Xuchang, China
Xuchang, China

Time filter

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Han H.-L.,XJ Power Co. | Tang H.,XJ Power Grid Corporation | Chen C.,XJ Power Grid Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

This paper summarizes main protection's action and tripping object after action when bus fault or line fault or transformer fault occurs in 500 kV voltage side or 220 kV voltage side or 35 kV voltage side of 500 kV substation. Aiming at breaker failure, the paper offers the scheme of failure protection as the nearby backup protection. On the basis of the scheme, it brings out the remote back-up relay's action when nearby backup failure occurs and the assorting relationship among protections. It details the way of starting nearby backup and remote backup when breaker failure occurs. Aiming at line-protection's transferred tripping, starting breaker failure of bus protection and transformer's synchronism tripping or delay tripping, the paper comprehensively discusses their principles and practical way. Dead zone protection and charge protection of bus tie breaker are discussed, too.


Patent
State Grid Corporation of China, XJ Group Co. and XJ Power Co. | Date: 2013-08-07

A battery replacement apparatus and a battery replacement system are applicable to an electric commercial vehicle. The battery replacement apparatus comprises: a main frame; a positioning mechanism constituted by a vertical positioning mechanism and a horizontal positioning mechanism, the vertical positioning mechanism being arranged within the main frame, and the horizontal positioning mechanism being arranged under the main frame; a rotating mechanism arranged under the vertical positioning mechanism; a a lateral movement mechanism arranged on the rotating mechanism; and a push-pull mechanism arranged on the lateral movement mechanism. The battery replacement system comprises the battery replacement apparatus, and also comprises a power supply unit, a charging unit, and a monitoring and communication unit. The battery replacement apparatus can automatically replace battery packs in electric commercial vehicles, thus the efficiency of battery replacement is increased, and more battery replacements can be completed per unit of time, thereby allowing a charger to perform a fuller charge and to have an improved utilization rate.


Hao Z.,XJ Power Co. | Zhang J.,Sichuan Electric Power Corporation | Duan J.,XJ Power Co. | Wang T.,XJ Power Co. | Zheng Y.,Chongqing University
Dianwang Jishu/Power System Technology | Year: 2011

To research corona inception voltage characteristics of single-phase/monopole bundled conductor, combining charge simulation method with manual-consulting, a mathematical model to calculate corona inception voltage of bundled conductor is built. Considering the difference of conductor's corona discharge due to different positions where the bundled conductor is located and the different positions of sub-conductor surfaces, the electric field intensity distribution of sub-conductors' surfaces are determined by manualconsulting method, and the corona inception voltage of bundled conductor is obtained with charge simulation method. Calculation results of the proposed approach well conform to the test data, so it is shown that the proposed method is effective. Finally, using the proposed method, the influences of geometric dimension of bundled conductor, such as bundling spacing, radius of sub-conductor and number of sub-conductors on corona inception voltage are discussed with the proposed method, thus optimal scheme to select the type of bundled conductor is obtained.


Zhang D.,XJ Power Co. | Qiu Z.,XJ Power Co. | Li Y.,Zhejiang University | Chen G.,Zhejiang University | He X.,Zhejiang University
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2011

Shunt active power filter (APF) is suitable to compensate current-type harmonics generated by nonlinear load, but high compensation precision is difficult to be obtained due to very high slew rate of harmonic current e. g. inductive rectifier and phase lag of close-loop control system. In this paper, LCL-filter is used as output filter to obtain high slew rate of compensation current and sufficient attenuation ratio for switching frequency. The design approach of LCL-filter based on slew rate of compensation current and bypass effect for switching ripple is proposed. What's more, repetitive control with differential compensator is adopted to eliminate steady-state error of control loop. Based on these two approaches, very high steady-state compensation performance both at low and high frequency range can be obtained. Experimental results validate the feasibility of the schemes proposed by this paper.


Yu J.-H.,Chongqing University | Zhang J.,Chongqing University | Zhang H.-Q.,Chongqing University | Hao Z.-D.,XJ Power Co.
Gaodianya Jishu/High Voltage Engineering | Year: 2010

We put forward an improved method to calculate the ground-level electrical field values on the EHV/UHV AC transmission lines by corona discharge. Space charge, which was generated by corona discharge, was simulated by equivalent charge, and was calculated by a new formula, according to the Shockley-Ramo theorem. The calculation by the proposed method is simple. Then the calculated maximum values of the electric field agree with those available in the literatures. Meanwhile, in the real example, the calculation of ground level field can be used to analyze the electromagnetic environment characteristics of the 750 kV compact AC transmission line.


Zhang D.-J.,XJ Power Co. | Qiu Z.-L.,XJ Power Co. | Chen T.-J.,XJ Power Co. | Zhang J.-X.,XJ Power Co.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

Grid Connected Converter (GCC) is an important type of power electronic converter. LCL-filter, because of which considers both gain of low-frequency band and decay of high-frequency band, is suitable to be used as output filter in GCC. However, LCL-filter, as a three-order control object, is difficult to stabilize. To achieve good dynamic and steady-state performance, a double-loop current control approach based on phase lag is proposed. In the control scheme, the inner loop uses additional phase lag and improves amplitude margin, to stably control LCL filter, and thus fast dynamic response of LCL-filter can be obtained. As control accuracy of inner loop for AC signal is not satisfied, repetitive controller, as outer control loop, is used to improve high steady-state performance. Theoretical analysis and experimental results indicate that this control approach used in active power filter can provide good compensate performance, the sine wave of compensated grid current is better and dynamic response is fast. In static var compensator, the double-loop control can suppress dead-band effect of IGBT very well and the quality of output current waveform is ensured. In a word, the double-loop control proposed in this paper can be successfully used in fundamental and harmonic wave with good dynamic and steady-state performance.


Zhang D.-J.,XJ Power Co. | Qiu Z.-L.,XJ Power Co. | Chen T.-J.,XJ Power Co. | Zhang J.-X.,XJ Power Co.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

Power modules parallel is necessary for the high power grid connected converter (GCC) in low voltage grid. The whole parallel system with the ability of operating with parallel module failure is required to achieve high reliability. The current loop should guarantee output current balance in unbalanced circuit. According to the feature that the repetitive control can ensure a high accuracy of AC signal, this paper proposes a simple control method in ABC steady frame by combining the repetitive control, as outer control loop, with the inner control loop of one-beat delay to ensure balanced output current of parallel GCC based on LCL-filter. Principle analysis indicates that the proposed control approach can conserve enough stability margin and has good robustness when the filter parameter is changed. Regarding the steady-state pricision, the slight decrease of the steady-state performance due to the gain loss can also satisfy engineering practice. Experimental results prove that three-phase output current is balanced under failure condition and the efficiency of the proposed control approach is validated.


Yang Y.,Northeastern University China | Wei Y.,Northeastern University China | Li Z.,XJ Power Corporation | Qin S.,Northeastern University China
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2013

Aiming at the features that modern industrial processes always have a large number of process variables and the process data usually contain both Gaussion and non-Gaussion information at the same time, a new system performance monitoring and fault diagnosis method based on mixed subspace is proposed in this paper. First, wavelet denoising, PCA and ICA methods are used to carry out process monitoring. Then, the distance similarity method based on PCA characteristic subspace and the cosine similarity method based on ICA subspace are combined to set up fault diagnosis library, calculate the mixed similarity and determine the diagnosis thresholds of various faults. Finally, the online process measurement data are monitored to judge whether the process is normal. We could judge the source and type of the fault in a short time based on mixed similarity when abnormal condition appears. This method could make full use of Guassion and non-Guassion information in the process data. A simulation case study of Tennessee Eastman (TE) process indicates that the proposed method is feasible and efficient. Compared with the variable contribution plot method, the proposed method can locate the fault more quickly and efficiently.


Dai Q.,Huazhong University of Science and Technology | Duan S.,Huazhong University of Science and Technology | Cai T.,Huazhong University of Science and Technology | Chen T.,XJ Power Co. | Huang L.,Huazhong University of Science and Technology
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014

Battery charging and swapping stations (BCSSs) for electric vehicles has become an important infrastructure contributing to the development and spread of electric vehicles in China. The cost-benefit model of BCSS is crucial for its commercialization. In this paper, the battery lease mode is chosen as the operation mode of the BCSS. On the grounds of the chosen mode, the cost-benefit model of the BCSS based on the time-varying economic assessment index including net present value is built that considers the whole capital costs, the maintenance and operation fees, employee wages and service returns from swap and charging. Finally, with a BCSS based on leased mode in China as an example, the whole life cycle cost-benefit model is presented and the key elements affecting the station's revenue arc found through a sensitivity analysis. The sequence of sensitivity elements is as follows: the battery swapping price, lease rental of batteries, electricity price, and so on. The model of BCSS and its sensitivity analysis has provided a basis for cost-benefit assessment and decision marking for commercial operation of BCSS of electric vehicles. © 2014 State Grid Electric Power Research Institute Press.


He Z.,XJ Power Co. | Hu X.,XJ Power Co. | Di S.,XJ Power Co. | Song B.,XJ Power Co. | Yang C.,XJ Power Co.
Advanced Materials Research | Year: 2013

At present, the power of electric vehicle mainly relies on li-ion battery module. The temperature field of lithium-ion power battery pack assembly is an important factor which affects the security and reliability of EV when the vehicle is running [1,2]. In this paper, by simulating the typical discharge condition of Li-ion battery module, it is realized that the detailed temperature field and air flow field of battery pack assembly. According to the results of thermal analysis, li-ion battery module layout can be improved, and the high-temperature region of battery pack assembly can be found clearly. © (2013) Trans Tech Publications, Switzerland.

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