Hardware in Loop Simulation Test of Photovoltaic Virtual Synchronous Generator

In order to improve the friendliness of the grid connection of new energy power generation, the new energy photovoltaic (PV) unit is equivalent to a synchronous generator in the power system and a virtual synchronous generator (VSG)-controlled PV energy storage complementary grid-connected power generation system model is established and studied to analyze the VSG. When power is supplied to the load together with the power grid, the energy storage unit inside the VSG will release and store the electrical energy according to the fluctuation of the PV output, which plays the role of the adjustment of the prime mover; in the case of load power fluctuations, and power grid assume the corresponding active power regulation according to their capacity. The amount of active power adjustment to jointly and maintain the power balance inside the system under the condition of fluctuating load power. The overall system architecture and control strategy of PV grid-connected inverter based on VSG algorithm are proposed. The PV-VSG proposed here not only takes into account the maximum power point tracking control but also has independent participation in the power supply. A series of characteristics of synchronous generators, such as network frequency modulation voltage regulation and inertia damping, can effectively improve the new energy PV power generation system and promote the new energy consumption. The results of system simulation and field demonstration operation fully show the effectiveness and correctness of the proposed control strategy based on VSG algorithm.

As more and more power electronic based generation units are integrated into power systems, the stable operation of power systems has been challenged due to the lack of system inertia. In order to solve this issue, the virtual synchronous generator (VSG), in which the power electronic inverter is controlled to mimic the characteristics of traditional synchronous generators, is a promising strategy. In this paper, the representation of the synchronous generator in power systems is firstly presented as the basis for the VSG. Then the modelling methods of VSG are comprehensively reviewed and compared. Applications of the VSG in power systems are summarized as well. Finally, the challenges and future trends of the VSG implementation are discussed.

With the increasing proportion of distributed power in power grid, the system has problems such as reduced mechanical inertia and excessive frequency shift during load disturbance. In order to solve these problems, some scholars have proposed the concept of Virtual Synchronous Generator (VSG) to make the inverter simulate the characteristics of traditional synchronous generators. A complete parameter analysis in different working conditions are carried out in this paper. According to the different effects of rotational inertia and damping on the dynamic response of output power, a new self-adaptive inertia and damping control to improve system dynamics is proposed by changing the values of inertia and damping in different stages of power angle response. Simulation results verify its superiority over traditional VSG control and the classic bang-bang control.

In order to realize the solar photovoltaic (PV) system connecting with grid friendly, a PV system with voltage-controlled inverter based on virtual synchronous generator (SG) is presented. This kind of system has features of SG, which supply the virtual moment of inertia to grid. The mathematical model of PV and virtual SG is built, and the control strategy of the maximum power point tracking (MPPT) is also studied in the paper. Simulation model of the grid-connected PV power system is built on Matlab/Simulink. Finally, correctness and feasibility of this system are verified by simulation results.

The technology of Virtual Synchronous Generator (VSG), which can make the inverter connected to distributed generation work like traditional synchronous generator, plays an important role in improving the stability of the power system because of its good voltage and frequency supporting capability. In this paper, an improved VSG control method is proposed, which can ensure seamless transfer between grid-connected and stand-alone modes, and achieve accurate tracking control of active and reactive power. The control topology and mathematical model of VSG are constructed firstly based on the rotation equation and electrical equation of synchronous generator; then, the corresponding VSG active-frequency droop control, reactive-voltage droop control and inner loop voltage-current control are designed, and the influences of key parameters are analyzed through frequency domain method. Finally, two simulations with different operation modes and loads are conducted to verify the effectiveness in Matlab/Simulink environment, and the results show that the performance is well.

The conventional synchronous generator (SG) can regulate the active and reactive power for frequency and voltage stability, when the system fluctuates. In renewable energy generation system (RES), the stability problem of RES can be solved by adding virtual inertia and damping in the control strategy of the grid-connected inverter. The grid-connected inverter and renewable energy system with this kind of control strategy, called as virtual synchronous generator (VSG), acts as a synchronous generator. In this paper, the topology of grid-connected PV array and energy storage system is proposed. The VSG used in grid-connected inverter, is modelled as stator and rotor model by stator voltage equation and rotor motion equation, respectively. Meanwhile, the VSG control mechanism, based on droop control and model of VSG, can be divided as active power-frequency and reactive power-voltage control. Besides, the system stability is analyzed based on small signal model, for the design of inertia and damping. The simulation model is designed by MATLAB/Simulink for the implementation of VSG. In simulation, it is compared that the dynamic regulation performance of VSG with different control coefficient, such as virtual inertia, virtual damping, droop coefficient and integral coefficient. The optimization for regulation performance in simulation provides an appropriate selection method of the control coefficient for VSG.

As an important part of electric multiple units (EMU), the auxiliary power supply system plays an important role in the normal operation of the vehicle. In order to improve the reliability of the auxiliary power supply system, the virtual synchronous generator (VSG) technology is applied to the parallel control system of auxiliary inverter. The essence of VSG technology is to control the inverter to simulate the working principle of synchronous generator, so as to obtain similar operation characteristics of synchronous generator. The auxiliary inverter controlled by VSG technology can avoid the disadvantage of hard external characteristics of power electronic devices. Its rotating inertia can obviously prevent frequency fluctuation, and the system has high stability and reliability. In this paper, the frequency and voltage of the auxiliary inverters are controlled independently with VSG technology, so that the output voltage can be controlled stably and the power quality can be improved. Finally, the MATLAB simulation results show that the parallel control of auxiliary inverter based on VSG achieves the expected goals.

• The paper focuses on optimising Virtual Synchronous Generator (VSG) control in Modular Multilevel Converter (MMC)-based HVDC systems to enhance power system stability and oscillation damping. • It introduces virtual inertia and damping to mimic synchronous generator behaviour, improving frequency and voltage regulation. • The proposed control strategy ensures smooth transitions between grid-connected and islanded modes, suppresses harmonics, and addresses challenges like low inertia and weak grid conditions. • Simulation results validate the effectiveness of the VSG-controlled MMC in maintaining stability during dynamic and transient events, making it suitable for future power systems with high renewable energy integration. This paper discusses the development of a Virtual Synchronous Generator utilizing a Modular Multilevel Converter. The control system employs an internal simulation of the electromechanical swing equation to replicate the inertia and damping characteristics of a synchronous generator, enabling the generation of the necessary frequency and phase angle for MMC control as a VSG. The ac-side management involves cascaded voltage and current controllers operating within a synchronous reference frame defined by the virtual swing equation. Simulation findings validate the performance of the VSG-controlled MMC when connected to an external AC grid and in islanded mode with a resistive load. This paper validates, through experimentation, the effectiveness of controlling a Modular Multilevel Converter (MMC) as a Virtual Synchronous Generator (VSG) designed to deliver virtual inertia and robust frequency stabilization in power systems with low physical inertia. The proposed control structure incorporates a virtual swing equation, cascaded voltage and current regulation loops, reactive power control, and emulated impedance. A 60 kVA MMC model was employed to demonstrate the system’s capabilities. During frequency disturbances such as a drop from 50 Hz to 49.8 Hz, the controller facilitated dynamic power injection up to approximately 35 kW while capping peak currents at 100 A. Frequency deviations were mitigated within 300 milliseconds, and the converter exhibited seamless transitions to islanded operation along with reliable voltage control during load variations. These findings confirm the proposed controller’s effectiveness in maintaining grid stability under diverse operating conditions.

A comparative study of single-loop VSG and multi-loop VSG

Aiming at the difference between conventional power electronic interface converter and traditional synchronous generator in microgrid, it cannot provide inertial support and damping effect for microgrid. In this paper, a converter based on virtual synchronous generator technology is used to design the power outer loop and the electromagnetic equation, so that the power electronic converter has some external characteristics of the synchronous generator while providing some damping and inertia for the microgrid, It is clarified that sag control is essentially a kind of virtual synchronous generator control. Finally, the feasibility and correctness of the method are verified by MATLAB simulation.

Due to various implementations of the voltage control, a virtual synchronous generator (VSG) may have different behaviors. This paper compares several voltage control strategies used in the VSG as well as the technology applied in a traditional synchronous generator. The performances are evaluated by the small-signal model and frequency-domain analysis, where the relationship and differences among various control strategies are revealed. The experimental results verify the theoretical analysis. The outcome of this paper is a reference to properly design the voltage control of a VSG and to understand the differences between a VSG and an actual synchronous generator.

The trend of future power systems is rapidly changing towards renewable energy resources (RESs) due to the depletion of fossil fuels. Meanwhile, the integration of RESs leads to the instability of the power system due to the lack of inertia and frequency instability. In this paper, the virtual synchronous generator (VSG) model is originated from imitating the synchronous generator characteristics. The VSG control approach is systematically researched and studied for different inverter-interfaced systems that include RESs integrated with the power grid. Parallel multi VSG based Photovoltaic (PV) systems are analyzed to validate the frequency response and power stability under high penetration of PV system. An advanced master-slave droop control approach is proposed for frequency regulation. Additionally, three case studies are analyzed under various effects of irradiance and temperature on the PV-VSG based system based on a specific area during a year. Meanwhile, an advanced particle swarm optimization (PSO) technique is utilized which effectively optimized the optimal parameters of droop control of VSG and improved the frequency regulation.

This electronic The pan microgrid under the isolated island is a renewable energy with high permeability, yet the lack of inertia and damping characteristics of conventional synchronous generators may lead to frequency and voltage fluctuations, and then may cause instability. In order to suppress these fluctuations, a model predictive control virtual synchronous generator (VSG) is proposed. Which provides inertial support during system transients, enhances the dynamic characteristics of the system voltage and frequency, and avoids the complex parameter adjustment process in traditional voltage and current dual-loop control. By establishing the prediction model of VSG, designing the cost function of frequency and power, calculating the increment of the required active power and reactive power, making corrections to VSG power, reducing the change of grid frequency and voltage, and providing inertial support through energy storage and electric vehicles, the simulation results show that the frequency and voltage are suppressed, verifying the effectiveness and feasibility of the proposed control strategy.

In order to emulate the frequency support characteristics of conventional synchronous generators (SGs), control algorithms based on the virtual synchronous generator (VSG) have been extensively applied to grid-tied converters. However, in the case that a large inertia is used in VSGs, active power oscillations can be introduced in the transients, due to the lack of enough damping effects. To avoid this phenomena, various solutions with additional damping terms have been proposed. This paper analyzes and compares six relevant fixed- parameter active-power-oscillation damping solutions in detail, where responses under set point and phase angle changes, the parameter sensitivity, and capabilities of limiting the rate of change of frequency (RoCoF) and attenuating power ripples are included. The results show the advantages and drawbacks of each solution, leading to the conclusion that extra damping terms may significantly degrade the inertial response of VSGs and have high dependency on the parameter estimation accuracy.

Virtual synchronous generators can provide the virtual inertia for power grids via simulating the characteristics of traditional synchronous generators. Nowadays, it is widely used in distributed generations. However, under unbalanced grid conditions, problems such as power oscillation and current distortion will occur. By introducing a new power reference calculation method which derived from the 1/4 cycle delay of the grid voltage, a power oscillation suppression strategy for virtual synchronous generators under unbalanced grid conditions is proposed in this paper. Compared with the conventional strategies which based on the calculation of the positive and negative sequence current reference, the power oscillation is suppressed and the current distortion is improved, at the same time, the proposed strategy is simpler because of not requiring the positive and negative sequence extraction. Simulation results show that the proposed strategy is correct and effective.