Active/passive switching control method for MMC-HVDC island power grid

A MMC-HVDC, island power grid technology, applied in the direction of power transmission AC network, circuit devices, electrical components, etc., can solve the problems of unrecoverable stability, electrical quantity fluctuations, etc., and achieve the balance of active power in the whole network and high waveform quality , The effect of low switching frequency

Inactive Publication Date: 2019-07-19
CHINA UNIV OF PETROLEUM (EAST CHINA)
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Problems solved by technology

[0004] During the process of the island grid changing from an active network to a passive network, the electrical quantities in the island grid will fluctuate significantly, and the stability cannot be restored in a short time

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  • Active/passive switching control method for MMC-HVDC island power grid
  • Active/passive switching control method for MMC-HVDC island power grid
  • Active/passive switching control method for MMC-HVDC island power grid

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Embodiment Construction

[0026] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0027] Such as figure 1 , provides a flow chart of an active / passive switching control method for an MMC-HVDC island power grid, and the specific implementation steps are as follows:

[0028] Step 1: First of all, it is necessary to ensure that the island power grid works in the active network state, which is the initial state by default, that is, the inner loop adopts fast current control, and the rectifier side in the outer loop control link adopts constant DC voltage control and constant reactive power control, and the inverter The side adopts constant active power control and constant AC voltage control, and uses a phase-locked loop to lock the grid phase;

[0029] Step 2: On the basis of step 1, determine whether the power generation system in the island power grid is in normal operation. If the power generation system is in normal operation, the island...

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Abstract

An active/passive switching control method for an MMC-HVDC island power grid is a control method capable of enabling an island power grid to realize smooth and stable switching at active/passive switching moments. The method includes the following steps of: firstly, when an island power grid is in an active network state, judging whether a power generation system is normally operated, and if the power generation system is normally operated, determining that the island power grid continues to operate in the active network state; if the power generation system exits the operation in the event ofa fault, determining that the island power grid generates active power vacancy and results in power grid frequency oscillations, dynamic load changes and other phenomena, wherein at this time, a phase angle following and outer loop power optimization control method needs to be added at the switching moment, so that the fluctuation of each electrical quantity at the switching moment is minimized,and the system gradually returns to a stable state; and finally, smoothly switching the island power grid to a passive network state. By adopting the method, the reliability of the island power grid at the switching moments can be improved, the normal operation of the island power grid at both the active and passive states can also be ensured, and the stability of the system can be enhanced.

Description

technical field [0001] The invention relates to the field of flexible direct current transmission, in particular to an active / passive switching control method for an MMC-HVDC island power grid. Background technique [0002] An island power grid refers to a local power grid constructed by multiple groups of small power generation systems. However, due to the limited capacity of the island power generation system, external power supply can be used to meet the power demand. [0003] Nowadays, flexible direct current transmission technology has been widely used in many fields, among which, the power supply of island grid by flexible direct current transmission technology has received more and more attention. Compared with the traditional voltage source converter, the Modular Multilevel Converter (MMC) proposed by German scholars in 2002 has a modular design, more levels of output voltage, high waveform quality, With the advantages of low switching frequency and low loss, it ca...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38H02J3/36H02J3/24
CPCH02J3/381H02J3/36H02J3/24H02J3/388Y02E60/60
Inventor 马文忠古丽帕丽·赛力江周冠宇孙鹏张子昂
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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