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Huang G.X.,Hefei University of Technology | Li Z.Y.,Hefei University of Technology | Huang Y.,Guilin Power Capacitor Co.
Applied Mechanics and Materials

Power capacitor is one of the key equipments of the high-voltage direct current (HVDC) transmission system. It is also the main noise source difficult to control. Presently in the world, there are none explicit requirement and regulation on the evaluation and measurement of the noise generated by the power capacitor, which has seriously restricted the development of the further research on the noise control in power capacitor. So the research on the noise measurement method and technology has extremely important significance in scientifically evaluating the noise of power capacitor. Power capacitor in HVDC Converter Station under practical conditions has apparent fundamental frequency and rich harmonic frequency components. In order to simulate this condition, a whole condition loaded bridge circuit of noise measurement on power capacitor has been designed and studied. Two arms of the bridge are used to load fundamental frequency and a parallel resonance compensation inductance is used to reduce the fundamental current, while the other two arms are used to load harmonic frequency. The harmonic frequency load power supply composed of harmonic signal generator and power amplifier which can simultaneously load any combination of harmonics under 48th to simulate the various actual working conditions. The tests indicated that the noise spectrum measured under the designed circuit completely accorded with the one in HVDC Converter Station. © (2014) Trans Tech Publications, Switzerland. Source

Guo Q.,Guilin University of Technology | Xie X.L.,Guilin University of Technology | Li Y.,Guilin University of Technology | Chen X.Y.,Guilin Power Capacitor Co.
Applied Mechanics and Materials

This paper is for the problems of the 400V low voltage power capacitor reactive power compensation and for the problems existing in the transient process, resuming the principle of lowvoltage capacitor intelligent technology and its implementation briefly. Propose a synchronization of reactive compensation capacitor switching on-off control system based on the micro controller and adaptive control. Real-time monitoring system is used to access system active and reactive power changes in order to extract the zero voltage signals; intelligent control algorithm is used to realize the intelligence of capacitor reactive power compensation on-spot and cutting, which greatly reduce the over-voltage and flow phenomenon produced by the capacitor in the cutting process. The result checked by actual measured shows that the device is stable, reliable, and can be effective to on-site system reactive power compensation and realize intelligent cutting. © (2013) Trans Tech Publications, Switzerland. Source

Duan X.,Hebei Electric Power Research Institute | Zhu M.,Anhui University | Hu W.,Hebei Electric Power Research Institute | Zhou W.,Hebei Electric Power Research Institute | And 3 more authors.
Dianwang Jishu/Power System Technology

The capacitor voltage transformer (CVT) has been widely used in the power system; However, it is hard to measure correctly the system harmonic with CVT because of its structure containing capacitors and non-linear inductors. This article describes a harmonic impedance model of CVT and derives its complete transfer function, considering the CVT manufacturing parameters and stray capacitance and other factors. The accuracy of the model was verified by comparing the CVT model simulating results and measured results of harmonic, then the impact of key parameters of CVT on its harmonic transfer characteristics was analyzed by simulation. Also, certain reference function is provided for accurate measurement of CVT harmonics, CVT design, manufacturing and process optimization. ©, 2014, Power System Technology Press. All right reserved. Source

Zhang X.,Guilin University of Electronic Technology | Fan X.-M.,Guilin University of Electronic Technology | Fan X.-M.,Sunrise Group | Zou Q.-T.,Sunrise Group | And 2 more authors.
Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV

A new type controlled switching device is introduced, which based on vacuum circuit-breaker (VCB) and power electronic switch(IGBT) to form the combination switch module. The structure and working principle of provided combination switch were emphatically expounded, especially the open and closing process and controlling strategy were discussed in detail. The researched VCB with permanent magnet actuator, and the synchronous controller of combination switch module based on the digital signal processor, in which the algorithm of average series for zero-crossover phase difference is adopted, so the phase information of power grid can be extracted rapidly and accurately, and synchronous tracing pulses can be procreated. When remote control instructions are received, according to the phase information of power grid the combination switch acts synchronously to ensure that the operation time of combination switch opened and closed in right position. The application of introduced combination switch for power quality control and improvement is present in this research also. In this control device, the real-time acquisition of electrical parameters is adopted and the crossover point of reference signal is detected by average series for zero-crossover phase difference algorithm. Accompanied with improved appropriate switching strategy, the device can operate shunt capacitor banks on expected target point. © 2012 IEEE. Source

Ma Q.,China Electric Power Research Institute | Cui X.,North China Electrical Power University | Ren C.,Xian XD Power Capacitor Co. | Wang Z.,Guilin Power Capacitor Co. | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering

To improve the manufacture technique, transient performance, and reliability of ultra high voltage(UHV) capacitor voltage transformers(CVT), we studied its impedance measurement and wideband circuit modeling method based on frequency-domain data. In order to obtain the frequency-dependent impedance, we adopted various methods to measure the impedance of two types of CVT capacitor voltage dividers, namely, the compression type and the welding type. The wideband impedance measurement results were validated using the two different impedance measurement methods. Thereby, we developed a CVT wideband equivalent circuit model with physical denotation, which was verified through comparing with the measurements. Furthermore, we defined several electrical network functions and analyzed the sensitivity of CVT circuit parameters, such as accumulation resistance, accumulation inductance, capacitor capacitance, capacitor conductance, and ground capacitance of grading ring. The results could be used as references for optimizing design, fabrication technology and transient performance analysis for UHV CVTs. Source

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