Study On The Realization Method Of Automatic Generation Control In Cascade Hydropower Plants

Because of the flexibility of the hydraulic power plants, and the compensation and correspondence among cascade hydraulic power plants, the cascade hydraulic power plants are playing a more and more important role in the operation of the power system. The main aim of the research works on AGC (Automatic Generation Control) is to reduce the cost and improve the proficiency. In the power system, the benefit of economical dispatching is not so significant respectively, but would be a big figure absolutely. Thus, the optimized dispatching among cascade hydraulic power plants is very important theoretically and has promising application. Research works on AGC has been carried out for a long period of time, but till now, there is no mathematical model or algorithms that are both practical and precise. The research works remains on the theoretical stage.The main content of this thesis is as follows:Some new information on cascade AGC area is reviewed, some key elements and deficiency of AGC are pointed out, and the future trend of AGC is outlined.Technically, the AGC can be divided into two parts: AGC in and out of hydraulic power plants. A hydraulic power plant minimum water consumption model of plant AGC is set up, with the power generated by the plants remained constant. Dynamic programming is used in optimizing dispatching, and a new starting-stopping principle is introduced: In a certain period of time, the generator can not be stopped unless all plants have satisfactory loads. The combination of generators and loads dispatching between generators are considered and optimized. This method is used in scheme evaluation for the former loads of Qingjiang- Geheyan hydropower plants, i.e. the former loads of the plants is analyzed with this method to optimize dispatching generator combination and contribution, and then the optimized status and contribution are compared with those real value. The result of this contribution indicates that this method can lead to considerable benefit and has important value in practical operation.According to the situations in our native power system, the maximum storage rule is selected among various AGC rules. Models are set up accordingly and after simplification on rule and models, analysis on constraint conditions, and comparisons among various algorithms, an effective method-Rosenbrock method is chosen. This method has no memory requirements in calculation, and thus, is easier and faster comparatively.At last, a conclusion is drawn and some unsettled problems are mentioned.