Research On Custom Power Technology Based On RT-LAB

Custom power use power electronic equipment on 1-35kV distribution system,to supply reliable and superior power for consumer with special needs.As two key device in custom power,Uninterruptable Power System(UPS)and Static Transfer Switch(STS)are widely applied in important conference venues,intelligent buildings,advanced manufacturing plants,hospitals,financial data centers and so on.This thesis centers on control technology,voltage sag detection technology,switching control technology revolved in these two device to launch research.This thesis selects the appropriate topology of fore-end rectifier and rear-end inverter circuit of UPS,and analysis the building model of three-phase VSR.Then adopt the efficient controlling mothod,and adjust the PI parameters synergistically.Design the inductance and capacity parameter.Make the UPS system rated power up to 100kW,output voltage waveform’s THD within 5%.Meet the performance requirements of mainstream products.Both the UPS and STS need to use the voltage sag detection technology,and except the RMS,FFT,STFT,and wavelet transform,we want to obtain a method can detect both the amplitude and phase of sag voltage fast.So explore the three-phase dq detection method,single-phase dq detection method,and single-phase αβ detection method.And further obtain better detection speed by diffing the latter two.This thesis discovered that owe to the effect of the filter,single-phase dq method cannot lead 30°(that is 3.33ms)before the single-phase αβ method.And owe to the voltage distortion when the sag occurs,the two derivatives do not have practicality.To sum up,the single-phase dq is widely used in engineering practice,and its speed and precision can satisfied the need of sensitive load.In the end of this chapter,put forward the digital PLL to substitute the traditional analog PLL,and improve the PLL program to lock the before-sag phase in the register.The simulation results proved the PLL method effectively.The switch method of STS mainly contains the natural commutation,auxiliary commutation,and forced commutation.This thesis analyses the process of the LC resonant auxiliary commutation,the LC resonant auxiliary commutation with feed diode,LC bridge auxiliary commutation and the forced commutation.To improve the forced commutation’s performance(the switch time)in the influence of load power factor,the phase difference of primary and alternative source,modify the switch algorithm to more simple to meet the time requirement of high-performance products.The simulation results prove the improved algorithm can work well in forced commutation,without voltage peak and circulating current.Last,program the voltage sag detection method and STS switch control way in CCS and download in DSP,carry out Hardware-in-the-loop real-time simulation experiment in RT-LAB,and the experiment results testify the method validity.