Grey Fuzzy Synthesis Of Relay Protection State Based On Subordinate Cloud Research On Evaluation Methods

Relay protection system is of great significance to ensure the safety and stability of power system and good power quality.With the development of national economy and the increasing attention of all sectors of society to power quality,the regular maintenance and post maintenance in the development process of power system relay protection can no longer meet the requirements of operation and maintenance of power system relay protection system.It is urgent to carry out the state evaluation of relay protection to provide help to ensure the safe and stable operation of power system relay protection.To make scientific research on the state evaluation of relay protection and formulate scientific maintenance methods of relay protection,we need to understand the relay protection equipment first.Based on the understanding of the relay protection equipment,this paper expounds the types,causes and effects of faults in the relay protection system in detail,and fully recognizes the importance of the stable operation of relay protection to ensure the operation reliability of power system.In order to evaluate the status of relay protection,it is necessary to establish the model of relay protection status evaluation:Firstly,this paper establishes the index system of relay protection status evaluation.As a complex system,relay protection has many indexes that affect its operation.Each index reflects the operation status of relay protection from different aspects.Based on the complexity of the composition and operation mode of relay protection equipment,the combination of online data collection and on-site personnel inspection and monitoring is used to collect the data of relay protection system.According to the principles of scientificity,representativeness and feasibility of relay protection status evaluation indicators,this paper takes the relay protection system of the Winter Olympic venues as the research object,combined with the "guidelines for relay protection status maintenance" and "detailed rules for on-site safety supervision and inspection of relay protection discipline in substations within the scope of power supply guarantee for the Winter Olympic Games",from the acceptance and production of relay protection system,standardized operation and maintenance of relay protection system The state indicators are selected from the three aspects of technical transformation and expansion of relay protection system,and the evaluation indicators are relatively perfect and reliable,so as to establish the index system of relay protection state evaluation.The composition and operation of relay protection system are relatively complex.The indicators of relay protection state evaluation have the characteristics of fuzziness,grey and randomness.This paper combines grey fuzzy mathematics theory and cloud model to evaluate the state of relay protection.By introducing the grey fuzzy mathematics theory and analyzing the equipment index state in the relay protection status evaluation system through the membership function in the fuzzy mathematics theory,the fuzziness and gray of the relay protection status evaluation index can be fully analyzed.The mathematical model of relay protection status evaluation needs to establish the grey fuzzy evaluation matrix of relay protection status evaluation,which is composed of module and grey part,The module represents the relative importance of each index,and the gray part represents the unreliability of the module;On the basis of learning fuzzy mathematics theory and mathematical probability theory,this paper introduces the mathematical method of cloud model,which can transform qualitative and quantitative data,so as to analyze the fuzziness and randomness of relay protection system.In the mathematical model of relay protection state evaluation,the weight set of the index system is established.The weight set can represent the grey correlation between the relay protection system and the relay protection state evaluation index.The relay protection status evaluation index system established in this paper consists of two levels of indicators.The module of the weight set of the first level indicators in the relay protection status evaluation index system is calculated by the optimal combination weight method,the grey part is evaluated by the relay protection expert group,the module of the weight set of the second level indicators is analyzed by the fuzzy analytic hierarchy process,and the grey part is also evaluated by the relay protection expert group.In terms of analyzing and calculating the index weight of relay protection status evaluation,this paper fully discusses the scientific meaning of index weight.This paper fully analyzes the subjective weight and objective weight.The subjective weight is the weight determined by the scientific research of relay protection experts on the relay protection system and the scoring of the indicators in the relay protection index system,which can be combined with the evaluation experience of relay protection experts,But it is easily affected by the subjective judgment of relay protection evaluation experts;The objective weight method is to calculate the index weight by using the intelligent algorithm.Based on the analysis and calculation of the collected data of the relay protection index system,the objective weight of the relay protection index is determined,which will not be affected subjectively.However,there is a lack of subjective suggestions from relay protection experts.This paper combines the subjective weight algorithm and the objective weight calculation method to complement each other,Based on this,the optimal weight of relay protection state evaluation index system is calculated.Through the comprehensive evaluation of the first-class grey fuzzy evaluation matrix and the first-class index weight set,the first-class index comprehensive evaluation matrix is obtained.On this basis,the second-class grey fuzzy evaluation matrix is obtained.Through the comprehensive evaluation of the second-class grey fuzzy evaluation matrix and the second-class index weight set,the second-class index comprehensive evaluation matrix is obtained.After obtaining the grey fuzzy comprehensive evaluation matrix,it is necessary to convert the grey fuzzy evaluation matrix into a quantifiable value in order to judge the state of relay protection and realize the state evaluation of relay protection.In this paper,the inner product method is used to solve the norm of the vector of grey fuzzy evaluation matrix.After obtaining the norm corresponding to each vector,the evaluation result that most conforms to the relay protection state is selected through the principle of maximum membership.Through the example verification and analysis of two substations supplied by the ring network in the core area of the Winter Olympic Village in China,the scientificity and feasibility of the relay protection state evaluation model are proved.