On-line voltage stability evaluation method of AC-DC system based on wide-area measurement

Abstract

The invention discloses an online voltage stabilization assessment method for an alternating current and direct current system based on wide-area measurement. The method comprises the following steps:obtaining state quantity information under the current alternating current and direct current system based on real-time measurement; through the real-time measurement information of a direct currentsystem converter station, based on a direct current system quasi-steady-state mathematic model, establishing the online equivalent models of rectification side and inverter side converters respectively; based on wide-area measurement information and a direct current system converter equivalent model, establishing a load node Thevenin's equivalent circuit; expanding the voltage stabilization L index of an alternating current system into a voltage stability index applicable for the alternating current and direct current systems, and proposing the expanded L index to assess the voltage stabilityof the alternating current and direct current system. According to the method, the operation mode and control system actions of a direct current system can be taken into account accurately, and the voltage stability level of an alternating current and direct current power grid is assessed comprehensively by the system.

Description

technical field [0001] The invention relates to an online voltage stability evaluation method of an AC / DC system based on wide-area measurement. Background technique [0002] Grid-commutated UHVDC (LCC-HVDC) transmission technology has become an important form of power transmission from energy bases to load centers due to its advantages of large long-distance transmission capacity and strong asynchronous interconnection capabilities. With the development of energy Internet, modern power grids have formed the following UHV AC and DC are the main transmission channels, the interaction of AC and DC systems is complex, and the contradictions in power grid operation are more prominent. The DC system is widely connected, and the proportion of its transmission capacity is increasing day by day, which weakens the strength of the AC system at the receiving end. The DC converter equipment needs to consume a large amount of reactive power. When the reactive power reserve of the system ...

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Problems solved by technology

[0005] 1) Lack of systematic on-line AC-DC system voltage stability assessment method, not effectively combining real-time measurement information of the system, it is difficult to meet the real-time requirements of on-line voltage stability assessment

[0006] 2) The influence of different operating modes of DC system converters, DC control system and converter transformer actions on voltage stability is not fully considered

[0007] 3) The mathematical model of the DC system adopted is complex, it is difficult to meet the requirements of online applications, and the voltage stability index of the original AC system cannot be extended to apply to the system structure of the AC-DC hybrid

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