A control system and control method for a converter parallel system

Abstract

The invention relates to a converter parallel system control system and a control method; the converter parallel system control system mainly comprises a current decoupling unit, a full Fourier poweranalysis unit, a voltage decoupling and harmonic wave voltage extraction unit, a harmonic wave elimination phase lock algorithm unit, a harmonic wave elimination unit, a synchronization sagging and virtual impedance unit, a synchronization rotating coordinate voltage synthesis unit and a SVPWM synthesis unit. The method uses a new decoupling sagging algorithm and adds a virtual impedance so as tofurther improve the control precision; in addition, a new harmonic wave elimination algorithm is provided so as to extract a harmonic wave component from an output voltage and to negate in the algorithm, thus enabling the system output voltage to keep a low harmonic wave voltage content under a non-linear load condition. The control system and method can improve the converter parallel running stability and control precision, can reduce the auxiliary parallel system circulation, and can improve the converter resistivity and redundancy against the output voltage disturbances.

Description

technical field [0001] The invention belongs to the field of rail vehicle power supply systems, and in particular relates to a control system for a parallel system of subway auxiliary converters and a control method using the system for control. Background technique [0002] The existing control algorithm of the auxiliary inverter parallel system of the subway mostly adopts the direct droop mode, and uses the reactive power and active power output by the inverter to adjust the output voltage and frequency of the system, but the reactive power and active power output by the inverter There is not a one-to-one relationship with the system output voltage and frequency, and there is variable coupling, which leads to inaccurate system control, resulting in circulating current between inverters, and the stability and reliability of its operation are reduced. At present, the loads of the auxiliary converters of the subway are mostly nonlinear inverter air conditioners. Using the par...

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Problems solved by technology

[0002] The existing control algorithm of the auxiliary inverter parallel system of the subway mostly adopts the direct droop mode, and uses the reactive power and active power output by the inverter to adjust the output voltage and frequency of the system, but the reactive power and active power output by the inverter There is not a one-to-one relationship with the system output voltage and frequency, and there is variable coupling, which leads to inaccurate system control, resulting in circulating current between inverters, and the stability and reliability of its operation are reduced

At present, the loads of the auxiliary converters of the subway are mostly nonlinear inverter air conditioners. Using the parallel inverter system can improve the impact of nonlinear loads on the three-phase inverter grid and reduce harmonics, but this effect mainly depends on the auxiliary inverter hardware. The filter capacitor and the parallel system improve the overall auxiliary capacity. In the high-power subway auxiliary inverter application system, if the nonlinear load is too large, the output voltage of the auxiliary inverter will be distorted, which will affect the control accuracy and even cause algorithm crash

[0003] CN103457494A discloses a parallel power supply control system for auxiliary converters of EMUs without interconnection lines. The auxiliary converter control system mainly includes a phase-locked synchronous control unit, an instantaneous power calculation unit, a droop control unit, a voltage closed-loop control unit, and an intermediate voltage front Feedback control unit, CN103457494A only provides the main unit module of the converter control system, and does not involve the optimization design of the specific control system unit, harmonic elimination, circulating current control and resistance to output voltage disturbance of the converter parallel control system, etc. Aspects are less effective

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