Surge impedance loading aware reactive power management system for offshore oil and gas facilities

Long HVAC submarine cables inject substantial charging MVARs. They cause the Ferranti effect at the receiving end and also shrink the cable’s ampacity margin. This paper presents a Surge Impedance Loading Aware Reactive Power Management System (SILARPMS) that coordinates offshore and onshore variable shunt reactors using a rule-guided multi-criteria weighted score. It aims at keeping the receiving bus voltages near 1.0 pu. Moreover, it minimizes unnecessary MVAr absorption and ensures that submarine cable ampacity is reserved primarily for active power flow. It uses a scoring index based on the equivalent inductance obtained from all feasible inductance combinations of the Variable Shunt Reactors (VSRs). This index is then used to determine the optimal tap positions in real time, thereby eliminating the need for forecasting or large-scale Optimal Power Flow (OPF). The proposed method has been validated on a 230 kV system with parallel 26 km overhead transmission line and 89.61 km submarine cables. The present contribution is a simulation-validated supervisory control methodology. Results show that SILARPMS flattens the voltage profile of the submarine cable, preserves its ampacity margin, and reduces shunt MVAr consumption. The approach fits both new VSR deployments and retrofits to existing systems.