Research On The High Voltage Power Quality Combined Compensator In Distribution Grid

With the widespread application of the high-power electronic devices, the problem of power quality is becoming increasingly conspicuous. Harmonic pollution and reactive power shortage which is caused by power quality not only concerns energy waste, but also have an effect on safe operation of power system. At the present stage, active power filter, static var compensator and switching capacitor bank which are widespread adopted in high-voltage of distribution can only solve the single power quality problems. This paper starts with fundamental principles of power quality, and comes up with synthetical dynamic compensation device of which the circuit structure, detecting method, composite control technology and the software-hardware design are researched.Firstly,the operation principle of basis compensation device (active power filter, static var compensator) is analyzed in this paper.And on that basis combining the actual conditions of high voltage distribution grids, the paper puts forward a new topological structure, that is to say HVPQC(High Voltage Power Quality Combined Compensator) which combined the advantages of injection type hybrid active power filterI(IHAPF) and TCR type static var compensator(SVC). It is effective on dynamic var, harmonic conditioning and it also can make the voltage stable. It is a synthetical power quality compensator. The paper arrives at the fundamental domain and harmonic domain model by the analysis of topological structure of HVPQC.The detecting part is the premise of power quality control. The performance of HVPQC is heavily determined by the accuracy and real time of detection. The research is based on the classical ip-iq reactive detection theory in this paper. In order to reduce the response time of detection resulting from the improvement of voltage imbalance, a new type of DFT-based sliding-window iterative and ip-iq detection is put forward in this paper. Also the paper researches the low pass filter, and designs the Bathurst filter, with which the new type of detection has faster processing speed and higher performance of detection.The control method is the important and difficult point in HVPQC. The controller is the most important factor which affects HVPQC directly. The paper analyzes the internal effect of HVPQC, and puts forward a specific compound control method which is based on this analysis. SVC unit improves against traditional PID control, and puts forward a Ziegler-Nichols—based voltage control optimization which mainly researches model reference adaptive control of IHAPF unit. At last, the paper verifies that the control strategy is distinctly superior on control accuracy of power quality and reliability of system safety by simulation and experiment results.Combining above-mentioned theories, the paper overall designs power quality regulating device according to the actual condition of enterprise high voltage distribution network, and researches the hardware and software of system. The method of implementation of monitoring system has also been given.And finally there is an experimental verification on the prototype developed by laboratory in the paper.