with an intermediate boost converter extracts maximum power more efficiently as compared to the traditional MPPT technique. On the other hand, it curtails the generated active power and provides margin for the PV inverter to generate the reactive power. Further, the PV inverter generates active and reactive power to the local loads as well as transfer power to the grid using inverter control. The inverter control comprises of decoupled instantaneous active and reactive power control. In this control scheme, it maintains the DC-link voltage and power flow between the GIPV system and the grid under all available irradiance conditions. In this respect, a 30 kW GIPV system is simulated and performance of the system is validated using real-time OP4510 hardware-in-loop (HIL) setup. • Modified P&O MPPT technique is proposed to extract the PV power. • Derated mode of Modified P&O MPPT technique is implemented to curtail the active power. • Smart utilization of PV inverter's capability for the reactive power compensation. • Simulation results are validated using Opal-RT OP4510. [ABSTRACT FROM AUTHOR]

The adaptive finite-time anti-disturbance fuzzy control method for n -dimensional uncertain nonlinear systems with input delay is proposed in this paper. For unknown nonlinear terms of the controlled system, the fuzzy logic systems (FLSs) are utilized to approximate them. To further improve the robustness of the controlled system, the disturbance observer is established to estimate external disturbances, facilitating the designed controller to compensate for the influence of external disturbances. Moreover, the Pade approximation method is used to transform the time-delay system model, which is convenient for controller design. With the aid of the finite-time command filtered backstepping technique, the adaptive finite-time disturbance rejection controller with low computational complexity is designed, which can compensate for the errors caused by the filters and assure that system state variables are stable and bounded in a finite time. In the end, the simulation for the single-machine infinite bus (SMIB) system with static var compensator (SVC) is presented to illustrate the effectiveness of the proposed control approach. [ABSTRACT FROM AUTHOR]

The necessity of power is growing in response to today's growing population. In order to reduce both real and reactive power losses, three devices have been combined in this research. The distributed generations (DGs) and static var compensator (SVC) with static synchronous compensator (STATCOM) play important role for reduction of power losses (both real and reactive power) and improvement of voltage profile. The research outcome presented here outlines that presents genetic algorithm (GA) may be utilised to improve power system performance and voltage profile (VP) of distribution networks by integrating DG, SVC and STATCOM planning properly. On a 37-bus distribution network, the proposed methodology has been applied. The results of this study are helpful to those focusing on the functionality of viable and upcoming electrical grids, as well as those working in the disciplines of DG, SVC and STATCOM integration for improved system performance. [ABSTRACT FROM AUTHOR]

This paper presents an interpolation-based solution that allows the application of traveling wave (TW)-based algorithms even using sampling rates lower than those typically considered as a requirement for classical approaches. Two phasor (PH)-based and one TW-based fault location methods are compared with the proposed technique and applied through Alternative Transients Program (ATP) fault simulations in a 500 kV/60 Hz Brazilian double circuit series-compensated transmission lines with high-voltage direct current lines (HVDCs) and static var compensators (SVCs) in the vicinity. The results show that the proposed interpolation-based technique is reliable and suitable for TW-based fault location using data records with sampling rates lower than those used in commercially available equipment. Moreover, its accuracy is comparable to classical TW-based fault location solutions, revealing its usefulness for practical application when only traditional digital fault recorders (DFRs) are available. • Application of traveling wave (TW)-based algorithms using low sampling rate records. • Interpolation technique combined with TW-based applications. • Application for inferior band of frequency spectrum from fault induced transients. • Use low sampling rate digital fault recorders (DFRs) for (TW)-based applications. [ABSTRACT FROM AUTHOR]

• Real-world HIL setups for hybrid SVC with full-bridge MMC. • Regular and small time-step simulations match exceptionally well. • Regular and small time-step simulation approaches valid in this case. • Small time-step contrivances introduce significant discrepancy from reality. • Small-time step partitioning contrivances must be considered. Hydro-Québec built two static var compensators at the 735-kV La Verendrye substation in 1985. Each has a capacity of +330/-110 Mvar to help regulate system voltage and power system dynamic. They exceeded their useful life, and their operation was becoming challenging due to the aging control technology. Spare part availability and cost were also becoming an issue. A refurbishment project was thus undertaken. Due to design constraints, a hybrid SVC was selected: traditional thyristor-switched capacitors are used, but thyristor-controlled inductors are replaced by full-bridge modular multilevel converters. Throughout the ongoing project, hardware-in-the-loop real-time simulation was used for dynamic performance testing, factory acceptance tests and pre-commissioning studies. Two modeling approaches were used to represent the hybrid SVC: conventional electromagnetic transient simulation and small time-step approach. As this paper demonstrates, both approaches are valid in this case and produce matching results if simulation contrivances are not neglected. [ABSTRACT FROM AUTHOR]

• Recursive least squares and generalized regression neural network are used to build a real-time dynamic system model for adaptive control. • A static var compensator additional dual-channel damping controller structure is proposed for the dominant mode of low-frequency oscillation. • Static var compensator additional damping controller parameters tuning problem converted Markov decision process and a soft actor-critic algorithm is also introduced to solve the Markov decision process. As the access rate of wind energy in a power system has significantly increased, stabilizing the power system has become challenging. Among these challenges, low-frequency oscillation is one of the most harmful problems, effectively resolved by adding a damping controller according to the relevant properties of the low-frequency oscillation. However, the controller often fails to adapt to the constantly changing wind energy system owing to the lack of a targeted dynamic change strategy. Thus, to address this issue, an adaptive stabilization strategy that uses a static var compensator with an additional damping controller structure is proposed. Specifically, the entire power system is equivalently represented as a generalized regression neural network, with a deep reinforcement learning algorithm called soft actor-critic introduced to train the agent based on the generalized regression neural network model. After the training process, the agent can provide additional efficient static var compensator damping controller parameters under different operating conditions, vastly improving the system stability. Simulation results verify the improved performance using the proposed strategy compared to other optimization methods, regardless of whether the low-frequency oscillations were suppressed in the time or frequency domains. [ABSTRACT FROM AUTHOR]

Highlights • This paper proposes two controlling methods for SVC in smart grid with connected EV charger. • SMC, ASRFC with a HVC are separately applied in the grid. • This paper presents usage of proposed methods for decreasing size of capacitor and value of apparent power loss. • The proposed scheme is validated through computer simulations of a 22.9-kV grid. Abstract Electric Vehicles (EVs) play a pivotal role in reducing the emissions of greenhouse gases in the world. Currently demand for EVs has abruptly increased for transportation and other applications. Using more EVs causes an increasing load on the power system. Random EV charging yields voltage distortion, which results in an unbalanced grid. In a distributed system, the connection of EVs to the grid may diminish the power factor, which increases the apparent power loss. The Static VAR Compensator (SVC), which is a FACTS device, is applied to the power system to compensate the voltage distortions and apparent power loss. In this paper, two controlling methods are contemplated and tested in a SVC to reduce the apparent power loss and minimize the capacitor size of the SVC in comparison with the conventional control method in a SVC. Proposed methods are also compared with the conventional control method used for SVC. The Slide Mode Controller (SMC) and Asymmetric Synchronous Reference Frame Controller (ASRFC) with a Harmonic Voltage Compensator (HVC) are separately applied in the grid. This paper presents usage of SMC and ASRFC methods for decreasing size of capacitor and value of apparent power loss through computer simulations of a 22.9-kV grid. With application of new controllers, apparent power loss of grid will be reduced as compared with conventional method of SVC controller. Moreover, the size of SVC capacitor can also be reduced. [ABSTRACT FROM AUTHOR]

Abstract This work discusses the implementation of JAYA-DE algorithm with Static Var Compensator for optimum voltage control through Reactive Power compensation inside solar based hybrid power system.The stability aspect of isolated solar based hybrid power system is enhanced through compensation of the reactive power by optimized SVC and are further analyzed with different stability criterion. The dynamic performance of the new hybrid technique under intermittent wind power input and variable load show superiority over the conventional control methods. [ABSTRACT FROM AUTHOR]

In this research, a complex engineering failure analysis is done for a static VAR compensator (SVC), it was installed in Perú 220 kV system. The research introduce the selected results of the simulations and field tests completed during the fault, mitigation and corrective activities performed at the thyristor valve, which is installed in the thyristor switched capacitor (TSC) and thyristor controlled reactor (TCR) of the SVC. This paper proposes the most feasible solution to overcome the failure of the TSC based on snubber resistor in the SVC. In order to investigate the causes of this failure, various measurements were carried out on the TSC. It was concluded that a snubber resistor design needs two special test for determinate a problem or abnormal condition; a special test should be done in the factory acceptance test (FAT), site acceptance test (SAT) and to execute a maintenance diagnosis, to prevent a failure in the thyristor valve from TSC. This failure has happened in the standby system, the susceptance reference is forced to follow the susceptance reference received from the active system. There is however, a delay in the transfer of data from the active to the standby system. During transient conditions this may cause a difference in thyristor firing angles between the systems. The simulated current in the standby system does not agree with the measured current, which is controlled by the active system, an advanced diagnosis and design review is developed for to avoid a sudden failure. The feasibility of these solutions was verified through the computer simulation with PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]

This paper presents a novel multi-objective model of active distribution network planning based on stochastic programming and uncertain random network (URN) theory. The planning model is proposed to find the final scheme with optimal alternative, location, size and operational strategy for the candidate distribution lines, transformer substations (TSs), distribution generations (DGs), static var compensators (SVCs) and on-load tap changers (OLTCs). Firstly, a scenario-based approach is developed to analyse the uncertainties in network system, such as the demand and intermittency of renewable sources. Since the impact of multiple uncertain factors on network cannot be ignored, a network frame is then modelled by uncertain and random weights of spanning tree (ST) instead of fixed value. In order to achieve the minimization of total cost, and further the selection of a minimum spanning tree (MST) with the uncertain and random weight, a 3-dimensional uncertain space is constructed based on the combination of the previous two targets. In addition, a second-order cone programming (SOCP) is applied to cope with the multi-objective, mixed-integer nonlinear nature of the proposed planning model. Simulation is performed on a modified Pacific Gas and Electric Company (PG&E) 69-bus distribution system, and the results demonstrate the effectiveness of the proposed model. [ABSTRACT FROM AUTHOR]

With the integration of high shares of distributed generators (DGs), both volatile DGs and demand-side resources make it increasingly difficult to cope with the various uncertainties and put forward a higher requirement for the operational flexibility in active distribution networks (ADNs). The highly integrated distribution-level power electronic devices represented by soft open point (SOP) significantly benefit the operation of ADNs. Due to the accurate and rapid power flow control provided by SOP, various flexible resources can be coordinated in the spatial and temporal aspects, which effectively increases the DG penetration of ADNs. In this paper, the multi-dimensional characteristics of distribution system flexibility are analysed and the maximum DG hosting capacity is adopted as the index to evaluate the flexibility brought by SOP. The flexibility evaluation model is further proposed to quantify the benefits of SOP-based flexible resources, such as conventional SOP, multi-terminal SOP and SOP with energy storage. Then, the original non-convex nonlinear model is converted into an effectively solved second-order cone programming (SOCP) model using convex relaxation. To tighten the deviation of convex relaxation to the predefined accuracy, a difference-of-convex programming (DCP)-based approach is developed to solve the proposed model. Finally, case studies are performed on the modified IEEE 33-node system to verify the effectiveness and efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

Electric power system is complex interconnected system that is subjected to rapid change in its structure. Addition of new equipment, operation close to stability limits and variation of load in summer and winter are some factors that make power system unstable and introduce electro-mechanical oscillations in the system. These oscillations, though of small magnitude often persist for long periods of time and restrict the power transfer capacity. To stabilize the power system different control strategies are used to damp the oscillations previously but all rely on linearized model of the power system. Synergetic controller based on synergetic control theory, is a non-linear controller that forces the system toward global stability. In this paper, synergetic synthesis of the Static Var compensator (SVC) is proposed for a nonlinear model of the power system. The proposed synergetic controller is implemented in a Single Machine Infinite Bus (SMIB) system with HVDC link and the performance is compared with linear dynamic compensator based on eigen-value assignment technique. The results provided show the effectiveness of the controller for damping system oscillations in the case of variation in load whereas the linear dynamic compensator destabilized the system. [ABSTRACT FROM AUTHOR]

The use of a static var compensator (SVC) as a component of flexible alternating current transmission system (FACTS) devices to control power systems has been investigated for decades. Its aim is to regulate the system voltage and improve the stability and loadability of power systems. A typical assumption in such a system is that the parameters of the controlled system are known accurately, which is rarely satisfied in practice. This paper explores the development of a simple but effective controller for a single-machine infinite-bus power system with SVC subjected to both matched and mismatched disturbances where the controller derivation is based on the assumption that all parameters used in the system modeling are unknown , but bounded in size. The research in this paper illustrates how an indirect robust control can be incorporated with a modified disturbance observer-based feedforward term to attenuate the influence of parameter variations and disturbances from the outputs of the system. Simulation results are presented to confirm the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

Excessive penetration of renewable energy resources into the distribution grid without additional preventive measures has led to several operational problems. However, most strategies developed to accommodate more renewable energy units suffered from other operational problems. Therefore, further efforts are needed to address the other key vulnerabilities of the grid in addition to maximizing the hosting capacity. In this regard, this study is devoted to a new multi-objective formulation to maximize the hosting capacity and minimize the total energy losses while satisfying the operational constraints and maximizing the energy transferred to off-peak hours. The Multi-Objective Advanced Gray Wolf Optimization (MOAGWO) algorithm is used as a solution tool. The proposed formulation and solution algorithm are tested on IEEE-33-bus and 69-bus medium voltage test systems. The impacts of energy storage systems, voltage regulators, and static var compensators on the hosting capacity and the objective functions are identified using several scenarios. The results showed that the optimal device type and locations depend on the level of DG penetration. Finally, a comparison according to two popular multi-objective performance indices showed that the quality of the Pareto front distribution obtained by MOAGWO was better than the ones obtained with the two other popular heuristic methods. • Maximization of the hosting capacity while minimizing the energy losses. • Maximization of the energy transferred to the off-peak hours through intelligent control. • Multi-Objective Advanced GWO algorithm to determine the Pareto front solutions. • Singular and collaborative impacts of the reinforcement units on the objectives. • High-quality Pareto solutions and high computational efficiency of MOAGWO. [ABSTRACT FROM AUTHOR]

• Large scale wind farm is designed including SCIG and DFIG units in two sites. • Proposed control strategy designs off-grid and grid-tied functionality for sites. • Sites and grid are supported by STATCOM and SVC to deal with voltage imbalance. • Fault ride through capability is enhanced by the proposed control strategy. • Frequency control is designed under grid-tied and off-grid operations. This paper presents a multi-objective control scheme on the interconnected wind farms which are formed by different wind turbines including doubly fed induction generators (DFIG) and squirrel cage induction generators (SCIG). The proposed control system aims to control voltage, frequency, and mechanical power in the wind farms under wind/load alterations, faults, and outages. The voltage stability and fault ride through capability are improved. The proposed model also deals with unbalanced loading and faulty conditions. All the aforementioned points are realized under both off-grid and grid-tied conditions. For voltage stability improvement, each wind farm is integrated with one static VAR compensator (SVC) and the grid-side is integrated with one static synchronous compensator (STATCOM). In the grid-tied, the resilience following events is improved by proper control of STATCOM. In the off-grid, the installed SVC at each site is responsible for increasing resilience. The proposed control systems are modeled and implemented on a typical test grid, and numerical simulations are carried out in MATLAB/SIMULINK software. It is demonstrated that the proposed multi-objective control scheme efficiently controls all individual wind farms, achieves a coordinated management between different wind farms, deals with stability/unbalanced operating condition/faults, increases resilience and improves fault ride through capability. [ABSTRACT FROM AUTHOR]

• Computational modeling to evaluate the LOE protection of synchronous generators connected to a transmission line with static var compensator (SVC). • Comparative of traditional LOE protection of with a proposed LOE protection method based on a multilayer perceptron-type artificial neural network (ANN). • Show the effectiveness of the proposed ANN LOE protection to reach faster actuation time than the traditional LOE protection. Flexible Alternating Current Transmission Systems (FACTS) connected to Transmission Lines (TLs) make systems more flexible, and optimize their operational capacity. Despite improvements in TL operational aspects, added FACTS can modify the amplitude, voltage, and current angles of the system wherein they are inserted and consequently the measured impedance, which can affect synchronous machine protections that are based on this feature. Firstly, this paper presents a set of computational simulations to evaluate possible changes in the synchronous machine protection connected to a TL with Static Var Compensator (SVC). Finally, is this context the traditional loss of excitation (LOE) protection is comparing with a proposed approach based on the use of a multilayer perceptron-type Artificial Neural Network (ANN). The simulation results show the effectiveness and robustness of the proposed ANN LOE protection to reach faster actuation time than the traditional LOE protection. [ABSTRACT FROM AUTHOR]

• An optimal VVC model considering diverse controllable resources including energy storage devices, distributed generators, step voltage regulators, static var compensators, and switchable capacitor banks in the ADN is proposed in this paper, in which the VVC problem is considered in a more complete energy management framework coupling with active power control. • Given that the active distribution network VVC problem is a computation-intensive MINLP problem with high-dimensional variables and strong non-convexity, the Kriging assisted surrogate model is trained to approximate the computationally expensive black-box nonlinear system, reducing the total number of actual time-consuming simulations, and moderating the computational burden without losing precision. • By expected improvement and dynamic updating techniques, the Kriging assisted modified adaptive particle swarm optimization (KA-MAPSO) is ultimately developed to solve the proposed VVC optimization problem, avoids the low convergence in non-convex and nonlinear power flow calculations. And the simulation result shows that the proposed method outperforms other referred algorithm and accelerate the solving process of traditional heuristic calculation. The increasing penetration of distributed energy resources exacerbates the risk of power loss increment and voltage violations in active distribution networks (ADN). The Volt/Var control (VVC) involving multiple controllable resources is widely considered to be an effective means of ensuring the secure and stable operation of ADN. Firstly, considering diverse controllable resources including energy storage devices, distributed generators, step voltage regulators, static var compensators and switchable capacitor banks in the ADN, a comprehensive/novel VVC optimization model is established as a mixed-integer non-linear programming problem with high-dimensional variables. In order to mitigate the computational burden with enormous networks and reduce the dependence on an initial physical model of the distribution network, a Kriging-assisted evolutionary computation method for VVC problem is proposed in this paper. The surrogate model is used to approximate the nonconvex and nonlinear network, reduce the frequency of complex simulations, assist optimization decision-making and avoid the complicated explicit analysis. Furthermore, the surrogate-assisted model enabled heuristic algorithm, owning promising performance in approximating the computationally expensive black-box system, can be obtained via continuous training and dynamic updating. Finally, the numerical results on the modified IEEE 33-bus and PG 69-bus systems verify the effectiveness of the proposed method. The simulation results indicate that the proposed Kriging-assisted evolutionary algorithm outperforms other algorithms in the aspect of calculation efficiency and robustness while accelerating the solving process of traditional evolutionary calculation. [ABSTRACT FROM AUTHOR]

• Improving the voltage in a wind farm by a self-corrective static VAR compensator. • Considering the steady-state and transient modes under harsh faults in analysis. • Enhancing the system performance by employing an optimized Battery Energy Storage. • Reporting the results in different cases, with or without the mentioned equipment. Maintaining synchronism and voltage stability, especially in the presence of wind farms, has a crucial role in confirming the reliability requirements of the power grid, as the natural fluctuations of wind speed result in intermittency and uncontrollability of power generation. To this end, an optimized Battery Energy Storage System (BESS) was suggested to make an equilibrium between the generation and consumption in wind farms under harsh conditions. Additionally, the instability of wind farms is very likely after transmission line faults occur. To overcome this problem, in this paper, the impact of a constant capacitor bank, connected in parallel with the wind generators, is investigated. Also, a novel self-corrective Static Volt-ampere reactive Compensator (SVC) is proposed to overcome the variations of voltage and damp the reactive power oscillations after occurring the faults. The proposed SVC compares the network voltage profile as the reference voltage with the voltage deviations in a control block diagram. For this purpose, three similar wind farms of Permanent Magnet Synchronous Generator (PMSG) type are considered in a wind park. The simulation case studies are performed in Matlab/Simulink under different conditions of transient and steady-state voltage stabilities in the presence of proposed BESS including, only capacitor bank (without self-corrective SVC), and with self-corrective SVC. The results authenticate the ability of the proposed SVC strategy to correct the voltage deviations, and voltage stability improvement of the under study system. [ABSTRACT FROM AUTHOR]

Presence of shunt FACTS (Flexible Alternating Current Transmission System) device significantly affect the performance of protection system and may create security and reliability issues. This paper introduces a novel approach for zone identification in transmission line employing shunt FACTS devices such as Static Var Compensator (SVC) and Static Synchronous Compensator (STATCOM). The technique depends on the modified apparent impedance seen by the impedance relay for all possible operating conditions. In this technique the Support Vector Machine (SVM) is used for discriminating faulty zone (zone 1 or zone 2). In addition an optimization technique viz. Genetic Algorithm (GA) is used to optimize SVM parameters. A typical 230 kV system was simulated in PSCAD/EMTP software and the results show that the proposed scheme is secure, accurate and reliable under the wide variation in power system parameters like load angle, fault resistance, fault location, inception angle and compensation level. [ABSTRACT FROM AUTHOR]

In our recent work [1] , we constructed a reduced-order model of the Western Electricity Coordinating Council (WECC) power system using mathematically derived parameters from real Synchrophasor data. These parameters include inter and intra-area impedances, inertias, and damping factors for aggregate synchronous generators representing five geographical, and yet coherent, areas of WECC. In this paper, we use this reduced-order model as a tool to design a supplementary controller for a Static VAr Compensator (SVC), located at the terminal bus of one of the aggregate generators. Wide-area feedback consisting of phase angle and frequency measurements from Phasor Measurement Units (PMUs) in the other areas is used to design this controller. The objective is to damp the inter-machine oscillation modes of the reduced-order model, which in the full-order system corresponds to inter-area oscillations. The controller input is chosen via statistical variance analysis, and its parameters are tuned to improve the damping factors of the slow modes. The model is implemented in a real-time digital simulator, and validated using a wide range of disturbance scenarios. The closed-loop system is observed to be highly robust to all of these disturbances as well as the choice of operating points. Detailed experimental analyses of the capacity of the SVC to satisfy the damping specifications of supplementary control are also presented via multiple contingencies. The results are promising in aiding damping of inter-area modes in WECC, especially at a time of increasing penetration of wind and other renewable resources. [ABSTRACT FROM AUTHOR]

In this study main reactive power calculation methods are evaluated and compared. Furthermore, a novel simple method that can be used for calculation of reactive power in electric arc furnace (EAF) plants is proposed. The focus here is on their application in the control system of static VAr compensators (SVCs). SVC can compensate only the fundamental harmonic component. So the reactive power signal used in the control system should be sensitive only to the main harmonic component. In addition, the reactive power calculation should be fast enough that SVC can follow the quick changes of the load to mitigate the flicker efficiently. To compare various reactive power calculation methods and to evaluate the proposed method, the simulated known loads are used beside huge amount of practical data recorded in Mobarakeh Steel Company in Isfahan/Iran. Results show the proposed method has the best performance for SVC control system. [ABSTRACT FROM AUTHOR]

Based on differential algebraic (DA) subsystem models of power system components including the nonlinear controllers, which are called component structural complex models, this paper presents a model reduction method (MRM). For the dynamic differential equations, based on the property that the nonlinearity of the controller compensates that of the component completely (or partially), the presented method uses the linear dynamic equations to describe the compensated dynamics. For the algebraic connection equations, the new defined state variables are used to substitute the original state variables for keeping the connection relation invariable. By selecting generators and static var compensators (SVC) as examples, the paper presents the basic procedure of the proposed reduction method for power system component complex models in detail. The numerical simulation indicates that the derived simplified models matches the original one very well in both dynamic response behaviors and the connection relation with the external system. [ABSTRACT FROM AUTHOR]

• The proposed protection strategy enhances the stability and reliability of power systems by. • Precise discrimination between transient and permanent SLG faults. • Fast and precise diagnosis of the successful reclosing time in a case of the transient SLG fault. • Significant reduction in the dead time in a case of the transient SLG fault. • Being efficient even in noise exposure situations and not dependent on the fault location or threshold values. Opportune detection of transient faults and restoration of the faulty phase in the least possible time plays a key role in improving the stability of high voltage transmission lines (HVTLs). This paper presents a novel four-step strategy for the protection of HVTLs so that the stability and reliability of power systems are enhanced. Firstly, the cumulative sum (CUSUM) algorithm is used to quickly detect the transient and determine the faulty phase. In the second step, the settings of the static var compensator (SVC) are changed to reduce the reclosing dead time as much as possible. Afterward, the transient or permanent type of the fault is identified based on the proposed principal component analysis-support vector machine (PCA-SVM) algorithm. In the fourth step, if a transient fault is recognized, the successful single-phase reclosing time is identified by the PCA-SVM and the reclosing command is issued to high voltage circuit breakers (HVCBs). Simulation results obtained by using EMTP-RV and MATLAB for a sample 400 kV power system illustrate that the proposed protection strategy can increase the reliability of the power system via reduction of the dead time, correct detection of transient faults from permanent ones, and accurate detection of the reclosing time. [ABSTRACT FROM AUTHOR]

Variable speed wind turbine generators (WTGs) are replacing traditional fossil fuel based synchronous generators in the generation fleet as wind penetration increases. These variable speed WTGs are decoupled from the grid by power electronics inverters and usually generate less fault current compared to synchronous generators. As a result, system strength (indicates the fault recovery capability) at the point of common coupling (PCC) of wind power plants may reduce. A minimum value level of system strength is essential for wind power plants to properly identify and overcome a fault. To enhance system strength at wind PCC buses, supplementary devices such as synchronous condenser and Static VAR Compensator (SVC) can be deployed to have additional fault current. Since these devices are expensive, their optimal allocation considering economic feasibility is a major concern. In the existing literature, locations and ratings of the optimally allocated synchronous condenser are reported. However, this approach may cause oversizing of synchronous condensers. In addition, a SVC can be utilised instead of a synchronous condenser to enhance system strength. However, no detailed study is carried out yet to find the optimal size of SVCs. Evidently, both synchronous condenser and SVC can be installed to improve system strength. However, no comprehensive techno-economic assessment is performed for selecting an appropriate choice between them. To address these research gaps, this paper develops a framework to find the optimal sizes of synchronous condensers and SVCs by taking into account the long-term financial viability. Also, to ensure the maximum possible fault contribution, synchronous condensers/SVCs are connected directly to those wind PCC buses where system strength is below the acceptable limit. Afterwards, a detailed techno-economic assessment using synchronous condenser and SVC is performed in a wind dominated grid. In addition, post-fault voltage recovery characteristics with optimally sized synchronous condenser and SVC are explored. The developed methodology is applied to the IEEE 39 bus test system considering 45% wind power penetration scenario. Also, the performance of the proposed approach is compared to that of an existing technique. Finally, based on the technical and economic aspects, a better choice between synchronous condenser and SVC is recommended to improve system strength under high wind penetration. • System strength is improved in a wind dominated grid. • Optimal sizes of synchronous condenser and SVC are found. • Long-term techno-economic assessment is performed. • Technical and economic aspect of synchronous condenser and SVC are compared. • Synchronous condenser is found to be a better choice than SVC. [ABSTRACT FROM AUTHOR]

Intermittent power generation of wind turbines and photovoltaic plants creates voltage disturbances in power distribution networks which may not be acceptable to the consumers. To control the deviations of the nodal voltages, it is necessary to use fast dynamic control of the reactive power in the distribution network. Implementation of the power electronic devices, such as Static Var Compensator (SVC), enables effective dynamic state as well as a static state of the nodal voltage control in the distribution network. This paper analyzed optimal sizing and location of SVC devices by using genetic algorithm, to improve nodal voltages profile in a distribution network with dispersed photovoltaic and wind power plants. Practical application of the developed methodology was tested on an example of a real distribution network. [ABSTRACT FROM AUTHOR]

This paper presents a novel Flexible AC Transmission Systems (FACTS) placement method based on mixed integer quadratically constrained programming (MIQCP). The method is capable of allocating both Static VAR Compensator (SVC) and Thyristor-Controlled Series Capacitor (TCSC) either separately or simultaneously, to determine concurrently their numbers, locations as well as sizes. The optimization objective is to maximize loadability and minimize compensation. The proposed MIQCP formulation partially incorporates key quadratic constraints, which were absent in mixed integer linear programming (MILP) placement methods reported in the past. The authors demonstrate significant improvements in accuracy over past MILP methods, with case studies presented on the simplified Southeast Australian network, and on a large scale real-world power system, Powerlink Queensland's HV transmission network, with 886 buses and 1087 branches. In addition, results and observations for simultaneous allocation of multiple TCSCs and SVCs in these networks are demonstrated in this paper. [ABSTRACT FROM AUTHOR]

Microgrids are small scale energy grids that can provide adequate energy supply to cover regional demand by integrating renewable energy generation and storage technologies. This paper develops a high performance dynamic model of a microgrid system comprising a wind turbine, a PV, a fuel cell, a micro gas turbine generator, an energy storage, electric loads with variable load profile and flexible AC transmission system (FACTS) devices. The FACTS devices based on static VAR compensators have been employed as a supervisory controller. Key performance indicators such as microgrid power losses, buses voltage deviations, buses power factor, buses voltage total harmonic distortion and voltage-frequency deviation are used to evaluate the performance of this microgrid in grid-connected and islanding modes. The results obtained from the Matlab/Simulink environment show that the proposed microgrid design with SVC has the ability to meet its special requirements such as bus voltages stabilization, reduction of feeder losses, power factor enhancement and mitigation of total harmonic distortion using SVC in grid-connected and islanding modes. [ABSTRACT FROM AUTHOR]

In this paper, a new control synthesis framework is developed to solve a robust stabilization problem for a single-machine infinite-bus power system with a static var compensator (SVC). The uncertainties in the infinite bus voltage and the internal and external reactances to the generating station are considered. First, control inputs for the excitation and the SVC are obtained via immersion and invariance (I&I). Then, the controller is redesigned using a parameter update law and a filter using indirect I&I adaptive control and a two-time-scale technique. The transient and steady-state performances are enhanced by introducing class K functions. The simulation results show that the developed controller improves the system performance. [ABSTRACT FROM AUTHOR]

• A modified minimum switch count magnetic energy recovery switch (MERS) topology has been proposed as a shunt static VAr compensator (SVC-MERS). • The conduction loss of the switch is reduced due to the minimum switch count and thus promises a high-efficiency compensator. • An equivalent harmonic model using mathematical equations has been developed by introducing switching functions for performance analysis of the proposed compensator. • A suitable ratio of resonant angular frequency to line angular frequency has been chosen to select the optimum L and C parameter of MERS unit for low harmonic injection. In this paper, a minimum switch count modified magnetic energy recovery switch (MERS) topology has been proposed as a shunt static VAr compensator (SVC-MERS). Whereas, the existing scheme uses four active switches for the same purpose. Thus, conduction loss of the switch is reduced in the proposed scheme due to the minimum switch count and thus promises a high-efficiency compensator. Moreover, a coupling inductor (L) and a capacitor (C) are used in the proposed scheme for reactive energy storing and exchanging. Improper selection of L and C may instigate harmonic resonance. To examine its impact on modified MERS performance, an equivalent harmonic model using mathematical equations has been developed by introducing switching functions. The characteristics analysis of the proposed modified MERS has been done by using this harmonic model. Based on the above analysis a suitable ratio (S) of resonant angular frequency to line angular frequency and corresponding optimum L , C parameters have been selected for low harmonic injection. The key features of this proposed scheme are low current total harmonic distortion (THD), lesser switching losses, reduced cost, and low voltage rating of the switch as compared to the existing MERS scheme. To verify the proposed concept simulation has been carried out using a 6 kVA rating inductive load in MATLAB Simulink environment. The both analytical and simulation results confirm that the proposed reduced switch count compensator model with optimum L = 30 m H and C = 150 μ F can be used efficiently for power quality improvement in a low voltage grid. \ [ABSTRACT FROM AUTHOR]

Highlights: [•] Different components of TCR–FC type SVC are introduced. [•] Using Markov process, a reliability Markov model for TCR–FC type SVC is obtained. [•] An equivalent three-state model for TCR–FC type SVC is proposed. [•] A sensitivity analysis for the availability of the equivalent model is carried out. [Copyright &y& Elsevier]

Highlights: [•] Combination of optimal reclosing of circuit breakers and SVC is proposed for power system transient stability enhancement. [•] The performance of the proposed combination of optimal reclosing and SVC is compared with the combination of conventional reclosing and SVC. [•] The performance of the proposed combination of optimal reclosing and SVC is better than that of the combination of conventional reclosing and SVC. [•] Combined operation of optimal reclosing and SVC can be considered as an effective means for power system transient stability enhancement. [ABSTRACT FROM AUTHOR]

Highlights: [•] A new method called the CE approach is used for location and setting of FACTS. [•] To enhance the convergence speed a modification of the CE approach is proposed. [•] The Bernoulli distribution is used because the locations are discrete variables. [•] The performance of the CE algorithm is compared with GA and sensitivity analysis. [ABSTRACT FROM AUTHOR]

Highlights: [•] The effect of Static Var Compensator (SVC) connected in transmission line on adaptive distance protection is studied. [•] The SVC is connected at three locations in transmission line. [•] Measured impedances by the relay with and without SVC is determined. [•] SVC connected at mid-point affects seriously on the characteristics of relay. [•] Discrete Fourier Transform (DFT) is used to estimate the phasors of the voltage and current at the relaying bus during fault. [ABSTRACT FROM AUTHOR]

• Static var compensator causes a delay in operation of loss of excitation protection. • Delay also depends on the power dispatch and the severity of the loss of excitation. • Static var compensator causes under-reach of commercial loss of excitation relay. • Presence of static var compensator causes a displacement of impedance trajectory. • Positive offset relay adjustment seems to be more adequate than negative adjustment. The static var compensator (SVC) is one of the devices that has been widely used for reactive compensation to improve the capacity and flexibility of power transfer in the electrical power system. However, the SVC changes the voltages and currents of the power network to which it is connected. Consequently, the measured impedance can be changed and affect protection relays operation based on this characteristic. Several papers have been published about the SVC effects on distance protection applied in transmission lines (TL). However, it is not widely known the impact of SVC on the transient behavior of generators, such as protection against loss of excitation (LOE) in synchronous machines connected to TL with SVC. In this sense, based on the modeling of a test electrical power system in the PSCAD/EMTDC simulation environment, the assessment of the effects of SVC on the behavior of the ANSI 40 protection function for the conditions of the total LOE and partial LOE since these events can cause the synchronous machine to operate in conditions above the rated ones. In addition, this paper presents a testbed that allows performing secondary tests in physical relays when simulated signals are applied to perform protection studies in the presence of SVC in power systems. [ABSTRACT FROM AUTHOR]

• Categorization of FACTS devices as HSRF, MSRF, and LSRC devices by response speed. • Mathematical modelling for the coordination of MCR with SVC and FC. • Control strategy to enhance the compensation capacity of high response speed SVC. • Control strategy to enhance the low compensation speed of MCR and FC. • The proposed strategy is suitable for full range of compensation for power system. Traditional devices in flexible AC transmission system (FACTS) like magnetically controllable reactor (MCR), and fixed capacitors (FC) are less expensive and have medium or low response speed that can only provide excessive inductive or capacitive reactive power compensation. However, modern FACTS devices like static var compensators (SVC) are expensive and have high response speed which can provide limited inductive to capacitive reactive power compensation as compared to the MCR and FC. In addition, if there is no proper coordination between these traditional and modern FACTS devices they absorb each other's reactive power and may results in the decrease of compensation margin and wastage of the resources. Therefore, to make an effective use of these categories of FACTS devices in the existing power system, the coordination control that shares high speed and excessive compensation ability without wastage of resources is essential. This paper presents coordinated control of multi-FACTS devices to provide efficient reactive power compensation based voltage regulation. At first, the characteristics of various categorical FACTS devices are presented in relation to response speed by incorporating high speed response FACTS (HSRF), medium speed response FACTS (MSRF) and low speed response compensator (LSRC). Finally, the MCR with SVC and MCR with FC coordination controls have been developed sequentially with minimal efforts of compatibility issues and compensation speed while ensuring an increase in the reactive power reserves for the SVC. The simulation is carried out on PSCAD/EMTDC to test the coordination control efficiency of several three phase multi-FACTS devices with series and parallel configurations and validated on a modified IEEE 30 bus power system. The results show that multi-FACTS coordination control increases the SVC reserves and is promising in providing voltage regulation for the power system under various scenarios. [ABSTRACT FROM AUTHOR]

One of the prominent problems in wind farms is voltage flicker emission. To prevent flicker emission or mitigate the impact as best as possible, a static VAr compensator (SVC) is a great candidate both economically and technically. However, SVCs cannot completely compensate the fast-changing reactive power due to delays caused by the reactive power calculation unit and the triggering fire angle of the SVC. This paper proposes a predictive control system for SVCs, by merging an additional predictive control block into the conventional control system. It is constructed based on deep neural networks, namely adaptive one-dimensional convolutional neural network (1D-CNN). The training process is conducted based on the adaptive learning weights process to enhance the prediction accuracy and training computational complexity of the 1D-CNN. Numerical results on the actual dataset in a wind farm in Manjil, Iran, have verified the forecasting accuracy and flicker mitigation of the proposed controller. [ABSTRACT FROM AUTHOR]

Abstract: Static VAr Compensators (SVCs) can balance the phase currents of three-wire three-phase loads and compensate their reactive power. Thus, the SVC-load set becomes a balanced load with any desired power factor. This paper proposes a method to use SVCs with four-wire three-phase loads which still perform those functions: load balancing and reactive power compensation. As a result, any load connected to a three-(or-four-)wire three-phase system can be transformed into a balanced load with unity power factor, even if it is a single-phase load. Other properties that appear in particular cases are also analyzed. [Copyright &y& Elsevier]

• Yet there are few studies for the extremely short-term forecasting of wind power. • Since the proposed approach is nonlinear, it provides more accurate modelling than the ARMA approach. • The proposed approach only uses the EKF algorithm to update the parameters which makes it suitable for online implantation. • It is robust against noisy easements and probabilistic behavior of the wind speed profile. • A proper model for the wind farm to simulate and evaluate the performance of the SVC based on real data is proposed. The inherent time-varying nature of the wind farm power causes undesired voltage flicker in the power network. In order to mitigate the flicker to enhance the performance of the wind power system with very fast dynamics, the static VAr compensator (SVC) is utilized. However, the SVC operates with some delays which negatively affects its performance. This persuades us to predict the reactive power of the wind farm to compensate for the real-world delay. The predicted reactive power is then utilized in the SVC. Therefore, this paper develops a novel fuzzy one-step-ahead prediction approach for the wind farm reactive power. The proposed fuzzy prediction uses a Takagi-Sugeno (TS) fuzzy representation whose unknown parameters are tuned online based on an extended Kalman filter (EKF). The wind farm is modeled as a time-varying current source which its amplitude and phase change every 0.01 s. A large set of the actual data of a wind farm in Manjil, Iran is gathered and directly utilized in the simulation process. Several flicker indices are calculated to evaluate the proposed prediction method. The obtained results show the performance enhancement and flicker mitigation of the suggested power scheme. [ABSTRACT FROM AUTHOR]

Abstract: New insights into the application of One-Machine Infinite Bus (OMIB) equivalents to the analysis and study of the inter-area mode phenomenon in stressed power systems are provided. First, the notion of a time-varying OMIB equivalent is briefly reviewed and details of the adopted analytical model are introduced. On the basis of this representation, a systematic technique is then proposed to extract the underlying dynamics of the process directly from time-domain transient stability simulations. The analysis tool takes into account both, the dynamics of the slow inter-area oscillations and the dynamics of the fast inter-machine oscillations. Criteria to interpret inter-area oscillations in terms of the kinetic energy transfer between the most disturbed machines, and the rest of the system following the onset of a major contingency are given and methods to implement the proposed approach are discussed. A case study on a 5-area dynamic equivalent model of the Mexican interconnected system in which several static VAR compensators are used to support system voltage is presented to illustrate the developed procedures. Studies are conducted to identify and characterize the energy transfer process that accompanies the inter-area mode separation as well as to evaluate the effect of voltage support on system damping. The results show that time-varying OMIB dynamic equivalents can be used to capture the dominant features of the inter-area mode behavior, which are needed in the analysis and control of system dynamic performance. [Copyright &y& Elsevier]

The power and energy of the ASDEX Upgrade (AUG) tokamak are provided by two separate 10.5 kV, 110–85 Hz networks based on the flywheel generators EZ3–EZ4 in addition to the generator EZ2 dedicated to the toroidal field coil. The 10.5 kV networks supply the thyristor converters allowing fast control of the DC currents in the AUG poloidal field coils. Two methods for improving the load power factor in the present experimental campaign of AUG have been investigated, namely the control of the phase-to-neutral voltage in thyristor converters fitted with neutral thyristors, such as the new 145 MVA modular thyristor converter system (Group 6), and reactive power control achieved by means of static VAr compensators (SVC). The paper shows that reliable compensation up to 90 MVAr was regularly achieved and that electrical transients in SVC modules can be kept at an acceptable level. The paper will discuss the results from the reactive power reduction by SVC and neutral thyristor control and draw a comparative conclusion. [Copyright &y& Elsevier]

• The proposed method based on support vector multi-regressors, is able to capture the non-linear and chaotic dynamic in an electric arc furnace model. • Estimation of the arc furnace model parameters takes into account the harmonics and sub-harmonics of the voltage waveform generated by the electric arc furnace. • The proposed method can be used to evaluate the accuracy of any parametric model of an electric arc furnace. In the iron and steel industry, electric arc furnaces (EAFs) are used in the melting and refining process of metals. They are known to demand large amounts of reactive power and cause significant power quality (PQ) problems due to their highly non-linear time varying voltage-current characteristic. Several EAF models have been proposed with the purpose to predict the voltage and current waveforms, to assess the performance of different compensating devices such as static var compensator, synchronous static compensator, active power filters, and –still under study– energy storage systems, and also for planning the installation of iron and steel facilities considering existing real data from similar facilities. An important aspect of these models is related to the estimation of their parameters. This paper presents a new method to estimate the parameters of an EAF model. The method utilizes a multiple-input multiple-output regressor based on support vector machine, that maps from voltage characteristics of the electric arc to the values of the model parameters. The multidimensional support vector regressor (M-SVR) is designed in the training phase, using data from several simulations of the EAF model. These simulations are carried out adjusting the parameters of the model within the search space, and considering the real arc current as input to the model. Then, in the validation phase, for the real voltage waveform, the estimated parameters are obtained using each regressor of the M-SVR. The proposed method is validated by the comparison between the waveforms obtained using the EAF model with actual data from a steel plant. Results show that the relative error between the fundamental component of the current and voltage, for real and simulated waveforms, are 2.1 % and 6.3 % respectively. [ABSTRACT FROM AUTHOR]

• Basic flicker effect mitigation techniques description. • SVC control system adjusted for industrial applications, especially for industrial system with EAF. • Study and comparison of different signal processing techniques od input SVC controller signals. • Using of field measured data for testing proposed techniques by laboratory scale SVC system. • Evaluation flicker effect for proposed techniques and comparison with results of previous works. The work focuses on the possibilities of improving the Static Var Compensator (SVC) control system for more effective reduction of the flicker effect. The studied SVC control system consists of an open control loop, which provides a fast response to dynamic changes in Electric Arc Furnace (EAF) power, and a closed control loop, which provides precise control to ensure the required value of the power factor in the Point of Common Coupling (PCC). The improvement consists in the use of alternative techniques for signal processing of input control variables. The first alternative technique is the use of Second Order Generalized Integrator (SOGI), which is also used in other related applications. The second alternative technique is to use the flicker weighting function, which corresponds to the function used to measure the flicker effect using a standardized flicker meter. Experimental laboratory equipment and theoretical model in frequency domain was used to verify the properties of the proposed techniques. To simulate the dynamic behavior of EAF, data measured from real operation were used, which were implemented into an experiment using VSC. Analysis of measured data and data obtained from laboratory apparatus shows high similarity. The experiments were carried out in several variants to reflect the differences in the various stages of the production process in the EAF. For all variants, the resulting flicker effect was evaluated and the individual techniques were compared with each other and with the results of other works. [ABSTRACT FROM AUTHOR]

• A new reintegration-driven ICI framework, called R-ICI, is proposed. • The proposed R-ICI model improves frequency stability of islands using ESSs. • Transient voltage stability of islands is improved using ESSs and SVCs. • The interaction between frequency and voltage is considered by a linear IFR model. • An active/reactive charging and discharging scheme is introduced for ESSs. In this paper, a reintegration-based multi-objective intentional controlled islanding (ICI) model is proposed to enhance resiliency of electrical power systems under catastrophic events. This remedial measure plan relies on a mixed-integer linear programming model with two objective functions including reintegration risk and total load shedding value. While ensuring that each island includes only coherent generators, the proposed multi-objective model solves the controlled islanding problem using lexicographic optimization approach. To ease the islands' reintegration, charging reactive power, reliability, capacity, and power flow disruption of transmission lines are considered in the model. After implementation of controlled islanding, each resulted island may face temporary active/reactive load-generation imbalance, which may put the islands at the risk of frequency instability, transient voltage instability or a combination of both. The proposed model reduces these risks by modeling energy storage systems (ESSs) and static VAR compensators (SVCs) as fast corrective control actions. In addition to modeling voltage dependent loads in the controlled islanding problem, a linear island frequency response (IFR) model is proposed for frequency stability assessment. The test results of the proposed ICI model on the IEEE 39-bus and IEEE 118-bus test systems demonstrate its performance. [ABSTRACT FROM AUTHOR]

• Impacts of non-periodic are similar to harmonic current but more difficult to mitigate. • Time-frequency distortion index is most suitable for non-periodic loads. • Hybrid time-frequency method provides temporally distributed current reference. • Temporal distribution of compensation increases efficiency and reduces overall cost. • Fuzzy algorithm based on non-periodic characteristics decreases bandwidth requirements. This paper presents a new technique for the compensation of non-periodic load current. The method provides control references for three co-located devices, each corresponding to one moving calculation window and one decomposed part of the compensated current. They are slow compensator with high power rating, large calculation window, and low switching frequency; fast compensator with lower power rating, shorter calculation window, and higher switching frequency; and the reactive compensator which is an ordinary static VAR compensator (SVC). A fuzzy based adaptive window is proposed for the slow compensator to find the optimum window for different load characteristics. The technique is evaluated using real-world data and controller hardware-in-the-loop (HIL) implementation. [ABSTRACT FROM AUTHOR]