An Investigation On The Theory And Method Of Security Monitoring Of The Power System

Electric power is the pillar energy and economic lifeline of a country, whose safe and stable operation not only plays an important part in the economic development of a country, but also maintains its security. China is at present in a special historical period of "power transmission from west China to east China, mutual supply between north and south, nationwide interconnection" and the power market. With the gradual expansion of the power network scale, the range affected by security accidents is becoming increasingly large and the problem of security more and more apparent. Following the blackout on August 14, 2003 in the United States and Canada, the safe operation of the power system has already become a hot topic of worldwide concern. It is against such a background that a preliminary study is made on the security of power system equipment, environment security, security knowledge flow, transmission of security information, security decisions, and the measure of the degree of security by systematically summing up the status quo of the research in the relevant areas of the security monitoring of the power system, with safety science as the guide and the strengthening of the technical means of power system security monitoring, the reduction of the expected number of faults with the power system, the prevention or reduction of disastrously serious faults of the power system as the objectives of study. First, the basic line of thought and method of implementation of power system security monitoring is macroscopically investigated. It has been proved in theory by investigating the statistical difference model used in predicting the number of expected annual faults in a power system and the small sample estimating method for the model's parameters that when the power security system is in a certain stable state, the expected number of faults in a power system tends to a constant rather than a zero value. It is proposed that the adoption of the means of security monitoring can reduce the expected number of faults in a power system. That is, the variation of all the fault influencing factors of the power system, especially those that exert rather great influences on the fault control indices, the sensitivity of hazard indices and the fault chain of the power system, should be monitored. At the same time, adequate security measures should be taken. Guided by such a concept, the monitoring of the fault influencing factors and the fault chain of the power system is studied. The methods of quantization of the quantitative and qualitative fault influencing factors are briefly discussed. It is proposed from the statistical point of view that the analytic hierarchy process be adopted to analyze and calculate the estimates of the sensitivity of the fault control indices and hazard indices with the quantized values of the fault influencing values. The control conditions for carrying out pre-control over the fault influencing factors are put forward and an analysis is made of the effects of the impossibility of real time observation and real time control of the fault influencing factors on their monitoring. The fault chain influencing function and the fault condition function for measuring the fault chain are defined and the method for judging a hazard fault chain and its pre-control is presented. Then the selection of the security monitoring point and the security monitoring variables for a power system is investigated. As the security tree analyzing method is an efficient tool for studying the problem, the concept of the power system security tree is defined with a number of methods suitable for analyzing the non-monotonically dynamic security tree of a power system expounded. The concept of providing the security monitoring equipment with a demand graph and the point of view of providing the security monitoring equipment according to the importance of the electrical installation construction are proposed. Also presented is the concept of the security variables monitoring graph along with that of implement...