Negative sequence compensation method of cascade connection multi-level circuit based on isolation type bidirectional transducer

A bidirectional converter, cascaded multi-level technology, applied in reactive power compensation, reactive power adjustment/elimination/compensation, AC network to reduce harmonics/ripples, etc., can solve energy storage capacitor energy exchange and other issues

Inactive Publication Date: 2009-01-14
BEIJING JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The technical problem to be solved by the present invention is to solve the problem of energy exchange of energy storage capacitors in diff

Method used

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  • Negative sequence compensation method of cascade connection multi-level circuit based on isolation type bidirectional transducer
  • Negative sequence compensation method of cascade connection multi-level circuit based on isolation type bidirectional transducer
  • Negative sequence compensation method of cascade connection multi-level circuit based on isolation type bidirectional transducer

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Embodiment Construction

[0013] Embodiments of the present invention will be further described in conjunction with the accompanying drawings:

[0014] figure 1 It is a block diagram of the negative sequence compensation structure of a typical three-phase single-stage multi-level circuit, three power units A 1 , B 1 、C 1 Respectively form A, B, C three-phase bridge arm, capacitor C A1 、C B1 、C C1 Respectively power unit A 1 , B 1 、C 1 the energy storage capacitor. When the negative sequence current appears, it will cause the capacitor voltage on each phase to be unbalanced, and the negative sequence current will cause the voltage on the energy storage capacitor to fluctuate, the capacitor voltage of the energy flowing into the phase will rise, and the capacitor voltage of the energy flowing out phase will drop . Each bidirectional converter unit has three ports, P A1 ,P B1 ,P C1 , the three ports are connected to C A1 、C B1 、C C1 Connected to realize energy exchange between the three, t...

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Abstract

The invention discloses a negative sequence compensatory method of a cascade multilevel circuit based on isolation type bidirectional converter, furthermore relates to an improvement method of a power supply quality, which implementing the energy exchange of an energy storage capacitor between different phases through the high frequency isolated multi-port bidirectional converter. The multi-port bidirectional converter is connected to an energy storage capacitor (CAk) of (Ak) by the port (PAk), connected to an energy storage capacitor (CBk) of (Bk) by the port (PBk) and connected to an energy storage capacitor (CCk) of (Ck) by the port (PCk), wherein K>=1; the negative sequence compensatory is implemented by balancing each energy storage capacitor in cascade multilevel circuit between each phase through the multi-port converter. The capacitor energy exchange between phases of the cascade multilevel circuit is implemented according to the invention and the problem of unimplementation of negative sequence balance in the prior cascade multilevel circuit is overcome. The method of the invention is also used in the polyphase system, which greatly expands the application field of the cascade multilevel circuit.

Description

technical field [0001] The invention relates to a method for improving power quality, in particular to a negative sequence compensation method for cascaded multilevel circuits. Background technique [0002] In the power system, due to the use of asymmetric or nonlinear loads, the three-phase unbalanced negative sequence and high-order harmonic currents generated by it are injected into the three-phase power grid system, which affects the power quality of the power supply system and also causes a large number of additional loss. Devices such as active power filters and reactive power compensators are effective solutions to improve power quality. However, in applications in the high-voltage field, due to the limitation of device withstand voltage, the common way is to connect the general-purpose inverter bridge main circuit and high-voltage power grid through a power frequency transformer. However, the heavy power frequency transformer greatly increases the power electronic c...

Claims

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Application Information

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IPC IPC(8): H02J3/18H02J3/01
CPCY02E40/30Y02E40/40
Inventor 郑琼林贺明智杨晓峰游小杰林飞郝瑞祥黄先进
Owner BEIJING JIAOTONG UNIV
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