Dual-loop compound control method of unified power quality controller

Abstract

The present invention relates to a dual-loop compound control method of a unified power quality controller (UPQC). The method comprises the following steps of: (1) employing a UPQC topology structurechart of a three-phase three-wire system to establish a mathematical model in a synchronous rotating reference frame; (2) performing double closed-loop voltage control of the UPQC: taking a serial three-phase converter circuit as a voltage source, outputting a compensation voltage with a size being the same as the difference of a load voltage and a power grid voltage and with a direction being opposite to the load voltage and the power grid voltage, and obtaining a sine load voltage through double closed-loop PI control; (3) taking a parallel three-phase converter circuit as a current source,and outputting a compensation current with a size being the same as the difference of a power grid current and a load current value and with a direction being opposite to the power grid current and the load current value; (4) designing a current loop PI, and adding a zero-order holder in a control model; (5) designing a repetitive controller: establishing a transfer function of the repetitive controller; and (6) combining a PI control inner loop and a repetitive controller outer loop to perform recombination coordination control, tracking a current compensation instruction, outputting the compensation current, and indirectly controlling a power grid input current as a sine current. The dual-loop compound control method of the unified power quality controller can effectively improve the traceability and the compensation performance.

Description

Technical field [0001] The invention relates to the field of power quality analysis and control, in particular to a double-loop compound control method for a unified power quality regulator. Background technique [0002] In recent years, with the rapid development of social economy, a large number of power electronic devices have been widely used in various industries. The operation of these power electronic devices has caused great pollution to the power grid and affected the power quality of the public power grid. Due to the mutual influence between the power grid and the user, the voltage quality and the current quality appear at the same time, and a single power quality adjustment device can hardly solve the new requirements for power quality put forward by the power supply side and the power user. The Unified Power Quality Conditioner (UPQC), as a new type of power quality compensation device, performs multiple power quality adjustments at the same time, and compensates for ...

AI Technical Summary

Problems solved by technology

Double-loop control is widely used in this field, but due to the poor tracking ability of PI control, the compensation accuracy is not high, and it is impossible to accurately track the UPQC compensation command

The repetitive controller can improve the steady-state performance of the system, but its dynamic performance is poor

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