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Wu D.,Zhejiang University | Wang Y.,Zhejiang University | Guo C.,Zhejiang University | Liu Y.,East China Grid Company | Gao Z.,Yantai Power Supply Bureau
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

An economic dispatching model of the power system considering wind power forecast error in the electricity market environment is developed. For a certain wind power forecast value, a Beta function is used to fit the probability density distribution of the real-time available output power. Considering the probability of the forecast error and the economic compensation cost they caused, a more reasonable dispatching model in statistics is proposed. The model is based on the more sound electricity market environment, and the cost of greenhouse gas emission right that needs to be considered by the power company is taken into account. A simulation case compares the effects of the wind power forecast errors on the market clearing price and average purchasing cost of the power grid. The result shows that the proposed model can effectively reduce the operating cost of the power company, and promote the optimal allocation of resources. © 2012 State Grid Electric Power Research Institute Press.


Zheng X.,Shanghai JiaoTong University | Nengling T.,Shanghai JiaoTong University | Guangliang Y.,East China Grid Company | Haoyin D.,Shanghai JiaoTong University
IEEE Transactions on Power Delivery | Year: 2012

The relation between the parameters of dc transmission line and the variation of transient energy has been analyzed under various fault conditions in this paper. According to that, a new transient energy protective scheme is proposed. It is developed based on the distributed parameter line model in which the transient energy distribution over the line can be obtained from the voltage and current measurements at both terminals and the fault can be recognized from the calculated value simply. The test system is modeled based on the CIGRE benchmark and considered the distributed parameters of the dc transmission line. Comprehensive test studies show that the performance of transient energy protection scheme is encouraging. It can not only identify internal fault and external faults correctly and quickly, but can also respond to the high ground resistance fault. Finally, two main factors, including fault resistance and transmission distance, that affect the performance of the protection are also discussed. © 2012 IEEE.


Zheng X.-D.,Shanghai JiaoTong University | Tai N.-L.,Shanghai JiaoTong University | Thorp J.S.,Virginia Polytechnic Institute and State University | Yang G.-L.,East China Grid Company
IEEE Transactions on Power Delivery | Year: 2012

Based on the boundary characteristic of a dc transmission line, the response of transient harmonic current in the line-commutated converter HVDC transmission system is analyzed under various fault conditions in this paper. A new transient harmonic current protection scheme is proposed. The discrete Fourier transform is used to extract transient harmonic currents at both terminals of the dc transmission line and the type of fault can be identified by the transient harmonic currents. Two main factors including fault resistance and fault location that affect performance of the protection are also discussed in this study. The test system is modeled based on the CIGRE benchmark including distributed parameters of the dc transmission line. Comprehensive test studies show that the performance of the transient harmonic current protection scheme is encouraging. It can not only identify internal faults and external faults correctly and quickly, but also can respond to high ground resistance faults. © 1986-2012 IEEE.


Liu L.,Shanghai JiaoTong University | Cheng H.,Shanghai JiaoTong University | Ma Z.,East China Grid Company | Yao L.,China Electric Power Research Institute | Bazargan M.,Alstom
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012

In order to overcome the defect that the applications of life cycle cost (LCC) technology are limited to specific equipment or phase, a three dimensional LCC hierarchy model for entire transmission network was established, which includes time dimension, component dimension and cost dimension. The cost dimension was further divided into device layer, system layer and the cost of externalities. The impact of the reliability centered maintenance (RCM) strategy on the maintenance cost was analyzed. The expected energy not supply (EENS) was used to calculate failure cost. On this basis, four uncertainties such as wind power were simulated, and then the multi-objective chance-constrained transmission expansion planning model was proposed with minimum LCC and minimum load cut. The normal boundary intersection (NBI) algorithm integrated with improved niche genetic method was adopted to solve the model effectively. Finally, case studies were carried out respectively on an 18-bus system and 77-bus system. The results generate distributed Pareto set and recommend the optimal planning scheme. Additionally, the distribution structure of LCC shows the proportion and influence of each cost and can instruct the asset management of power systems in the future. © 2012 Chin. Soc. for Elec. Eng.


Gong W.-Z.,East China Grid Company | Fang X.-Y.,Shanghai JiaoTong University
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

A chromosome hybrid encoding model is established to enhance the genetic algorithm's efficiency of solving problems of distribution system service restoration. After node-depth encoding of distribution network topology and corresponding crossover and mutation operation, feasible distribution network spanning trees are generated. 0-1 encoding is applied to interrupttable load in the non-fault load loss regions to control load shedding and increase the flexibility of fault restoration. Using the hybrid encobing mode, the infeasible solutions can be reduced greatly, and the algorithm convergence is speeded up. Multi-objective optimization algorithm NSGA-II reduces the influence of weight coefficient subjectivity on optimum solution, and attains co-evolution of each optimization objective. It provides dispatcher with more than one service restoration plan. Simulation of the proposed model and the algorithm has verified their feasibility and correctness.


Gao C.,Nanjing Southeast University | Liang T.,Nanjing Southeast University | Li H.,East China Grid Company | Zhai H.,East China Grid Company
Dianwang Jishu/Power System Technology | Year: 2013

Automated demand response (Auto-DR) is one of the key technologies of smart grid in United States and the open automated demand response communications specification (OpenADR), which provides a public, open and standardized demand response (DR) interface, is listed in the Priority Action Plans of smart grid in United States. The development course of OpenADR, its necessity and contents as well as the OpenADR alliance are presented, and the communication architecture and data model of OpenADR are expounded. On this basis, a series of application of OpenADR are given. Related products of OpenADR and its pilot project prove that OpenADR can provide technical support to Auto-DR, and through low-cost standard communication structure the reliability, handleability, robustness and cost-effectiveness of DR can be improved. The development of DR technical standard in China, especially the development of Auto-DR technical standard, will contribute to the promotion of the research and development of related products and services by equipment manufacturing enterprises and service providers, and attract more power consumers to participate in DR projects to provide technical support for the reduction of peak load of industry and commerce, well-organized power consumption management, lowering cost in electricity and promoting energy conservation and emission reduction.


Patent
East China Grid Company and Tsinghua University | Date: 2012-02-07

A method of substation-control center two-level distributed modeling for power grid is provided. The method comprises: (1) building a substation model for each of substations, each substation model comprising a network model having a topological structure of the substation devices, parameters of the substation devices and measurement information of each substation devices, and a wiring diagram of each substation based on a whole line identification consistency; (2) uploading each substation model for each of the substations to the control center through a state power dispatching data network; and (3) splicing network models for the substations according to the wiring diagrams of the substations to build a whole power grid model of a whole power grid so as to monitor and control the whole power grid.


Zhang Y.,East China Grid Company | Yan C.,China Haisum Engineering Co. | Xie Q.,Tongji University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

The current design code requests that wind actions should be considered in the design of icing transmission tower. Taking 1000 kV double circuit transmission lines of an ultra high voltage (UHV) transmission project as the prototype, a large wind tunnel test on icing aeroelastic model was carried out to find out the dynamic interaction of wind-induced vibration for icing transmission tower-line coupling system. The aerodynamic characteristics of the transmission tower-line system were simulated and the boundary conditions were simulated by the equivalent towers. The vibration response of acceleration and displacement were observed in the test. Compared with its counterpart without icing, it was found that the damping ratio in the icing system increased a lot. The dynamic strains of the eight-bundled conductors were measured by using fiber Bragg grating (FBG). The dynamic property variation of the icing conductor and its impact on the transmission tower under the wind load were investigated. The results show that the reasonable dynamic interaction under turbulence flow in the icing tower-line coupling system should be taken into account. © 2010 Chin. Soc. for Elec. Eng.


Wang D.,East China Grid Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

As a spin-off from the paper "Comparison of CPS and Its Assessment Between North America and China", some academic discussions are held about frequency checking and control performance assessment periods, frequency checking method, methods of improving the CPS1 value, and drawing of conclusions. Meanwhile, it is pointed out that when making an adjustment of the frequency control method, investigations should carefully be made by referring to the actual conditions of China's power grids prior to circumspect modification.


Jiang Q.,Zhejiang University | Zhou B.,Zhejiang University | Zhang M.,East China Grid Company
IEEE Transactions on Power Systems | Year: 2013

This paper presents a transient stability constrained unit commitment (TSCUC) model which achieves the objective of maintaining both transient stability and economical operation. In the TSCUC model, transient stability constraints are incorporated into the framework of unit commitment. In order to solve TSCUC problem, augmented Lagrangian relaxation (ALR) combined with variable duplication techniques and the auxiliary problem principle (APP) is used to decompose the TSCUC problem into two sub-problems: one sub-problem is a traditional unit commitment (UC) problem with prevailing constraints; another sub-problem is modeled as a transient stability constrained optimal power flow (TSCOPF) problem. The first sub-problem is solved by dynamic programming, while the second sub-problem is solved using a reduced-space interior point method. In ALR, an efficient hybrid sub-gradient method is developed to update all Lagrangian multipliers. The iterative process continues until the duality gap is sufficiently small. Finally, case studies show that the proposed methodology is very efficient for solving TSCUC problems within a parallel computing framework. © 2012 IEEE.

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