Online Voltage Stability Assessment for Load Areas Based on the Holomorphic Embedding Method

Liu, Chengxi
Wang, Bin
Hu, Fengkai
Sun, Kai
Bak, Claus Leth
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Institute of Electrical and Electronics Engineers

This paper proposes an online steady-state voltage stability assessment scheme to evaluate the proximity to voltage collapse at each bus of a load area. Using a non-iterative holomorphic embedding method (HEM) with a proposed physical germ solution, an accurate loading limit at each load bus can be calculated based on online state estimation on the entire load area and a measurement-based equivalent for the external system. The HEM employs a power series to calculate an accurate P-V curve at each load bus and accordingly evaluates the voltage stability margin considering load variations in the next period. An adaptive two-stage Padé approximant method is proposed to improve the convergence of the power series for accurate determination of the nose point on the P-V curve with moderate computational burden. The proposed method is first illustrated in detail on a four-bus test system and then demonstrated on a load area of the Northeast Power Coordinating Council 48-geneartor 140-bus power system.

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continuation power flow, holomorphic embedding method, Padé approximant, voltage stability assessment, voltage stability margin
Liu, C., Wang, B., Hu, F., Sun, K., & Bak, C. L. (2018). Online Voltage Stability Assessment for Load Areas Based on the Holomorphic Embedding Method. IEEE Transactions on Power Systems, 33(4), 3720-3734. doi:10.1109/TPWRS.2017.2771384
Electrical and Computer Engineering