A voltage source control method for lcl type grid-connected converter

Abstract

The invention provides a novel voltage source control method for an LCL type grid-connected converter. The grid-connected control method takes the DC side voltage and output reactive power of the converter as the control targets, and adopts the outer loop of reactive power, the middle loop of AC voltage, and the parallel loop. The three-loop control structure of the grid current inner loop; the ratio of the DC side voltage to the reference value is multiplied by the rated angular frequency of the grid voltage and then passes through the integrator, and the output of the integrator is converted from three-phase AC voltage and current to two-phase voltage and current The phase of the phase; the reactive power control outer loop controls the adjustment of the output reactive power and active power of the grid-connected converter, the output of the filter capacitor voltage control loop is used as the reference value of the current inner loop, and the output of the current loop is rotated and modulated. As the trigger pulse of the grid-connected converter. In the grid-connected control method of the present invention, the converter presents external voltage source characteristics, can dynamically realize the autonomous synchronization of the converter to the power grid according to the DC capacitance, and has the function of limiting the current on the AC side of the converter.

Description

technical field [0001] The invention relates to the technical field of electrical control of a new energy grid-connected converter, in particular to a voltage source control method of an LCL grid-connected converter with an autonomous synchronizing power grid and an output current limiting function. Background technique [0002] The conventional control strategy of the converter adopts a phase-locked loop (PLL) to synchronize and orient the power grid, and realize power regulation in the form of current injection, which reflects the characteristics of a current source. This control strategy can be called current source control. Current source control is a grid-following control, lacking active inertia support capability, and is suitable for a grid environment dominated by synchronous generators. The voltage source control directly controls the amplitude and phase of the output voltage of the converter by simulating the synchronous generator equation. [0003] After searchin...

AI Technical Summary

Problems solved by technology

However figure 1 The control architecture of the grid-side converter is relatively simple. The phase θ output by the DC voltage control loop and the voltage amplitude output by the reactive power control directly generate a modulation voltage. This control architecture lacks a current control loop and cannot limit the output current of the converter. piece

When abnormal conditions such as sudden voltage changes occur in the power grid, the converter is prone to overcurrent, which will damage the converter

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