Identifying Nodal Reactive Power Demand for Steady-State and Dynamic Voltage Control Using Linear Programming

The transformation of the European power system results in the loss of reactive power potential for voltage control at the transmission grid level. At the same time, higher grid utilisation and new voltage-related fault scenarios increase the demand for steady-state and, in particular, dynamic voltage control. Future reactive power procurement concepts rely on a combination of mandatory procurement by grid users following technical connection guidelines, transmission system operator-owned compensation devices, and market-based mechanisms, necessitating a nodal identification of reactive power demand decoupled from technology-specific investment decisions. However, conventional methods for reactive power planning focus on determining as few optimal locations as possible for reactive power compensation devices. In contrast, this paper presents an approach for identifying nodal reactive power demand for steady-state and dynamic voltage control during (n-1) outages. The method modifies a conventional reactive power planning approach by shifting the objective from determining an optimal portfolio of compensation devices to identifying nodal reactive power demands that can subsequently be met through different procurement mechanisms. The method consists of a two-stage linearprogramming algorithm. In the first stage, the reactive power demand for steady-state voltage control is identified to ensure adherence of all grid voltages to valid limits. In the second stage, the linear program is extended to identify reactive power demand during (n-1) outages. Exemplary results on a modified IEEE 9-bus system validate the approach.