Studies On Flexibility Of Power System Dispatch With Controllable Loads

Power system dispatch is one of the most important aspects of grid production management, which should have flexibility to cope with uncertainties during grid operation. The integration of large-scale renewable power sources not only makes system in face of increased uncertainty and highlighting the importance of system dispatch flexibility, but also results in inadequacy of power supply side regulation capacity, and difficulty of system operation. On the other hand, as a new means of power system operation, the load regulation and control is on the rise in support of smart grid technology. Therefore, the research on dispatch flexibility in system with integrated controllable loads has important theoretical significance and practical value.Firstly, this thesis focuses on analyzing and modeling of controllable loads, in order to discuss the mechanism of controllable loads participating in system dispatch. We choose air-conditioning loads with wide distribution areas and large scale which have serious effect on system operation as study objects.Taking Shandong power grid as an example, we deliberately analyze characteristics and control potential of air-conditioning loads by means of reference load comparison and regression analysis considering non-meteorological factors. Based on the work mentioned above, air-conditioning loads control model is introduced, and preliminary discussion on the feasibility of air-conditioning loads participating in system operation is done.Then, on the basis of existing research, the nature and characteristics of system dispatch flexibility are studied. We give definitions of available regulated capacity(ARC) and flexibility demand(FD), and propose four basic attributes to describe the nature of power system dispatch flexibility. Based on those, general mathematical description and characterization indexes of dispatch flexibility are provided. And then, considering unit uncertainty of failure, we build a unit commitment model which can optimally coordinate economy and reliability of system operation, to analyze basic attributes of dispatch flexibility, such as reliability, timeliness and spatiality.Finally, this thesis analyzes dispatch flexibility in system with integrated controllable loads. The unit commitment joint optimization model is built by using controllable loads involving in active power dispatch and regulated capacity(RC) allocation. Based on the model, taking different involving ways of controllable loads into consideration, we analyze the contribution and effect of controllable loads on system dispatch flexibility using the proposed dispatch flexibility theory.In conclusion, the subject of this thesis is the problem needed to be earnestly studied of power system operation under the new situation. Discussions on dispatch flexibility have contributed to properly understanding the vital role of controllable loads on the power system operation, and providing new ideas and methods for effective utilization of controllable loads to achieve large-scale renewable power sources consumption.