A step-down angle statcom and its control method

Abstract

The invention relates to a step-down angle type STATCOM and a control method. The method is characterized by superposing output quantity of a master controller and output quantity of a valve side voltage controller of a corresponding phase to obtain a result serving as an instruction value of reactive current, wherein the valve side voltage controller comprises an upper limit controller and a lower limit controller; calculating the difference value between an upper limit reference voltage of the upper limit controller and a line voltage of the corresponding phase, and then, carrying out closed-loop control to obtain upper limit closed-loop control output quantity; calculating the difference value between a lower limit reference value of the lower limit controller and a line voltage of thecorresponding phase, and then, carrying out closed-loop control to obtain lower limit closed-loop control output quantity; and adding the upper limit closed-loop control output quantity and the lowerlimit closed-loop control output quantity to obtain a result serving as the output quantity of the valve side voltage controller. The method can enable the valve side voltage to be stabilized within apreset range during voltage and reactive power control and the like of the STATCOM, and realizes automatic coordination of a main control target and a valve side voltage control target.

Description

technical field [0001] The invention belongs to the technical field of flexible alternating current transmission, and in particular relates to a step-down angle-type STATCOM and a control method thereof. Background technique [0002] In recent years, with the advancement of power electronic switching technology and the increasing maturity of the application of modern control theory, the Static Synchronous Compensator (STATCOM) in reactive power compensation technology has gradually emerged. STATCOM has multiple functions such as compensating system inductive and capacitive reactive power, improving system power factor, improving power intelligence, and improving power system stability. It is an important member of Flexible AC Transmission Systems (FACTS). [0003] STATCOM generally includes three main control strategies: voltage control, reactive power control and transient control. [0004] The voltage control adopts the droop control method. When the positive sequence amp...

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Problems solved by technology

[0008] The purpose of the present invention is to provide a step-down angle-type STATCOM and its control method, which is used to solve the problem that the step-down angle-type STATCOM cannot control the valve side voltage when the high-voltage side of the step-down transformer is used as the control point

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