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As the scale of China's interconnected power grid continues to expand, traditional serial computing methods are no longer sufficient for the rapid analysis and computation of electrical networks with tens of thousands of nodes due to their small scale and low efficiency. To enhance the capability of online grid analysis, this paper introduces an accelerating batched power flow calculation method based on a heterogeneous CPU-GPU platform. This method, based on the fast decoupled method, combined with the tremendous parallel computing capability of GPUs with the multi-threaded parallel processing of CPUs, efficiently resolves the exceeding bus type conversion issues in GPU-batched power flow calculation and improves the accuracy of the power flow calculations. Then, a binary-based power flow data exchange format was introduced, which utilizes a single binary file for data exchange. This format significantly minimizes I/O time overhead and reduces file size, further enhancing the method's efficiency. Case studies on real-world power grids demonstrate its high accuracy and reliability. Compared to the traditional single-threaded power flow calculation method, this method dramatically reduces time consumption in batch power flow calculations. It proves the significant advantages of dealing with large-scale power flow calculations. [ABSTRACT FROM AUTHOR]

The stable and efficient regulation of voltage and frequency is a critical issue associated with the functioning of modern power system network having renewable integration. This manuscript focuses on the concurrent regulation of voltage and frequency in a power network comprising multiple generating sources. Herein, along with conventional thermal and diesel plants, renewable generations from different sources have been considered such as wind and solar photovoltaic (PV) resources. Further, in a fresh attempt, the authors have modeled wind and solar PV generation using two different stochastic modeling methods concerning combined voltage and frequency loops in the regulated power system model. Furthermore, the novel Leader Harris Hawks Optimized Model Predictive Controller (MPC‐LHHO) has been applied to concurrently minimize the voltage and frequency deviations in the given power network. To address the intermittent nature of load and renewable generations, various auxiliary frequency controllers, such as the unified power flow controller (UPFC) and electric vehicle (EV) integration with the grid, have been implemented. The robustness of the proposed control method has been successfully validated through diverse scenarios of random loadings. [ABSTRACT FROM AUTHOR]

The hybrid AC/DC grid, based on a significant share of renewable energy sources, is gradually becoming an essential aspect of the modern energy system. The integration of intermittent renewable generators into contemporary energy systems is accompanied by the decommissioning of power plants containing synchronous generators. Consequently, this leads to a reduction in system inertia and an increase in the risk of stability disruption. The abrupt disconnection of the primary generator or power line can result in an unanticipated mismatch between power generation and consumption. This discrepancy can trigger substantial and swiftly evolving alterations in power distribution, angular speed, load flow, and the frequency of generators. The risks of an energy system collapse can be mitigated through automation, enabling rapid adjustments to generation and load capacities, as well as power flows, in the electrical network. This article justifies the utilisation of a power control method for high-voltage power line interconnections. The technology of hydro storage power plants and measurements of voltage phasors are employed. The potential for easing power flow restrictions and realising substantial economic benefits is supported by the results obtained using simplified dynamic model of the Baltic power system and Nord Pool electricity market model. [ABSTRACT FROM AUTHOR]

In the operation and control of power systems, load frequency control (LFC) plays a critical role in ensuring the stability and reliability of interconnected power systems. Modern power systems with significant penetration of highly variable and intermittent renewable sources present new challenges that make traditional control strategies ineffective. To address these new challenges, this paper proposes a novel LFC strategy that employs a cascaded fractional-order proportional integral-fractional-order proportional integral derivative with a derivative filter (FOPI-FOPIDN) as a controller. The parameters of the FOPI-FOPIDN are optimised using a variant of the particle swarm optimization (PSO) in the literature called ADIWACO. The effectiveness and scalability of the proposed strategy are validated by extensive simulations conducted on two- and three-area test systems and performance comparisons with recent LFC control strategies in the literature. The performance metrics used for the evaluation are ITAE values, deviations in the power flows in the tie-lines, and deviations in the frequencies of the control areas with the power systems subjected to diverse load and RES generation disturbances in several experimental scenarios. Governor dead band, communication time delay, and generation rate constraints are considered in one of the scenarios for more realistic evaluation. Again, the controller's robustness to uncertain model parameters is validated by varying the parameters of the three-area test system by ± 50%. The simulation results obtained confirm the controller's robustness and its superiority over the comparison LFC strategies in terms of the above performance metrics. [ABSTRACT FROM AUTHOR]

Maintaining stability in modern power systems is challenging due to complex structures, rising power demand, and load disturbances. The integration of renewable energy sources further threatens stability by causing imbalances between generation and demand. Conventional load frequency stabilization methods fall short in such scenarios. This paper proposes an optimal fractional‐order proportional‐integral‐derivative‐acceleration (FOPIDA) controller, enhanced by a robust adaptive neuro‐fuzzy inference system (ANFIS), to improve load frequency control and reliability in power systems with wind and solar generators. First, the dynamical model of a multi‐area interconnected power system, including a thermal power plant, wind turbine, and solar photovoltaic generators, is developed. A decentralized ANFIS‐FOPIDA controller is then designed for load frequency control objectives. The gains of this controller are optimized using the whale optimization algorithm (WOA), focusing on frequency deviation and tie‐line power exchange. Simulations on a New England IEEE 10‐generator 39‐bus power system demonstrate the approach's effectiveness under various disturbances, including random load‐generation disturbances and nonlinear generation behaviors. Comparisons with other strategies, such as fractional order (FO) beetle swarm optimization algorithm (FOBSOA)‐FOPIDA, WOA‐PIDA, and WOA‐ANFIS‐PIDA, and recent control approaches highlight the superior performance of the WOA‐ANFIS‐FOPIDA method in enhancing power system stability. [ABSTRACT FROM AUTHOR]

As the percentage of renewable energy source within the energy production mix has expanded, it is become gradually difficult to determine the appropriate values for controller gains and model parameters. Controlling system frequency of interconnected power system during sudden load disturbance requires careful consideration of the controller gain values and small signal stability model parameters. This study proposes an innovative methodology for ascertaining controller gain values and model parameters for plug-in electric vehicles (PEVs) in load frequency control (LFC) applications. Proposed method uses the root locus (RL) approach to find the suitable controller gain values and model parameters for PEVs. This paper offers a thorough mathematical description of the proposed RL approach. Routh approximation method is used for reduced-order modelling (ROM), which comprises thermal and PEV systems, to reduce complexity of higher-order system while designing controllers. Fractional-order proportional-integral-derivative controller (FO-PID) is proposed, and its parameters are adjusted using particle swarm optimization (PSO) tool. To validate the efficacy of suggested method, a comprehensive comparison of time response parameters and performance indices (PI) is carefully carried out. Also, the various PEVs state of charge (SOC) levels is investigated, and effects of these levels are studied in LFC with robustness analysis of controller. The proposed method for determining gain value is highly reliable and efficient, outperforming existing methodologies in the literature. [ABSTRACT FROM AUTHOR]

Network frequency is considered to be one of the most crucial parameters that strongly affect the stability and economic achievements of interconnected electric power grids. System frequency usually fluctuates and deviates from the nominal values due to random and continuous load changes over time, affecting the electric equipment to significantly decrease efficiency and increase instability. A Load-Frequency Control (LFC) strategy has been proposed to solve this problem. This study compared several different control strategies, namely Fuzzy Particle Swarm Optimization (Fuzzy-PSO), Proportional Integral Derivative (PID), Fuzzy-PID, Fuzzy-Proportional Integral (PI), PSO-PI, and FPID to investigate the effectiveness of intelligent hybrid LFC controllers. The above controllers were simulated on a three-area interconnected power network with the participation of renewable energy sources. Taking into account different load cases, the Fuzzy-PSO-PID controller obtained frequency deviations in the range of 0.0015 to 0.002 Hz. The settling time was about 10 s to reach zero frequency error in each area. With the above controller quality parameters, the Fuzzy-PSO-PID controller provided better quality than the other controllers. A comparative numerical simulation in MATLAB/Simulink for various load change scenarios revealed the effectiveness of hybrid smart controllers, such as the Fuzzy-PID-PSO, outperforming the traditional ones. [ABSTRACT FROM AUTHOR]

Available transfer capability (ATC) is an important measurement index to evaluate the security margin of interconnected power grids and serve as a reference for the transmission right transaction. In modern power systems, ATC is affected by the transmission network topology, renewable power output uncertainty, and load demand uncertainty. Traditional works usually model the power source-load uncertainty by using robust optimization, interval optimization, or chance-constraint optimization, which cannot fully reflect the probabilistic distribution of the daily source-load uncertainty. This paper proposes an ATC assessment methodology based on the typical stochastic scenarios of renewable output and load demand of multiarea power systems. Furthermore, the conditional generative adversarial network (CGAN) algorithm is adopted to generate and select representative scenario sets based on historical raw data, which can fully reflect the usual operating condition of a system with high renewable energy penetration. The scenario set that is fed into the ATC assessment model can fully characterize the impact of source-load uncertainty on daily ATC. Finally, the proposed method is verified by a modified three-area IEEE 9-bus system and a real-world provincial power system. [ABSTRACT FROM AUTHOR]

Modern power systems are confronted with widespread concern on the frequency stability issue due to the widespread integration of randomly fluctuating renewable resources. To address the above concern, this work introduces a load-frequency-control (LFC) scheme based on a parameter tuning strategy for fractional-order proportional–integral–derivative (FOPID) controller. Firstly, a two-area interconnected power system (IPS) model, including thermal, hydro, solar, wind, and gas power generator and a hydrogen-based energy-storage unit, is established. Then, a FOPID controller is designed for this IPS model, and an improved gradient-based optimizer (IGBO) is developed to adaptively regulate the parameters of the FOPID controllers. Finally, the effectiveness of the offered LFC scheme is tested through load disturbance and renewable energy fluctuations test scenarios and provides a comparison and robustness analysis among different schemes. The test results validated that the offered LFC scheme can effectively suppress the frequency fluctuations of the IPS and has excellent robustness. [ABSTRACT FROM AUTHOR]

The interconnected power system connects the power grids of different regions through transmission lines, achieving power interconnection and resource sharing. However, data is transmitted through open power networks and is more susceptible to network attacks. To improve the stability of interconnected power systems under deception attacks, three scenarios of system security load frequency control were studied. Based on the construction of a dynamic model of load frequency control, an event-triggered strategy was used to reduce the communication frequency between nodes, resulting in a reduction in the amount of network transmission data. A sliding mode controller was constructed to solve the problem of event-triggered sliding mode security load frequency control. Elastic event-triggered sliding mode load frequency control for interconnected power systems under mixed attacks. The simulation results showed that using the load frequency control model triggered by events, the load frequency deviation of the interconnected power system can be stabilized at around 12 seconds, effectively saving the cost of network resources. Under the regulation of the load frequency control model based on sliding mode control, the interconnected power system stabilized in 10 seconds, reducing the load of network transmission. The elastic event-triggered sliding mode load frequency control model can ensure stable transmission of power data under various attacks and has good anti-interference performance. The results of this study have played an important role in achieving the stability of power resource supply. Compared with previous studies on individual power systems, this study solves the attack problem of interconnected power systems and considers the frequency control problem of system security loads under mixed attacks, enabling the system to recover stability faster. [ABSTRACT FROM AUTHOR]

Load flow is an important tool for studying, designing, and analyzing power systems. It allows power system engineers to determine whether the operation and configuration of the power system is safe under varying loading conditions. It is necessary to model and simulate such a system in order to determine the power flow and losses. This research paper focuses on using numerical methods such as Newton Raphson and Gauss Seidel power flow equations for load flow analysis to calculate bus voltage magnitudes, phase angles, real and reactive power of each bus of an IEEE 9-bus test system. Newton Raphson’s computation offers fast, accurate convergence but demands complex implementation, whereas Gauss Siedel is simpler but converges slower with lower accuracy. The analysis was carried out using a MATLAB program. By manipulating variables such as power injections, voltage magnitudes, and phase angles, it solves nonlinear equations iteratively to establish stable operating points which aids in enhancing power system analysis. The line losses for the two methods are compared and the system's total load and generation power are also displayed. The consideration of line losses and assessment of total load generation is crucial for maintaining system efficiency, reliability and preventing voltage instability and equipment damage. The results are also used to generate a directed graph which shows the interconnected nature of the power system, aiding engineers in understanding power flow paths, identifying potential issues, and making informed decisions about system operations. The Newton Raphson method yields the lowest loss, with 4.585MW and 10.789Mvar. In comparison, the Gauss Seidel method achieved 4.809MW and 10.798Mvar. [ABSTRACT FROM AUTHOR]

This article presents frequency regulation of an interconnected three-area power system (Thermal + Wind + Hydro). Fractional Order PID (FOPID) and Proportional-Integral-Derivative (PID) controllers are applied as subsidiary regulators to control the electrical power interconnected system at the time of sudden load variation. To accomplish this study, Genetic Algorithm (GA), Grey Wolf Optimizer (GWO), Sine Cosine Inspired Algorithm (SCIA) and Atom Search Inspired Algorithm (ASIA) are implemented to optimize the secondary regulators' gains (PID and FOPID) by considering various cost functions such as Integral Absolute Error (IAE), Integral Time Absolute Error (ITAE), Integral Square Error (ISE), and Integral Time Square Error (ITSE). Performance analysis in this work is conducted using various cost functions based on GA, GWO, SCIA and ASIA. The comparative analysis of the attained results reveals that GWO-PID and ASIA–PID settle at (83.83 s) and (30.31 s), respectively and ASIA-FOPID at (25.12 s). The controllers based on ITSE as a cost function outperform the comptrollers with other cost functions (ISE, IAE and ITAE). In addition, the ISE-based GA–PID and SCIA–PID settle at (113.92 s) and (35.1 s), respectively and SCIA-FOPID at (24.78 s). The ISE-based regulators yield improved response equated to other cost functions (ITSE, IAE and ITAE) optimized controllers. The robustness test also is carried out to validate the effectiveness of the proposed optimization techniques by changing the system parameters within ± 25% and ± 50% from their nominal values as well as changing the load pattern. [ABSTRACT FROM AUTHOR]

This paper proposes an approach for segmentation of power systems to prevent uncontrolled islanding. With the development of microgrids (MGs) and increased penetration of renewable energy sources (RESs) in the power system, it is necessary to consider the effect of MGs and the stochastic behaviour of RESs in the controlled islanding process. First, the enormous search space for finding the boundary points is reduced by the clustering of the coherent generators and the buses which are placed in sections that cannot be separated from the coherent groups. Then, linear AC power flow is defined as a sub‐problem and solved by linear programming to satisfy the power system and MG constraints. In this step, an optimization model is defined, and a mixed‐integer linear programming (MILP)‐based model is suggested to find cut‐sets and islands arrangement with reduced load shedding. In view of the fact that the fluctuation of RESs may have the significant effects on the power imbalance, to cover the uncertainties a scenario based stochastic simulation is considered. Finally, the effect of uncertainties on cut‐sets and load curtailment is evaluated. The effectiveness of the proposed methodology is demonstrated by the simulation on the test system. [ABSTRACT FROM AUTHOR]

In today's rapidly evolving interconnected electric power system network, ancillary service such as automatic generation control (AGC) plays a critical and important role in safeguarding the system's power supply quality by establishing an equilibrium between generation and load demanded plus losses. A power system with a robust and smart AGC strategy is obligatory for better power quality and system security. Cascade control schemes cope up better with nonlinearity by tuning the gain of controller of power system amid continuous load changing. Therefore, in this article, a supplementary control approach that is, cascade optimal controller‐proportional integral with derivative filter (COC‐PIDN) is suggested for AGC performance advancement of the power systems under deregulated environment. The OC designed consuming full state feedback control approach acts as master controller and PIDN plays the role of slave controller. The nature inspired salp swarm algorithm is employed to adjust the PIDN parameters. Initially, the efficacy of the COC‐PIDN control‐method is explored on a two‐area restructured reheat thermal system and then to validate its excellence and extensibility, the study is protracted to restructured two‐area thermal‐hydro system. Extensive analysis of the findings establishes that the dynamic performance of the COC‐PIDN controller is more valuable than the OC and COC‐PID approaches. The results of COC‐PIDN get further improved in presence of redox flow battery. Finally, the sensitivity analysis as well the acquired results with the COC‐PIDN controller with system nonlinearities demonstrate its robustness. [ABSTRACT FROM AUTHOR]

In an interconnected multi-area deregulated power system, the dynamics of AGC depends on the frequency oscillations and variations in tie line power flow according to the bilateral contracts scheduled between GENCOs and DISCOs. This paper presents an algorithm for solving optimal power flow problem through the application of Differential Evolution. The optimal electric power flow is obtained by using DE method and the performance of the controller is investigated on a three-area interconnected power system consisting of Thermal-Thermal-Thermal unit in one area, Hydro-Thermal unit in the second area, and Thermal-Hydro unit in the third area. Simulation results have shown that the bilateral contracts are implemented in the system. The new Differential Evolution Algorithm (DEA) method is used for designing the concept of Automatic Generation Control (AGC) of hydro-thermal system which is under open market scenario. Open transmission access develops gradually with more socialized companies for generation, transmission and distribution which generally affect the formulation of AGC problem. The simulation results by the use of MATLAB simulink show the effectiveness of DE-PID controller considered and executed appropriately, which improves the performance based on metrics such as frequency and Tie line power deviations. [ABSTRACT FROM AUTHOR]

The increased penetration of wind and solar power, as well as the liberalized electricity market, makes the power system network interconnected and complex. As the power demand is increasing daily, the complexity of operating large power systems is also increasing. Congestion in the transmission network may become more common than previously, making power flow management a problem that becomes increasingly important. Unexpected power flows (also known as loop flows) are becoming a bigger issue in today's linked power networks. These flows have a detrimental impact on the safe functioning of integrated power networks, which hinders their ability to conduct cross-border trade. Phase shifting transformers (PSTs) allow real power flow to be controlled by changing the phase shift across the device. This study deals with two interconnected parallel power system networks and the power flow controlled through a PST in between. The simulation results emphasize the importance of the PST in facilitating the transfer of energy throughout the regional transmission interconnection. [ABSTRACT FROM AUTHOR]

The energy supply entities widely adopt distributed generators (DG) to meet the additional power requirement due to scheduled or unscheduled interruptions. The expansion of transmission and distribution systems via the inclusion of loads and generators and the occurrence of line interruptions are significant causes of congestion of transmission lines in interconnected systems. The management and alleviation of congested lines is a primary requirement for a power system network's reliable and efficient operation. The researchers investigated the potential scope of distributed generation (DG) to alleviate the congested branches in interconnected transmission systems. The development of a reliable scheme to arrive at the best location and size of local generators for alleviating congestion deserves considerable importance. This paper attempted to develop a simple and reliable strategy for the optimum placement and sizing of DGs to be integrated with a transmission line system of DGs for congestion relief in transmission lines by analyzing power flow solutions. This research work considered the 14-bus system of IEEE for the preliminary analysis to identify the parameters employed for assessing the severity of line congestion and the best placement and sizing of DGs for congestion relief. This work analyzed power flows by load flow algorithms using ETAP software in the 14-bus IEEE system for different line outage cases. The analysis of power flow solutions of the 14-bus system of IEEE revealed that the percentage violation of the system can be regarded as an essential parameter to assess the extent of congestion in an interconnected system. A detailed power flow analysis of the system with various capacities of DG integration at several buses in the system revealed the application of two indices, namely the index of severity (SI) and sensitivity factor (SF), for optimum placement with the best capacity of DGs for congestion alleviation in the system. This work proposed a reliable algorithm for the best siting and sizing of DGs for congestion relief by using the identified indices. The proposed methodology is system indices allied load flow-based algorithm. This work produced a fast simulation solution without any mismatch through this developed scheme. The approximations linked with the algorithm were very minute, resulting in comprehensive bests instead of inexact limited bests with less simulation time and more convergence probability and availing the benefits of the mathematical approach. The work investigated the feasibility of the proposed methodology for optimum placing and quantifying DGs for congestion solutions for a practical interconnected bus system in the supply entity of the Kerala grid with many buses. Any transmission system operator can adopt this method in similar connected systems anywhere. The proposed algorithm determined the most severe cases of congestion and the optimum site and size of DGs for managing congested feeders in the grid system. The analysis of the losses in the system for different cases of DG penetration by load flow analysis validated the suitability of the obtained results. [ABSTRACT FROM AUTHOR]

Load-frequency-control (LFC) is employed for frequency stability and balanced power flow among control-areas. Inverters are becoming critical assets in modern power networks with increasing renewable energy. As these inverter-based resources prevail, the system inertia decreases, leading to potential frequency instability problems. Grid-forming (GFM) inverter development and applications are gaining significant attraction because of their ability to maintain quality power-grid operations. GFM inverter, acting as a voltage-source-converter, adjusts its output frequency by contributing a portion of the load change to reduce the frequency deviations. The virtual synchronous generator (VSG) control mechanism for GFM is implemented in this work. A two-area interconnected power system model emulating an enhanced IEEE 9-Bus system is developed and simulated in MATLAB-Simulink® for analysis. Secondary controllers are applied in each LFC and GFM-loop of the proposed LFC-GFM system with a magnetotactic-bacteria-optimization (MBO) algorithm for simultaneously tuning these parameters. The proposed control strategy's effectiveness is verified by comparing simulation results with the basic LFC system under varying inverter penetration levels. The simulated dynamic responses verify the efficacy of the controlled penetration of the GFM inverter in the proposed LFC-GFM system with enhanced damping characteristics, improving small-signal stability and reducing settling time by 43.46% and frequency deviation by 55.5%. [ABSTRACT FROM AUTHOR]

The performance and transient stabilizing using a unified power flow controller (UPFC) anticipated for a grid consisting of parallel connected two number of three-phase transmission lines is presented in this paper. The interruption that happened in absence of UPFC connected to three phase line increases the impedance of the transmission line and consequently reduces the flow of active power. The volume of active power flowing through the grid can be controlled by installing UPFC on the grid. The conditions for transient stability are suggested by the transient model and UPFC interconnected power grid. The complete dynamic control is modeled by the active and reactive power waves developed during transient events. A series of simulations are presented in this paper to show the effectiveness and correctness of the methodology applied for transient stability. [ABSTRACT FROM AUTHOR]

Oscillations are an intrinsic phenomenon in interconnected power systems, leading to steady-state stability, safety decline, transmission power limitation, and electric power systems' ineffective exploitation by developing power systems, particularly by connecting these systems to low-load lines. In addition, they affect the economic performance of the systems. In this study, PSS2B power system stabilizers and TCSC compensators are used to improve the stability margin of power systems. In order to coordinate TCSC compensators, the MOPSO multiobjective algorithm with integral of the time-weighted absolute error (ITAE) and figure of demerit (FD) objective functions was used. The MOPSO algorithm optimization results are compared with nondominated sorting genetic algorithm (NSGAII) and multiobjective differential evolution (MODE) algorithms. The optimization results indicated a better performance of the proposed MOPSO algorithm than NSGAII and MODE. The simulations were iterated in two scenarios by creating different loading conditions in generators. The results indicated that the proposed control system, where the coordination between PSS2B power system stabilizers and TCSC compensators using the MOPSO algorithm, is better than power systems in which PSS2B Stabilizers or TCSC compensators are utilized solely. All criteria, e.g., ITAE, FD, maximum deviation range, and the required time for power oscillation damping in hybrid control systems, have been obtained. This means more stability and accurate and proper performance. [ABSTRACT FROM AUTHOR]

In this paper, Levy flight and Fitness Distance Balance (FDB)-based coyote optimization algorithm (LRFDBCOA) is proposed to improve the performance of automatic generation control (AGC) of three different PV-based interconnected power systems. First, the achievement of the proposed algorithm is evaluated on the two-area PV-reheat thermal power system with PI controller, which is widely used in the literature, and the results are compared with the results obtained using genetic algorithm (GA), firefly algorithm (FA), and modified whale optimization algorithm (M-WOA) introduced in previous studies. Then, the control performance of the proposed algorithm is demonstrated on the newly constructed two-area PV-non-reheat thermal power system with governor dead band (GDB) and two-area PV-multi-source power system with electrolyser and fuel cell. As the costs of solar energy systems decrease, the microgrids containing these resources increase. Therefore, such a study will make an important contribution to the literature. For the AGC of these two systems, proportional–integral–derivative (PID), tilt-integral-derivative (TID) and fractional order PID (FOPID) controllers are used. Thus, both the performance of the proposed algorithm on AGC and the compatibility of the two newly tested systems with PID, TID and FOPID controllers are revealed. As a result, the proposed LRFDBCOA algorithm outperforms algorithms such as GA, FA, M-WOA and arithmetic optimization algorithm (AOA) in interconnected two-area power systems controlled by PID, TID and FOPID, and it shows superior control performance in terms of settling time, maximum/minimum peak value of Δ f 1 , Δ f 2 and Δ P tie under varying load conditions and perturbed system parameters. [ABSTRACT FROM AUTHOR]

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Most cascading failure analysis methods successfully capture cascading developments within one control zone, or region comprised of multiple control zones, controlled by a single transmission system operator (TSO). They neglect, however, the operations of multi-zonal systems. To bridge this gap, the authors introduce the multi-zonal method for cascading failure analyses of large interconnected power systems. The method accounts for all control zones in amulti-zonal system, assesses their power flows, re-evaluates the system topology after disturbances and applies frequency balancing measures in each control zone independently, thus effectively simulating the actions of multiple TSOs. To demonstrate the capabilities of this method, a case study is investigated which compares the security benefits of the multi-zonal (national) versus the single-zone (regional) frequency balancing methods in a multi-zonal system. The application to the IEEE 118-bus test system shows that the regional approach increases the security of this system in small and medium cascades, whose expected demand not served is reduced by 28% and 26%, respectively, in comparison to the national approach. However, the expected load shedding for large-scale cascading events in the regional approach is 42 times as large as in the national approach. This is mainly caused by overloads occurring in transmission lines adjacent to the cross-zonal tie lines, which are 154% higher with the regional method compared to the national in large cascading events. The capability to identify congestions is presented by devising an upgrading strategy, which makes the regional frequency balancing approach viable from a security aspect. [ABSTRACT FROM AUTHOR]

The uncertainty of wind power poses a serious challenge in peak regulation for multi-area interconnected power system, and this paper proposes a method for quantitatively assessing the peaking resource demand of a multi-area interconnected power system, which takes into account the complementary characteristics of inter-area regulating resources and the wind power forecast error. First, wind power historical data are analysed with a data-driven model-based wind power forecast error, to reduce the impact of renewable energy uncertainty on power system peaking demand. Subsequently, a multi-area peaking demand analysis method considering power flow constraints, which is proposed for the effective utilization of peaking resources in areas with complementary characteristics. The method can adequately quantify the area power margin, adjustable power, and area grid peaking demand. On this basis, a two-layer assessment model of multi-area peaking resource demand is constructed, the areas are divided into different categories of peaking aggregation based on the area peaking characteristics. The upper layer takes the area operating cost as the optimisation objective, to derive the optimal output of each area in the system, and the lower layer ensures the optimal matching of power among clusters, which is solved by using a Nash equilibrium. Finally, the effectiveness and superiority of the method is verified by case analysis, and the numerical results show that compared with the traditional global optimal method, the cost of operation and transmission has been decreased by 21.5% and the security of power flows has been significantly enhanced. • proposes a methodology for assessing peaking resources that incorporates a two-tier optimization structure. • propose a methodology for assessing the peaking demand of a multi-regional interconnected system, on the basis of analysing the characteristics of regional peaking. • propose a method to consider the uncertainty of new energy and the constraint of power flowt simultaneously. • propose an analysis method for the power system's demand for peak shaving resources under different power flow constraint margins. [ABSTRACT FROM AUTHOR]

In terms of power generation, Automatic Generation Control (AGC) has taken care of the interchange power flow deviations in order to sufficiently alleviate both the frequency and tie-line power deviations as a perturbation occurs in the interconnected multi-area power system. To provide a high-quality electrical power, a robust and intelligent controller can effectively augment the operational function of the AGC system. The wide-ranging bandwidth, flexible memory and uniform phase contribution in the Fractional Order Proportional Integral Derivative (FOPID) frequency response have been utilized to enhance the dynamic performance of control system against the various power system uncertainties. Since type-2 Fuzzy Logic Controller can significantly overcome the drawbacks of type-1 FLC, it has been satisfactorily combined with FOPID to more abate the low- frequency oscillations. The so-called T2FLC-FOPID has been thoroughly evaluated in two distinct multi-machine power systems under different perturbations. The dynamic stability strategy is formulated as a nonlinear constrained multi-objective optimization problem. As a result, T2FLC-FOPID parameters have been optimally extracted using Non-Dominated Sorting Genetic Algorithm-II (NSGA-II). The dynamic performance of T2FLC-FOPID has been more validated when it has been compared with the conventional PID, FLC and T1FLC-FOPID. [ABSTRACT FROM AUTHOR]

Recently the raise in interconnection of the power system leads to vigorous change of power flow, as well as load in tie‐line. Hence, there is a need of robust control in both tie‐line power flows and systems frequency. This research work aims to design a dual‐mode switch controller‐based load frequency control in multi‐area interconnected power system (MAIPS). In this, the incremental control action's influence is taken along with the constraints of the system dynamic such as Governor with Dead Band, Capacitive Energy Storage, and Generation Rate Constraint. This work on the proposed controller of the multisource‐MAIPS (MS‐MAIPS) is operated on the basis of dual mode switching function. For this purpose, a threshold value ξ$$ \xi $$ is evolved. The control on MPC and optimized hysteresis modulation based sliding mode control (HMSMC) is varied according to this switching function. For attaining the fascinating performance, the optimal tuning of switch threshold ξ$$ \xi $$ and the gain of HMSMC controller K$$ K $$ is exploited by a new Self‐Adaptive Sea Lion algorithm. To the end, variation of control parameters like Tr$$ {T}^r $$,Trb$$ {T}^{rb} $$, Cg$$ {C}^g $$, as well as TCD$$ {T}^{CD} $$ for reducing unwanted variances in power flows among control areas is used to verify the effectiveness of the implemented scheme. [ABSTRACT FROM AUTHOR]

This study examined the design of a Load Frequency Control (LFC) component in a four-area interconnected power system. LFC maintains the frequency of a power system within a prescribed limit. Various controllers for the LFC of a power system have been proposed. The PID controller is a classical approach to LFC. A PID controller that uses a filter in the derivative part amplifies and smooths out the high-frequency noise. The selection of the appropriate optimization method to tune controller gains plays a vital role for LFC. In this work, the PID controller was optimized using the Particle Swarm Optimization (PSO) and the JAYA optimization methods and was simulated in Matlab-Simulink. After studying and comparing the results, it was concluded that the PID controller using the JAYA algorithm provided better LFC in terms of system settling time, overshoot, undershoot, and performance index compared to other optimization methods. [ABSTRACT FROM AUTHOR]

Modern era power systems may include not only traditional primary energy sources like hydro or thermal energy, but also a variety of Renewable Energy (RE) sources such as solar and/or wind power. This leads to the complexity of the electrical networks related to their design and construction as well as system stability and control issues. Considered to be one of the most crucial control issues, Load Frequency Control (LFC), must be continuously improved in order to ensure the control goals. For an interconnected power system, the control purposes are to maintain the net frequency at nominal value, e.g. 50 or 60Hz as well as to ensure that tie-line power flows are stable at scheduled values. This work proposes a novel LFC strategy applying Particle Swarm Optimization (PSO) ~ PID -- like fuzzy logic--based controllers. PSO is one of the most effective optimization techniques. It is used to optimally determine four scaling factors for each LFC proposed in this study. A three-area power network consisting of a hydraulic station, a non-reheat plant, and a reheat unit along with RE sources such as wind and solar power are taken into consideration. The control performance of the proposed control strategy is compared to those of existing controllers, i.e. Genetic Algorithm (GA), Bacteria Foraging Optimization Algorithm (BFOA), Fractional Order-PID (FPID), and fuzzy logic-based PI controllers for the same interconnected power grid model with various case studies of load changes along with nonlinearities and different RE source conditions. Simulation results implemented in MATLAB/Simulink demonstrate the feasibility and applicability of the proposed control strategy. [ABSTRACT FROM AUTHOR]

Frequency control of an interconnected power system in the presence of wind integration is complex since wind speed/power variations also affect system frequency in addition to load perturbations. Therefore, improving existing control schemes is necessary to maintain a stable frequency in such complex power system scenarios. In this paper, a new 2-degree of freedom combined proportional-integral and derivative control scheme is applied to a wind integrated interconnected power system. In designing the controller, several inputs used for a secondary frequency control loop are considered along with the merits of the existing controllers. The combined controller provides better control action than existing controllers in the presence of wind as is evidenced by the wide variety of results presented. For tuning of the controller gains, a crow search optimization algorithm (CRSOA) is used. Results are obtained via the MATLAB/Simulink software. [ABSTRACT FROM AUTHOR]

This paper proposes a new hybridised approach comprising the flower pollination algorithm and pathfinder algorithm (FPAPFA), in order to address optimisation problems and for load frequency control system. Although the FPA is a popular algorithm that has been widely used in diverse applications, its implementation is met with the tendency to be trapped in local optimal due to an imbalance between the exploration and exploitation process. Consequently, the FPA’s exploration functionality can be enhanced by using the PFA features to shift certain pollens to moderately enhanced locations rather than leading them to random positions. Furthermore, a modified fluctuation rate is incorporated into the PFA to reinforce the exploitative competence of the FPAPFA. Compared to other popular techniques, the proposed algorithm’s performance was evaluated against 23 standard mathematical optimisation functions and statistically tested using the Wilcoxon rank-sum and Friedman rank tests. Moreover, the FPAPFA is applied to regulate two unequal multiarea interconnected power systems with different generating units (thermal, hydro, diesel, and wind power plants) while also integrating redox flow batteries (RFBs) and interline power flow controller (IPFC). Simulation results show that the proposed FPAPFA delivered better results than other algorithms with improved convergence speed, stability, and robustness. [ABSTRACT FROM AUTHOR]

This article is concerned with modelling, controllability analysis and the design of aggressive robust controllers for interconnected electric power systems. The proposed Load Frequency Control (LFC), relying on H ∞ methodologies enhanced with integral action and pole clustering, can provide frequency regulation and fast transient response despite the presence of unknown disturbance load application. The inherent saturation constraints are handled by the combination of a controller gain minimisation framework and an anti-windup enhanced controller design which provides stability guarantees, while avoiding frequency and tie-line power oscillations. For this scheme, particular attention should be paid on the modelling and controllability aspects of the power system, where it is shown that due to the singularity of the Laplacian matrix of the network's graph, a reduction of the state vector is necessary. Simulation studies are offered to illustrate the effectiveness of the suggested scheme. [ABSTRACT FROM AUTHOR]

In this paper, an objective function considering performance index and an improved gravitational search algorithm (IGSA) are proposed to optimize the parameters of fuzzy PID (FPID) controller. IGSA is obtained by combining elite strategies and the mining capability of PSO algorithm. The IGSA FPID method which integrates IGSA and FPID controller is tested in a typical two-area non-reheat system, and system responses reflect the advantages of proposed objective function and IGSA. Additionally, the proposed IGSA FPID method still has excellent effects even on the two-area multi-source system with thermal power, hydropower and gas turbines. Meanwhile, the effect of high voltage direct current (HVDC) links in suppressing fluctuations is verified. Due to the popularity of wind power, a novel three-area interconnected power system with nonlinearity connected wind turbine (WT) is designed. Under the control of IGSA FPID, the good stability and dynamic performance of mentioned three-area system are verified. Therefore, FPID controller optimized by IGSA has excellent control effects, stability and universal applicability on the different power systems with multiple area and sources. [ABSTRACT FROM AUTHOR]

The increasing demand for electricity and global attention to the environment has led energy planners and developers to explore developing control techniques for energy stability. The primary objective function of this research in an interconnected electrical power system to increase the stability of the system with the proposed RRVR technique is evaluated in terms of the different constraints like THD (%), steady-state error (%), settling time (s), overshoot (%), efficiency (%) and to maintain the frequency at a predetermined value, and controlling the change of the power flow of control between the areas renewable energy generation (solar, wind, and fuel cell with battery management system) based intelligent grid system. To provide high-quality, reliable and stable electrical power, the designed controller should perform satisfactorily, that is, suppress the deviation of the load frequency. The performance of linear controllers on non-linear power systems has not yet been found to be effective in overcoming this problem. In this work, a fractional high-order differential feedback controller (FHODFC) is proposed for the LFC problems in a multi-area power system. The gains of FHODFC are best adjusted by resilience random variance reduction technique (RRVR) designed to minimize the overall weighted absolute error performance exponential time. Therefore, the controller circuit automatically adjusts the duty cycle value to obtain a desired constant output voltage value, despite all the grid system's source voltage and load output changes. The proposed interconnected multi-generation energy generation topology is established in MATLAB 2017b software. [ABSTRACT FROM AUTHOR]

Summary: This paper studies the distributed load frequency control problems for the multi‐area interconnected power system in smart grid. Compared with current results, we develop a new model transformation for traditional interconnected systems with unknown communication time delays and uncertainties. The load frequency control problem becomes the state synchronization problem of multi‐agent system (MAS) consisting of linear double‐integrator system with uncertainties and delays. Then, the H∞ distributed controller is designed based on the new MAS model, which weakens the impact of communication delays, parametric uncertainties, and load disturbance. Meanwhile, the proposed distributed controller only needs its neighbors' information and some rough information about the communication network to achieve the frequency's synchronization. In addition, the power flow in the power system can achieve the power scheduling and peak regulation with the changes of each area's load, which can cause unacceptable frequency deviation. The switching topologies are used to express this new power flow distribution. The corresponding distributed controllers are designed to achieve the frequency's synchronization. Finally, simulation result shows the effectiveness of the proposed methods. [ABSTRACT FROM AUTHOR]

This study investigates the observer-based sliding mode load frequency control for multiarea interconnected power systems under deception attack. By introducing the observer and combining it with the system state equation, the expression of the system error is obtained. A sliding mode surface is proposed to make sure the state of the systems to be stable. Then, the state equation of the system under sliding mode control is derived. The asymptotic stability of the whole system is proved by using the linear matrix inequality (LMI) technique and Lyapunov stability theory. Furthermore, a sliding mode control law is proposed to ensure that the attacked power system can reach a stable position. Numerical simulation results are presented to support the correctness of the results. [ABSTRACT FROM AUTHOR]

The energy storage devices and renewable energy integration have great impacts on modern power system. The optimal site selection and network expansion under several uncertainties, however, are the challenging tasks in modern interconnected power system. This paper proposes a robust optimal planning strategy to find the location and the size of the energy storage system (ESS) among the power network buses and transmission lines expansion to accommodate the wind power energy integration to serve the future demand growth under uncertainties. The proposed methodology provides the optimal location concerning the required size of ESS at each bus, along with the optimal selections to reinforce existing lines or recommending new ones in a single solving stage. The co-optimization problem is formulated as a mixed-integer linear programming problem, in which the power balance constraint is developed as an optimal power flow. The stochastic optimization problem is solved robustly using the chance-constrained method. Furthermore, the load shedding and wind curtailment are taken into account in the cost function. The methodology is tested in the IEEE RTS-96 system. The simulation results demonstrate the effectiveness of the proposed strategy to find optimal size and location of ESS. The optimal candidates and transfer capacity for the tie-lines expansion planning are also determined. The results are found using different confidence levels to assess the optimality when the confidence level changes. The primary generation adequacy indices are evaluated to highlight the effectiveness of the proposed methodology. The optimally sized batteries allocated in the optimally selected locations around the system enhance the system's performance economically and reliably. [ABSTRACT FROM AUTHOR]

In high power applications, 3-phase ac/dc Voltage Source Converters (VSCs) are paralleled to increase the overall aggregated converter power rating, effective switching frequency and control bandwidth. For this, interleaved Pulse Width Modulation (PWM) and current limiting paralleling inductors are required. Interphase Transformers (ITRs) are often used for the converter paralleling because they provide large magnetizing inductances for the currents flowing between the converters while introducing negligible leakage inductances for the currents flowing from the converters to the ac grid. This large asymmetry in the inductance values makes it difficult to independently control active power flows in the individual converters. Thus, if the converters dc buses are not mutually interconnected, instabilities in active control of balance of converter dc bus voltages can occur in certain operational conditions. This paper presents a theoretical analysis of the active power flows produced by the currents flowing among the converters and explains origins of potential instability in the active control of balance of dc bus voltages in multi-converter systems with floating dc buses, paralleled using the ITRs. [ABSTRACT FROM AUTHOR]

This study focuses on designing an effective intelligent control method to stabilize the net frequency against load variations in multi-control-area interconnected power systems. Conventional controllers (e.g. Integral, PI, and PID) achieve only poor control performance with high overshoots and long settling times. They could be replaced with intelligent regulators that can update controller parameters for better control quality. The control strategy is based on fuzzy logic, which is one of the most effective intelligent strategies and can be a perfect substitute for such conventional controllers when dealing with network frequency stability problems. This paper proposes a kind of fuzzy logic controller based on the PID principle with a 49-rule set suitable to completely solve the problem of load frequency control in a two-area thermal power system. Such a novel PIDlike fuzzy logic controller with modified scaling factors can be applied in various practical scenarios of an interconnected power system, namely varying load change conditions, changing system parameters in the range of ±50%, and considering Governor Dead-Band (GDB) along with Generation Rate Constraint (GRC) nonlinearities and time delay. Through the simulation results implemented in Matlab/Simulink software, this study demonstrates the effectiveness and feasibility of the proposed fuzzy logic controller over several counterparts in dealing with the load-frequency control of a practical interconnected power system considering the aforesaid conditions. [ABSTRACT FROM AUTHOR]

This paper proposes a novel nonlinear decentralized control method for a class of multi‐machine power systems. The aim is to construct a suitable decentralized feedback control law so as to guarantee that the large‐scale interconnected power system is exponentially stable and robust against load fluctuations. To this end, we propose a novel design algorithm based on the backstepping, which involves five steps and actively utilizes the locally measurable part of the tie‐line power to improve the performance. The effectiveness of the proposed control scheme is demonstrated through extensive simulation studies. [ABSTRACT FROM AUTHOR]

This article proposes a non-fragile control model approach for the design of an event-triggered control (ETC) for frequency and tie-line power regulation in a networked power system with communication delays. The proposed non-fragile control approach can tolerate controller parameter variations without any degradation in the system performance. The event condition is designed based on the relationship between the ETC and the non-fragile system. The effectiveness of the proposed design is validated with three-area interconnected power systems under load disturbances. The superiority of the proposed work is shown by comparative analysis with recently reported works. Furthermore, system robustness is validated with random step load disturbance, matched uncertainty, power system nonlinearities, communication link noise, integration of renewable energy resources, and with the IEEE 39 bus system. The closed-loop system stability is theoretically proved using the Lyapunov candidate function and verified by simulations. [ABSTRACT FROM AUTHOR]

Voltage stability issues are most common in severely loaded systems. Today's demand for electricity is enormous, putting the vast interconnected network of power systems under stress. This problem may be solved by boosting generation or lowering transmission losses. The voltage magnitude changes over the permitted voltage stability limit when the load rises unexpectedly. However, for the system to function properly, the voltage magnitude must be kept within the limits. As a result, by providing enough reactive power adjustment, voltage stability may be enhanced. The aim of this paper is to maximize the loading capacity of load buses and simultaneously maintain its voltage stability. STATCOM, a FACTS device is the tool selected for achieving these objectives. This paper explains the analysis carried out to understand the impact of STATCOM on load limit and voltage stability. The required simulations were performed using IEEE 14-Bus Test System. The simulation results are subjected to a power flow continuation procedure, during which critical points for voltage stability and maximum load are determined. [ABSTRACT FROM AUTHOR]

Load Frequency Control (LFC) plays an essential role in interconnected power systems for maintaining power system frequency by regulating power generation to match load demand. However, nonlinearities and external disturbances pose significant challenges for LFC of interconnected power systems. In this paper, a robust deep Koopman model predictive control (MPC) method is introduced for effective LFC of a nonlinear interconnected power system. The method uses Koopman operator to obtain a linearized system model and introduces a deep neural network (DNN) to approximate this operator. By applying the Koopman operator to acquire the linearized system model, a linear MPC controller can be used for LFC of the nonlinear interconnected power system. Furthermore, a feedback controller is proposed to incorporate with the MPC controller to mitigate approximation errors and external disturbances, thereby enhancing the robustness and control performance of the controller. The robustness and stability of the proposed controller are studied using a Lyapunov-based technique, and the advantages and effectiveness of our approach in addressing the challenges of LFC in interconnected power systems are demonstrated through simulations. • A robust deep Koopman MPC method is used for LFC in nonlinear interconnected power systems to ensure stable system frequency. • A DNN is implemented to approximate the infinite-dimensional Koopman operator for controller design. • A feedback controller is incorporated to mitigate the approximation errors and external disturbances. • A rigorous analysis of the controller's stability using Lyapunov-based techniques. • Simulation results demonstrate the effectiveness of the controller for LFC in interconnected power systems. [ABSTRACT FROM AUTHOR]

Integrated Multiple-Energy Carrier (MEC) systems with electricity and natural gas infrastructure systems offer distinctive opportunities to enhance the efficiency and the flexibility of energy supply. Efficient operation of these interdependent infrastructure systems faces several challenges corresponding to the risk associated with the uncertainty in the environmental parameters. In this paper, a risk-based framework for energy management of interconnected energy hubs in MEC systems is proposed to minimize the expected system operation cost. The conditional value at risk (CVaR) method is used to quantify the risk associated with uncertainties in the electrical and thermal loads, and the real-time price of electricity. The probability distribution function of the uncertain parameters and auto regressive integrated moving average (ARIMA) models are used to generate scenarios to represent the uncertainty in the system parameters. The proposed model is formulated as a mixed integer linear programming (MILP) problem and solved using CPLEX solver. The developed case studies show the risk-averse and risk-taker operator strategies to demonstrate the merits of the proposed risk-based scheduling over the risk-neutral operation scheme. It is further investigated that how the expected operation cost depends on the risk measures in the risk-averse operation. Also, sensitivity analyses are conducted to assess the energy procurement scheduling based on the proposed approach. Furthermore, the effect of risk parameter on managing the congestion in electricity and natural gas networks is examined. [ABSTRACT FROM AUTHOR]

The low inertia of electrical power networks as renewable energy penetration levels increase is regarded as a significant issue confronting worldwide ambitions for the anticipated renewable energy transition. Load frequency control (LFC) is an efficient way of improving the frequency stability and dependability of renewable energy-based power networks. Therefore, this paper introduces a novel three-degree-of-freedom (3 DoF) load frequency control method for two-area-linked power systems. To implement the suggested LFC approach, the proposed control employs an enhanced hybrid fractional order control method (namely FOTPID), and the tilt integrator differentiator with filter (TIDF) is employed in the frequency deviation and tie-line power loop feedforward compensation. As a consequence, this study proposes a novel 3DoF cascaded FOTPID-TIDF controller. Furthermore, this work proposes a modified method of the recently developed Manta-Ray Foraging Optimizer (MRFO) to optimize the parameters of the new suggested 3DoF cascaded FOTPID-TIDF controller. The paper includes extensive performance comparisons and discussions to validate the superior performance metrics of the new proposed control and optimization methods. The results reveal that by taking into account the characteristics and uncertainties of renewable sources, interconnected loads, and grid inertia, the results perfectly mitigate various existing deviations in frequency and tie-line power compared to existing contemporary LFC approaches. [ABSTRACT FROM AUTHOR]

In this paper a methodology is proposed for assessing the required running capacity in weakly interconnected insular power systems. This information is of crucial importance for system operators, when deciding the operation policy of the interconnected power system. In the proposed methodology, a probabilistic analysis is initially employed to identify probable extreme stress conditions of the local oil-fired units of the insular power system and the interconnector. Then, based on the unit commitment guidelines and the technical limitations of the interconnector, a power flow analysis is proposed to be followed. Hence, useful insights can be obtained for the system operators, regarding the required running capacity and the interconnection operation. To validate the proposed methodology's efficacy, the case of the interconnection of Crete with the Hellenic Transmission System is considered. The presented case study follows the recently proposed guidelines for unit commitment in the power system of Crete following to the interconnection, while considering the extreme scenarios derived from the probabilistic analysis. The existing oil-fired units that will be required to remain available for dispatching after the operation of the AC interconnector are identified, while the interconnection operation is characterized. • The required running capacity in weakly interconnected insular power systems is investigated. • A new methodology is proposed to assess the requirements of such systems based on extreme stress scenarios. • The Crete interconnection is utilized as the case study validating the proposed approach. [ABSTRACT FROM AUTHOR]

For the load frequency control (LFC) of the interconnected power system, a two-level coordinated control frame based on multi-agent system is proposed to improve the frequency control performance of the power system. In the control frame, the upper-level agent, in a centralized manner, coordinates the lower-level LFC agents to deal with the conflict between narrowing the area control error and stabilizing the system frequency. The lower-level LFC agents, in the distributed cooperative manner, realize the mutual power support among the neighboring areas to guarantee the frequency stability in an emergency. To verify the validity of the proposed method, the numerical simulations are performed on the three-area interconnected power systems. [ABSTRACT FROM AUTHOR]

Smart grid planning and control is becoming a theme of high interest in the last years. This is due to the presence of distributed generation, power from renewable resources and storage systems, to the different actors present over the territory, and to the difficulty of defining appropriate models for decision support. A bilevel optimal control scheme is proposed for grids characterized by renewable and traditional power production, bidirectional power flows, dynamic storage systems, and stochastic modeling issues. In this scheme, the upper level decision maker (UDM) views the lower level decision makers (LDMs) or microgrids as single nodes. In the statement of the UDM problem, the LDM control strategies are structurally and parametrically constrained inside a nonlinear optimization problem that includes load flow equations. Then, the LDMs can follow references from the UDM and use available information at the local level to solve a stochastic optimization problem. The proposed control architecture has been applied to a specific case study (Savona, Italy). [ABSTRACT FROM AUTHOR]

This paper presents the effect on application of biogeography optimization (BBODMFOPI) based dual mode gain scheduling of fractional order proportional integral controllers for load frequency control (LFC) of a multi source multi area interconnected power systems. This controller has three parameters to be tuned. Thus, it provided one more degree of freedom in comparison with the conventional proportional integral (PI) controller. For proper tuning of the controller parameters, Biogeography-Based Optimization (BBO) was applied. BBO is a novel evolutionary algorithm which involves the methodology of making the system effectively by using mathematical techniques. The dual mode concept is also incorporated in this work, because it can improve the system performance. In this work, simulation investigations were taken out on a two-area power system with different generating units. The simulation results show that the proposed biogeography optimization based dual mode gain scheduling of fractional order PI controllers, provide better transient as well as steady state response. It is also found that the proposed controller is less sensitive to the changes in system parameters and robust under different operating condition of the power systems. [ABSTRACT FROM AUTHOR]