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Zhuhai, China

Ji X.,Shandong University of Science and Technology | Zhang W.,Zhuhai XJ Electrical Co. | Yu Y.,Shandong University of Science and Technology | Liu Q.,Shandong University of Science and Technology
Journal of Electrical Systems | Year: 2015

As an effective measure to improve electricity supply reliability, loop-closing operation is widely used in distribution network. Due to various distributed generation were involved into distributed system, problems such as circuit breaker overcurrent may arise if loop-closing and DG status were not well coordinated. In this paper, a new loop-closing control model which including distributed generation is proposed, and the genetic algorithm with diversity control approach is used to solve the problem. A typical case with two feeders and three distributed generations is used to illustrate the performance of the proposed method. © JES 2015.

Huang W.-J.,Zhuhai XJ Electrical Co. | Qian Y.-C.,Zhuhai XJ Electrical Co. | Lu Z.-L.,Beijing XJ Electrical Co.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

In the open-loop distribution network, the reliability can not be increased and the DG can not be connected better. However, in the closed-loop distribution network, the faulty line section can be isolated automatically, the normal line section can be recovered rapidly, and it needs not outage in non-fault zone. So, the civil line and industrial line which form a closed-loop system can improve the utilization rate of equipment and the voltage qualification rate by loads complementary. The maximum short-circuit current value of faulty line is similar between the closed-loop system and the open-loop system, but short-circuit current flows through more lines. The paper proposes the centralized protection to solve the protection problems in the closed-loop operation system. The new distribution network planning principle of using typical connection mode and planning according to the partition, section, load density and load characteristics is given.

Xiao D.-Y.,Southwest Petroleum University | Tan W.-B.,Zhuhai XJ Electrical Co. | Zhang W.,Zhuhai XJ Electrical Co.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2014

To solve the problem of asynchronous frequency-fixed and sampling system's complex computation and weak real-time for power system frequency measurement, a practical real-time frequency measurement algorithm is proposed. This method is based on the interpolation principle of periodic zero-crossing point, the frequency estimated value is calculated by digital filtering of FIR band-pass for A/D sampling discrete sequence and by interpolating for adjacent zero-crossing point with the same direction. The signal under test in power system is simulated and vertified under three different circumstances: excluding harmonic, including second to sixteenth harmonic and the random noise. The simulation result is compared with that of Discrete Fourier Transform (DFT) method. The result shows that this method is superior to DFT in anti-interference and measurement accuracy, it can satisfy the requirement of frequency measurement for power system due to its simplicity, strong practicability, high instantaneity and measurement accuracy. ©, 2014, Power System Protection and Control Press. All right reserved.

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