Research on the Motor Drive Based Operating Mechanism for High Voltage Circuit Breaker

Abstract

This paper describes an operating mechanism driven by a three-phase permanent magnet synchronous motor (PMSM) for high voltage circuit breakers (HVCB). It analyzes the relationship between the optimal moving contact travel of HVCB and the PMSM torque, and proposes the main parameters and requirements of PMSM to be suitable for the optimal contact travel. The simulation model of the operating mechanism driven by PMSM was builtusing Matlab. It simulates and calculatesthe mechanism’sopening and closing operations characteristics. The voltage waveforms of stator currentsanalyzing, offers a helpful reference to compile the Digital Signal processing (DSP) programs. The performances of the opening and closing operationscould be improved by debugging the DSP programs in the control unit. Introduction High Voltage Circuit Breakers (HVCB) isthe most important switches apparatus in the electric power system. They are responsible forcontrol and protect of the power system. The operating mechanism is the basic device which controls the opening and closing operations of HVCB. At present, there are several conventional types of operating mechanisms which have been widely used, such as spring, hydraulic or pneumatic. Such mechanisms have many prominent merits, but also have some insurmountable limitations. These conventional mechanismsconstructedby complex frames, need periodic check-ups, highly costsoperating and maintenance,and they are quite difficult to be debugged. Additionally, they are especially incontrollable and non-detectable during the opening and closing operations. To overcome such inherent limitations, and to improve the performance of conventional mechanisms, the operating mechanism driven by PMSMis introduced to meet the requirements. The proposed operating mechanism is based on power electronic and motor digital control technologies. This mechanism has quite a lot of good advantages: simple frames, manipulative opening and closing operations, wide range of uses and so on. Design of the operating mechanism The suggested operating mechanism consists of AC (or DC) power supply, energy buffer, converter unit, control unit, and the motor. Fig.1 (a) shows the System diagram of motor driven mechanism.The motor is controlled by an IGBT Converter, rotate speed and positions of the motor aremeasured using a fixed sensor on the rotating shaft. The travel of the moving contactor is measured by the position sensor.The control unit adopts DSPas the processing core, and according to the vector control of the motor, the control unit generates PWM signals to activate the IGBT Converter, and then drives the motor to implement the opening and closing operations of HVCB. International Industrial Informatics and Computer Engineering Conference (IIICEC 2015) © 2015. The authors Published by Atlantis Press 959 AC R ec tif ic at io n ci