A robust time-delay compensation grid-connected control method for lcl-type inverters

Abstract

The invention discloses a robust delay compensation grid connection control method for an LCL inverter, which mainly includes three parts: power feedforward control, voltage outer loop control and current inner loop robust delay compensation grid connection control, wherein , power feedforward control can speed up the one-way transfer process of photovoltaic DC side energy to grid AC side energy, and speed up the transient response of the system; the voltage outer loop control is used to stabilize the DC side capacitor voltage; the current inner loop adopts robust delay compensation Grid-connected control, including capacitive current feedback delay compensation and zero-pole delay compensation strategy, which effectively reduces the control delay of the system, improves the robustness and dynamics of the system, and realizes high-quality grid-connected current feeding into the grid . The invention enables the LCL type inverter to have higher robustness and faster dynamic response, and better satisfies the requirement of grid-connected operation of the inverter.

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 ...

AI Technical Summary

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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