电网模拟装置的研究

Research on Grid Simulator

研制了一种电网模拟装置用来模拟电网的各种故障工况,进而实现变流器电网适应性的测试。该装置采用背靠背方式的四象限变流器组成。整流侧变流器采用直流电压外环、有功电流内环的经典双环控制,实现了对直流电压及功率因数的控制。逆变侧变流器采用基于比例谐振(PR)控制器的双环控制,能够实现任意可调的电压幅值和频率,并可模拟电压三相不平衡跌落。分析推导了电压三相不平衡跌落的算法,同时为了保证在各种负载条件下电网模拟装置输出的电能质量,利用电容并联虚拟阻抗控制策略实现了输出滤波器的谐振抑制。通过实验验证了所提出算法和控制策略的有效性和正确性。

A grid simulator is presented to simulate various fault working conditions and to test the performance of converter when connected to grid.The grid simulator adopts the four-quadrant converter consists of back-to-back mode. The rectifying-side converter adopts the classic double-loop control strategy which contains DC voltage loop and active current loop to control the DC voltage and power factor.And the inverting-side converter adopts double loop control strategy based on proportional resonant （PR） regulator to adjust voltage amplitude, frequency and simulate the unbal- anced three-phase voltage sag.The analysis of unbalanced three-phase voltage sag algorithm is deduced.In addition, in order to ensure the quality of output voltage in various working conditions, a method of virtual resistor in parallel with capacitor is applied into suppress the resonant output filter.At last, experimental results are given to verify the validity and effectiveness of the proposed algorithm and control strategy.