Triangular connection type comprehensive compensation system integrated with cascaded active filter and reactive compensator

Abstract

The invention discloses a triangular connection type comprehensive compensation system integrated with a cascaded active filter and a reactive compensator. The system comprises triangular connection type N-grade cascaded converters and a three-phase filter inductor connected with each N-grade cascaded converter; triangular connection type thyristor reactors and star-shaped connection type thyristors are used for switching the reactive compensator composed of fixed capacitors; and the triangular connection type N-grade cascaded converters and the reactive compensator are connected in parallel between a connection node and a ground node of an input power grid voltage and a load. According to the system provided by the invention, reactive power and harmonic current in a medium-voltage power grid are subjected to dynamic compensation and the efficiency of the power grid is improved; when the system is used for compensating, the system has no negative influences on the power grid, and has advantages of stable system, simple structure, strong stability and flexibility in compensation.

Description

technical field [0001] The invention relates to the technical field of reactive power compensation and harmonic control, in particular to a delta-connected cascaded active filter and reactive power compensator comprehensive compensation system. Background technique [0002] There are a large number of inductive loads in the power grid, and the application of electric drive is more and more widely, so that there is a large amount of inductive reactive current in the power grid. At the same time, with the development of power electronics technology, more and more nonlinear loads are running in the power grid. A large number of harmonic currents are generated, causing electromagnetic pollution. In order to ensure the power quality of the power grid, it is necessary to compensate the reactive power and harmonics of the power grid. Therefore, dynamic reactive power compensation technology and active filter technology are two key technologies in the field of power quality. [000...

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Problems solved by technology

[0010] (1) Deng Likuan et al. conducted a preliminary study on the stability control of the low-voltage three-phase four-wire system APF and SVC joint operation, mainly aiming at the control coupling problem of APF and SVC under a specific structure, and pointed out that by selecting the appropriate control algorithm bandwidth of APF and SVC , can suppress the oscillation of the two, or only detect specific harmonics in the APF current detection link, and can also eliminate the instability problem, but only the stability analysis of the simple simultaneous operation of the two is done, and the APF and SVC are not analyzed. Integrated control, joint compensation and optimization for further study, also not for high voltage level cases

[0011] (2) San-Yi Lee et al. proposed the combined operation of hybrid APF and SVC to compensate the medium-voltage or high-voltage power grid. The fundamental reactive power and negative sequence current are compensated by the large-capacity SVC, and the grid voltage is adjusted to improve the dynamic process of the power grid. capacity of the mixed APF to filter out the harmonics of the SVC, a preliminary study of this comprehensive compensation system, this system still has a series of shortcomings of passive filters; An Luo et al. studied the comprehensive compensation of mixed APF and SVC The improved control algorithm of SVC compensation effect and the stable control of APF, the method of frequency division compensation is proposed to solve the stability problem, and the improved generalized integral controller is used to reduce the harmonic detection lag and compensation delay, which improves the compensation accuracy, but still No further study on integrated control of APF and SVC

[0012] (4) Yu Hongxiang et al. proposed a PWM-modulated SVC structure, using turn-off devices to achieve reactive power compensation and reduce harmonics. This structure still has higher-frequency harmonics, and the applicable voltage level is subject to turn-off Break device withstand voltage limit

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