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Direct voltage control feature analysis method of grid-connected MMC

A technology of control characteristics and analysis methods, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve problems such as difficult determination of transfer function and difficulty in MMC application

Active Publication Date: 2018-12-07
POWER DISPATCHING CONTROL CENT OF GUANGDONG POWER GRID CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current research mainly uses DC voltage as a part of the control system, but the control system parameters need to be determined by the transfer function of the converter, and the transfer function of MMC is difficult to determine, so the application of the above method in MMC is difficult

Method used

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  • Direct voltage control feature analysis method of grid-connected MMC
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  • Direct voltage control feature analysis method of grid-connected MMC

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Experimental program
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Embodiment Construction

[0088] specific implementation plan

[0089] The invention adopts mathematical derivation to obtain the equivalent model of the modularized multilevel converter (MMC). Based on the model, the possibility and range of the MMC working under low DC voltage are studied.

[0090] 1. The process of establishing MMC equivalent model

[0091] In each sub-module of the MMC, there are two switch tubes connected in series, and the upper and lower switch tubes work complementary. When the upper switch is turned on, the lower switch is turned off. At this time, the module capacitor C is connected to the circuit and charged according to the direction of the bridge arm current. Or discharge. For the bridge arm, it is equivalent to adding a capacitor voltage, that is, a level. At this time, the module state can be defined as "on" or "1"; when the upper tube is turned off, the lower tube is turned on. At this time The module capacitor C is bypassed by the lower tube. For the bridge arm, it is...

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Abstract

The present invention provides a direct voltage control feature analysis method of a grid-connected MMC (Modular Multilevel Converter). On the premise of rigorous mathematical derivation, an equivalent static model of a grid-connected MMC meeting a mathematical relation established by employing a power electronic device is taken as a basis to analyze the possibility and the approximate scope of direct voltage control. The analysis is simplified after the MMC is accessed into the power system for operation, and it is clearly pointed out that the direct voltage control is related to a value of an inductor Lsac and a capacitor Cac. The inductor Lsac is different from the capacitor Cac so that the system is located in different modes, when the system meets different conditions in different modes, the direct voltage control is feasible, the range of the direct voltage control is determined to promote the application of the MMC in the power system and promote the development of the power system.

Description

technical field [0001] The invention relates to the technical field of power electronics, and relates to a characteristic analysis method of a grid-connected modular multilevel converter (MMC) controlled by DC voltage. Background technique [0002] As a special two-level voltage source converter (voltage sourced converter, VSC) structure, the modular multilevel converter MMC (Modular Multilevel Converter) was first developed by Marquardt and Lesnicar at the Bundeswehr University in Munich. It has many advantages, such as four-quadrant operation of rectification and inverter states, modular structure that can meet different levels of voltage, high-voltage and high-power requirements, no need to connect transformers, and redundant design. More and more extensive development and research. Its topology and sub-module structure are shown in figure 1 , three-phase MMC topology and half-bridge sub-module structure such as figure 1 As shown, the three-phase MMC is composed of 6 b...

Claims

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Application Information

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IPC IPC(8): H02M7/483
CPCH02M7/483H02M7/4835
Inventor 钱峰罗钢杨银国吴国炳娄源媛刘俊磊伍双喜张子泳
Owner POWER DISPATCHING CONTROL CENT OF GUANGDONG POWER GRID CO LTD