| The distribution network is a link directly connected with users in the power system,and its power supply reliability level will have a direct impact on the safety and stability of the user’s power consumption.Distribution network dispatching is an important link to ensure the safe and stable operation of distribution network.At present,in the process of dispatching decision-making,dispatchers of distribution network mainly rely on the load reduction,network loss and switching action times,while ignoring the risk factors in the process of dispatching.Distribution equipment is an important part of distribution network.When the equipment itself is aging or is affected by operation conditions and environmental conditions and failures occur,it will lead to the failure of distribution network dispatching.In order to comprehensively consider the risk factors in the process of distribution network dispatching and improve the effectiveness of distribution network dispatching decision-making,this paper first proposes a comprehensive risk assessment method for distribution network dispatching considering equipment risk,and then combines the comprehensive risk of distribution network dispatching with the commonly used mathematical model of distribution network dispatching.Finally,based on the mathematical model,an improved harmony search algorithm is used to make dispatching decisions.Firstly,the risk theory and risk assessment method are analyzed and studied.The main equipments of distribution network are divided into operation equipment and static equipment.Combining with the risk theory,the dispatching results of distribution network are divided into three categories: dispatching success,dispatching failure and indirect dispatching failure.The risk sources of distribution network dispatching are analyzed,which lays a foundation for comprehensive risk assessment of distribution network dispatching.Secondly,based on the condition evaluation results of distribution equipment,the real-time failure rate of equipment is calculated in combination with operation conditions and environmental conditions,and the load risk and voltage risk evaluation index of equipment failure are proposed based on utility function.On this basis,the operational risk and equipment risk of distribution network dispatching are determined,and then the comprehensive risk of distribution network dispatching is obtained by combining the two.The comprehensive risk assessment method for distribution network dispatching is validated by using the IEEE 16-node test system.The results show that when the static equipment is in good condition,the risk of indirect dispatching failure is small,and the decision can be made according to the existing dispatching decision-making methods.When the static equipment involved in the dispatching scheme has equipment with high failure rate due to aging,overload or environmental impact,the equipment risk of the degree scheme is relatively high,which leads to a significant increase in the comprehensive risk.At this time,the influence of equipment risk on the dispatching results should be considered comprehensively,and the scheme with less comprehensive risk should be recommended for scheduling.Subsequently,the commonly used objective functions and constraints of distribution network dispatching are analyzed and studied.In view of their shortcomings,a mathematical model of distribution network dispatching considering comprehensive risks is proposed.The operation risk and equipment risk of distribution network dispatching are combined with the common dispatching objective function,and the switching action constraint is added.In order to reflect the key points in the process of dispatching decision-making,the weight coefficients of each index in the objective function are determined by the method of ordinal relation analysis.The mathematical model is validated by an actual distribution system in a certain area.The results show that the commonly used mathematical model of distribution network dispatching can not reflect the potential equipment failure in the process of dispatching.The one considering comprehensive risk can truly reflect the increase of failure rate caused by aging,overload or environmental impact of equipment,thus affecting the feasibility of dispatching scheme.Finally,the harmony search algorithm is studied.Based on the mathematical model of distribution network dispatching considering comprehensive risk,the penalty function is used to combine the objective function with the constraint conditions,and the parameters of the harmony search algorithm are modified to obtain the distribution network dispatching decision method based on the improved harmony search algorithm.The method is validated by using the IEEE 33-bus test system.The results show that the method can accurately obtain the optimal scheduling scheme under the corresponding mathematical model,and has fast convergence speed.By comparing the results of optimization under different objective functions,it can be seen that the common objective function of distribution network dispatching can not reflect the potential risk of dispatching schemes when stationary equipment has high failure rate centralized.Under the objective function of considering comprehensive risk,the optimal dispatching scheme has changed.The objective functions corresponding to the optimal scheduling scheme without considering risk and comprehensive risk are 0.1686 and 0.1045 respectively,which shows that the proposed scheduling model can fully reflect the impact of equipment risk on the effectiveness of the scheduling scheme.The comprehensive risk assessment method for distribution network dispatching proposed in this paper can comprehensively reflect the risks caused by the faults of operating equipment and static equipment in the dispatching process.In the process of dispatching decision-making,using the dispatching model which considers the comprehensive risk will help to evaluate the dispatching scheme comprehensively and objectively,warn the potential risk of the dispatching plan,and assist the dispatching operator in making the dispatching decision so as to avoid the dispatching loss caused by the equipment failure. |
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