Direct current voltage control method for multi-terminal flexible direct current system

Abstract

The invention discloses a direct current voltage control method for a multi-terminal flexible direct current system. The direct current voltage control method of the multi-terminal flexible direct current system specifically comprises the steps that firstly, modeling analysis is conducted on the multi-terminal flexible direct current system, and modeling objects comprise the multi-terminal flexible direct current system comprising a wind power plant, a PQ current converter and a main current converter; secondly, a norm control method is applied to design of a controller, the norm control method allows controlled local direct-current voltage to correspondingly change according to scheduling requirements, and the control precision of the direct-current voltage of the system is improved; and finally, the system is simulated by adopting the provided control method through MATLAB / SIMULINKR, and the feasibility and effectiveness of the control strategy of the system are verified. The method has the advantages that the norm controller is adopted for voltage regulation, power reserve can be effectively managed in the form of a wind turbine, and the robustness and the control precision of the system are improved.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a DC voltage control method for a multi-terminal flexible DC system. Background technique [0002] Since the 1950s, the high-voltage direct current (HVDC) transmission system has been established and operated, and the voltage source converter (VSC) was only applied to the high-voltage direct current transmission system in the late 1990s, although two multi-terminal VSC-HVDC have been operated in China Engineering, but the control of DC voltage is still the focus of research. The multi-terminal VSC-HVDC system only uses one converter for DC voltage control. The remaining converters operate in fast active / passive (PQ) control mode. The droop control method is the extension of the power frequency droop characteristic adopted by the synchronous generator. The main disadvantage of this control logic is that the multi-terminal HVDC (MTDC) power flow control is inaccurate due to the ...

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Problems solved by technology

[0002] Since the 1950s, the high-voltage direct current (HVDC) transmission system has been established and operated, and the voltage source converter (VSC) was only applied to the high-voltage direct current transmission system in the late 1990s, although two multi-terminal VSC-HVDC have been operated in China engineering, but the control of DC voltage is still the focus of research

The main disadvantage of this control logic is that the multi-terminal HVDC (MTDC) power flow control is not accurate enough due to the constant droop coefficient

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