Design Of The Control System Of Static Var Compensator In Milling Unit

When the rolling mill is connected into the power networks as a non-linear and irregular load in rolling process, it will produce severe and frequent reactive power, and cause the bus voltage fluctuation and flicker. At the same time it will bring large amounts of harmonic current into power system and cause voltage distortion. So it will make a negative impact on other load. In order to solve these problems, using a Static Var Compensator (SVC) composed of TCR+FC on the bus to provide dynamic var compensation can improve the quality of power supply.The paper discusses the principle and composition of the SVC control system. Importantly general structure of SVC control system is finished in this thesis, including upper computer and lower computer. The SVC control system is processed with computer and network. Mainly the paper finishs the design of lower computer.The paper mainly designs the static var compensator based on digital signal processor. Based on the vetor controlling of the symmertrical components method and the compensate admittance model of Steinmetz theory, a method is put forward which use the method of synchronous symmetrical component of load current and voltage to denote it. In this paper the rational interpolation method is used as the trigger angle of thyristor, this method is proved to be more accurate.The controller makes up of TMS320F2407DSP chip, relatively complete control circuit and its periphery device circuit. The flowchart of the control software of the whole system is designed in this paper.The results show that both the hardware and the software design are reasonable, the control method is feasible and the system operation is reliable. The design meets expected requirements.The analysis of application results indicates the control unit of the SVC designed for hot rolling mill that can control the breakover of thyristor in real time and split-phase according to the change of three-phase voltage and current and can adjust continuously. The SVC makes the power factor close to0.96and compensates unbalanced load effectively. And the SVC achieves good control effect.