Optimal Planning of Power System Underfrequency Load Shedding Using Immune Algorithm

• Main Authors: Chih-Ting Yu, 余致廷
• Other Authors: 陳昭榮
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/zv2f4b

碩士 === 國立臺北科技大學 === 電機工程系研究所 === 98 === When a power system experiences malfunctions, the power generator may trip and the transmission lines may break down, resulting in a load far exceeding the generated power. In such a situation, the generator’s attempt to increase its output can lead to a drastic drop in the system frequency. There is, however, a cap on the decline of frequency for each generator. Failure to facilitate instant recovery of frequency may reduce the generator’s life; the system may even collapse due to huge contingencies or generator tripping. Underfrequency relays are therefore used as protection mechanism against such accidents as they are capable of facilitating load shedding to contain accidents and keep the power system in stable operation. However, low shedding rates may reduce the speed of frequency recovery while excessive shedding can exacerbate the general public’s property loss during power outage. Optimal planning for and effective execution of underfrequency load shedding are thus an issue of crucial importance. The paper aims at using immune algorithm to develop optimal underfrequency load shedding strategy in the scenario of serious generator tripping for the 2007 Taipower systems. Imitating biological evolution, immune algorithm strives to reach the optimal solution by utilizing the function of memory cells to preserve the elite solutions of each generation and the function of suppressor cells to restrain the high affinity solutions that can increase diversity of solutions. Application of the immune algorithm is then coupled with the use of PSS/E power system simulation software to simulate the underfrequency responses of the power systems and to obtain the optimal underfrequency load shedding rate capable of minimizing the damages caused by load shedding.