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Liao N.-H.,North China University of Water Conservancy and Electric Power | Hu Z.-H.,Zhengzhou University of Light Industry | Ma Y.-Y.,Shandong Province Construction High Pressure Vessel Co. | Lu W.-Y.,Zhoukou Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

The definition and meaning of short-term load forecasting are introduced. The characteristics and factors affecting the precision of short-term load forecasting of power system are discussed. The current forecasting methods are divided into classical methods, traditional methods, intelligent methods, and new load forecasting methods, the applicable principle of every method is analyzed comprehensively, and the advantages and disadvantages of every method are analyzed and compared in detail. Therefore, to improve the precision of short-term load forecasting, we should not only focus on the accumulation of historical data, but also pay more attention to select the righting forecasting model. Composite forecasting model is the direction of future development.

Liu S.-M.,Zhoukou Power Supply Company | Shi H.-W.,Zhoukou Power Supply Company | Yan J.,Zhengzhou University | Min X.,Yuzhou Power Supply Company of Henan Power Company | Chen G.-Y.,Yuzhou Power Supply Company of Henan Power Company
Advanced Materials Research | Year: 2012

To further improving the precision of harmonics measurement, a new interpolation FFT algorithm based on Rife-Vincent (I) window is provided in this paper. First the spectrum leakage of FFT briefly and the frequency response of the Class I Rife-Vincent window is discussed, and then paper analyzes the interpolation algorithm on Rife-Vincent (I) window in detail. At last the cubic spine function is adopted to calculate the frequency and the harmonic amplitude modification coefficient. An example of simulation is given, and simulative calculation results show that Rife-Vincent (I) window interpolation algorithm by using cubic spine function has the amplitude error less than 1×10 -6 %, the frequency error less than 1×10 -7Hz, and the phase error less than 0.0001%. Comparing with other cosine windows interpolation FFT algorithm, the new interpolation FFT algorithm based on Rife-Vincent (I) window has the highest accuracy. © (2012) Trans Tech Publications.

Liu S.-M.,Zhoukou Power Supply Company | Shi H.-W.,Zhoukou Power Supply Company | Qian Z.,University of South China | Hu Z.-K.,University of South China
Advanced Materials Research | Year: 2012

In this paper, the impuissance of traditional i p-i q method in reactive power compensation applications under nonideal mains voltages is illustrated first, and then a novel current reference calculation method for Shunt Active Power Filter (SAPF) based on p-q transformation is proposed. By means of the proposed method, the positive sequence fundamental active current component of the load current can be isolated under distorted and/or unbalanced mains voltages, which makes SAPF be capable of harmonic cancellation and reactive power compensation at the same time under nonideal mains voltages. The effectiveness of the new proposed method is mathematically studied and verified by computer simulation under ideal and nonideal mains voltages. © (2012) Trans Tech Publications.

Kong L.-K.,XJ Co. | Zhang A.-L.,XJ Co. | Cao S.,XJ Co. | Chang Z.-T.,XJ Flexible Transmission System Corporation | Zhang H.-Z.,Zhoukou Power Supply Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

This paper presents a control and protection system for operational test of ultra high voltage thyristor valves to fully meet the requirement of IEC60700-1 specifications. The system is composed of control and protection hosts, HMI system, control device of converter pulse, analog measurement unit, etc. In this system, there are PCI bus, CAN bus, and TDM bus, which transmit data among functional units. By means of controlling circuit source, voltage source and auxiliary equipments, configuring parameters of converter pulse, switching test items automatically, the system makes the whole test process flexible and stable. The protection system provides comprehensive, effective protection for primary equipments by monitoring the status of the operational test system. The operational test results show that this C&P system is reliable and effective and provide a substantial base and platform for research and development of high voltage thyristor valves and related fields.

Hu B.,University of Shanghai for Science and Technology | Ma L.-X.,University of Shanghai for Science and Technology | Yuan S.-J.,University of Shanghai for Science and Technology | Yang B.,Zhoukou Power Supply Company
China International Conference on Electricity Distribution, CICED | Year: 2012

Corona discharge often occurs in high voltage equipment and transmission lines with the elevating of the electrical network capacity and voltage level, which can lead to noise, loss of power and interference with TV and radio. Worse, the insulation of power equipment might be badly destroyed. Therefore, corona discharges in power system get more attention. In this paper, a non-line monitoring system of double channel ultraviolet is introduced for detecting the UV spectrum in ultraviolet sun-blind band (240∼280 nm) of the corona discharge in the high voltage equipment. And also, the IHS space image fusion algorithm is proposed to locate where corona discharge occurs. © 2012 IEEE.

Xu M.,Zhengzhou University | Zhang W.-Q.,Zhengzhou University | Wang Z.-Q.,Zhoukou Power Supply Company | An Q.,Zhoukou Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

A new method, phase difference correction method, is presented to correct the frequency and phase by separating the continuous time-domain signal into two segments and making FFT respectively, then correct the phase difference of corresponding discrete spectral lines. For minimizing the enormous computational complexity of FFT, the method uses recursive DFT, which makes the computation more simplified. The Blackman-harris window has small influence of frequency spectrum leakage, and the results of computation are consicer than before. So Blackman-harris window is adopted. The amplitude can be rectified using the formula of window function, and spectral analysis is also used for improving the calculation precision. The results show that the frequency error is less than 0.0001 Hz, amplitude error less than 0.02%, and phase error less than 0.5%..

Zhang H.,Zhoukou Power Supply Corporation | Zhu L.,Zhoukou Power Supply Corporation | Han A.,Zhoukou Power Supply Corporation | Li X.,Zhoukou Power Supply Corporation | Liu Z.,Zhoukou Power Supply Corporation
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

Under the assumption of equal electromotive force (EMF) amplitude ratio of both ends in power systems, based on the pre-fault phase relationship between EMF and load current the contra-lateral source impedance is legitimately estimated. With measured impedance of traditional distance protection and real-time phasors on protection location, adaptive math models for calculating both resistance and reactance of line fault are established. Both models are functions of positive-sequence current branch coefficient phase angle. According to increase or decrease relationship between reactance, resistance components of measured impedance and positive-sequence current branch coefficient phase angle, two cases solutions are separately proposed in order to prevent overreaching and under-reach problems of distance relay. Simulation results show that the adaptive distance protection has satisfactory performance, enhanced reliability and high sensitivity. © 2011 State Grid Electric Power Research Institute Press.

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