Scheduling hydro power systems with restricted operating zones and discharge ramping constraints

被引:64
作者
Guan, XH [1 ]
Svoboda, A
Li, CA
机构
[1] Xi An Jiao Tong Univ, Syst Engn Inst, Xian 710049, Peoples R China
[2] Pacific Gas & Elect Co, B18E, San Francisco, CA 94177 USA
基金
中国国家自然科学基金;
关键词
power generation scheduling; hydrothermal scheduling; restricted operating zones; mixed-integer programming; network flow algorithm;
D O I
10.1109/59.744500
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
An optimization-based algorithm is presented for scheduling hydro power systems with restricted operating zones and discharge ramping constraints. Hydro watershed scheduling problems are difficult to solve because many constraints, continuous and discrete, including hydraulic coupling of cascaded reservoirs have to be considered. Restricted or forbidden operating zones as well as minimum generation limits of hydro units result in discontinuous preferred operating regions, and hinder direct applications of efficient continuous optimization methods such as network now algorithms. Discharge ramping constraints due to navigational, environmental and recreational requirements in a hydro system add another dimension of difficulty since they couple generation or water discharge across time horizon. Integrated consideration of the above constraints is very challenging. The key idea of this paper is to use additional sets of multipliers to relax discontinuous operating region and discharge ramping constraints on individual hydro units so that a two-level optimization structure is formed. The low level consists of a continuous discharge scheduling subproblem determining the generation levels of all units in the entire watershed, and a number of pure integer scheduling subproblems determining the hydro operating states, one for each unit. The discharge subproblem is solved by a network flow algorithm, and the integer scheduling problems are solved by dynamic programming with a small number of states and well-structured transitions. The two sets of subproblems are coordinated through multipliers updated at the high level by using a modified subgradient algorithm. After the dual problem converges, a feasible hydro schedule is obtained by using the same network flow algorithm with the operating states obtained, and operating ranges modified to guarantee satisfaction of ramping constraints. Numerical testing based on the data sets of the PG&E power system shows that this method is efficient and effective in dealing with cascaded hydro systems with restricted operating zones and discharge ramping constraints.
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页码:126 / 131
页数:6
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