Method for calculating power flow of radial power distribution network based on variable substitution

Abstract

The invention discloses a method for calculating the power flow of a radial power distribution network based on variable substitution. The method comprises the following steps of: firstly, converting 2 / 3 of unbalance equations into linear equations in power flow calculation by using variable substitution according to the special topological structure and characteristic of the radial power distribution network, wherein the other 1 / 3 of unbalance equations are also relatively simple; then, because nonzero elements of a jacobian matrix formed by an unbalance equation set are relatively fixed, respectively calculating the invariant elements and a small number of variable elements of the jacobian matrix by using a sparse technique, wherein the invariant elements do not need to be repeatedly calculated, and a calculation formula of the variable elements is also relatively simple; and finally, carrying out iteration solving on the unbalance equation set to obtain the power flow of the system. The calculation speed and efficiency of a power flow algorithm are improved foundationally through the variable substation and the sparse technique; and the method has the characteristics of clear calculation process, easiness for programming and the like. Finally, the effectiveness and efficient calculation capability of the method are proved through a plurality of test cases.

Description

technical field [0001] The invention belongs to the field of power system analysis and calculation, and in particular relates to a method for calculating the power flow of a radial distribution network based on variable substitution. Background technique [0002] Distribution network power flow calculation is an important basis for distribution network economic operation and system analysis. In terms of topology and operation mode, there are obvious differences between the distribution network and the transmission network. The distribution network has a high R / X ratio, many branches, and a radial network structure. In addition, the distribution network operates normally. It is an open loop, and only a short-term ring network operation will occur when there is a fault or load adjustment. Therefore, the traditional transmission network power flow algorithm cannot be directly applied to the distribution network, and it is very important to study the power flow algorithm suitab...

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Problems solved by technology

Therefore, the traditional transmission network power flow algorithm cannot be directly applied to the distribution network, and it is very important to study the power flow algorithm suitable for the characteristics of the distribution network

Scholars at home and abroad have proposed various distribution network power flow algorithms according to the characteristics of the distribution network, such as the forward pushback method, the implicit Zbus Gaussian method, the loop impedance method, the improved Newton method, and the fast decoupling method. The calculation speed of the algebraic method is fast, but the number of iterations is large; the calculation speed of the implicit Zbus Gauss method is slow, and the iteration convergence is slow; the loop impedance method contains large matrix operations, and the calculation speed is slow; the improved Newton method has second-order convergence, Since the elements of the Jacobian matrix are variable, the Jacobian matrix needs to be calculated repeatedly in each iteration. Therefore, the calculation efficiency of the algorithm is low and the calculation speed is slow; the fast decomposition method requires that the line reactance of the system is much larger than that of the line Resistance, and the R / X ratio of the distribution network is large, so the algorithm is difficult to apply to the distribution network

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