A Calculation Method of Thevenin Equivalent Parameters Based on Power Series Expansion

Abstract

The present invention relates to a method for calculating system Thevenin equivalent parameters based on power series expansion. The method includes the following steps: according to the Thevenin equivalent mathematical model, on the premise that the amplitude of Thevenin equivalent parameters does not change within adjacent sampling time points, Establish the circuit equation of Thevenin system at adjacent sampling time; process the circuit equation of Thevenin system according to the power function property and power series expansion, and obtain the mathematical expression of the argument increment of Thevenin equivalent parameter at adjacent sampling time; collect According to the local phasor measurement information, according to the Thevenin system circuit equation and the mathematical expression of the Thevenin equivalent parameter argument angle increment in the adjacent sampling time, the Thevenin equivalent parameter of the Thevenin system at the current moment is calculated through the Euler formula. Compared with the prior art, the present invention has the advantages of taking into account the influence of load disturbance on the argument angle of Thevenin equivalent parameters, avoiding parameter drift, fast calculation speed and the like.

Description

technical field [0001] The invention relates to the field of on-line monitoring and control of electric power systems, in particular to a method for calculating system Thevenin equivalent parameters based on power series expansion. Background technique [0002] With the continuous improvement of the load intensity and the rapid expansion of the scale of the power grid, the state of the power system has been approaching its stable operation limit. How to get closer to the actual operating state of the power grid and accurately predict and evaluate the critical point of the system's limit power flow and voltage stability has become a research hotspot. [0003] The widespread use of phasor measurement unit (PMU) makes the measurement-based on-line voltage stability assessment method one of the main means to study voltage stability. Among them, the voltage stability analysis method based on Thevenin equivalence and impedance matching principle has attracted extensive attention ...

AI Technical Summary

Problems solved by technology

Although the algorithm is simple and quick, but because the assumptions are seriously inconsistent with the actual situation, it is only applicable to the situation where a suitable disturbance occurs at the equivalent node (the disturbance cannot be too large or too small), and there is almost no disturbance in the equivalent system , the limitation is very strong, and it will also bring the problem of parameter drift

(2) Single-time cross-section algorithm based on external measurement information: This type of algorithm is an improvement on method (1). By selecting the initial value and performing iterative correction, the change of Thevenin equivalent parameters can be tracked in real time. However, this method is still based on the assumption that the electrical quantity does not change significantly in the two sampling time intervals before and after, and has high requirements for the selection of the initial value.

However, due to the need to collect the information of the entire network, the amount of calculation is greatly increased and the time required is longer

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