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The 2022 energy crisis highlighted the dependence of the Europe electricity sector on imported natural gas and the need to accelerate the adoption of renewables to the power system. However, operating a reliable power system with high share of renewables might require curtailing some renewables and activating conventional generators not scheduled in the day-ahead markets to ensure system reliability. These actions can result in environmental impacts, higher system costs and welfare impacts for customers. We use a novel high-granularity data from the Spanish power system for the period 2019–2022 to estimate the effects of these actions and forecast future impact of implementing ambitious targets of the European Gas Reduction Plan. We show that reliance on conventional generators will sharply increase with the addition of renewables. However, higher electricity consumption reduces the negative welfare impacts of integrating renewables. Until renewables and storage technologies advance further, conventional generators are needed for reliable operation of the systems. [ABSTRACT FROM AUTHOR]

A polarity identification is very important for operation of transformers, measurement and protection equipment, where it is useful in analyzing of transformer connections and operation as well as testing of protective systems. Moreover, it's essential in assessment of power systems performance during both normal and abnormal operation. Ensuring the correct polarity of the primary and secondary windings in voltage and current transformers is of paramount importance for various measurement and protection schemes in power networks. This paper proposes a digital polarity detector and tester using correlation coefficients and nine polarity indices calculated for instrument transformer signals. In order to test the performance of the proposed polarity tester algorithm, MATLAB code is imported to the LABVIEW model, and the numerical data obtained from the synchronous generator terminals via instrument transformers are interfaced with the computer through the Data Acquisition Card (DAC). The experimental system consists of a motor-generator set supplying a three-phase inductive load with instrument transformers connected to measure each phase voltage and current. The obtained results for various operating conditions and different types of abnormal conditions prove that the suggested algorithm is accurate, reliable and applicable to smart grids and substation automation systems. It can be considered as an integrated system incorporated with digital fault recorders, relays and meters. [ABSTRACT FROM AUTHOR]

A power system is a complex, nonlinear, and dynamic system, with operating parameters that change over time. Because of the complexity of big load lines and faults, high-voltage transmission power systems are usually vulnerable to transient instability concerns, resulting in power losses and increased voltage variation. This issue has the potential to cause catastrophic events such as cascade failure or widespread blackouts. This problem affects Ethiopia's high-voltage transmission power grid in the northwest area. Because of the increased demand for electrical energy, transmission lines' maximum carrying capacity should be enhanced to maintain a secure and uninterrupted power supply to consumers. To address the problem, ANFIS-based UPFC is used for high-voltage transmission lines. This device was chosen as the ideal alternative due to its capacity to rapidly correct reactive power on high-voltage transmission networks. The PSO algorithm was used to determine the best location for the UPFC. The ANFIS controller receives voltage error and rate of change of voltage error as inputs. Seventy percentage of the retrieved data are used for ANFIS training and 30% for ANFIS testing. To show the performance of the proposed controller, three-phase ground faults are used from a severity perspective. When a three-phase ground fault occurs at the midpoint of the Beles to Bahir Dar transmission line, for instance, the settling time of rotor angle deviation, rotor speed, rotor speed deviation, and output active power of synchronous generators using ANFIS-based UPFC is reduced by 70.58%, 37.75%, 37.75%, and 43.75%, respectively, compared to a system without UPFC. At peak load, PI-based UPFC and ANFIS-based UPFC reduce active power loss by 51.25% and 71.50%, respectively, compared to a system without UPFC on the Beles to Bahir Dar transmission line. In terms of percentage overshoot and settling time, ANFIS-based UPFC outperforms PI-based UPFC for transient stability enhancement. [ABSTRACT FROM AUTHOR]

The primary objective of a power system is to provide safe and reliable electrical energy to consumers. This objective is achieved by maintaining the stability of the power system, a multifaceted concept that can be divided into three distinct classes. The focus of this study is on one of these classes, voltage stability. A critical component in maintaining voltage stability is the automatic voltage regulator (AVR) system of synchronous generators. In this paper, a novel control method, the sigmoid-based fractional-order PID (SFOPID), is introduced with the aim of improving the dynamic response and the robustness of the AVR system. The dandelion optimizer (DO), a successful optimization algorithm, is used to optimize the parameters of the proposed SFOPID control strategy. The optimization process for the DO-SFOPID control strategy includes a variety of objective functions, including error-based metrics such as integral of absolute error, integral of squared error, integral of time absolute error, and integral of time squared error, in addition to the user-defined Zwee Lee Gaing's metric. The effectiveness of the DO-SFOPID control technique on the AVR system has been rigorously investigated through a series of tests and analyses, including aspects such as time domain, robustness, frequency domain, and evaluation of nonlinearity effects. The simulation results are compared between the proposed DO-SFOPID control technique and the fractional-order PID (FOPID) and sigmoid-based PID (SPID) control techniques, both of which have been tuned using different metaheuristic algorithms that have gained significant recognition in recent years. As a result of these comparative analyses, the superiority of the DO-SFOPID control technique is confirmed as it shows an improved performance with respect to the other control techniques. Furthermore, the performance of the proposed DO-SFOPID control technique is validated within an experimental setup for the AVR system. The simulation results show that the proposed DO-SFOPID control technique is highly successful in terms of stability and robustness. In summary, this study provides comprehensive evidence supporting the effectiveness and superiority of the DO-SFOPID control technique on the AVR system through both simulation and experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a comparative study between four techniques recently used to improve the wind energy conversion system (WECS) to water pumping systems. The WECS is a renewable energy source which has developed rapidly in recent years. The use of the WECS in the water pumping field is a free solution (economically) compared to the use of the electricity grid supply. The control of WECS, equipped with a permanent magnet synchronous generator, has the objective of carefully maximising power generation. A comparative study between the proposed Fuzzy Logic Control, optimised using a genetic algorithm and particle swarm optimisation algorithm, and the conventional Perturb and Observe MPPT method using Matlab/Simulink, is presented. The performance of the proposed system has been verified against the generated output voltage, current and power waveforms, intermediate circuit voltage waveform, and generator speed. The presented results demonstrate the effectiveness of the control strategy applied in this work. [ABSTRACT FROM AUTHOR]

The escalating demand for energy and the mounting environmental impacts of fossil fuel usage necessitate a paradigm shift toward the integration of renewable energy sources (RES) as the core of the electrical energy sector. Solar photovoltaic (SPV) and wind-based generation have emerged as the most promising and viable solutions, leading to a significant increase in the RES-based microgrid penetration into the power grid. However, the grid-connected microgrid operation presents challenges to the stability of the main grid. Due to small aggregated physical inertia of these microgrid, there is a significant deviation in system inertia that contributes to low frequency oscillations (LFO). These oscillations have a significant risk to power system stability. In the proposed work, a grid-connected microgrid that incorporates a synchronous generator along with SPV and wind integration is investigated. A synchronized governor combined with a power system stabilizer features a cascade structure, encompassing tilt integral derivative and fractional-order proportional integral derivative with a filter to effectively mitigate the oscillations. Furthermore, this cascaded controller is optimized using the improved reptile search algorithm. The controller efficacy is validated in the MATLAB platform by subjecting it to random variations in reference torque. Comparative analysis against conventional controllers, including Proportional Integral, Lead-Lag and Fractional Lead-Lag, demonstrates superior damping efficiency of the proposed controller since it damps LFO within the time period of 15 s. [ABSTRACT FROM AUTHOR]

Grid-forming VSG is widely used due to its advantages such as active frequency/voltage support and self-organized network operation. The grid-forming under extremely weak power grids has good adaptability. As power grid intensity increase, grid-forming virtual synchronous generator (VSG) is prone to resonance. To enhance the ability of grid converter to adapt to complex grid changes and ensure distributed generation can operate stably without grid disconnection, a grid-forming VSG converter resonance suppression control strategy based on grid voltage feedforward control (GVFC) and active virtual inductor (AVI) compound control is proposed. Firstly, sequence impedance modeling is established and stability analysis is carried out for grid-forming VSG. Secondly, GVFC and AVI resonance suppression methods is designed, respectively, and grid connection stability is, respectively, analyzed. To further suppress grid-forming VSG resonance, GVFC + AVI compound control strategy for grid-forming VSG is proposed. Sequence impedance model is established and grid connection stability analysis is carried out. Finally, a simulation model and experimental platform based on GVFC + AVI grid-forming VSG resonance suppression method is, respectively, established for simulation testing and experimental verification. The test results show VSG system based on GVFC and AVI compound control strategy has better resonance suppression capability with the increase in power grid strength, compared with GVFC/AVI/unimproved method. The GFVC + AVI resonance suppression method broadens the stability of grid-forming VSGs under different power grid strengths, which can make system better adapt to the changes of complex power grids. [ABSTRACT FROM AUTHOR]

A self-adaptive energy storage coordination control strategy based on virtual synchronous machine technology was studied and designed to address the oscillation problem caused by new energy units. By simulating the characteristics of synchronous generators, the inertia level of the new energy power system was enhanced, and frequency stability optimization was achieved. This strategy is integrated with the frequency response model of the new energy power system to improve the system's frequency regulation capability and achieve more stable and efficient operation. From the results, the damping of the system increased, the oscillation frequency decreased after a duration of about 15 s, and the system stability improved by 76.09%. The proposed strategy based on virtual synchronous generator adaptive energy storage coordination control strategy was improved by 83.25%. In addition, the proposed strategy has improved stability indicators and system completion efficiency by 40.57% and 22.21% respectively, both of which are better than the comparative strategies. As a result, this strategy significantly enhances the frequency regulation capability of the system, which has a positive effect on achieving efficient operation of the new energy power system and maintaining the stability of the power system. [ABSTRACT FROM AUTHOR]

To solve the problem of oscillation instability in permanent magnetic synchronous generator (PMSG)-based wind power connected systems during low-voltage ride through (LVRT) process, a parameter adjustment strategy based on interaction energy path optimization is proposed in this paper. Firstly, a modular state-space model of PMSG under fault transient conditions is constructed, and the system is divided into five subsystems. Then, the dynamic energy function of subsystems reflecting the oscillation stability of the system is derived. Based on that, the dynamic energy flow path is described considering the introduction of LVRT control. On this basis, the interaction energy between LVRT control links and subsystems is analyzed, and the coupling mechanism of voltage support and damping characteristics in the LVRT process is explained. Further, aiming at the optimal change rate of the total interaction energy in the LVRT process, the adjustment strategy of LVRT control parameters is constructed to meet voltage and damping requirements. Finally, a PMSG-connected system model is built on the MATLAB/Simulink platform to verify the effectiveness of the adjustment strategy. The results show that the proposed method can effectively improve the damping level under the fault transient condition, as well as supporting system voltage. [ABSTRACT FROM AUTHOR]

In this study, a small wind turbine prototype was developed to provide electric power for a mobile cooling unit The aim of this study was to design and develop a 600-W small wind turbine that can generate electric energy to power a mobile cooling unit used for the storage of fruits and vegetables, mainly for the benefit of smallholder farmers. Smallholder farmers suffer from high postharvest losses, approximated at 50%, some of which can be avoided by using efficient low-cost cooling units, rather than open transport. Cooling slows down the metabolic rate which consequently extends the produce's shelf life and prevents spoilage, allowing farmers to provide high-quality produce to the market. This could potentially increase the farmers' monetary returns. The study was conducted in KwaZulu-Natal on the road that stretches between Pietermaritzburg and Estcourt. The wind turbine is made of a 600-mm-diameter rotor with three PVC blades, a permanent magnet synchronous generator, a bridge rectifier, a 230-V AC inverter and a battery for energy storage. The wind turbine was tested against three vehicle speeds of 60, 80, and 100 km h−1, and the two opening levels, level 1 at 45 ∘ and level 2 at 80 ∘ relative to the louvre mechanism frame. The results of this study revealed that the power generated by the wind turbine is greatly influenced (p < 0.001) by both the vehicle travelling speed and louvre opening level. The power output of 113.4, 159.6 and 210.0 W per hour was observed for the vehicle speeds of 60, 80 and 100 km h−1, respectively, on louvre opening level 1. The power output of 142.8 W h−1, 268.8 W h−1 and 294.0 W h−1 were observed for a wind speed of 60 km h−1, 80 km h−1, and 100 km h−1, respectively, on Louvre opening level 2. This shows that higher wind speeds (vehicle speeds) produce high-power output which accounts for the small size of the wind turbine rotor. A maximum power coefficient of 0.49 was achieved for this study. The wind turbine can generate the power required to run a cooling technology to a limited extent, thus must have a backup power supply from the diesel engine or be used in a hybrid system. [ABSTRACT FROM AUTHOR]

Rotor interturn short circuit (RISC) is a common electrical fault in generators. Investigations about such fault on the rotor vibrations, magnetic field variations, and current/voltage changes have been widely carried out, while the thermal properties of the stator side have been rarely studied. This paper presents a comprehensive study on the stator thermal behavior in synchronous generators under different RISC position and varied power load cases. Such thermal behavior includes not only the core loss, copper loss and temperature variations of the stator, but also the mechanical responses of the stator core due to the unbalanced thermal distribution. The whole work is based on the magnetic flux density (MFD) analysis, the core loss and copper loss calculation. Theoretical analysis, finite element calculation, and experimental study are carried out, respectively, by taking a 5 kV A two-pole prototype generator as the case study. During the analysis, the reinforced excitation performance by the automatic control system of the generator set due to the voltage sag caused by RISC is fully considered. It is shown that RISC will significantly increase the stator temperature due to the reinforced excitation. The farther RISC position away from the big tooth is, the larger temperature/thermal risk will be. Besides, the stator temperature will also enlarge with the increase in power load. [ABSTRACT FROM AUTHOR]

The sub-synchronous resonance (SSR) characteristics and countermeasures of grid-forming permanent magnet synchronous generators (PMSGs) controlled by DC voltage synchronization control (DVSC) are investigated in this paper. First, small-signal models of two PMSGs connected to a series-compensated network are established, where a recently developed grid-forming control, i.e., DVSC is applied. Then, a modal-analysis method is conducted to evaluate the impacts of the control parameters, series compensation level (SCL), and electrical distances on stability. It is interesting to see that PMSGs with DVSC exhibit unstable SSR like traditional synchronous generators. Moreover, the dominant wind turbine (WT) is investigated using participate factor analysis. Then, a simple but effective SSR damping controller (SSRDC) is designed using feedforward control signals, which is only activated when SSR occurs. It is shown that the designed controller can provide strong damping support for SSR suppression. Electromagnetic transient simulations are performed in different scenarios to find the unstable SSR conditions, as well as to verify the correctness of the SSR analysis and the effectiveness of the proposed SSR damping scheme. [ABSTRACT FROM AUTHOR]

The large-scale wind power grid connection will change the power distribution between the original system tide and synchronous machine, and the interaction between wind turbine and synchronous machine affects the system's damping oscillation characteristics. Traditional synchronous generators' extra damping control provides an important means for DFIG to improve system damping characteristics. Different types of PSS have different suppression effects on low-frequency oscillations. In this paper, four types of IEEE PSS models are built in DIGSILENT/PowerFactory to study the suppression effects of DFIG additional different types of PSS on low-frequency oscillations of power systems, and the suppression effect of four types of PSS on system low-frequency oscillation after connecting to the DFIG reactive power control loop is compared and analyzed from two perspectives: eigenvalue and time-domain simulation. The MRAC control principle is used to improve PSS4B, and the total least squares-estimation of signal parameters via rotational invariance technique identification method is used to obtain the system transfer function, and the controller parameters are calculated in real time using the adaptive law based on the gradient approach. Finally, the MRAC–PSS4B is connected to the DFIG rotor-side controller's reactive power control loop, and the improvement effect of the designed MRAC–PSS4B controller on the power system's low-frequency oscillation characteristics under different contact line transmission power is confirmed. [ABSTRACT FROM AUTHOR]

It is well-known that co-ordination of protective devices and fault localization techniques in active distribution networks require results of various short-circuit (SC) analyses in the time domain. Accordingly, the main aim of this paper is to calculate the three-phase bolted SC current in the time domain for a radial medium voltage (MV) feeder, which is connected to a MV distribution network, and which has one induction generator (IG) and one synchronous generator (SG) at two different locations. The SC analysis of this concrete case study can be regarded as a novelty. The SC analysis is based on the well-known equivalent circuit models for the MV distribution network, IG and SG, as well as the applications of Kirchhoff's laws and the theorem of superposition. In addition, the proposed analysis method enables calculation of the SC current in the cases where the arc resistance at the fault location cannot be neglected. Finally, the results showed that there are no limitations on the application of the proposed method to the task of calculating asymmetrical SC currents. [ABSTRACT FROM AUTHOR]

This research investigates the impact of renewable energy integration on blinder-based Out-Of-Step (OOS) relays, which protect synchronous generators from unstable power swings. Challenges arise in distinguishing stable and unstable power swings due to fault ride-through (FRT), control operation, and weak inertia of renewable sources. Modified blinder-based OOS relays are analyzed in MATLAB using a modified Kundur two-area system. Findings show that high renewable energy penetration increases the likelihood of blinder-based relay failures during transient and small-signal stability incidents. The study also explores the effects of power swings on neighboring and remote OOS relays. Additionally, it examines the interaction between synchronous generators and renewable sources, and their impact on system stability during FRT. Modifications to single and double blinder-based OOS relays and their synchronization are proposed. The study concludes that the modified relay protection functions as inoperable for stable swings and operable for unstable swings, enhancing overall relay performance. [ABSTRACT FROM AUTHOR]

The estimation of armature reaction is of great importance in the design and operation of synchronous machines. This paper proposes a new method to reduce quadrature armature reaction in salient-pole synchronous generators. The proposed method is to reduce the quadrature axis synchronous reactance of a salient-pole synchronous generator by novel flux barrier to the rotor poles. Finite element analysis by Maxwell software was used to evaluate the nonlinearity of the synchronous reactances and to obtain the result that the quadrature axis synchronous reactance decreases when the flux barrier is introduced into the rotor pole of a salient-pole synchronous generator. As part of the study, a new flux barrier was introduced and experimented on the rotor pole of a 50 kW, 4-pole salient-pole synchronous generator without damper winding used for diesel generator. [ABSTRACT FROM AUTHOR]

Controlled power converters have found many applications in the power industry during the last decade. Virtual synchronous generator (VSG) is a truly good example of these converters that can be used to induce desired dynamics to the network. Despite the excellent performance of VSGs in balanced conditions, they do not carry the flexibility to suppress unbalanced components. To deal with this conflicting issue, a decoupled double synchronous reference frame-based VSG is proposed in this paper. Applying this method to the VSG structure under unbalanced voltage conditions by decoupling the positive and negative components, the oscillating terms are mostly eliminated, and DC values are extracted with the aim that the controllers can perform better. The benefits of the proposed scheme include higher accuracy, better controllability, effective component separation, and robust performance under heavy load conditions. The simulation results prove the validity and effectiveness of the proposed strategy against traditional VSG and previous techniques presented to enhance VSGs under unbalanced conditions in an islanded microgrid. [ABSTRACT FROM AUTHOR]

This work presents the study of a wind energy conversion system based on permanent magnet synchronous generator controlled by an advanced frequency techniques applied to two levels of control system: turbine speed control which allows to extract the maximum wind power based on the control of the PMSG electromagnetic torque and Vdc (DC-link voltage) control based on vector control to ensure a constant tension under the variations in the wind speed. The robust H∞ control efficacy is validated in comparison with the MPPT controller based on perturb and observe algorithm and conventional regulator PID. The computer simulation results obtained by a realized graphical user interface (GUI) using robust H∞ controller with robustness test (variations in electrical and mechanical parameters) show considerable improvements in dynamics performances, robustness stability and good adaptation of the robust H∞ parameters under uncertain constraints. [ABSTRACT FROM AUTHOR]

The energy matrix is rapidly changing in recent years mainly due to concerns with the environment. The participation of renewable resources connected to the power system via frequency inverters is increasing, adding new challenges to the power systems operation and control. The system inertia reduction as a result of the conventional synchronous generators replacement makes the system more susceptible to frequency variations, leading to the deterioration of the system dynamic response. In this paper, a control scheme is proposed, aiming to improve the system frequency response after disturbances. The control scheme is based on the online identification of a system model. Changes in system inertia, resulting from changes in the dispatch of renewable sources and disconnection of conventional sources, are taken into account by the periodic update of the identified model. A design method is applied to update the control in order to limit frequency excursions and improve dynamic response. The impact of PMUs and transmission latency on the control performance are also evaluated. Simulations are performed in order to validate the proposed approach. [ABSTRACT FROM AUTHOR]

In the parallel supply system of synchronous generator and virtual synchronous generator, the physical structure and control structure of the two kinds of power supply are quite different, and it is difficult to distribute the transient power of the two kinds of power supply evenly when the load changes abruptly. Especially in the case of sudden load increase, virtual synchronous generator bears too much load in the transient process because of its fast adjustment speed, and even causes short-term overload, which makes the capacity of virtual synchronous generator can not be fully utilized. In view of this problem, firstly, the mechanism of transient power uneven distribution of two heterogeneous power sources is explained from the differences of frequency modulation, voltage regulation and output impedance. Secondly, virtual speed regulation, virtual excitation and dynamic virtual impedance are added to the traditional virtual synchronous generator control to simulate the speed regulation characteristics and electromagnetic transient characteristics of the synchronous generator, so as to realize the transient and steady-state power equalization between heterogeneous power supplies when the virtual synchronous generator and the synchronous generator run in parallel. Thirdly, in order to ensure the fast dynamic response characteristics of the virtual synchronous generator in independent operation mode, the traditional virtual synchronous generator control algorithm is still maintained in independent operation mode, and the mode switching control link based on state tracking is designed to realize smooth switching between the two working modes. Finally, the hardware in loop experiment results based on RT-LAB show that the proposed control method can realize the transient and steady-state power equalization when the virtual synchronous generator and the synchronous generator operate in parallel, it can keep the fast voltage regulation and frequency modulation ability when the virtual synchronous generator operates independently, and can realize smooth switching between independent and parallel operation modes. [ABSTRACT FROM AUTHOR]

In this paper, a virtual synchronous generator (VSG) controller is applied to a hybrid energy storage system (HESS) containing a battery energy storage system and supercapacitor storage system for maintaining the frequency stability of an isolated microgrid. The microgrid contains a photovoltaic generation system and a diesel generator in addition to the HESS and two constant impedance loads that are fed through a medium voltage radial feeding system. The adaptive virtual inertia constant (H) with constant virtual damping coefficient (D) based on ' bang-bang' control for the microgrid's frequency stability enhancement is investigated and compared with the constant parameter VSG. In addition, the bang-bang control is modified to adapt the D beside the adaptive H, and the system response is investigated and compared with the conventional adaptive H technique. The VSG parameters are evaluated based on two different methods. The first is a computational method based on the simplified small signal stability analysis, while the other is based on an optimization method using two different objective functions and the particle swarm optimization technique. This paper also investigates the superiority of the proposed technique compared to other techniques in enhancing frequency stability, accelerating steady-state frequency restoration, and reducing the energy requirement of the HESS. The required power from the HESS is shared between the two energy storages using the low pass filter technique so as to reduce battery peak current. [ABSTRACT FROM AUTHOR]

In this paper, the influence of stator teeth deformation on electromagnetic force and acoustic noise of claw pole alternators was investigated. The characteristics of stator teeth deformation caused by welding and assembly were first illustrated, and the influence of stator teeth deformation on the frequency and spatial order of electromagnetic force harmonics was deduced analytically. Then the electromagnetic forces of three alternators with different stator teeth deformation types were simulated by the finite element method, and compared with the electromagnetic force of nominal alternator. In addition, a multi-physics simulation model was established and the electromagnetic noise of the above three different stator teeth deformation alternators was calculated. Finally, the changes in phase current and output current of claw pole alternator with and without stator teeth deformation were analyzed. The analysis results were verified by back-EMF bench test and noise bench test. Results showed that although stator teeth deformation would not change the frequency components of the electromagnetic force, but would generate additional electromagnetic force harmonics. When the number of deformed teeth was not an integer multiple of the rotor pole-pair number, the electromagnetic force harmonics with extra spatial order would appear. [ABSTRACT FROM AUTHOR]

With the enormous stress of energy lack and air pollution, renewable energy sources such as photovoltaic sources become an effective solution to solve these problems. The penetration of inertia-less photovoltaic sources into power system has adverse effects on the overall system inertia which threatens system stability. As a solution for this problem, virtual inertia technique can be used as a system controller in order to enhance the system performance and maintain its stability. In this paper, an adaptive virtual synchronous generator (VSG) controller based on the oscillation motion of the synchronous machine is introduced. Then, a proposed VSG with adaptive neuro-fuzzy inference system (ANFIS) is presented as an inverter controller. The system response is investigated and compared with other control methods under different operating scenarios. To verify the effectiveness of the proposed adaptive VSG, an experimental setup is presented with real-time implementation for the system using dSPACE DS1104 interfacing with MATLAB software, and the system response is investigated under different operating scenarios. Upon the presented results, there is an enhancement in the system response when the proposed adaptive VSG with ANFIS controller is used, and this emphasizes the superiority of using such controller in PV systems over other techniques. [ABSTRACT FROM AUTHOR]

This paper presents a novel PI λ 1 I λ 2 D μ 1 D μ 2 controller for the automatic voltage regulator (AVR) system. The AVR system controls the terminal voltage of synchronous generators. In this way, it contributes to voltage stability in power systems. The parameters of the proposed controller are optimized with the recently developed Mayfly algorithm for various objective functions. These objective functions are Zwe-Lee Gaing, the integral of time multiplied absolute error, the integral of squared error, the integral of time multiplied squared error and the integral of absolute error (IAE). The best result in terms of transient response parameters (settling time, rise time, and maximum overshoot) at terminal voltage is compared to controllers developed in recent years. Both time domain analysis and frequency domain analysis is used in this comparison. From the comparison results, it has been observed that the proposed controller provided better performance as compared to existing controllers in the literature. In addition to time and frequency domain analysis, robustness, nonlinear effect, and external disturbance rejection performances of the proposed controller are analyzed for the AVR system. As a result of all these analyses, it is seen that the proposed controller displays outstanding performance. [ABSTRACT FROM AUTHOR]

This Paper is related to solar powered (PV) fed five level of Cascaded H-Bridge Multistage Inverter for Submersible Asynchronous motor for rural pumping applications. Sinusoidal Pulse Width Modulation (SPWM) has been implemented to Multilevel Converter and the motor is protected from subsequent faults such as Low Water Level-Dry Run, Insulation failure (short circuit), Pump Lock Condition (Foreign particles), and line fault, and MPPT P&O technique is implemented in order to maximize the output power. The proposed technique is simulated in MATLAB and hardware has been executed. ATMEGA controller is used as a platform to code. [ABSTRACT FROM AUTHOR]

Virtual synchronous generator (VSG) not only increases the inertia of grid-connected system, but also brings the problem of active power oscillation under grid disturbance. Therefore, VSG control strategy and system model order reduction method with transient electromagnetic power compensation are proposed. The closed-loop active power small signal model of the system is established, and the influence of transient electromagnetic power compensation on the power stability of VSG is analyzed based on root locus method. By removing the items which have little influence on the stability of the system in the small signal model, the order is reduced to obtain the equivalent second-order model of the system. According to the second-order model, the quantitative design criteria of the system parameters are given. The proposed transient electromagnetic power compensation strategy not only increases the transient equivalent damping of the system, but also does not affect the primary frequency modulation characteristics and will not cause large overshoot of the output active power. The experimental results are consistent with the theoretical analysis, which testify the effectiveness and correctness of the system control strategy and the model reduction method. [ABSTRACT FROM AUTHOR]

Smart cities require effective device communication through consideration of key features of instrumentation, intelligence, and interconnections. Internet-of-Things (IoT) is implemented in smart cities for larger communication with heterogeneous communication and devices in smart cities. Through the implementation of IoT devices in smart cities power management can be effectively managed through the implementation of renewable systems. Power system contributed on the economic growth of the country through offering adequate power for demand. The conventional synchronous generator is replaced with wind power system those demand for evaluate the stability of the system. In view of the problem that the inertia of the system is reduced and the frequency modulation capability is insufficient due to large-scale wind power connected to the power grid, this paper proposed Pitch Angle Load Shedding Frequency Modulation wind turbine control strategy and inertia support and primary frequency modulation. This scheme is based on the characteristics of the pitch angle of the wind turbine to set the load shedding control of the wind turbine, reserve the reserve capacity required for the wind turbine frequency modulation. To analyse the impact of WTGs on transient stability, a line fault is applied near bus-7 of IEEE 9-bus based on consideration of swing in rotor angle, speed and oscillation with consideration of magnitude of voltage, active and reactive power of WTGs. It is found that, with SCIGs, rotor angle swing increased indefinitely, rotor speed deviation is more and oscillation duration is more. [ABSTRACT FROM AUTHOR]

This paper discusses the power coupling problem of the traditional virtual synchronous generator (VSG) control strategy in medium and low-voltage microgrids, analyzes the cause of power coupling, and discusses the necessity for decoupling. In addition, a power decoupling control strategy based on an adaptive diagonal matrix compensation matrix is proposed. By compensating for the coupling component, the output power of the VSG is completely decoupled. To cope with the operating characteristics of frequent load switching on the grid side of a microgrid, the proposed strategy tracks variations in the static operating point of the VSG and automatically adjusts the compensation component. Simultaneously, the stability of the VSG is analyzed, using the transient instability criterion of the power system, to ensure decoupling. Finally, the effectiveness of the proposed control strategy is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

Loss of Excitation (LOE) is the most considerable fault in Synchronous generators since it affects both the generators and power network. The traditional protection method for LOE is based on impedance trajectory of the machine with negative offset mho relay. Meanwhile the traditional method experiences malfunctions and speed dip in LOE detection. This paper presents machine learning approach to detect LOE fault as well as classification logic to discriminate LOE fault from power swing conditions due to Line fault. This paper utilizes Hotelling's-T2 statistical method to calculate Hotelling's-T2 based Fault Indices (HT2-FI) for fault detection and Support Vector Machine (SVM) for classification. The time series data of electrical quantities such as Terminal voltage and Reactive Power of the generator are extracted from simulated Single Machine Infinite Bus test system and used as input data. These data involved in calculation of HT2-FI and in development of classification logic. The proposed method is simulated and verified for complete, partial LOE conditions and power swing conditions. Simulation outcomes depict the remarkable signs of the proposed method in LOE identification from power swing. Comparative assessment also reports that the method is capable of saving time in detecting LOE. [ABSTRACT FROM AUTHOR]

The terminal voltage of the synchronous generator must be kept between determined values by a closed-loop control system called automatic voltage regulator (AVR). To enhance the performance of the AVR system, this study introduces a new type of controller design. In this context, a novel controller named fractional order (FO) proportional-integral-derivative plus second-order derivative (FOPIDD2) has been proposed for the first time, and an optimization method known as the reptile search algorithm (RSA) has been utilized in order to tune the six parameters of FOPIDD2 controller. The performance of the proposed RSA-FOPIDD2 controller is compared with twenty-two studies employing a variety of controllers such as PID, PIDA, FOPID, and PIDD2 and published within the last three years. The results of the comparison show that the proposed controller provides improved performance for the AVR system when compared to other methods. [ABSTRACT FROM AUTHOR]

With the increasing penetration of distributed generation in the distribution network, mainly solar photovoltaic (PV) generation, the reactive power's planning must be revised to minimize problems arising from the massive penetration of this kind of generation. Therefore, the differential of this work is to study the impacts on the reactive power flows and power factor regulation arising from the massive penetration of PV generation when allocating capacitor banks (CB) and voltage regulators (VR). Given the available technology of the power electronics inverters, this work aims to model the reactive power dispatch of these generators in an optimal power flow to act as reactive power compensators throughout the day even at night, known as PV-STATCOM. The allocation process of CB and VR is solved by genetic algorithms, modeled to allow the CB placement in medium-voltage (MV) and low-voltage buses, while VR is placed only in MV. As PV-STATCOM penetration increases, the results show that this approach eliminates the need for fixed CB in the system, requiring only automatic CB on periods of maximum PV-STATCOM active power dispatch. Also, the combination of CB, VR, and PV-STATCOM is efficient for solving problems of power quality. [ABSTRACT FROM AUTHOR]

The stability of a voltage source converters (VSC) system based on phase-locked loop (PLL) is very important issue during asymmetric grid faults. This paper establishes a transient synchronous stability model of a dual-sequence PLL-based VSC system during low voltage ride-through by referring to the equivalent rotor swing equation of synchronous generators. Based on the model, the synchronization characteristics of the VSC system under asymmetric grid faults are described, and the interaction mechanisms, as well as the transient instability phenomena of positive and negative sequence PLL during asymmetric faults are explained. Using the equal area criterion, the influences of sequence control switching action, detection delay, and interaction between the positive and negative sequence PLL on the transient synchronous stability of the VSC system are analyzed, respectively. In addition, a transient stability assessment criterion based on the critical fault clearance angle and time and an enhancement control strategy based on the improved positive and negative sequence PLL are proposed. Finally, the analytical results are validated through simulation and experiments. [ABSTRACT FROM AUTHOR]

In this paper, a linear active disturbance rejection controller (LADRC) is introduced to control the speed loop and current loop of a permanent magnet synchronous generator (PMSG). The speed loop uses a first-order LADRC (FLADRC) to avoid overshoot and to speed up the dynamic response of speed tracking. In the current loop, considering the influence of the converter, a second-order LADRC (SLADRC) is designed. In addition, the convergence of the proposed strategy is verified, and the tuning method of the control parameters is given. The proposed control strategy has strong anti-interference capability in a wide frequency band, and its effectiveness and practicability are verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

A pattern recognition-based plan for detecting islanding and non-islanding conditions is presented in this paper. This plan is used in distribution systems in the presence of synchronous generator-based distributed generation resources with doubly fed induction generators (DFIGs), a generating principle widely used in wind turbines. The main idea behind the suggested plan is the measurement of total magnetomotive force (MMF) in the SG air gap less than 2 s based on IEEE std.1547 after the occurrence of islanding and non-islanding events. First, a mathematical morphology (MM) filter was used to lessen the possible noise in a total MMF signal sampled in SGs. Then, spatial features like variation, energy, median, rms and mean values of the output magnitude of MM filter were computed. Finally, to distinguish the islanding condition from the non-islanding conditions, support vector machine (SVM) classifier with radial basis function (RBF) kernel was taught based on the above-mentioned features. Different scenarios were considered in various loading conditions in distribution systems for the occurrence of islanding and non-islanding conditions and the determination of the ability of the suggested plan. The outcomes show the method suggested with the SVM (RBF kernel) classifier has much better results in comparison with some other methods. [ABSTRACT FROM AUTHOR]

The provision of system support services by converter-interfaced generation (CIG), which were previously assigned to the conventional synchronous generation, is a challenging task extremely necessary for the stable operation and control of modern power systems. The most promising solution in this direction is the application of grid-forming control strategies for the CIG. This paper proposes a CIG' control system based on a freely configurable structure of a virtual synchronous generator (FC-VSG). In this control system, different levels of the inverter control are implemented in parallel, and in order to improve the transient performance and damping properties of CIG, the inertial and governor response are coupled at the inner control level, a voltage regulator is added at the outer control level, as well as the combined use of a virtual damper winding and power system stabilizer is applied. Such solutions made it possible not only to mimic the behavior of a conventional rotating machines, but also to significantly improve the transients' dynamics. To show the effectiveness of the proposed control system, time-domain simulations and experimental case studies have been performed. In addition, the qualitative and quantitative assessment of the dynamic response of the FC-VSG in comparison with both the conventional voltage-controlled VSG structure and the dynamics of a practical synchronous machine have been carried out. [ABSTRACT FROM AUTHOR]

The virtual synchronous generator (VSG), as a grid-connected technology, has gain more and more attention because of its unique merits including its ability to reshape inertia and damping. These merits enable renewable energy to be smoothly integrated into the grid. Unbalance between three-phase voltage in the steady state is a common phenomenon in the grid, which distorts the output current of the VSG. However, on many occasions, inserting symmetrical current into the grid is necessary. To solve this problem, a dual-module VSG control strategy is proposed in this paper. Through this strategy, the positive and negative sequence output powers of the VSG can be correctly identified and separately controlled. Then the output current can be kept symmetrical by controlling the negative sequence output power of the VSG to be zero. Finally, the proposed strategy is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]

The influence of distributed generation sources in the Islanded microgrid has adverse effects on frequency stability because of the absence of inertia. Accordingly, the concept of a virtual synchronous generator (VSG) has been proposed, which follows the behavior of conventional synchronous generators. The virtual inertia control can be implemented on energy storage systems (ESSs) as a part of a virtual synchronous generator. Virtual inertial control does not perform optimally against the uncertainty of islanded microgrid parameters and disturbances. Therefore, virtual inertial control requires a supplementary controller in its structure that is resistant to these effects. In this paper, a new robust output feedback control method was used to control the virtual inertia in a two-area microgrid, which is based on the linear matrix inequality. The proposed control method does not need to measure all modes and only uses the output feedback. We compared the results of the proposed controller for controlling the virtual inertia in multiple different scenarios by considering the uncertainty of the two-area microgrid parameters as well as disturbances applied to the microgrid with the virtual inertia control based on optimized PI controllers (genetic algorithm), no controller (virtual inertia), and without considering virtual inertia (conventional methods). Accordingly, the effectiveness of the proposed method was demonstrated in terms of response speed, reduction of the frequency deviations and tie-line power deviations, robustness against parameters' uncertainty, and disturbances occurring to the two-area microgrid. [ABSTRACT FROM AUTHOR]

The power system industry is one of the pioneers in implementing machine learning (ML) methods which have acquired a lot of attention across various facets of contemporary life. Low-frequency oscillation (LFO) is purportedly a non-threatened but slowly poisoning concern with electrical power networks that, if not adequately addressed in a reasonable timeframe, could appear as the cause of a total network failure. The function of a well-known member of the ML family, the adaptive neuro-fuzzy inference system (ANFIS), is proposed in this paper for optimizing LFO damping in real-time in the power system networks. It adopts two power system networks, one in which the synchronous machine is equipped solely with a power system stabilizer (PSS). In the second one, PSS relates to a second-generation flexible alternating current transmission system (FACTS) device named the unified power flow controller (UPFC). The well-known genetic algorithm (GA) supports the proposed ML algorithm in generating the dataset and training them well. The designed approach is examined using various statistical performance measures and well-recognized stability performance measures, such as the minimal damping ratio, eigenvalue, and time-domain simulation. The article also includes comparing and discussing the results from the reference works to make inferences on the viability of the proposed GA-tuned ANFIS technique for improving real-time power system stability. [ABSTRACT FROM AUTHOR]

The fault current level of a photovoltaic source is much lower than the equally rated conventional synchronous generator, which may cause several protection issues, such as relay blinding and coordination loss in the conventional over-current relay scheme. This paper proposes a new scheme by modifying the plug setting multiplier of the conventional OCR. It upholds its performance under different levels of PV penetration. Further, it has better compatibility with traditional OCR and fuse. The proposed scheme's effectiveness is tested on the 10-bus primary distribution system using DIgSILENT/POWERFACTORY and the MATLAB/SIMULINK. The results show the effective compatibility of the proposed scheme under relay blinding and coordination loss. However, the proposed scheme has successfully sensed the fault with an operating time of 2.014s for the 100% penetration of the centralized photovoltaic where the conventional OCR may have maloperated. Furthermore, it is demonstrated on the real-time digital simulator platform to check its practical feasibility and has provided fruitful results. [ABSTRACT FROM AUTHOR]

For isolated micro grid applications, this article provides a unique multi-source and HES-integrated converter architecture. Other multi-input converter systems fail to manage power changes caused by wind, sun, or unanticipated load disruptions. Supply sustainability and reliability have become important considerations due to renewables' uncertainty. To reduce power efficiency and unbalanced loading uncertainty, the battery can respond quicker than diesel generators and micro turbines. This research examines the power generation of a solar, wind, battery, and super capacitor-based isolated micro grid. When the load abruptly decreases or increases, the PCC voltages are interrupted. As a consequence, we develop a novel control approach for PCC's voltage profile optimization. Reacting to high-frequency changes using a super capacitor increases battery life and minimizes storage unit size. Basic functions such as charging and discharging energy storage based on system power availability are also included in the control structure. The ANFIS Adaptive controlled proportional integral (IC-PI) controller optimizes synchronous generator speed management to enable exact wind MPP monitoring. The boost converter controls DC link voltage while the load side power converter harvests solar MPP. Important elements of the recommended configuration: (i) Built-in voltage boosting, super capacitor voltage control, and battery-super capacitor power sharing (ii) Less sensors and a simpler control system. Complete configuration and control structure analysis, modeling, and design using MATLAB simulations are provided. [ABSTRACT FROM AUTHOR]

In this paper, an intelligent optimizer has been developed and applied to tune fractional proportional integral power system stabilizer (FOPIPSS) to suppress the low frequency oscillation in a synchronous generator connected in single machine infinite bus system (SMIB). As, the power network is interconnected system, the conventional methods of tuning fractional PSS are complex and time-consuming. To avoid the mathematical and calculation burden of parameter tuning of FOPIPSS, a comparative performance class topper optimization is developed. The proposed optimized FOPIPSS is examined for SMIB system under three different conditions: disturbance in mechanical torque, mechanical torque change in the presence of fluctuation in exciter voltage and disturbance in exciter voltage in the presence of the governor-turbine system. The result analysis shows the effectiveness of the optimized FOPIPSS for SMIB systems comparing with the existing results. [ABSTRACT FROM AUTHOR]

The large application of renewable energy generation (REG) has increased the risk of cascading failures in the power system. At the same time REG also provides the possibility of new approaches for the suppression of such failures. However, the capacity and position of the synchronous generator (SG) involved in regulation limit the power regulation speed (PRS) of REG to the overload line which is the main cause of cascading failures, while the PRS of SG is related to the position and shedding power. REG and SGs have difficulty in achieving effective cooperation under constraints of system power balance. Particularly, the dynamic variation of line flow during power regulation causes new problems for the accurate evaluation of line thermal safety under overload. Therefore, a new strategy for quantitatively coordinating shedding power and power regulation to block cascading failures in the dynamic security domain is proposed in this paper. The control capability and dynamic security domain of the overload line are modeled, and the coordination control method based on power regulation is then proposed to minimize shedding power. The algorithm for the optimal control scheme considers the constraints of load capacity, power source capacity and bus PRS. The correctness of the proposed method is verified using case studies. [ABSTRACT FROM AUTHOR]

Induction generators have acquired significant notoriety in latest years owing to the reality that they have several benefits over other kinds of electrical generators such as standard synchronous generators. In this article, an equal SEIG mathematical model relying on circuit loop impedance technique is practiced. In order to attain the frequency and an unknown SEIG parameter, the goal of optimization is to diminish the full equivalent circuit impedance of the generator. An approach employing Dragonfly algorithm for the steady- and transient-state analysis of single-phase self-excited induction generator has been presented. Along with this, PID controller is utilized for efficient control. This research mainly involves using this novel algorithm to address the SEIG steady-state issue of optimization. The modeling layout of the suggested power algorithm is indicated and the simulation outcomes of the SEIG scheme are provided to validate change in voltage, harmonic mitigation and rapid response of the algorithm proposed. In a MATLAB/Simulink system, the suggested SEIG model technique is performed. The proposed dragon fly technique is compared with the existing methods such as Firefly Algorithm and Elephant Herding Optimization methods that are used to validate the efficiency. [ABSTRACT FROM AUTHOR]

A microgrid is created by combining several distributed generators (DGs), and each DG with integrated power electronic inverters connects to the load via a line. By applying the conventional droop control approach, DG current magnitude and their phase angle are not equal due to circulating currents introduced by the differences in the impedance of the lines. This circulating current causes unequal distribution of reactive power among the DGs. Virtual impedance can reduce the circulating current and enhance the reactive power distribution among the connected DGs, which requires physical line impedance information. This report recommends a unique and straightforward adaptive virtual impedance control strategy with a virtual synchronous generator (VSG) using a washout filter approach to solve this reactive power-sharing issue with inertia support by reducing frequency deviation without using physical line impedance information. The proposed control strategy is first simulated on the MATLAB/Simulink platform and further verified on the OPAL-RT 4510 hardware-in-loop RCP/HIL FPGA-based real-time platform. [ABSTRACT FROM AUTHOR]

This paper introduces a novel wind energy conversion system (WECS) incorporating a 1.5 MW dual-excited synchronous generator (DESG) connected to the grid. DESGs, recently gaining traction in WECS, integrate permanent magnet and wound field excitation for optimized performance. The system dynamically adjusts DESG flux using direct current excitation coils and permanent magnets to maximize wind energy extraction, improving efficiency and reliability. An advanced super-twisting control (ASTC) method is proposed to enhance control precision, which uses an attractive term and modifies the existing discontinuous term of super-twisting control (STC) with a smooth tangent hyperbolic function. This innovation aims to reduce chattering effects, effectively mitigating power fluctuations and improving response time and durability. Comparative simulations against traditional PI control and STC methods highlight ASTC's superiority, showcasing significantly lower-power fluctuations, response times, and total harmonic distortion (THD) of injected current. Notably, ASTC achieves a THD reduction ratio of 70% and an efficiency of 98.5% in varying wind conditions, outperforming STC and PI controllers, nearing unity power factor operation. [ABSTRACT FROM AUTHOR]

The energy storage unit is connected to the sub-module of the modular multilevel converter through the DC/DC link, which can effectively reduce the voltage-level requirements of the energy storage unit, and the energy storage capacity can be flexibly configured by changing the number of energy storage sub-modules. Virtual synchronous generator technology is applied to the top-level control strategy of the modular multilevel converter, which can effectively solve the defect that the system cannot perceive the frequency of the grid side. In addition, the adaptive parameter control of virtual synchronous generator can be realized by changing the moment of inertia J and damping coefficient D in real time according to the actual situation. On this basis, an improved adaptive algorithm is proposed in this paper. D is adjusted by active power deviation and active power change rate. J and D are selected by fast saturation function, and the range of parameters is reasonably limited to realize the optimization of energy storage capacity. Finally, the adaptive algorithm under frequency disturbance is modified to ensure its better transient performance. The simulation results show that the proposed adaptive algorithm can improve the dynamic performance of the system and reduce the energy storage capacity required by the system, which verifies the effectiveness of the proposed algorithm. [ABSTRACT FROM AUTHOR]

Machine learning (ML) techniques have gained substantial attention in many aspects of contemporary life during the last several years. As part of the digital revolution, the electricity industry is one of the leaders in implementing such appealing and effective technology for various applications. In general, low-frequency oscillations (LFO) are nonthreatening but slow-burning issues that, if not addressed appropriately, might lead to complete network collapse. Due to the significance of prominent ML family members in improving LFO damping in electric power system (EPS) networks, the applicability of the fuzzy c-means (FCM) clustering-based deep learning (DL) technique is modeled in this paper for two typical EPS networks by predicting the critical parameters of the power system stabilizers (PSS). The first network is a single-machine infinite bus (SMIB) network where the synchronous generator is equipped with a PSS. On the other hand, a unified power flow controller (UPFC) coordinated PSS is connected at one terminal of the synchronous generator of the second network. The clustering of the datasets obtained through the whale optimization algorithm (WOA) is performed based on the calculated silhouette values for both power networks. Then, several statistical performance indices (SPI) are evaluated to validate the robustness of the training and testing procedure of the DL method for the prepared data clusters using the FCM clustering technique. The efficacy of the proposed FCM-DL strategy in enhancing LFO damping for the two test networks is assessed based on standard analytical and time-domain analysis. Therefore, the minimum damping ratio (MDR), eigenvalue, rotor angle, and angular frequency with respect to time are simulated and analyzed. The article also includes a comparison of the findings of previous studies to illustrate the potential of the proposed FCM-DL strategy in improving EPS stability by damping out undesirable LFOs. It is worth noting that the developed FCM-DL models can predict the candidate parameters with a coefficient of determination (R2) value of more than 0.9974. During the implementation phase, the proposed strategy achieves competitive MDR, for instance, more than 0.50 and 0.74 MDR for the first and second networks, respectively. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to introduce a complete wind conversion system based on a hybrid excitation synchronous generator (HESG) for large-scale 1.5 MW, grid-connected wind turbines. The proposed architecture should be tested under realistic operating conditions. However, for this power, setting up an experimental test bench would require exceptional funding for the laboratory and a great expertise. So, instead, advanced software simulation tools are used. In this work, an integrated near-realistic simulation model is developed. Both, the harmonics of the generator and the aerodynamics of the wind turbine are modeled. To ensure an optimal operating of the aerogenerator, a CRONE robust control approach is adopted. It is used for the generator's velocity loop controller and for the pitch control loop. Comparisons with a robust H∞ controller and a PI-based fuzzy controller are presented. Both control loops are tested under severe loads and stochastic wind profile. It is shown that an efficient control is achieved. Then, two scaled down power electronic interfaces using both, multilevel and conventional inverters, are implemented and investigated in terms of cost and performance. A Cascade H-bridge three-level inverter is chosen as it offers a good total harmonic distortion (THD) using a simple modulation technique without an extra filter to connect to the grid. Results show that the proposed architecture can be used to conduct performances-based comparisons to similar wind systems based on other types of generators such as permanent magnets synchronous generators and doubly fed induction generators. [ABSTRACT FROM AUTHOR]

In this paper, an authentic near-real-time methodology is proposed for locating the sources of FOs using the fundamental frequency of the periodic external driving force based on the direction of the potential energies exchanged between the synchronous generators. First, A directed graph of the network reduced to the generator buses is defined in which the weight and direction of its branches are assigned based on a well-defined energy-driven function. Next, based on the cosine part appearing in the edge weights, subsequent decisions are made, depending on the generators' angular velocity and active power phases. The proposed algorithm can make a correct and swift diagnosis even under the most challenging operational circumstances, such as resonances and limit cycles. The methodological procedure has been validated on the WECC 3-machine 9-bus and New England 10-machine 39-bus benchmark power systems modeled in the Real-Time Digital Simulator and then analyzed in the MATLAB environment. The simulation results revealed that the presented approach reliably releases all different FOs sources with various kinds of origin. [ABSTRACT FROM AUTHOR]

Increasing the inertia is widely considered to be the solution to resolving unstable interactions between coupled oscillators. In power grids, Virtual Synchronous Generators (VSGs) are proposed to compensate for reducing inertia as rotating fossil-fuel-based generators are being phased out. Yet, modeling how VSGs and rotating generators simultaneously contribute energy and inertia, we surprisingly find that instabilities of a small-signal nature could arise despite fairly high system inertia if the generators' controls are not coordinated at the system level. Importantly, we show there exist both an optimal and a maximum number of such VSGs that can be safely supported, a previously unknown result directly useful for power utilities in long-term planning and prosumer contracting. Meanwhile, to resolve instabilities in the short term until system-level coordination can be achieved, we argue that the new market should include another commodity that we call stability storage, whereby—analogous to energy storage buffering energy imbalances—VSGs act as decentralized stability buffers. While demonstrating the effectiveness of this concept for a wide range of energy futures, we provide policymakers and utilities with a roadmap towards achieving a 100% renewable grid. [ABSTRACT FROM AUTHOR]