Zhang G.,Shanghai JiaoTong University |
Wang X.,Shanghai JiaoTong University |
Jiang C.,Shanghai JiaoTong University |
Zhang Y.,Guizhou Power Grid Corporation |
Wang Z.,Shanghai JiaoTong University
Dianwang Jishu/Power System Technology | Year: 2016
At present, distributed generations (DGs) are widely used in electric power systems. Due to low capacity and widespread locations, DGs are hard to manage. However, by setting up virtual power plant (VPP) operation center, this problem can be well solved. Through independent system operator (ISO) and VPP's proper bi-level optimization dispatch, all DGs can be equivalent to a virtual power plant, taking part in electricity market and promoting net profit of each individual. By introducing wind curtailment punishment into objective functions of bi-level optimization dispatch model, renewable energy is integrated into power system more effectively. To indicate VPP's internal dispatch advantage, an example was used to illustrate it. Based on analysis of different VPP's capacity ratios in whole system, its influence on VPP's and each individual's net profit was calculated and compared. Examples indicated that bi-level optimization and proper VPP's capacity ratio could play an important role in improving VPP's profit. © 2016, Power System Technology Press. All right reserved.
Li Y.,Chongqing University of Posts and Telecommunications |
Liao C.,Guizhou Power Grid Corporation |
Wang Y.,Chongqing University |
Wang C.,InterDigital Communications
IEEE Transactions on Wireless Communications | Year: 2015
Both capacity and energy efficiency are crucial for next-generation wireless networks. This paper investigates energy efficiency in cooperative cellular networks. Based on the double auction theory, we model the optimal relay assignment problem, which aims at improving the performance of cell-edge users (CEUs) with energy efficiency optimization. In the proposed auction-based model, the selfish nature of users is taken into consideration, which means users in the idle state are unwilling to relay the information for active CEUs unless they are paid enough. Therefore, we use mark-up to determine the bid and ask. Furthermore, the energy efficiency (EE) is defined and the model for optimizing the EE is built. An energy-efficient maximum weighted matching algorithm (EE-MWM) is proposed to solve the EE optimization problem. Finally, the performance of EE-MWM is evaluated in terms of EE, capacity and social welfare, which shows that EE-MWM can greatly improve the performance of cooperative cellular networks. © 2002-2012 IEEE.
Li Q.,Guizhou Power Grid Corporation |
Zhang D.,Guizhou University |
Xu T.,Guizhou University
Proceedings of the 2nd International Conference on Electronic and Mechanical Engineering and Information Technology, EMEIT 2012 | Year: 2012
With the method of modal analysis, the full Jacobian according to the power system power flow equations is studied and a method to identify the suitable bus for loading shedding is proposed in this paper. The proposed method makes use of the participation factors corresponding to the active power, by which the structural characteristic of the power system nonlinearity is included. As a result, the effective bus where the load shedding should be used can be found. In order to show the effectiveness of the proposed method, the WSCC 9-bus power system is used as an example. The simulation results indicate that with the load shedding at the place where the proposed method decided, the voltage stability indices are considerably increased. The proposed method in this paper is effective. © the authors.
Deng P.,Guizhou Power Grid Corporation |
Liu X.,Guizhou University |
Pi X.,Guizhou Power Grid Corporation |
Wang F.,Guizhou Power Grid Corporation |
Liu K.,Duyun Electrical Power Bureau
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2016
For the reasonable series reactance rate in capacitor of substations, the full parametric harmonic circuit and model for 220 kV and 110 kV substations are established, which consists of short impedance, transformer, capacitor, load, and harmonic source, and the resonance objective function that reflect the degree of resonance such as harmonic voltage amplification factor on load bus, etc. is given. With minimax optimization, the maximum values of objective function in all the power grid parameter space are minimized by changing reactance rate, and the technical and economic characteristics of the reactance rate of the capacitor are analyzed. The calculation results show that resonance is eliminated with best effect and generality by the rate 12%; resonance is eliminated with second effect by rate 4.2% ~ 4.5%, but the rate 4.2% ~ 4.5% one has better technical and economic value and is suitable for most of 220 kV and 110 kV substation. © 2016, Power System Protection and Control Press. All right reserved.
Fan A.,Pingdingshan University |
Yang Z.,Pingdingshan University |
Chang Q.,Guizhou Power Grid Corporation |
Xie L.,Pingdingshan University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013
In order to solve the problem of security of data transmission in the electric power dispatching system, the characteristic of high efficiency of the elliptic curve cryptosystem (ECC) calculation is made use of, and a certificateless signature scheme based on ECC without pairing is put forward. Based on the security of the discrete logarithm problem, the private key pair and public key pair are co-produced by the dispatching center and dispatching users to avoid the drawbacks of complex certificate management in the electric power dispatching system. Based on the realization of the idea without pairing, the ECC calculating method is used to improve the efficiency of the implementation of the security dispatch. The scheme is not only characterized by integrity, anti-denying, anti-forgery, verification of signature and dispatching identity, but also can meet the requirement on real-time transmission for the electric power dispatching system. © 2013 State Grid Electric Power Research Institute Press.
Zhang B.-B.,University of Sichuan |
Qiu X.-Y.,University of Sichuan |
Liu N.,University of Sichuan |
Sun B.,Guizhou Power Grid Corporation |
And 6 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013
Aiming at the question of balancing the fluctuating photovoltaic grid-connected generation system, a hybrid energy storage-based grid-connected PV power system model is proposed to overcome the fluctuation of grid-injected power caused by the change of illumination intensity and temperature. An ultracapacitor-battery based energy storage control system is employed to smooth the fluctuation of grid-injected power caused by the change of various weather conditions. A new method to track the maximum power point is proposed to modulate the maximum output power of PV system more stably and instantly, and it can also improve the power generation efficiency. Finally, this model is tested by using Matlab/Simulink. The result proves that the hybrid energy storage-based control system can efficiently improve the stability of PV grid-injected power.
Deng P.,Guizhou Power Grid Corporation |
Pi X.,Guizhou Power Grid Corporation |
Ma S.,China Electric Power Research Institute |
Wang Q.,China Electric Power Research Institute |
Zhang R.,China Electric Power Research Institute
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014
A composite generator-network-demand planning method is needed today. It requires connection of large capacity generators into 220 kV regional networks where the loading is relatively small. This method will help to cope with the increasing short circuit currents at 500 kV networks, and to develop a smart grid capable of withstanding nature disasters. In order to solve over-frequency stability problem of large generator in a small network, this paper presents a method of speed governor state transition control based on signal of power flow transfers. The method can quickly and precisely regulate power of generator unit following abrupt changes of an isolated grid. It can increase over-frequency stability margin of speed governor at steam turbine unit from 9% to 50%. The performance of speed governor at hydropower unit can also be significantly increased. The control system is decentralized robust and compatible with other systems. It can effectively maintain the operation of the remaining power networks with residual generation capacity after the overall system is damaged by natural disasters. Case studies are given to show the effectiveness of the proposed methods. ©2014 State Grid Electric Power Research Institute Press
Fan A.-W.,Pingdingshan College |
Chang Q.,Guizhou Power Grid Corporation |
Lu S.-X.,Pingdingshan College
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012
Targeting at the security problem of the electrical dispatching system, the ECC (Elliptic Curve Cryptography) Sequential Multiple Digital Signature Scheme based on electrical dispatching system is put forward. The confidence center is authenticated by means of zero-knowledge, the identification of signature and validity has been processed by Hash, to avoid the attack of identification switch and ensure the integrity of signature. Compared with similar algorithm, it is characterized with anti-denying, anti-forgery, verifiability of integrity of signature. It will avoid the security problem resulted from transferring message by plaintext, insure the integrity of massage and verifiability of legitimate operating tickets and solve the security problem of electrical dispatching system. The application test shows that the algorithm will meet the requirement of real-time for electrical dispatching system.
Peng B.,Zhejiang University |
Qiu Y.,Zhejiang University |
Chen J.,Guizhou Power Grid Corporation |
Wu H.,Zhejiang University |
Song Y.,Zhejiang University
Dianwang Jishu/Power System Technology | Year: 2015
Orderly power utilization is an important method to relief peak power shortage. For this reason, a comprehensive week-ahead decision model for orderly power utilization is proposed. Four peak shifting and averting strategies based on users' load profile and users' participation willingness as well as load distribution and transmission congestion are considered. Network loss is approximately considered through the improved DC power flow method. A multi-objective optimization model aimed at minimizing the cost of peak shifting and averting strategies and network loss is built. The solving time is decreased by some solving strategies, for example, only considering the peak time constraints. Case studies show that the proposed method can make personalized power utilization scheme based on users' characteristics. Orderly power utilization in both spatial and temporal dimensions can realize the optimal allocation of limited power resources, ease power shortage as well as reduce network loss and eliminate transmission congestion so that the security and economical efficiency of power network operation can be improved. ©, 2015, Power System Technology Press. All right reserved.
Li L.,Chongqing University |
Li L.,Hubei Electric Power Company |
Hu B.,Chongqing University |
Xie K.,Chongqing University |
And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2016
Firstly, imbalance power in isolated microgrids has been analyzed. Based on discrete Fourier transform (DFT), the imbalance power is decoupled into day and hour components, which can be balanced by compressed-air energy storage and sodium-sulfur cell, respectively. In order to obtain the optimal components, the DFT segmentation principle is studied. By considering investment and operating cost including energy storage, loss of load and wind abandoning penalty comprehensively, the capacity optimization model of hybrid storage systems for isolated microgrids is built. This model can simultaneously optimize the DFT segment point and the hybrid energy storage capacity. And its solving complexity has been greatly simplified as the model can thoroughly decouple the configuration optimization of compressed-air energy storage and sodium-sulfur cell. Finally, the correctness of the model and the method has been verified in a certain practical microgrid. © 2016 Automation of Electric Power Systems Press.