Study Of Load-shedding Model Based On Power Flow Tracing And Its Application In Bulk Power System Reliability Assessment

This dissertation is sponsored by the project ("Theory and application study of power market analysis",No.2003-7951) of science and technology of Chongqing science committee. Power flow tracing theory is used in bulk power system reliability assessment, a load-shedding model is put forward, and impact analysis on bulk power system reliability assessment based on power flow tracing method is conducted in this paper. This is a new application of power flow tracing. Reliability of a country's electric power networks is material fundamental of sustainable development and one of important factors of national security. Bulk power system reliability is a complex system, and it needs to be thought much and be planed carefully during the period of design,operation,management and consumption phases. So it is an important issue worth making a deep study. A power-flow-corrective scheme model is the core of bulk power system reliability assessment, and it can determine the necessary load shedding amount to restore the system from an emergency state to a normal state. Different remedial action models have different principles. So far, all load-shedding actions are based on logic distance, optimization or some proportion, but it is not reasonable because they don't consider the relationships between loads and generations. All these relations between loads and generations or lines can be made clear based on power flow tracing. Power flow tracing theory is used to overcome these shortcomings in the load-shedding model of bulk power system reliability assessment in the paper. The paper puts forward load-shedding model based on power flow tracing (LMBOPFT) in bulk power system reliability assessment. Usage factor of between loads and generators or lines is introduced in the model, the basic idea is: when loads are of same importance, the load whose usage factor is bigger should firstly shed to restore the system. The model makes the calculation simper than load-shedding strategy by neighbor. The method has been verified by the test system—RBTS and IEEE-RTS, and has been proved efficient by comparing results with optimal load-shedding model. Reliability indices of traditional bulk power system can only represent the reliability degree for total system and individual buses. If weaknesses of a system need to be found, it needs to get sensitivity indices of the bulk power system. But it is difficult to calculate sensitivity indices because of calculating derivative, and it is fit to use analytical method to calculate sensitivity indices. The paper puts forward impact factor analysis of the reliability in bulk power system using power flow tracing method on the basic of power flow tracing load-shedding model. The core of this method is to find the mapping relations between fault component and load-shedding buses or the system. It can get component distribution according to bulk power system buses and system reliability by the mapping relations, if the value is bigger than other values, which means it is the weakness of the system, vice versa. This method is fit for either analytical method or simulation method, and can avoid calculating the sensitivity indices of the component parameter of bulk power system.