Method for calculating voltage stability margin of regional power grid by considering outer network equivalence

Abstract

The invention discloses a method for calculating a voltage stability margin of a regional power grid by considering outer network equivalence and belongs to the technical field of analysis of static voltage stability of a power system. The method comprises the following steps of: adding a ground branch circuit into a conventional David south model to make an outer network equivalent; calculating outer network equivalence reactance and ground admittance by using a computer through a program according to outer network information under a typical running mode; calculating equivalent power supply electric potential according to inner network measured data and finally calculating an index of the static voltage stability margin of the regional power grid. By the method, the influence of the outer network on the ground branch circuit can be considered effectively and the problem of parameter drift in the conventional David south equivalence method can be solved effectively; therefore, the calculation precision of the stability margin index is high. In the method, only the information under the typical running mode of the outer network is needed and the data under all the running modes of the outer network is not needed, so that the requirement on the data of the outer network is low, the engineering practicability is high and the popularization and application are facilitated. The method can be widely applied to calculation and analysis of the index of the static voltage stability margin of the regional power grid which is connected with the outer network through a single point.

Description

technical field [0001] The invention belongs to the technical field of static voltage stability analysis of electric power systems, and in particular relates to a method for calculating the voltage stability margin of a regional power grid considering the equivalent value of an external network. Background technique [0002] The voltage stability problem of modern power grid is very prominent. How to accurately calculate and analyze the voltage stability margin of the power grid to avoid voltage instability and even voltage collapse and other vicious accidents is of great significance to ensure the safe and stable operation of the power system. [0003] In the actual system, most of the regional grids are connected to the main grid through a single 220kV substation. Since the regional power grid generally does not have complete models and state information of the external network (external system of the regional power grid), when performing static voltage stability analysis ...

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Problems solved by technology

The main disadvantage of this method is: the Thevenin equivalent circuit does not contain ground branches, which cannot accurately reflect the effect and influence of the ground branches (mostly capacitive branches) in the external network, resulting in the loss of the static voltage stability margin of the regional power grid. The calculation result is inaccurate (generally too small); secondly, it cannot effectively solve the drift problem of equivalent parameters, nor can it effectively avoid the influence of measurement errors on the equivalent results. The equivalent accuracy is not high, which directly affects the voltage stability of the regional power grid. Calculate and analyze results

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