Study On The Electrothermal Coordination Power Flow Considering Thermal Property Of Middle And Low Voltage Power Cable

As urban distribution network load increasing rapidly and distribution network structure becoming more and more complicated, how to improve safe transmission capacity of middle and low voltage cable line has became an increasingly important issue in distribution network dispatching analysis and decision. Building the electrothermal coordination power flow model considering thermal property of middle and low voltage power cable has essential theoretical significance and engineering practical value to excavate potential transmission ability and mitigate power supply-demand controdictary. However, the existing electrothermal coordination power flow research on middle and low voltage cable area is less which mainly focus on high voltage overhead grid filed. Therefore, This paper has carried out related research.Accurately calculating cable real-time temperature is the essential and premise to realize electrothermal coordination technical. The parameter precision and engineering practicability of existing cable temperature thermal circuit based on surface temperature remains to be further improved. Therefore, based on thermoelectric analogy theory, a simplified temperature thermal circuit model of middle and low voltage cable based on environment temperature and its parameter identification algorithm based on particle swarm optimization were proposed in this paper. A cable temperature experiment platform was established and the temperature of air laying power cable under various current was measured. Comparison of calculation results and experimental results shows that the precision of proposed model is higher than thermal circuit model based on surface temperature, the proposed model can meet the precision requirement of middle and low voltage power cable temperature calculation under various current, which can be applied to describe the middle and low voltage power cable thermal dynamic process more accurately.on this basis, a electrothermal coordination power flow model considering thermal property of middle and low voltage power cable was proposed in this paper through organic combinating the proposed cable simplified thermal circuit model and electrothermal coordination power flow model. In a three-node test system, the power flow was calculated under disconnection, sudden load-up and daily load curve through electrothermal coordination power flow decoupling algorithm. Simulation results show that the proposed cable electrothermal coordination power flow model can reflect operating cable temperature dynamic process accurately, which can be the basis for improving transmission capacity of middle and low voltage cable line and can provide security for line operation.