无功支撑对改善电压崩溃作用的研究

以单负荷无穷大母线系统推到得出电压不稳与功角不稳之间的关系，为了论证电压崩溃与电压不稳以及电压崩溃与功角不稳之间的关系，又以电力系统单机无穷大模型为基础，在此系统中只存在功角失稳问题，不存在电压崩溃问题，之所以这样是因为无穷大系统中有足够的无功支撑。倘若此处的无功补偿有限，当达到无功补偿的上限的时候，一个负荷扰动，便会使电压崩溃问题出现。电压不稳并不意味着电压崩溃，足够的无功支撑虽不能改变运行点处于电压不稳的现状，但是可以改善此运行点不发生电压崩溃的效果。电压崩溃与功角不稳发生的先后顺序取决于事故点的无功支撑能力的大小，并用仿真算例验证了所提的结论。

Reactive Power Support to Improve the Effects of Voltage Collapse

The relationship between the voltage instability and angle instability can be derived from the single load infinite bus system. To demonstrate the relationships between the voltage collapse and voltage instability and between the voltage collapse and angle instability, the single machine infinite model of the power system should serve as the foundation. In the system, there exists only angle instability issues rather than voltage collapse issues because the infinity has sufficient reactive power support. If the reactive power compensation is limited, when the ceiling of the reactive power compensation is reached, a load disturbance can cause the voltage collapse. However, the voltage instability does not mean the voltage collapse, because though enough reactive power support cannot change the operation point in voltage instability situation, it can improve the operating point to an effect that the voltage collapse does not occur. The occurrence sequence of voltage collapse and angle instability depends on the size of the reactive power support ability at the point of the accident. Finally, the simulation results have verified the proposed conclusion