增强型SVG多机并联谐振机理与抑制方法研究

增强型静止无功发生器(ASVG)由于同时具有补偿无功与改善波形的作用,得到了广泛应用。由于增强型SVG的核心部分为开关电路,因此其输出存在开关次谐波,为了抑制这一谐波,增强型SVG的出口通常都接有LCL型滤波器。单台SVG并网时,通过事先整定相关参数,能够较好地实现无功补偿与改善波形的功能。但实际系统中,通常会有两台甚至更多SVG并列运行,此时由于LCL型滤波器与电网自身的电气特性,系统中可能会出现谐振,从而对系统的稳定性带来不利影响,此时依靠参数整定难以进行有效处理。本文通过研究等效电路与仿真,分析了增强型SVG在并列运行时的谐振机理,并提出了一种谐振抑制协调控制方案。

Study on Multiple Parallel Resonance Mechanism and Suppression Method of Advanced SVG

The Advanced SVG has been used widely due to its function of compensating reactive power and improving waveform simultaneously.Since the core part of the enhanced SVG is the switching circuit,therefore its output exists switching sub?harmonics.For suppressing such harmonics,theoutlet of enhanced SVG is usually connected with the LCL filter.When a single SVG is connected to the network,the function of reactive power compensation and waveform improvement can be better realized by setting relevant parameters in advance.In a real system,however,there are usually two or more SVG’s running in parallel.In this case,due to the electrical characteristics of the LCL filters and the power grid itself,resonance may occur in the system,which has an adverse impact on the stability of the system and,at this time,it’s difficult to deal with the resonance effectively by parameter setting.In this paper,the resonance mechanism of enhanced SVG’s running in parallel is proposed and a kind of resonance suppression coordination control scheme is proposed through equivalent circuit study and simulation.