LCC-HVDC系统混合型有源滤波器谐振抑制策略

基于级联H桥的混合型有源滤波器因其耐高压、动态调节能力强等优点,为传统高压直流输电的谐波治理问题提供了较优的解决方案。但由于控制延时的影响,滤波器可能存在负阻抗特性,使系统存在较大的谐振风险,危及电网的安全稳定运行。针对该问题,文中首先建立考虑控制延时的滤波器阻抗模型,定量分析了延时和系统稳定性之间的关系,提出了基于最小均方算法的自适应谐振抑制策略。该方法通过预测电流波形,补偿控制延时引起的相位滞后,避免滤波器呈现负阻抗特性,从而消除谐振风险。最后,在PSCAD/EMTDC上进行仿真分析和验证。仿真结果表明,该滤波器具有良好的滤波效果,所提谐振抑制策略可在一个周期内有效抑制谐振,具有自适应电路参数和工况变化的能力。

Resonance Suppression Strategy of Hybrid Active Power Filter in LCC-HVDC System

The cascaded H-bridge hybrid active power filter (HAPF) has the advantages of high voltage resistance and strong dynamic adjusting ability, which provides a great solution for harmonic control of line commutated converter based high voltage direct current (LCC-HVDC) transmission systems. However, due to the influence of control delay, HAPF may have negative impedance characteristics which make the system have great resonance risk and endanger the safe and stable operation of the power grid. To solve this problem, a filter impedance model considering the control delay is established. On this basis, this paper quantitatively analyzes the relationship between delay and system stability, and proposes an adaptive resonance suppression strategy based on the least mean square algorithm. By predicting the current waveform to compensate the phase lag caused by the control delay and eliminate the negative impedance characteristic of HAPF, the strategy can eliminate the resonance risk. Finally, the simulation model is built in the PSCAD/EMTDC environment for verification. The simulation results show that the filter has a good filtering effect, and the proposed resonance suppression strategy can effectively suppress resonance in a power cycle and adapt to the change of circuit parameters and operation conditions.