The Research For Intelligent Reactive Power Compensation On DsPIC

In the power grid,reactive power is an important factor to the voltage stability, and it is also related to the secure and reliable operation of the electric power system,while reactive power compensation is one of the effective methods of maintaining the effective and steady operation of the electric power system. The thyristor switch, air switch,the control unit and the capacitor of the traditional reactive power compensation device are scattered in the power cabinet, and a controller controls a plurality of capacitors, so once the controller breakdown, the whole device can not work properly.The intelligent reactive power compensation device this paper developpped adopts modular structure,and each capacitor is controlled by a single controller, enhance the reliability of the system.The main research contents of this paper are as follows:Firstly,we discuss the key technology of the intelligent reactive power compensation,including the measurement method of the reactive power,control parameters of reactive power, the control method,FFT and the technology of zero-crossing.According to the functional specification and related standards of reactive power device and the actual situation of economy and reliability,we determine the overall design scheme of the intelligent reactive power compensation device.Secondly,the detailed design process of the intelligent reactive power compensation device form two aspects of hardware and software is introduced. On the aspect of hardware,we use dsPIC30F6014A produced by Microchip to fulfill data acquisition,the core algorithm, data display,keyboard control, data communication and other functions;At the same time,a basic model of zero-crossing switch of reactive power compensation device is built by using MATLAB simulation software,according to the waveform of voltage and current to input capacitor under different conditions,and considering the economic factor,a zero-crossing switch circuit is designed choosing the scheme of inputting capacitor under no residual voltage. On the software,we adopt the assemble language to write program following the principles of modular design under the MPLAB environment; we use the improved Volt/Var integrated control which can avoid excessive compensation and switching oscillation.The device also has the protection function such as lack-phase, under-voltage, over-voltage protection and so on.Finally,we do some field experiments such as data measurement,protection function and the performance of the compensation by using test device. The test results show that this device can switch capacitor at zero-crossing which can ensure no flashy flow during switching process,and the device can compensate the reactive power dynamically, improve the power factor and power quality.At the same time,it illustrates the reasonableness of the theory,the usefulness and correctness of the device.