Operation Risk Assessment Of Urban Distribution Network Considering Distributed Generation Access

Because of the dense population and complex load types,the power consumption of urban distribution networks is increasing,and as urbanization continues to accelerate,environmental pollution is becoming increasingly severe,and new energy generation technologies have been vigorously developed.Access to distributed generation in urban distribution networks has become a trend.However,the power output of distributed generation is random,which will affect the stable operation of the distribution network and increase the operating risk of the entire system.Therefore,the correlation of distributed generation output and the diversity of load types in urban distribution networks are comprehensively considered.The operational risk assessment of urban distribution network with distributed generation is realized by probabilistic load flow calculations.The main works are as follows:First,the random factors of the urban distribution network with distributed generation are analyzed.The power output probability model of wind power and photovoltaic power is established.A load power probability model based on a Gaussian mixture distribution is established by considering the diversity of load types.The correlation the power output of distributed generation is analyzed based on Copula theory,and the correlation model of the power output of distributed generation based on the Copula function is established.Secondly,based on the principle of probability conservation,a probabilistic load flow calculation method based on the probability density evolution equation is proposed.The probability density evolution equations of node voltage and line active power are deduced,and the Lax-Wendroff format in the finite difference method is used to solve the probability density evolution equation,the probability load flow calculation of the urban distribution network with distributed generation is realized.Taking IEEE34 node power distribution system as an example,probability distributions of node voltage and line active power are generated,and the results are compared and analyzed with the traditional Monte Carlo method and cumulant method.The validity of the proposed method is verified.Finally,based on the theory of power system operation risk,three indicators of voltage over-limit risk,line power over-load risk,and system comprehensive operation risk are established.Taking the IEEE 34-node power distribution system as an example,the operation risk assessment of the urban power distribution network considering distributed generation access is realized.The impact of distributed generation on the operation risk of urban distribution networks is analyzed from three perspectives: the distributed generation capacity,the location of the grid connection point,and the proportion of wind power and photovoltaic power.The work of this paper provides technical support for the operation and planning of urban distribution networks with distributed generation.