采用REI法进行大电网等值时会出现等值输电线路电阻为负值、与实际不符的情况,分析得知产生这一问题的原因在于等值过程中没有对外部系统的节点进行区分,以至于对研究系统稳态特性和暂态特性影响大、关联性强的关键节点被消去。针对此问题提出利用节点灵敏度分析的方法,即根据网络功率修正方程定义系统无功功率灵敏度矩阵和有功功率灵敏度矩阵。并结合电网实际灵敏度度量值,提出可判断外部系统等值过程中必须保留的关键节点的方法,并将此过程引入大电网同调等值法中。利用BPA仿真软件以新英格兰标准39节点系统为测试算例,采用改进后的同调等值法对外部系统进行简化等值,利用等值后系统稳态特性和暂态特性验证该方法的正确性和可行性。
Using the method REI to simplify the large-scale power system, the equivalented resistance of electric trassimision line is maybe negative;such things don’t tally with the reality. The cause of this problem is that the nodes in external systems aren’t distinguished in the process of equivalence, so that the key nodes which make a big difference with the researched system’s stationary and transient characteristics, and have strong correlation with the researched system are eliminated. Aiming at this problem the node sensitivity analysis approach is proposed; according to the network power correction equations to define the system’s reactive power and active power sensitivity matrix, and combining the practical measurement sensitivity of the grid, the method to estimate the key nodes in external systems which must be reserved is put forward;and this process is introduced in coherent-based equivalence of large-scale power system. Using BPA simulation software and taking the New England standard 39-node system as the test example, the external system is simplified by the improved coherent-based equivalence method;the validity and the feasibility of this method is verified by the stationary and transient characteristics of the equivalented system.