Converter control method and device

Abstract

The invention discloses a converter control method and device. The converter control method comprises the steps of: determining the actual output power of a converter according to a three-phase output voltage and a three-phase current of the converter; determining a coordinate transformation angle according to the active power and an active-frequency control model, and determining a positive sequence component of modulated waves according to the reactive power and a reactive-voltage control model; determining a voltage negative sequence control instruction and voltage negative sequence control feedback according to an operation mode of the converter, and determining a negative sequence d-axis component and a negative sequence q-axis component of the modulated waves, thereby determining the modulates waves under a dq-axis coordinate system; and performing coordinate transformation on the modulated waves under a dq-axis coordinate system to obtain a modulation signal under an abc coordinate system, so as to drive the converter to work according to the modulation signal. According to the converter control method and the device, the calculation structure is simple, the calculation amount is small, the basic characteristics of the voltage type VSG are ensured, and the unbalance degree of the off-grid output voltage can b+e reduced; and the unbalance degree of grid-connected current can be reduced, and voltage and frequency support is provided for the system.

Description

technical field [0001] The application belongs to the technical field of energy storage systems, and in particular relates to a control method and device for a converter. Background technique [0002] In order to improve the operation reliability of the energy storage system, scholars at home and abroad have proposed the virtual synchronous generator (VSG) technology, which simulates the characteristics of the synchronous generator body model, active frequency regulation and reactive voltage regulation, etc., so that the energy storage The converter is comparable to the traditional generator in terms of external characteristics and operating mechanism. However, with the variability and wide application of energy storage devices, there will be a large number of unbalanced loads in the system, and various unbalanced faults will also occur, which will cause unbalanced system voltage or grid current. [0003] Among the existing VSG control methods, most of them adopt the unbala...

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Problems solved by technology

[0003] In the existing VSG control methods, most of them adopt the unbalanced voltage compensation control strategy based on VSG to solve the problem of unbalanced output three-phase voltage when off-grid with unbalanced load. This method is simple and reliable, and can realize the ability to compensate unbalanced voltage. , but it is not suitable for unbalanced three-phase grid voltage conditions; and for unbalanced three-phase grid current when the grid-connected grid voltage is unbalanced, the power-current control method or negative sequence component control based on voltage and current double loops is usually used , the former improves the current quality and other issues by calculating the reference value of the current, but this method is based on the current-type VSG, which is not suitable for off-grid load unbalanced conditions, and the control logic of the latter is more complicated

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