Xuji Group Corporation

Xuchang, China

Xuji Group Corporation

Xuchang, China
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Li J.,Xuji Group Corporation | Zhang D.,Xuji Group Corporation | Zhang S.,Xuji Group Corporation
Proceedings of 2016 IEEE Advanced Information Management, Communicates, Electronic and Automation Control Conference, IMCEC 2016 | Year: 2016

Facing the problem and current situation of the power grid master-slave station dispatching system architecture, this paper using the master-slave station distributed file system and master-slave station two-level business platform to divide the traditional master station business into master-slave station interacted distribution business, also issued the master-slave station distributed integration application architecture plan. Then, discussed the technology include file system directory service, the concept of master-slave business partition, gateway proxy. Proceed further modeling analysis to the slave station business such as monitoring and control, smart alarm and also give a conclusion on apply authorization. Through the apply authorization to indicate the plan could effectively solve the current problem and the application development will have a brightened prospects. © 2016 IEEE.

Li R.,Xuji Group Corporation | Guo B.,Xuji Group Corporation | Zeng Z.,Chongqing University of Technology
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2017

The probability of islanding of grid-connected distributed generators is relatively large on the user side. Taking the user safety and power quality into account, the islanding mode should be detected quickly and accurately. An active islanding detection scheme based on 20 Hz low-frequency power supply injection is proposed. The 20 Hz component which is equivalent to zero sequence component is injected into the 380 V system and islanding is identified by the change characteristics of the 20 Hz component. The composition and detection principle of the proposed scheme, parameters selection and its influence on power quality are described and analyzed in detail. MATLAB is applied in the modeling and simulation, and correctness of the analysis is verified by simulation results. The identification criterion for the island mode based on comparison of the absolute value is proposed and realized in a grid-connected interface device. Finally, the scheme is experimentally verified in a small rooftop distributed photovoltaic generation project. © 2017 Automation of Electric Power Systems Press.

Huang J.,Shandong University | Gao H.,Shandong University | Peng F.,Shandong University | Liu X.,Xuji Group Corporation
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2017

The active power differential protection has unique advantages in dealing with distributed capacitance and high resistance faults. However, the defect of close metallic faults with small resistance limits its practical application. In order to overcome this shortcoming, a concept of virtual active power emanating from referring to the superposition principle is proposed, and the different characteristics for virtual active power under the internal fault and the external fault conditions are analyzed. On this basis, a split-phase action criterion for virtual active power differential protection is proposed and its operation characteristics are analyzed qualitatively. By using the model of 500 kV transmission lines on PSCAD, a number of simulations have been conducted for different fault locations, fault types, transition resistances, reactive elements operations and asynchronous data to evaluate the influences on the protection scheme performance comprehensively. Theoretical analysis and simulation results show that the proposed protection scheme is able to correctly identify the fault sections without dead zone for close metallic faults but a great capability against fault resistance, less data exchanges, a low requirement for synchronization and no need of capacitance compensation. © 2017 Automation of Electric Power Systems Press.

State Grid Corporation of China, Nanjing Southeast University, BEI JING XJ Electrical CO. and Xu Ji Group Corporation | Date: 2013-04-18

The present invention provides an integrated battery dispatching system with centralized charging and centralized allocation, which comprises an initial parameter setting module (101), a dispatching selection module (102), a delivery parameter setting module (103), a full battery number acquiring module (104), a logistics fleet delivery strategy submodule (105) and a centralized charging station charging strategy submodule (106). The present invention integrally dispatches centralized battery charging, battery dispatching and logistics vehicle allocation, and arranges the battery to be charged with cheap electric energy according to the battery replacement demand of a delivery station in combination with the capacity constraint for a centralized charging station and the power tariff of a power grid. The four integrated dispatching subsystems involved in the present invention can meet the needs of different users, and the users can select a suitable operation mode according to their own characteristics and practical situations.

State Grid Corporation of China and Xu Ji Group Corporation | Date: 2012-08-28

The present invention relates to an IEEE1588 protocol negative testing method, comprises steps of: connecting a IEEE1588 tester and a slave clock DUT to establish a real-time closed-loop feedback mechanism; taking the IEEE1588 tester as a master clock, and establishing a stable time synchronization with the slave clock DUT; obtaining the timing offset or path delay of the slave clock DUT before disturbance; assembling an abnormal message in a frame and sending it to the slave clock DUT; calculating the timing offset or path delay increment after disturbance of the abnormal message; determining whether there is a sudden change in the timing offset or path delay of the slave clock DUT, wherein if there is no sudden change, the test passes; otherwise the test fails. This testing method uses the field of correction field (correction Field) in the IEEE1588 message to magnify the response of the slave clock DUT to the abnormal message stimulus, and realizes a real-time closed-loop detection to efficiently verify whether the message processing logic of the slave clock DUT follows the IEEE1588 protocol.

Kong F.,Xi'an Jiaotong University | Zhang B.,Xi'an Jiaotong University | Wang Y.,Xi'an Jiaotong University | Zhen W.,Sichuan Electric Power Research Institute | Zhang A.,Xuji Group Corporation
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2014

In order to improve the reliability and sensitivity of single-terminal transient-based protection, an ultra-high-speed directional element is proposed for the relay protection of HVDC transmission line, which effectively determines the fault direction according to the difference between the forward traveling wave energy and the backward traveling wave energy when different fault directions exist. A closed-loop test system consisting of RTDS and HVDC control & protection devices is built to test the performance of proposed directional element. Results show that, immune to the fault location and transition resistance and suitable for different voltage levels and different operating modes of HVDC projects, it determines the fault direction accurately and rapidly, which improves the performance of single-terminal transient-based protection effectively. Besides, it can be used to form a pilot directional protection.

Zhang B.,Xi'an Jiaotong University | Kong F.,Xi'an Jiaotong University | Zhang S.,Xi'an Jiaotong University | Zhang A.,Xuji Group Corporation | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

To solve the problems existing in traditional main protection for transmission lines, such as insufficient sensitivity and poor reliability, the novel non-unit main protection device based on transient signals for high voltage direct current (HVDC) transmission lines was developed on the present HVDC control and protection platform hardware and software. The protection scheme for HVDC transmission lines is based on the attenuation characteristics of line boundary for high frequency voltage signals and is composed of starting unit, transient signal based directional unit, boundary unit, lightning disturbance identification unit and fault-pole identification unit. All commissioning tests for control and protection systems of HVDC transmission lines were performed on the transient signal based protection device, which used control and protection devices, and RTDS simulation models for actual HVDC secondary system commissioning. The results show that the protection device can accurately identify internal faults, external faults and lightning disturbance at high speed, and is suitable for different HVDC projects. The protection principle is reliable and the amount of calculation is small; besides, the threshold values of each unit do not need to be changed when applied to different HVDC projects and the protection is feasible. © 2013 Chinese Society for Electrical Engineering.

Fu M.-P.,Xuji Group Corporation | Ma H.-W.,Xuji Group Corporation | Mao J.-R.,Xuji Group Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

Photovoltaic power forecast is significant to reducing the impact of PV generation integration on the power grid. According to the characteristics of power generation of photovoltaic and the factors impacting PV power output, a method of selecting similar days is proposed. By calculating and analyzing similarity degree, the historical data similar to the features of forecasted day are selected and considered as the training samples together with weather data. The least square support vector machine(LS-SVM)is used to calculate PV power output. The method is validated by photovoltaic system data of a micro-grid demonstration project and the forecast error is calculated and analyzed. The results show the method has high accuracy, which provides reference to forecast generation power of PV system.

Zhang J.,Xuji Group Corporation | Jiang Y.-J.,Xuji Group Corporation | Guo D.-Q.,Xuji Group Corporation
Gaoya Dianqi/High Voltage Apparatus | Year: 2010

Aiming at the opening current character and opening velocity character of the single coil and single stable permanent magnetic actuator which is used in 12 kV vacuum circuit breaker, the double coils and single stable permanent magnetic actuator which has one closing coil and one opening coil is suggested in this paper. In order to decrease opening current and increase opening velocity, a short circuit ring is fixed in the permanent magnetic actuator. The analysis and optimal design on the permanent magnetic actuator are performed by using the finite element method. The design scheme and test results are presented which indicate that the technical parameters meet the design requirements and the feasibility of the approach is verified.

Zhang H.,Xian Xuji Power Electronics Technology Corporation | Wu J.,Xian Xuji Power Electronics Technology Corporation | Yang M.,Xian Xuji Power Electronics Technology Corporation | Yao W.,Xuji Group Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2015

For restraining inner circulating current in modular multilevel converter (MMC), this paper presents a novel restraint strategy for bridge arm circulating current, including improved topology of MMC, circulating current restraint method, constant voltage control of voltage correcting module (VCM). Second, for engineering applications, this paper proposes a redundancy control method of VCM, and the parameters of VCM are designed, including modular voltage and support module capacitance value. Simulation results show the reasonableness of the design of the proposed VCM parameters and verify the redundancy control scheme can maintain VCM voltage stability as well as effectively restrain bridge arm circulating current of converter. The proposed scheme applies to all MMC system and has obvious advantages in case of high voltage and large capacity like IGBT connecting MMC in series. © 2015, Power System Protection and Control Press. All right reserved.

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