偏远地区小电网与主网解列后高频高压风险及抑制策略

Over-frequency and overvoltage risk of isolated small power grid in remote area and its suppression strategy

随着无电地区电网的建设,大量具有小机组、轻负荷特性的偏远地区小电网逐渐通过极长的联络线路与主网相连。一旦由于故障等因素,这些小电网与主网解列而转为孤网运行时,小电网中过剩的有功功率以及充电无功极有可能导致严重的高频高压风险,造成设备以及负荷的损毁。首先,结合四川某藏区电网,对小电网与主网解列后的高频高压现象进行了研究,分析了高频高压现象出现的机理。其次,探讨了电网内发电机调速、励磁装置的控制方式以及负荷特性对高频高压风险的影响。最后,在分析传统抑制策略所存在不足的基础上,提出了一种基于高周解列的偏远地区电网与主网解列后高频高压风险的抑制策略。仿真结果验证了策略的有效性。

As the expansion of the power grid, many small power grids in remote areas with small generators and light loads are connected to the main grid through very long transmission lines. Once such a small power grid is split from the main power grid due to a certain fault, over-frequency and overvoltage is very likely to occur due to its excessive real power or capacitive reactive power, which could damage power equipments and local loads. First, the mechanism of over-frequency and overvoltage and their interaction in an isolated small power grid are analyzed. And then the influences of generator speed governor and excitation system as well as load characteristics on over-frequency and overvoltage are also introduced. Finally, a new suppression strategy is proposed for over-frequency and overvoltage of the isolated small power grid in remote area. Simulation results verify the effectiveness of the proposed suppression strategy.