Virtual impedance and reactive droop-based cascade energy storage converter parallel operation control method

Abstract

The invention relates to a cascade energy storage converter parallel operation control method based on virtual impedance and reactive droop. The method comprises the following steps: a) carrying out power distribution solution on a cascade energy storage converter system in parallel operation; b) according to the power distribution and the characteristics of the energy storage converter, adding virtual impedance in a control loop to enable an equivalent line of the cascaded energy storage converter to present resistance, so the purposes of active power equalization and power decoupling are achieved; c) under the action of the virtual impedance, realizing equal distribution of reactive power by adopting a reactive power-frequency droop control mode; d) compensating the voltage drop caused by the virtual impedance by adopting a proportional resonance controller. According to the cascade energy storage converter parallel operation control method, under the condition that a communication tie line is not needed, power equalization is achieved, voltage drop in traditional droop control is reduced, power distribution can be achieved when multiple cascade energy storage converters are in parallel off-grid operation, and voltage drop is reduced.

Description

technical field [0001] The present invention relates to a parallel control method of cascaded energy storage converters, and more specifically, to a parallel control method of cascaded energy storage converters based on virtual impedance and reactive power droop. Background technique [0002] With the rapid advancement of carbon peaking and carbon neutrality, the utilization rate of clean energy and renewable energy has increased significantly. At the same time, in order to stabilize the intermittency and volatility of solar and wind power generation, energy storage devices have become the standard for new energy power stations. match. The output voltage of the AC side of the traditional energy storage device is low, and it needs to be connected to the transmission and distribution network with high voltage levels such as 10kV and 35kV through a step-up transformer. The high-voltage cascaded energy storage device is a relatively new energy storage converter. The device is c...

AI Technical Summary

Problems solved by technology

However, traditional droop control will cause changes in output voltage and frequency, and the premise of droop control is that the line impedance of the energy storage device needs to be resistive or inductive. When the difference between the resistive component and the inductive component is not large, it is difficult to choose the droop relationship.

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