基于直流频率限制控制器的超低频振荡抑制方案

Suppression Scheme for Ultra-low Frequency Oscillation Based on Frequency Limit Controller

随着鲁西背靠背以及渝鄂背靠背工程的相继推进,异步联网后送端电网出现的超低频振荡威胁着系统的稳定运行。针对异步联网后的多直流送出系统,分析了超低频振荡产生原因及直流频率限制器(FLC)抑制超低频振荡的机理。结合直流FLC影响因子和直流控制敏感度提出了一种考虑送端电网水电分布的直流排序方法。并据此提出了一种的超低频振荡抑制方案,该方案利用最小二乘法–旋转不变技术的信号参数估计算法和改进粒子群优化算法,将多直流优化问题转化为多个单直流顺序循环优化问题,以实现对超低频振荡较好的抑制。最后以渝鄂异步联网后的川渝电网为算例,仿真验证了所提方案的有效性。

With the developmment of Luxi Back-to-Back HVDC project and Yu’e Back-to-Back HVDC project, ultra-low frequency oscillation becomes a serious threat to the stability of power system. For an asynchronous interconnection multi-send HVDC system, the mechanism of ultra-low frequency oscillation and suppressing ultra-low frequency oscillation by FLC(frequency limit controller) is analyzed. Considering the distribution of hydropower in the sending end, a new DC sorting method is proposed, which combines the influences of DC power change on AC system and sensitivity of ultra-low frequency oscillation mode. Based on the results above, a new suppression scheme is proposed. In order to achieve a better suppression effect, the multi DC optimization problem is transformed into multiple single-DC sequential optimization problems in the scheme by TLS-ESPRIT(total least squares-estimation of signal parameters via rotational invariance techniques) and improved PSO(particle swarm optimization). Finally, the effectiveness of the scheme is verified by simulation results of Sichuan-Chongqing power system which already has an asynchronous interconnection with Hubei power system.