A New Method for Testing Voltage Stability

Abstract

The invention discloses a novel voltage stability detection method. Through analysis on the various conventional voltage stability judgment methods based on a single-port impedance matching method, the conventional methods have obvious in errors in the aspect of margin estimation and are not suitable for a multi-load system. In order to overcome the shortcoming, on the basis of the single-port impedance matching method, an 'equivalent impedance matching' concept is supplied; all loads are transferred out of the equivalent system; and a power system is decomposed into a series of different single-port networks, namely 'coupled single-port' circuits. Under a coupling condition, interaction between the loads is simulated according to an impedance matching theory, so that an aim of monitoring the voltage stability on line is fulfilled. Theoretical analysis and simulation experiment verify the effectiveness of the method.

Description

technical field [0001] The invention relates to a novel voltage stability detection method, in particular to a method belonging to the field of power system research. Background technique [0002] Voltage stability is one of the most concerned issues in the power industry. Several major blackouts in recent years have been related to voltage collapse. Preventing voltage collapse requires an effective online voltage stability monitoring tool in addition to good offline system planning practices. Based on this consideration, many scholars have proposed many online voltage stability indicators. [0003] Among these indicators, the technology of using local phasor measurement to judge voltage instability has attracted extensive attention of experts and scholars. The main method of this type of technology can be summarized as: measure the local voltage and current phasors on the bus, and then obtain the Thevenin equivalent circuit of the system seen from this bus. If the load ...

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Problems solved by technology

However, [Y.Wang, W.Y.Li, and J.P.Lu.A new node voltage stability index based on local voltage phasors[J]. Electric Power Systems Research, pp.79(2009) 265271.] There are obvious defects in this method : When estimating the equivalent Thevenin parameters need to assume that they are all constant

However, this condition is difficult to satisfy during the voltage collapse process, because the system will experience continuous changes, such as line tripping, shunt capacitor switching, generator reaching reactive output limit, etc.

Also this approach is not suitable for multi-load systems

[0006] Chinese patent 200810016922.6, literature [Wang Yi, Liu Zhuo. System parameter tracking estimation based on Thevenin equivalent [J]. Grid Technology, 2000, 24(11):28-30], [Liao Guodong, Wang Xiaoru. Based on wide-area measurement On-line monitoring method of voltage stability [J]. Chinese Journal of Electrical Engineering, 2009, 29(4): 8-13], [Fu Ying, Li Xingyuan. On-line real-time voltage stability analysis based on static equivalence [J]. Power system automation , 1997, 21(11):25-28], [Wang Yang, Lu Jiping, Li Wenyuan, etc. Equivalent model based on local network voltage phasor and its voltage stability index[J]. Chinese Journal of Electrical Engineering, 2008, 28 (34):52-58] Although the voltage stability judgment method only needs to detect voltage and current data in the local bus, it is easy to implement, but there are obvious defects

First of all, this type of method needs to assume that these parameters remain unchanged when estimating the Thevenin equivalent parameters. However, this condition is difficult to meet during the voltage collapse process, and the entire system (including Thevenin equivalent parameters) will continue to change

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