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Liu M.,Tianjin University | Wang C.,Tianjin University | Guo L.,Tianjin University | Zhao B.,Zhejiang Electrical Power Test and Research Institute | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Aimed at the island microgrid integrated with wind turbine, photovoltaic, diesel generator, energy storage, and desalination plant, a multi-objective optimal design model considering the allocation ratio of net present cost (NPC) in the full life cycle, the utilization of renewable energy and the pollutant emission level is proposed. The optimal number of distributed generators and the optimal capacity of energy storage are determined as optimization variables. Based on the established control strategy, a floating elitist preserved genetic algorithm is used to solve this problem. The island microgrid is designed and the simulation results are compared with the HOMER optimization results to illustrate that the proposed method is more reasonable and feasible than that of HOMER. © 2012 State Grid Electric Power Research Institute Press. Source


Liu M.,Tianjin University | Guo L.,Tianjin University | Wang C.,Tianjin University | Zhao B.,Zhejiang Electrical Power Test and Research Institute | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

Considering the operating constraints of typical equipments in a hybrid isolated microgrid consisting of wind power, photovoltaic system, diesel generator, and battery storage, a coordinated control strategy is proposed. The control strategy aims at ensuring a long-term stable operation of the isolated microgrid and reducing the system cost over lifetime. A typical and practical isolated microgrid is simulated via a self-developed simulation tool named quasi-steady simulation and optimization tool for microgrid (QSOT-MG). The simulation results are compared with those of Hybrid2, a simulation tool developed by National Renewable Energy Laboratory (NERL) of USA. The effectiveness and correctness of the control strategy proposed are verified by comparison. Source


Yan L.,Fuyang Power Supply Bureau | Li W.,North China Grid Company | Cao J.,Beijing Sifang Automation Co
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2010

A synchronized sampling scheme of MU(Merging Unit) with FPGA(Field Programmable Gate Array) is proposed to improve the synchronization precision of analog sampling for digital substation. Analysis shows that the synchronization error is mainly caused by the crystal oscillator of MU. According to the requirement of MU synchronized sampling, the reception and processing of PPS(Pulse Per Second) is realized separately in two function modules: the PPS reception and the equal-interval sampling, which precisely detects the rising edge of PPS and divides the sampling interval to improve the synchronization precision. These two modules are compensated and treated separately with FPGA to control the error within a certain range. Experiments prove the synchronization accuracy reaches 1μs. Source


Bi T.,North China Electrical Power University | Li W.,North China Electrical Power University | Xu Z.,North China Electrical Power University | Xu Z.,Beijing Sifang Automation Co | Yang Q.,North China Electrical Power University
IEEE Transactions on Power Delivery | Year: 2012

A novel distance protection algorithm for the first-zone distance relay of parallel transmission lines is proposed for cross-country grounded faults. The algorithm calculates the fault impedance using one-end sampling voltages and currents from a single line. The theoretical basis of the proposed algorithm is described in this paper, which is based on the symmetrical component method for parallel lines. And an attempt is made to express the zero-sequence current of the adjacent parallel line at the relay location by the zero-sequence current of the concerned line in combination with the fault characteristics of the system model, by which the impact of the mutual coupling between the lines can be eliminated. And, thus, the distance algorithm for cross-country grounded faults is presented. The simulations show that the proposed algorithm can obtain the accurate fault reactance when cross-country bolted faults occur, which is superior to the existing distance protection algorithm based on one-end data from a single line. © 1986-2012 IEEE. Source


Patent
Beijing Sifang Automation Co | Date: 2013-10-28

This invention relates to a method for making 32-bit addressing of SV data by utilizing FPGA, which may be applied to processing digital sampling data in an equipment of an intelligent substation. Specifically, the method includes the following steps: FPGA receiving naked SV data packages generated based on IEEE802.3 standard; analyzing data structure of Ethernet frame; based on characteristics of the Ethernet frame of the SV data, the SV data of the network byte sequence being reorganized by utilizing ASN.1 coding rules, so that the SV data being converted into a data that can be directly accessed by 32-bit addressing processors. As a result, SV data decoding efficiency is improved greatly. This invention may make the decoding efficiency of 32-bit addressing processor improved by 5-10 times, thus solve problem of declined efficiency due to processing network byte order by splitting and reorganization.

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