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Zhu Y.,Tsinghua University | Liu F.,Tsinghua University | Zhang M.,Tsinghua University | Min W.,State Grid Electric Power Research Institute of China | And 3 more authors.
IET Electric Power Applications | Year: 2013

This study concerns the analysis and minimisation of the force ripples existing in ironless permanent magnet planar motors. The force ripples is one of the key factors for moving accuracy of the planar motors. One of the main sources of the force ripples, the neglected higher harmonics of the magnetic flux density distribution, is analysed for synthesis of real-time control model in this study. An analytical model of the planar motor is firstly developed, which illustrates that the force ripples part caused by some higher harmonics can cancel each other when the length of the coil is an even multiple of the pole pitch of the magnet array. As a result, the force ripples caused by the higher harmonics can be basically eliminated with a selected coil. Finally, the analysis results are both validated by comparative simulation and experiment of two partial motors. © The Institution of Engineering and Technology 2013.

Jie T.,Shaoguan Power Supply Bureau | Yongjun Z.,Guangdong Key Laboratory of Clean Energy Technology | Sihua P.,Guangdong Key Laboratory of Clean Energy Technology | Mei H.,Shenzhen Power Supply Bureau Co.
Asia-Pacific Power and Energy Engineering Conference, APPEEC | Year: 2013

To realize differentiated configuration of reactive power compensation (RPC), 10 kV distribution feeders are classified into four types according to their electricity characteristics firstly, and their corresponding base-state models are established for reactive power optimization. Several indicators have been defined in order to facilitate the base-state analysis, such as the configuration rate of RPC, the average load rate of distribution transforms on the feeder, the natural power factor of distribution transforms, the generation-consumption ratio, and the sensitivity between characteristic parameters and the configuration rate of RPC. Secondly, the configuration rate of RPC of each base-state model has been calculated by reactive power optimization computation and the sensitivity analysis on various electricity characteristic parameters, and then the configuration rate of non-base-state feeders can be reckoned according to it. At last, the recommended table of the configuration median rate about RPC capacity can be provided and can be used to guide the reactive power configuration planning on different types of 10 kV feeders and different transformers. © 2013 IEEE.

Wang H.,Northeast China Institute of Electrical Power Engineering | Yu T.,Northeast China Institute of Electrical Power Engineering | Tang J.,Shaoguan Power Supply Bureau
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

This paper proposed a multi-agent decentralized correlated equilibrium Q(λ) (DCEQ(λ)) learning algorithm to tackle automatic generation control (AGC) under strong random gird environment considering emerging renewable energy sources. This algorithm does not need to consider the tradeoffs between exploitation and exploration, it also does not need any knowledge of the system model and uses the trial and error methods to find the most desired policy. After the adaptive problem of this algorithm in AGC fields had been figured out, an improved reward function and an equilibrium selected function integrated with fair factor were proposed. Three kinds of eligibility traces were also analyzed and SARSA(λ) was introduced in this algorithm to reassign the delayed reward appropriately due to the long time-delay control link such as AGC thermal plants. Simulation tests on a two-area load frequency control (LFC) power system model and China Southern Power Grid demonstrated that DCEQ(λ) controller has better control performance than Q(λ) controller, and can effectively smooth the instantaneous value of automatic generation control (ACE) and control performance standard (CPS), and thus improve the stability and robustness of interconnected power systems. © 2014 Chin. Soc. for Elec. Eng.

Zhang X.,South China University of Technology | Yu T.,South China University of Technology | Tang J.,Shaoguan Power Supply Bureau
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2015

A hierarchical correlated Q-learning (HCEQ) approach is presented to solve the dynamic optimization of generation command dispatch (GCD) for automatic generation control (AGC). In order to decrease the dimensions of GCD, the AGC units are classified into different clusters according to their time delay during frequency control. Compared with single-agent reinforcement learning, the HCEQ method introduces the solution of equilibrium objective function, which effectively improves the optimization speed. The generating error, hydropower capacity margin and AGC regulating cost are turned into the Markov decision process reward function via the linearly weighted aggregate algorithm. The application of the hierarchical correlated Q-learning algorithm in China southern power grid (CSG) model shows that the method proposed is capable of reducing the converging time in the pre-learning process and the AGC regulating cost while improving the control performance of AGC systems in a complicated environment of random perturbation. ©2015 State Grid Electric Power Research Institute Press

Chen Z.-F.,Shaoguan Power Supply Bureau | Wu Y.,Shaoguan Power Supply Bureau | Jin D.-Q.,Shaoguan Power Supply Bureau
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

In small hydroelectric power system, conventional automatic bus transfer equipment has the defects of needing more time to detect bus non-voltage, at the cost of islanding all the small hydroelectric power and taking a long time to restore power supply. Based on the theory of automatic synchronous capture and high-frequency generation shedding, an intelligent automatic switching scheme suitable for tie-line in small power source area is put forward. According to this method, automatic bus transfer mode of islanding the small hydroelectric power quickly is selected in low water period, while automatic bus transfer mode of high frequency generator tripping round by round and automatic synchronous capture reclosure in high flow period, which enables regional power supply to restore quickly. This method has been used in automatic bus transfer equipment. Furthermore, simulated experiment using fault recorded data in recently years and parameters of power system has been made. Experiments proved that the new method can improve the stability of the grid and the reliability of power supply.

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