基于SVG的光伏并网SSO附加阻尼抑制策略

针对大规模光伏(photovoltaic, PV)并入弱交流电网的次同步振荡(sub-synchronous oscillation, SSO)问题，提出一种基于静止无功发生器(static var generator, SVG)附加阻尼控制策略抑制的方法。该方法提取PV并网点电压作为输入信号，通过附加次同步阻尼控制器(supplementary sub-synchronous damping controller, SSDC)生成与并网点次同步电压同相位的次同步电流信号，使SVG在次同步频率下等效为并联接入系统的正电阻，消耗SSO能量实现抑制。此外，详细分析了SSDC的结构和参数设计方法。最后，以西北某PV电站为实例，通过电磁暂态仿真验证了上述抑制控制策略在多种工况下的有效性，该控制策略可提高光伏系统的稳定裕量。

SVG Based Supplementary Damping Mitigation Strategy for Sub-Synchronous Oscillation in Grid-connected Photovoltaic Plants

To mitigate the sub synchronous oscillation (SSO) in large-scale photovoltaic (PV) plants integrated to weak AC networks, a static var generator (SVG) based supplementary damping control strategy is proposed. The strategy extracts the voltage at the PV coupling point as input signal, and produces the sub-synchronous current that is in the same phase with the sub-synchronous voltage at the coupling point through supplementary sub-synchronous damping controller (SSDC). Thus, the SVG is equivalent to the positive resistance of the accessing the system in parallel at the sub-synchronous frequency, and dissipates the SSO energy for suppression. In addition, the structure and parameter design method of SSDC are analyzed in detail. Finally, taking a PV plant in northwest China as an example, the mitigation effectiveness of the proposed control strategy is verified under various working conditions through electromagnetic transient simulation, which shows that the proposed control strategy can improve the stability margin of the photovoltaic system.