Robust delay compensation grid-connected control method of LCL inverter

Abstract

The present invention discloses a robust delay compensation grid-connected control method of an LCL inverter. The method mainly comprises three parts which are power feedforward control, voltage outer ring control and current inner ring robust delay compensation grid-connected control, wherein the power feedforward control can speed up the unidirectional transfer process from photovoltaic DC side energy to grid AC side energy, and the transient response of the system is accelerated, the voltage outer ring control is used for stabilizing DC side capacitance voltage, and robust delay compensation grid-connected control is employed by a current inner ring. The method comprises a capacitive current feedback delay compensation and zero pole delay compensation policy, the control delay of a system is effectively reduced, the robustness and dynamic performance of the system are improved, and a high quality grid-connected current feed-in grid is realized. According to the method, the LCL inverter has higher robustness and a fast dynamic response, and the need of an inverter grid-connected operation is satisfied.

Description

technical field [0001] The invention relates to the field of new energy distributed power generation, in particular to a robust delay compensation grid-connected control method for an LCL inverter. Background technique [0002] With the increasingly serious energy crisis and environmental pollution, new energy distributed power generation technology has received extensive attention and research. Among them, the grid-connected inverter is the core part of the distributed power generation system, and the high-frequency power switching devices used in it will generate high-order harmonics, which will cause harmonic pollution. Therefore, a filter is required between the grid-connected inverter and the grid to attenuate or filter it out. [0003] Compared with L-type and LC-type grid-connected inverters, LCL-type grid-connected inverters have a greater attenuation effect on high-frequency harmonic currents. Therefore, it can select a smaller value of inductance and capacitance ...

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Problems solved by technology

[0004] The domestic literature proposes a mathematical control method for predicting the controlled quantity, which modifies the sampling signal to the predicted value of the controlled quantity in the next cycle and introduces it into the control loop. Although this method compensates for the delay generated by the calculation, it cannot compensate for the delay caused by the zero-order hold. delay caused by the

A zero-pole delay compensation method is also proposed. Although this method can improve the robustness of the system, it can only compensate the delay caused by the zero-order keeper, and cannot compensate the delay caused by calculation.

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