A Voltage Control Strategy of VSG Based on Self-Adaptive Inertia Coefficient and Droop Coefficient

Shizhi Lin,Buying Wen,Lei Lin,Qiuye Sun

doi:10.1155/2021/5567826

Abstract

With the increasing penetration rate of distributed renewable energy in power systems, the control strategy of virtual synchronous generator (VSG) is widely used for several years. Some existing VSG control strategies have been able to solve the stability problems caused by the abnormal grid voltage, but the effects of the inertia coefficient and the droop coefficient on the voltage stability are not taken into account. In order to further improve the voltage stability of the microgrid system, a voltage control strategy of VSG based on self-adaptive inertia coefficient and droop coefficient is proposed in this paper. When the voltage is far from the steady state, the increase of the inertia coefficient can decrease the voltage deviation. On the contrary, when it is close to the steady state, the decrease of the inertia coefficient can make the system response speed accelerate. According to the real-time voltage deviation, the droop coefficient can change adaptively to decrease the adjusting time and the voltage deviation during the disturbance. Finally, the simulation model of VSG is built by MATLAB/Simulink for conducting simulation experiments. Compared with other strategies, the correctness and effectiveness of the proposed control strategy are validated.

Highlights

With the energy crisis and environmental pollution becoming increasingly serious, the penetration rate of distributed renewable energy in power systems is constantly increased. erefore, the renewable energy such as solar and wind has been widely used and studied [1,2,3,4]
Where Kmax and Kmin are the maximum and minimum values of the inertia coefficient, respectively, Ks is the inertia coefficient in steady state, Dqo is the initial droop coefficient of the reactive power loop, Vk and Vd are the threshold of the output voltage change rate, and kd is the regulation coefficient between the voltage deviation and the droop coefficient
For the strategy II, the inertia coefficient K and the droop coefficient Dq of the reactive power loop are set as 21 var·s/V and 321 var/V, respectively

Summary

Introduction

With the energy crisis and environmental pollution becoming increasingly serious, the penetration rate of distributed renewable energy in power systems is constantly increased. erefore, the renewable energy such as solar and wind has been widely used and studied [1,2,3,4]. In order to further improve the stability of the system voltage, a control strategy of VSG based on self-adaptive inertia coefficient and droop coefficient is presented in this paper. (1) Based on the traditional droop control strategy, the integral link is introduced into the reactive power loop of VSG, which alleviates the dynamic response process of the output voltage and the reactive power. Ω is the mechanical angular velocity of the synchronous generator, ωn is the rated rotor angular velocity, Kω is the droop coefficient between active power and frequency, J is the virtual inertia, Dp is the damping coefficient, Pset and Pe are the given value of the active power and the output active power, respectively, and θ is the phase angle of output voltage. K is the inertia coefficient of the reactive power loop, Dq is the droop coefficient between reactive power and voltage, Un is the rated voltage amplitude, and Em is the valid value of the reference voltage

Adaptive Inertial Coefficient and Droop Coefficient Control Strategy

Stability Proof and Parameter Range Setting

Simulation Results

Conclusions