Bipolar short circuit fault current calculation method of MMC-based HVDC system

A technology of bipolar short circuit and fault current, applied in the fields of calculation, electrical components, electrical digital data processing, etc., can solve the problems of low fault current accuracy and little research on fault current quantitative calculation, and achieve the effect of error reduction.

Inactive Publication Date: 2017-02-15
NORTH CHINA ELECTRIC POWER UNIV (BAODING) +1
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Problems solved by technology

Due to the relatively late emergence of the MMC topology, the current fault research on MMC is mainly focused on the control strategy and simulation analysis of the AC system fault, and there is little research on the quantitative calculation of the fault current. not tall

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  • Bipolar short circuit fault current calculation method of MMC-based HVDC system
  • Bipolar short circuit fault current calculation method of MMC-based HVDC system
  • Bipolar short circuit fault current calculation method of MMC-based HVDC system

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Embodiment Construction

[0029] The embodiments will be described in detail below in conjunction with the accompanying drawings. The invention proposes a bipolar short-circuit fault current calculation method of an MMC-based HVDC system.

[0030] First analyze the bipolar short circuit fault mechanism and equivalent discharge circuit.

[0031] (1) During steady-state operation, collect bridge arm current data, and establish the composition of the AC side current and DC current when the bridge arm current is established.

[0032] (2) When a fault occurs, the sub-module capacitor discharges rapidly, which is similar to a three-phase short circuit for the AC system. The bridge arm current is the superposition of the short-time current and the sub-module capacitor discharge current.

[0033] (3) According to the sub-module input and cut-out rules, taking phase A as an example, the discharge circuit is as follows figure 1 shown.

[0034] (4) will figure 1 After performing equivalent simplification, it...

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Abstract

The invention belongs to the technical field of power system direct-current power transmission, and particularly relates to a bipolar short circuit fault current calculation method of an MMC-based HVDC system. The method comprises the following steps of: establishing an operation system of double-end MMC-HVDC, and obtaining element parameters of a power transmission system; setting direct-current system bipolar short circuit faults at different moments and fault points; carrying out equivalence on the discharging process according to a fault current component and a discharging current generation mechanism, importing a regulatory factor to an equivalence parameter, and simplifying a discharging current calculation formula; and firstly importing the regulatory factor to fit a curve of the discharging current on the basis of an Lsqcurvefit fitting function of MATLAB, so as to obtain a final discharging current calculation manner. Through a coefficient of determination, the superiority of the fitting effect is explained, and the calculation formula can provide reference basis for equipment selection, fault principle design and fault fixed value setting.

Description

technical field [0001] The invention belongs to the technical field of DC power transmission in power systems, and in particular relates to a bipolar short-circuit fault current calculation method of an HVDC (High Voltage Direct Current Transmission) system based on an MMC (Modular Multilevel Converter). Background technique [0002] As one of the key technologies of the smart grid, flexible DC transmission can realize rapid independent decoupling control of active and reactive power, reduce harmonic content and have no commutation failure problem, and is widely used in distributed generation grid connection and island power supply , asynchronous interconnection of AC systems, multi-terminal DC transmission and capacity expansion of urban distribution networks. As a new type of multilevel converter topology, Modular Multilevel Converter-High Voltage Direct Current (MMC-HVDC) uses sub-modules (Sub-Module SM) connected in series The method avoids the direct series connection ...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/50H02M7/483
CPCG06F30/20H02M7/483H02M7/4835
Inventor 姜斌龚雁峰曹军
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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