Managing high voltage constraints in transmission grids

Historically, low voltage plans on power systems were very frequent particularly in winter when the consumption was very high due to high transit of power in transmission lines. Today, periods of high voltage constraints are dramatically increasing on the transmission system (High voltage HV to Extra High Voltage EHV grid). These high voltage periods are caused by different evolutions of the power system: power flow decrease on transmission system network during the night or time of high solar and wind power generation connected to the distribution grid, burying of HV and EHV networks, and changes in the reactive power consumption of loads. The paper addresses high voltage stresses on transmission networks, offering operational, hardware, and functional solutions like capacitor bank management and Distributed Energy Resources (DER) power factor control. It uses a CIGRE benchmark model in Powerfactory to simulate and analyse these stresses and solutions over a day. The study highlights the impact on EHV voltage stress, and generator stability, supported by on-site measurements from EDF’s thermal plants in France.