A power flow calculation method for distribution network considering the thermal characteristics of cables

Abstract

The invention discloses a distribution network power flow calculation method considering cable thermal characteristics, which comprises the following steps: obtaining distribution network topologicalstructure and network parameters, and estimating distribution network initial operation state on the basis of the obtained distribution network topological structure and network parameters; Beginningwith the initial state as the starting point, the process flow calculation is carried out. Under the assumption that the whole network voltage is rated voltage, the forward calculation is carried outto obtain the branch currents. According to the calculated cable line current, the temperature of each layer of cable in k period is calculated, then the phase impedance matrix of cable line is updated, and the voltage of each node is calculated from the root node to the terminal node. The back-calculated node voltages are substituted into the forward calculation, and the forward-backward substitution process is repeatedly carried out until convergence is reached, and the cable temperature in the k-period is obtained. After obtaining the temperature of each layer of the cable in the k-period,the tidal current in the (k+1) period is calculated again with this initial value until all the NS-periods are calculated. The invention realizes the fusion with the traditional forward-backward powerflow substitution algorithm, so that the algorithm has better adaptability and engineering application potential.

Description

Technical field [0001] The present invention relates to the field of electrical technology, in particular to a power flow calculation method of a distribution network that takes into account the thermal characteristics of cables. Background technique [0002] At present, with the growth of load and the access of distributed power generation to the distribution network, the transmission capacity is facing challenges, which restricts the safe and economic operation of the distribution network and the consumption of new energy. How to make full use of the load capacity of the existing distribution network transmission components , Improving its utilization efficiency has become the focus of attention of power workers. Power cable is a widely used power transmission component in the distribution network. In addition to the short power supply distance, its load capacity is mainly determined by its thermal limit. Therefore, fully exploring the potential of cable thermal load is of gre...

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Problems solved by technology

However, the distribution network has the characteristics of high line impedance ratio and three-phase unbalance, the above-mentioned solution method based on fast decoupling is not suitable for the analysis and calculation of distribution network

[0005] According to the characteristics of distribution network structure and parameters, the literature "Gao Qin, Wei Zhinong, Sun Guoqiang, etc. Optimal power flow of power system considering the influence of line resistance with temperature change [J]. Power System Automation, 2015, 39(16 ): 76-80." Solving the steady-state heat balance model of overhead wires in the calculation of the power flow of the forward-back generation distribution network, and using the temperature to correct the resistance, effectively improved the calculation accuracy of the power flow of the distribution network, but did not consider the thermal characteristics of the cable and its Transient change process of temperature

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