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Feng Z.,Dalian University of Technology | Liao S.,Dalian University of Technology | Niu W.,Dalian University of Technology | Cheng C.,Dalian University of Technology | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015

With the rapid expansion of the huge cascade hydropower system in China, the computing scale of hydro scheduling optimization is undergoing an explosive growth and faces the increasingly severe curse of dimensionality. It is essential to find some novel and effective methods to enhance the computing efficiency. An orthogonal discrete differential dynamic programming (ODDDP) algorithm for mid-long term optimal operation of cascade hydroplants was proposed. On the basis of classical discrete discrete differential dynamic programming (DDDP), the proposed algorithm took advantage of orthogonal design to choose small but representive state combinations of different plants at each period, which led to a significant reduction in the computation time and memory requirement. The results of Wujiang River show that ODDDP is comparable to DDDP while making a significant reduction in computing time. The ODDDP is an effective algorithm for the mid-long term optimal operation of hydropower system. © 2015 Chin. Soc. for Elec. Eng.


Li S.,Dalian University of Technology | Li G.,Dalian University of Technology | Cheng C.,Dalian University of Technology | Fan X.,Dalian University of Technology | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2011

The sorted table of generating units and equal incremental principle are recommendatory methods for solving the load dispatch problem under energy conservation power generation. However, there are some issues for the practical applications. Hence, this paper presented an energy-saving load dispatch method for thermal unit, which took the durative constraints of generating units into account. The dynamic unit commitment algorithm, which can flexibly deal with the durative constraints and optimizes unit commitment, was designed using generating sorted table. In order to meet the climbing requirements and upper-lower limits of power generation units, the equal incremental principle was improved by using Kuhn-Tucker optimality conditions. The load modifying strategy was introduced to handle the difference of the load changing trend between unit generation and system load. This method was applied as a case study in Guizhou Power Grid, and the results show that the proposed methodology can implement better energy-saving, and better meet actual operation demands. © 2011 Chinese Society for Electrical Engineering.


Wang J.,Dalian University of Technology | Cheng C.,Dalian University of Technology | Liao S.,Dalian University of Technology | Wang M.,Guizhou Electrical Power Dispatching and Communication Bureau | Su H.,Guizhou Electrical Power Dispatching and Communication Bureau
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2015

The key problem of real-time scheduling of hydro cascaded system is how to fast and reliably adjust day-ahead scheduling according to deviation of load forecasting and runoff prediction. It encounters three primary difficulties: avoidance of unit's restricted zones, consideration of day-ahead scheduling and generation smoothness, and minimization of surplus water. This paper presented a real-time scheduling method and strategy for hydro cascaded system with complex constraints, including processes of computation order decision, plant commitment strategy, load deviation smoothing, load deviation dispatch and surplus water adjustment strategy. Load deviation smoothing process is adopted to shape load deviation to ensure generation smoothness constraint satisfied. In the process of load deviation dispatch among plants, plants' generation is modified dynamically based on day-ahead scheduling, and unit's restricted zones can be rapidly avoided. Simultaneously, an adjustment strategy for preventing surplus water is adopted to achieve pre-discharge by revising plants' generation along constraint boundary. The proposed method and strategy can implement the following effects: full coordination with day-ahead scheduling, prevent of frequent fluctuation of plants' generation, avoidance of unit's restricted zones, and surplus water prevention. Two case studies on Wujiang mainstream cascaded hydropower plants oriented to the coordination of power plants and power grid is used to test the proposed method and strategy, and shows that it is feasible and can meet actual operation demands. © 2015 Chin. Soc. for Elec. Eng.


Cheng C.,Dalian University of Technology | Yang F.,Dalian University of Technology | Wu X.,Dalian University of Technology | Su H.,Guizhou Electrical Power Dispatching and Communication Bureau
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2010

Hydroelectric plant operation is based on an operation chart. Most of the existing literatures, however, paid much more attention to the single reservoir chart than cascade reservoirs. In this paper, an approach of working out the optimal operation chart for cascade reservoirs is proposed and applied to the well-developed Wujiang River hydropower system in China. Based on the initial traditional operation charts for single reservoir and cascade reservoirs, power results of each single plant and the cascade system are obtained. Then the load dispatching strategy of cascade reservoirs is adopted to regulate the power variance between the sum power of all the single plants and the power of cascade system. By repeating this procedure, the simulated runoff history is obtained. Finally a dynamic programming successive approximation (DPSA) is used to modify the basic parameters of the two charts at an objective of energy maximizing. In comparison with the traditional effort, this approach can give an integrated optimal operation charts for single reservoirs and cascade system. Simulation results indicate that the proposed approach is valuable and feasible and it significantly improves the power generation benefit under the power grid requirements. © Copyright.


Zhao L.,Guizhou Electrical Power Dispatching and Communication Bureau | Gao C.,Guizhou Electrical Power Dispatching and Communication Bureau | Lin H.,Guizhou Electrical Power Dispatching and Communication Bureau
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

Configuration of zero-sequence inverse-time over-current protection in transmission lines and main transformers is proposed from view point of fault analysis, under the precondition that high resistance ground fault protections are needed for all power grids. Besides, the same configuration can be also applied to equipments of both 500 kV and 220 kV voltage grade. Then related setting coordination problem is discussed, and the method for selecting time constant from zero-sequence inverse-time curves is derived. In addition, the actual case of power grid is simulated with RTDS to verify the static and dynamic characteristics of the zero-sequence inverse-time over-current protection. © 2011 State Grid Electric Power Research Institute Press.


Yuan F.,State Grid Electric Power Research Institute of China | Teng X.,State Grid Electric Power Research Institute of China | Zhang X.,State Grid Electric Power Research Institute of China | Zhang X.,Guizhou Electrical Power Dispatching AND Communication Bureau
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

In view of the difficulty in satisfying the vibration zone striding demand because of the unclear vibration zone modeling method in the area power grid automatic generation control (AGC) software, a telemetering information-based dynamic vibration zone modeling method of unified control for the electric dispatch main station is proposed. Based on the dynamic model, the method for dodging or striding over the vibration zone of the hydro-electric units in the main station of the AGC system is further discussed. According to different base-point control modes, discussion is made on the control logic of pulling back the unit output fluctuation from the vibration zone after getting into it and striding over it on its own. On the premise that the hydro-electric units' security is ensured, the continuous regulation within the valid regulating area of the hydro-electric units can be realized by making full use of the regulating advantages of hydro-electric units. Test results from actual systems show that the method proposed can effectively improve the security of the AGC system of hydro-electric units and the area regulating effects. © 2010 State Electric Power Research Institute Press.


Zhao L.,Guizhou Electrical Power Dispatching and Communication Bureau | Gao C.,Guizhou Electrical Power Dispatching and Communication Bureau
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

The existing settings coordination of time-limit for zero-sequence over-current relay of 500 kV autotransformer is discussed. The emphasis is laid on the coordination of zero-sequence definite time-limit over-current relays in middle-voltage (220 kV) winding with zero-sequence inverse time-limit over-current relays in high-voltage winding and common winding. Then two un-equations are derived according to the questions discussed. In the meantime the influence of dynamic changed zero-sequence fault current on the coordination, the check method for dynamic problem is analyzed. At last, an optional protection scheme of over-current relays in 500 kV autotransformer is discussed, and some problems to be solved are pointed out. © 2010 State Grid Electric Power Research Institute Press.


Li G.,Dalian University of Technology | Cheng C.-T.,Dalian University of Technology | Zeng Y.,Dalian University of Technology | Sun B.,Guizhou Electrical Power Dispatching and Communication Bureau | Lin C.,Guizhou Electrical Power Dispatching and Communication Bureau
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2012

According to the practical conditions of Guizhou Power Grid, this paper discusses the practical problems faced by solving thermal load distribution by the equal incremental principle, and then presents a new algorithm, which includes generator assembled strategy and equal incremental principle. Based on generation sort of thermal units, this method determines combined alternatives by way of assembled strategy, and dispatches thermal units' load by using the equal incremental principle. The simulation data of load distribution of Guizhou Power Grid since the formal energy-saving generation operation in 2009 indicate that the method can solve the problem in real project application. Therefore, it's a practical load distribution calculation method.


Feng Z.-K.,Dalian University of Technology | Liao S.-L.,Dalian University of Technology | Cheng C.-T.,Dalian University of Technology | Su H.-Y.,Guizhou Electrical Power Dispatching and Communication Bureau
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2014

In order to overcome the curse of dimensionality of Progressive Optimality Algorithm (POA) in solving the long-term optimal scheduling of cascade reservoirs, Orthogonal Progressive Optimization Algorithm (OPOA) is proposed on the basis of the orthogonal experiment design method, reducing the dimensions of stages, the number of discretization of water level and cardinal number of set. Firstly, POA is employed to decompose multistage decision problem into several two stage sub-problems, and then solve each sub-problem by carrying out the orthogonal experimental design multiple times, taking the objective function as experimental index, reservoirs as experimental factors and discrete status as factor levels. All sub-problems are calculated respectively by building water levels in equilibrium distribution, until obtaining the optimal solution of each sub-problem successively. The computer simulation results of 4 reservoirs in the Wujiang River show that OPOA is distinctly superior to particle swarm optimization and takes only the 28.4 percent of the computing time compared to POA in obtaining the global optimal solution, which is an effective algorithm in long-term optimal operation for hydropower system.


Zhao W.-X.,Guizhou Electrical Power Dispatching and Communication Bureau | Lin C.,Guizhou Electrical Power Dispatching and Communication Bureau | Sun B.,Guizhou Electrical Power Dispatching and Communication Bureau | Xiong X.-F.,Chongqing University | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

This paper presents a new calculating method for economic power dispatch according to the practical conditions of Guizhou Power Grid. The proposed economic dispatch method consists of two stages. The first stage involves the classic economic power dispatch without considering network loss, where the generation plans are determined by the rank of consumption characteristics of the units and the equal incremental principle. The second stage involves calculating the power generation plans amendment when the network loss is minimal. In order to maintain the stability of unit adjustment, minimizing the change of power generation plan is one of the objects of network loss amendment. For showing the effectiveness of the proposed two stage economic dispatch approach, the Guizhou 520-bus system is used for testing. The test results show the two stage dispatch method can not only reduce the system losses and system fuel consumption, but also control the movement of the generator output.

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