Research On Security Defense System Of Distribution Network Based On Immune Mechanism

The distribution network,as the terminal link of power supply,has a decisive influence on the reliability of power supply.By sharing and calling the monitoring and control resources of the distribution system,security defense control prevents potential risks and system accidents during the normal operation of the distribution network,and quickly and accurately removes faults and restores power supply to the lost load after faults occur,which is an important means to ensure the safe and reliable operation.The immunity mechanism is a mature and highly intelligent defense system in the human body,which has the function of resisting the invasion of pathogens and maintaining the balance and stability of the body.Security defense control and immunity mechanism have a high degree of functional similarity:the security defense control system senses the risk and fault state of the power grid.and generates defense control strategies.which can be regarded as the immunity mechanism’s immune response process of identifying antigens and generating antibodies.At the same time.the immunity mechanism has many excellent heuristic characteristics,which can provide an effective source of technology and ideas to solve the problem of distribution network security defense control.Therefore.constructing the connection between the immunity mechanism and security defense control and applying the immunity mechanism to improve the distribution network security defense control is an effective way to improve the safe and reliable operation performance of distribution networks.The main work and results of this paper are as follows:(1)Based on the immunity mechanism.the security defense control system of distribution network is constructed.Based on the connection between the immunity mechanism and security defense control system,the definition of immunity of distribution network is proposed.For the improvement of immunity,a three-level security defense system of distribution network is proposed,which is "prevention of risk evolution before an accident,fast and accurate fault removal during an accident,and rapid restoration of power supply after an accident".Based on the inspiration of the immunity mechanism,the immunity characteristics of the security defense control function and its implementation scheme are proposed to lay the theoretical foundation for the application of the immunity mechanism to improve the operational reliability of the distribution network.(2)The distribution network risk prevention control technology based on the immunity mechanism is proposed.Considering the equipment’s own health condition and various external risk factors,the diagnosis method of equipment failure probability is proposed:the path analysis method is applied to analyze the outage loss caused by equipment failure,and the calculation model of distribution network risk operation index is constructed.With the help of immune danger theory,the risk warning signal is mapped from the equipment fault probability crossing limit to the system risk operation index crossing limit,and the risk defense activation signal is mapped from the system risk operation index crossing limit to the distribution network risk state,which enables the rapid identification of the distribution network risk state.On this basis,with the goal of reducing the risk operation index of distribution network,immune concentration regulation and hyper variance mechanism are introduced,and a risk defense decision algorithm based on immune particle swarm optimization algorithm is proposed.which effectively reduces the probability of accidents and reduces the loss of power outage to the system after a high-risk set-up failure.(3)Drawing on the immune network theory,multi-point and multi-type fault information is incorporated into the protection system,and a new principle of distribution network protection based on regional fault association information is proposed.A new protection composition model with the substation feeder side outlet switch as the basic unit is proposed.This system identifies and removes faults in a zone-autonomous manner,which can improve the reliability and speed of protection actions without imposing additional construction requirements.A distribution network fault location method based on divide-and-conquer is proposed.which adopts the recursive mode of "Divide-Conquer-Combine" to locate faults.The method has a linear-level computational efficiency,which enables it to output fault location results in milliseconds and is robust to small-scale distortions in fault information.(4)The distribution network distribution service restoration control technique based on the immunity mechanism is proposed.The adaptive formulation method of control range based on virtual impedance matrix,adaptive selection method of control mode based on basic meta-loop matrix and adaptive matching method of mathematical model based on fault impact degree are proposed to realize the extraction of fault characteristics and adaptive selection of distribution service restoration control model.which effectively improves the adaptability of distribution service restoration strategy to the actual fault scenarios of distribution network.The similarity of the topology of the network is described by applying the singular value sequence,and the adaptive matching method between the actual fault and the accident plan is proposed:the postimplementation calibration technique of the accident plan based on the basic meta-ring matrix is proposed to realize the fast secondary immune response to similar faults.which effectively improves the rapidity of the distribution service restoration decision.