Voltage sag, swell and flicker generator with series injected inverter

This paper proposes a new SSFG (sag, swell and flicker generator) with series injected inverter for the Korea Custom Power Test Center, which is being constructed with the fund of the National Project in Korea. The main purpose of this site is to test and to evaluate several different kinds of high power CPD (custom power device) under the several power disturbance conditions before installing it in real site. We can generate typical power disturbances such as sag, swell, over voltage, under voltage and voltage flicker by using the proposed SSFG composed of series inverter, energy storage DC capacitor, rectifier and voltage clamp circuit. Also we can generate the distorted voltage waveforms and the phase jumping waveforms by controlling the series inverter. In this paper, three kinds of control methods for the proposed 2 MVA SSFG are given. Typical voltage sag and swell waveforms are implemented by adopting simple control method. Also the voltage flicker is generated by changing the amplitude of the injected voltage in random. Owing to the limited bandwidth of the proposed SSFG, high frequency transient waveforms can be obtained by using the open loop control. The simulation and experimental results are given to verify the operation of the proposed SSFG. Finally, conclusions are given.