Abstract
This paper presents a partial Y-bus factorization algorithm to reduce the size of a power system model for transient stability analysis. In the proposed approach, steady-state operating conditions for dynamic equivalents are maintained using the traditional Ward admittance method. Fictitious generators are attached at boundary buses to preserve transient behavior following a disturbance. The equivalent dynamic effects from eliminated generators can be maintained by choosing appropriate dynamic parameters of fictitious generators, including machine inertia, transient reactance, and the damping coefficient. Parameters are determined using the idea that the contributions from external generators mostly depend on the network configuration and impedance characterized by the Y-bus matrix. The fictitious generators’ dynamic parameters are determined by conducting partial Y-bus factorization on dynamic parameter matrices. The proposed method’s performance is validated by conducting case studies with the IEEE 118-bus system and a 10,000 synthetic western U.S. power grid model and comparing simulation outcomes between the full system and reduced equivalent models. Simulation comparisons show that the equivalent model maintains high accuracy. The proposed method is promising alternative solution for power system dynamic equivalents.
Highlights
Electric grids worldwide are rapidly changing, partially because of the integration of newer types of generation and load, with one result being an increased need to study and simulate electric grid dynamics [1]
This paper presents a promising alternative approach to creating a dynamic equivalent for the computational reduction of transient stability analysis
This paper presented a new dynamic equivalent approach, enhancing the computational efficiency and maintaining high-level simulation accuracy for transient stability analysis
Summary
Electric grids worldwide are rapidly changing, partially because of the integration of newer types of generation and load, with one result being an increased need to study and simulate electric grid dynamics [1]. Many studies to speed up the simulation in power system areas have focused on developing efficient network-reduction algorithms These approaches partition electric power systems into internal and external systems. Based on the system model equations and the analysis purpose, network-reduction techniques are divided into static and dynamic equivalents. Static equivalent methods reduce a system model for power-flow studies. The Ward equivalent has been the most widely used [4] This approach eliminates the external system by performing Gaussian elimination on a complex nodal admittance matrix (Y-bus matrix) representing the system network. The Ward equivalent approach has two versions of how to model external bus power injections [5]. This paper presents a promising alternative approach to creating a dynamic equivalent for the computational reduction of transient stability analysis.
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