An Evaluation Method of Distribution Network Closing Loop Transfer Current Based on Combined Current Moment

Abstract

The invention discloses a current evaluation method based on the combined current moment for distribution network closing and switching to supply current. The value circuit calculates the total impedance converted to the 10kV side of the loop closing path, and calculates the equivalent resistance distance from each node load to the voltage reference point in the two divided systems; collects the actual current of each node before closing the loop, and calculates two The load current moment of each node in the system; calculate the combined current moment of the two systems; combine the total impedance of the loop closing path of the grid, the voltage reference value and the combined current moment of the two systems to calculate the closing loop transfer current; judge the closing loop transfer power supply If it is not satisfied, it is necessary to change the operation structure of the power grid and adjust the loop-closing transfer current until the loop-closing transfer current meets the loop-closing conditions. The beneficial effect of the present invention is that it can simplify the method for evaluating the loop-closing transfer current, reduce the calculation amount and improve the efficiency.

Description

technical field [0001] The invention relates to the technical field of power dispatching control, in particular to a current evaluation method for closed loop transfer of a distribution network based on combined current torque. Background technique [0002] In recent years, the main feeder of domestic AC distribution network generally adopts the power supply mode of "closed-loop design, open-loop operation". The gate operation is used to realize the uninterrupted power supply of the load, thereby improving the reliability and continuity of the power supply. However, the two 10kV feeders for loop closure generally belong to different 110kV systems. After the loop closure operation, a 220kV, 110kV or 10kV electromagnetic loop network will be formed. When the loop closure current generated is large, it is easy to cause protection tripping or equipment Overload, in severe cases, will even burn electrical equipment, which has a serious impact on the safe operation of the power g...

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Problems solved by technology

[0003] Among them, the calculation method of the superposition principle is to first calculate the initial power flow before closing the ring (radiation network) through the forward push-back method, and then calculate the equilibrium power flow caused by the voltage phasor difference on both sides of the ring closing switch, and the superposition of the initial power flow and the equilibrium power flow It is the power flow of the closed loop operation, but the steps of this method are very cumbersome and the amount of calculation is large, which is not conducive to the rapid evaluation of the current magnitude; the off-line simulation method requires a lot of preliminary work, including power grid modeling and parameter conversion, etc., and is not very practical And the simulation speed is slow; while using traditional experience to judge, there are problems such as fuzzy judgment conditions and inaccurate results, which are not objective and reliable enough.

Therefore, some local power grids minimize the closing loop current by adjusting the operation mode of the upper-level ground grid, that is, adjusting the 110kV system belonging to the distribution network to the same system before closing the distribution network. However, this method needs to frequently adjust the operation mode of the upper-level power grid This increases the risk of the main network; some local power grids also adopt the method of "stop first and then turn on" to transfer loads, so as to ensure the safety of the power grid and the planned power supply of customers by losing part of the reliability. have obvious defects

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