高渗透率水电接入的变电站备自投逻辑优化研究

Logic optimization of a transformer substation busbar automatic transfer switch with high penetration of hydropower

首先分析了含高渗透率水电区域电网的孤网运行频率特性,指出水电残压造成变电站备自投动作时间长、正确动作率低的问题,提出了含高渗透率水电区域电网的快速同期并网功能的方案,并指出了增加频率变化率作为快速同期并网判据以及水电机组高频保护判据的必要性。提出了基于扩展卡尔曼滤波的快速频率及频率变化率计算方法,给出了电网基波频率快速跟踪算法流程。在此基础上,根据小水电孤网初期频率不能突变的特征,提出了改进的备自投及水电机组高频保护逻辑。通过PSCAD仿真验证了对含高渗透率水电区域电网的孤网运行频率特性分析的正确性,并在自主研发的备自投装置中实现并验证了所提算法。通过实际工程验证了所提备自投方案的有效性。所提备自投方案可显著降低含高渗透率水电区域电网的备自投时间,提升电网的供电可靠性。

An analysis is made of the frequency characteristics of isolated grid operation of a regional power grid with high permeability of hydropower, and points out the problems of long operation time and low correct operation rate of substation standby automatic switching caused by hydropower residual voltage. It puts forward a scheme of a fast synchronous grid connection function of the regional power grid with high permeability hydropower, and points out the necessity of having increasing frequency change rate as the criterion of fast synchronous grid connection and the criterion of high-frequency protection of hydropower units. A calculation method of fast frequency and frequency change rate based on extended Kalman filter is proposed, and the algorithm flow of fast tracking fundamental frequency of power grid is given. From the knowledge that the initial frequency of a small hydropower isolated network cannot change suddenly, an improved standby automatic switching and high-frequency protection logic of hydropower units are proposed. PSCAD simulation is used to verify the analysis of the frequency characteristics of isolated network operation of a regional power grid with high permeability hydropower, and the proposed algorithm is implemented and verified in the self-developed standby automatic switching device. The effectiveness of the proposed automatic switching scheme is verified by practical engineering. The scheme proposed in this paper can significantly reduce the standby automatic switching time of a regional power grid with high permeability of hydropower and improve the power supply reliability of the power grid.