Study On The Multi-mode Voltage Swell/Sag Generator(VSSG) Based On The IGPT PWM Control

A solution of a multi-mode voltage swell/sag generator(VSSG)based on the IGBT PWM control is presented.It can accurately simulate various faults of the power system and responses fast.The VSSG is developed for the need of the research project of state grid Zhejiang electric power research institute on power source and grid coordinate technology of key auxiliary frequency converters in thermal power plant.This power generating device can be used as a voltage generator for testing the high/low voltage ride through ability of frequency converter and the high/low voltage ride through supporting devices.The VSSG is designed according to the common multi-mode voltage swell/ sag generator standard which can also be used for similar tests on other electrical equipment.The characteristics of various power system faults and their changing rules in the process of propagation are analyzed.A statistical analysis for the required simulation of the power system failure is conducted base on two classification methods of fault type and transformer model,which provides the basis for the design of VSSG output characteristics.In this paper,the solutions in the same field are compared and introduced.According to the predecessors' theory,the voltage swell/sag generator based on the topology of two series capacitors in the DC bus of three-phase inverter is presented.The mathematical model of the proposed scheme is established,and the control strategy which contains the double closed-loop control and feedforward control of the DC bus series capacitor voltage deviation is designed.The program control circuit and controller parameters are designed by the platform of Matlab/Simulink.The feasibility of the scheme is verified by the simulation results.Based on the simulation results,the hardware platform of the voltage swell/sag generator is built.The experimental results of no-load experiment and load experiment coincide with the theoretical expectation,which proves the correctness of the scheme.And the VSSG is certified by state grid Zhejiang electric power research institute.