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Qi L.,Nanyang Power Supply Company | Liu X.-D.,Nanyang Power Supply Company | Zhang H.-D.,Nanyang Power Supply Company | Dong Z.-R.,Luoyang Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

It's proved that the stability of power system can be affected by reclosing time of important transmission lines; the traditional fixed-time reclosing scheme could enlarge the oscillation magnitude of system after reclosing operation, and cause the loss of stability when reclosed to permenant faults. In this paper, an online optimization scheme of reclosing-time of power plant transmission lines based on positive sequence current magnitude is proposed under the study of transient energy function and power plants main connection characteristics. Theoretical analysis and BPA simulation have proved the two-machine characteristics between the power plant and the system it is connected to, and that the positive sequence current magnitude can accurately reflect the transient energy and capture the best reclosing time, restrain the oscillation of power system after reclosing operation, and improve the stability of the power plant. The proposed scheme also has advantages of less computation and easy realization, and is of great practical value.

Xiong J.H.,Beihang University | Xiong J.H.,North China University of Water Conservancy and Electric Power | Xu S.Q.,Nanyang Power Supply Company | Yun C.,Beihang University
Advanced Materials Research | Year: 2011

To measure and control thermal defects of power station, continuous power is provided to the ZigBee wireless temperature sensors by using monocrystalline silicon solar cells and thermoelectric generation modules, which can collect and process the real-time temperatures of high voltage equipments in the station. Simultaneity, the system can solve the problem that overheat faults can not alarm timely when efficiency of solar cell decreases during the continuous rainy days. The remote real-time controlling is realized by using client and server programs of VC + +.NET. The lossless compression and real-time image transmission are implemented through employing the screen grid-division method and the Huffman compression algorithm. All of these provide a technical assurance to the remote controlling of heat vice of high-voltage equipments in multi-stations. © (2011) Trans Tech Publications.

Zha C.-M.,Zhongyuan University of Technology | Wang C.-J.,Zhengzhou University of Light Industry | Wei Y.-B.,Zhengzhou University of Light Industry | Li T.,Nanyang Power Supply Company | Lu G.-H.,XJ Electrical Co.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014

To solve this problem that harmonic grounding system fault line zero sequence admittance levy does not highlight, this paper proposes a new resonant grounding line selection method based on EMD. In this method, each line zero sequence admittance is decomposed with EMD, characteristic component is extracted, and the fault line is selected by comparing the characteristic component symbols of the fault line and non-fault lines. Extensive simulations show that this method is not impacted by the ground fault resistance and the initial angle, and can accurately select the fault line.

Wei Y.-B.,Zhengzhou University of Light Industry | Li T.,Zhengzhou University of Light Industry | Zhang G.-L.,Zhengzhou University of Light Industry | Li P.,Nanyang Power Supply Company | Cui G.-Z.,Zhengzhou University of Light Industry
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

Over-compensation and under-compensation can often be found in the traditional reactive power compensation based on the switching state of capacitor banks, which is limited by the times of switching. In order to solve the problem, the operating principle of the magnetic-valve controllable reactor (MCR) based on the instantaneous reactive power theory is proposed. Based on instantaneous reactive power theory and through coordinate transformation, the real time detection for the reactive current of the MCR is realized. On this basis, the basic control strategy of MCR-based intelligent Static Var Compensator (SVC), and the control strategy for unbalanced system are researched and a method for enhancing the MCR response speed is also given. The validity of the above method is proved by experimental results.

Xu Y.,Hunan University | Yu J.,Hunan University | Cao Y.,Hunan University | Yu J.,Central South University | Gu Y.,Nanyang Power Supply Company
2016 IEEE 8th International Power Electronics and Motion Control Conference, IPEMC-ECCE Asia 2016 | Year: 2016

State variable feedback predictive control (SVFPC) obtains the advantage of predictive control and state feedback control, which is proposed to control the single phase shunt active power filter (SAPF) in nonlinear load (uncontrolled rectifier with inductive and capacitive load) conditions. The proposed control strategy suppresses most harmonics of different loads. The advantages of using SVFPC compared to conventional proportional-integral (PI) control are more accurate, strong robustness and small overshoot. Moreover, the adaptability of step-change disturbance of SAPF is improved. To verify the proposed control strategy, the simulation by MATLAB/Simulink is implemented to test the feasibility. © 2016 IEEE.

Yu J.,Central South University | Cheng M.,Central South University | Gao D.,Central South University | Gu Y.,Nanyang Power Supply Company | Yu J.,Hunan University
Chinese Control Conference, CCC | Year: 2016

This paper presents a Lyapunov stability theory-based control method for a three-level neutral-point-clamped active power filter (NPC-APF) in three-phase three-wire system. The mathematical model of NPC-APF is deduced, and the Lyapunov stability theory-based control is established for current control of NPC-APF. The current control is different from the conventional proportional integral control or proportional-resonant(PR) control, which maintain good steady-state compensation performance and fast dynamic tracking response in wide harmonics range compared to the traditional linear PR control systems. The extensive simulation results in MATLAB/SIMULINK validate the feasibility of the proposed method. © 2016 TCCT.

Huo Y.H.,China University of Petroleum - East China | Zhang L.X.,China University of Petroleum - East China | Zhang Q.L.,China University of Petroleum - East China | Li S.Y.,China University of Petroleum - East China | Gui J.T.,Nanyang Power Supply Company
Advances in Power and Energy Engineering - Proceedings of the 8th Asia-Pacific Power and Energy Engineering Conference, APPEEC 2016 | Year: 2016

With the development of Distributed Generation (DG) and the decrease of load rate, the impact of fluctuating load on voltage quality is becoming more and more important. In this paper, the effect of voltage quality, line loss and transformer loss in local fluctuant 10 kV power network are studied, and the impact of load fluctuations on the power grid voltage quality is analyzed from two aspects: the value of load and the distance from loads to the power points. For the power grid with a small proportion of fluctuating loads, a method is designed to control the power grid by using Static Var Compensator (SVC). Simulation results prove that using SVC flexibly can improve voltage, reduce line loss and transformer loss obviously. It can not only improve voltage quality, but also “release” additional capacity and extend supply power distance. © 2016 Taylor & Francis Group, London.

Zhou J.-J.,Nanyang Power Supply Company | Fan Q.-L.,Nanyang Power Supply Company | Fan G.-R.,Nanyang Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

The high voltage side current of main transformer differential protection may be obtained by method of sum current of section switch and line switch in internal bridge connection. Mal-operation of differential protection occurs when external short-circuit or CT break happens in high votage side of transformer. The reasons of mal-operation lie in that the sum current of line switch and section switch is not finished in internal software of protection device, which lead to the inconsistency between secondary current felt by protection device and the high voltage side current of main transformer, therefore, the correct latch-up protection can not be realized, as external short circuit or CT break occurs. The method that currents of section switch and line switch joining to differential protection separately is introduced, proceedings of protection operation program are presented as well.

Wang J.,Hubei Engineering University | Liu H.,Hubei Engineering University | Chen X.,Nanyang Power Supply Company
Dianwang Jishu/Power System Technology | Year: 2011

It is impossible to implement the furthest optimization of distribution by unilateral network reconfiguration or reactive power optimization, so it is necessary to comprehensively consider the two manners. For this reason, a differential evolution algorithm-based comprehensive optimization algorithm for distribution network is proposed. To unify with the integer encode mode for reactive power optimization, the circle branch integer encode mode with the shortest encoding length is applied to network reconfiguration to simultaneously lead network reconfiguration and reactive power optimization into evolutionary process. Meanwhile, the adaptive mutation and the adjusting strategy of parameter evolution are led into evolution process to ensure that the convergence can be accelerated while the optimal solution is obtained. Finally, the measures to reduce calculation burden is analyzed. Results of calculation example show that the proposed algorithm is effective.

Wu L.,Nanyang Power Supply Company | Mao H.-Z.,Nanyang Power Supply Company | Zhou J.-J.,Nanyang Power Supply Company
Gaoya Dianqi/High Voltage Apparatus | Year: 2011

Potential fault of transformer can be found by gas phase chromatography, and the fault characters such as overheat fault and discharging fault can be diagnosed. Regression analysis is applied to overheat fault, estimation to determine whether fault position is in magnetic circuit or electrical circuit. This paper adopts the regression analysis to an overheat fault due to local eddy in the magnetic circuit of a main transformer, determines the cause of the fault, and prevent an accident.

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