Method for selecting initial values of three-phase Newton-Raphson method power flow calculation of power distribution network

Abstract

The invention provides a method for selecting initial values of three-phase Newton-Raphson method power flow calculation of a power distribution network. The method comprises the following steps: S1, establishing a power distribution network three-phase system model; S2, establishing a power distribution network three-phase simplification system, and numbering nodes and branches of the power distribution network three-phase simplification system; S3, storing a three-phase load parameter of each node according to the serial number sequence of the nodes, and storing a three-phase impedance parameter of each branch according to the serial number sequence of the branches; S4, performing per-unit on the three-phase load parameter of each node and the three-phase impedance parameter of each branch; S5, establishing a power distribution network single-phase simplification system; S6, selecting convergence precision, performing power flow calculation on the power distribution network single-phase simplification system by a forward-backward sweep method to obtain the voltage amplitude and the phase angle of each node of the power distribution network single-phase simplification system; S7, selecting the initial value of the three-phase Newton-Raphson method power flow calculation of a power distribution network three-phase system. The method can select the initial value of the three-phase Newton-Raphson method power flow calculation by the forward-backward sweep method with high calculation speed and good convergence.

Description

technical field [0001] The invention relates to the field of power flow calculation of a distribution network of a power system, in particular to a method for selecting an initial value of a distribution network three-phase Newton-Raphson method power flow calculation. Background technique [0002] With the improvement of users' requirements for power supply reliability and power quality, the distribution network, which is a relatively weak power system, has been paid more and more attention. The most basic calculation of power system analysis can not only calculate network loss, verify the rationality of various operation modes, etc., but also provide initial values ​​for transient calculations. The importance of basic power flow calculations for distribution networks is self-evident. [0003] From the point of view of the way of dealing with three phases, power system power flow calculation can be divided into phase component method and sequence component method. However, ...

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Problems solved by technology

[0004] From the point of view of traditional power flow algorithms, forward-backward and Newton-Raphson methods are most widely used in distribution network power flow calculations: forward-backward and forward-backward methods make full use of the radial characteristics of distribution networks, and have good convergence and low memory consumption. It is recognized as a high-efficiency algorithm with less calculation speed and fast calculation speed. However, the forward push-back generation has weak processing ability for the weak rings existing in the distribution network, and it is necessary to reasonably number the nodes and branches of the distribution network. In addition, with the distributed It is also very inconvenient to deal with distributed power points when connecting power sources; Newton-Raphson method is theoretically suitable for solving all nonlinear equations, is not affected by the ring network, and is easy to handle distributed power nodes. However, it has the disadvantages of sensitivity to the initial value, poor convergence, large data storage capacity, and slow calculation speed. However, the distribution network has many nodes, long radial shape, and the voltage drop of the last branch node is large. The traditional Newton method power flow calculation Initial value flat start (V i =1.0pu, θ i =0) It is very easy to produce unreasonable initial value selection, which leads to non-convergence of Newton method iterations. Therefore, the problem of initial value selection needs to be solved when the distribution network adopts Newton method power flow calculation

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