A Network Boundary Equivalence Method for Power Grid Electromagnetic Transient Calculation

Abstract

The invention discloses a network boundary equivalence method for electromagnetic transient calculation of a power grid. The method comprises the following steps: S1, a step of presetting a harmonic impedance observation bus; S2, a step of presetting an equivalent boundary; S3, a step of obtaining a harmonic admittance matrix basic parameter; S4, a step of preprocessing the basic parameter; S5, a step of forming a full-network harmonic admittance matrix; S6, a step of calculating harmonic impedance seen from the observation bus to the full network; S7, a step of performing Ward equivalence on the preset equivalent boundary; S8, a step of calculating harmonic impedance seen from the observation bus to a reserved sub-network after network simplification; S9, a step of comparing harmonic impedance by scanning a bus set before and after equivalence; and S10, a step of determining a final equivalence scheme. The method has the beneficial effects that the harmonic impedance seen from any bus to a system in a network is quickly obtained, and an equivalent result for reserving impedance spectrum characteristics of an original network and complete electric relations among boundary nodes is provided for electromagnetic transient calculation, so that the accuracy of simulation calculation is improved.

Description

Technical field [0001] The present invention relates to the field of power system analysis and calculation, and in particular, to a network boundary equivalent method for power grid electromagnetic transient calculation. Background technique [0002] Electromagnetic transient calculation is widely used in the design, operation, research and analysis of power systems, and is an important technical means for power system equipment selection, risk assessment, decision-making and failure analysis. Due to the complexity of the model used and the large amount of calculation, the scale of the power grid that can be simulated by electromagnetic transient calculation is relatively limited, and the network boundary must be equivalently processed in practical applications. [0003] The electromagnetic transient calculation of the power grid needs to simulate the electromagnetic transient process from a few microseconds to a few seconds. Therefore, the accurate simulation of power grid compone...

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Problems solved by technology

The above method has the following defects: (1) cannot accurately describe the spectral characteristics of the external network impedance

If these characteristics are ignored, it will bring large errors to the electromagnetic transient calculation results; (2) the electrical connection between the boundary nodes cannot be correctly described

When the reserved network is inside the original network instead of the edge, besides the electrical connection in the reserved network, there is also an electrical connection in the external network between the border nodes. The traditional method separates the electrical connection of the border nodes in the external network; (3) The method of processing each boundary node separately may repeatedly include the short-circuit current provided by the external network, making the calculated power frequency equivalent impedance inaccurate

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