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Zhu L.,Xian Jiaotong University | Ji S.,Xian Jiaotong University | Shen Q.,Shaoxing Electrical Power Bureau | Liu Y.,Xian Jiaotong University | Liu H.,Xian Jiaotong University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2014

Capacitor stacks radiate a lot of noise in HVDC converter stations, and the noise level and the vibration should be predicted. The prediction method of capacitor tank vibration is concerned in this paper. A novel prediction method of capacitor tank vibration is proposed methodically based on a frequency response function. The frequency response function, which is the frequency domain quotient of vibration velocity of capacitor tank and the squared capacitor voltage, is defined as the electro-mechanical frequency response function and can be obtained by impulse discharge test. Under given excitation, the vibration velocity can be calculated by the product of electro-mechanical frequency response function and the squared voltage in frequency domain. The comparison of predicted and measured vibration of capacitor tank under two excitations is conducted to verify the effectiveness of the prediction method presented in this paper. ©, 2014, Chinese Machine Press. All right reserved. Source


Zhu L.,Xian Jiaotong University | Li H.,Shaoxing Electrical Power Bureau | Yao X.,Ohio State University | Ji S.,Xian Jiaotong University
Proceedings of the 2014 IEEE International Power Modulator and High Voltage Conference, IPMHVC 2014 | Year: 2014

The feasibility of increasing operating capacity of existing power transformers is studied based on a novel dynamic thermal circuit model in this paper. Hot-spot temperature of a transformer is the most important parameter to determine the operation capacity. However, only top-oil temperature is monitored and hot spots usually appear at windings. In this paper, a dynamic thermal circuit model considering environment factors and operation conditions is established. To implement and verify the dynamic thermal circuit, the real-time loss and cooling thermal resistance of the transformer is calculated firstly. And then hot-spot temperature based on the average oil temperature is calculated for a period of 24 hours. The calculated result is compared with the measured temperature data under the same conditions. The comparison shows that the accuracy of the proposed model is satisfactory. The proposed model is then used to evaluate the feasibility of increasing operating capacity. The evaluation indicates that the continuous operating capacity can be increased. After capacity increased, the transmission energy can increase remarkably, while the service life is reduced lightly. © 2014 IEEE. Source


Hu Y.,Nanjing Tuowei Power Technology Development Co. | Zhang X.,Zhejiang Electrical Power Test and Research Institute | Xu W.,Shaoxing Electrical Power Bureau | Wang S.,Zhejiang Electrical Power Test and Research Institute
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

The principle of IEEE 1588 clock synchronization system is discussed briefly. The possible error sources and factors influencing error are analyzed. The linear convergence comparision method is proposed for on-line clock synchronization system fault detection. The test results show that the fault or error in IEEE 1588 clock synchronization system can be found by proposed method. © 2010 State Grid Electric Power Research Institute Press. Source


Liang H.-H.,Fujian Electrical Vocational and Technical College | Zhang F.,Northeast Dianli University | Chang C.,Shaoxing Electrical Power Bureau | Zhao T.,Northeast Dianli University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

According to the deficiencies of substation monitoring system at present, this paper designs a kind of substation monitoring and alarming system based on ZigBee wireless technology. The system utilizes CC2430 produced by TI company as the ZigBee module, and designs the ZigBee coordinator and ZigBee monitoring terminal nodes. The system uses GPRS for remote transmission, realizes wireless substation monitoring system. The system saves cost and reduces the complexity of construction substantially, and thus has broad application prospects. Source


Zhu L.,Xian Jiaotong University | Ji S.,Xian Jiaotong University | Shen Q.,Shaoxing Electrical Power Bureau | Liu Y.,Xian Jiaotong University | And 2 more authors.
PLoS ONE | Year: 2013

The capacitors in high-voltage direct-current (HVDC) converter stations radiate a lot of audible noise which can reach higher than 100 dB. The existing noise level prediction methods are not satisfying enough. In this paper, a new noise level prediction method is proposed based on a frequency response function considering both electrical and mechanical characteristics of capacitors. The electro-mechanical frequency response function (EMFRF) is defined as the frequency domain quotient of the vibration response and the squared capacitor voltage, and it is obtained from impulse current experiment. Under given excitations, the vibration response of the capacitor tank is the product of EMFRF and the square of the given capacitor voltage in frequency domain, and the radiated audible noise is calculated by structure acoustic coupling formulas. The noise level under the same excitations is also measured in laboratory, and the results are compared with the prediction. The comparison proves that the noise prediction method is effective. © 2013 Zhu et al. Source

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