Multi-Criteria based Steady-State and Dynamic Reactive Power Planning for Transmission Systems

Abstract

Planning of reactive power compensation devices as part of the grid planning process is becoming increasingly important due to decreasing reactive power reserves from conventional power plants. Planning such devices requires the consideration of the reactive power demand both during steady-state operation and disturbances as well as gradual power-flow shifts. To control the voltage in these scenarios, a portfolio comprising location, rated power and technology of reactive power compensation devices must be identified. In this paper, a planning approach with a coupled determination of steady-state and dynamic reactive power demand is applied to a generic transmission system. Different characteristic grid use cases are analysed for the identification of the steady-state reactive power demand. The determination of the dynamic demand involves the analysis of critical power-flow shifts within an hourly generation time series. Shifts leading to insufficient voltage stability reserves and high voltage gradients are considered in the planning approach. Furthermore, critical line-outage and short-circuit scenarios are analysed in connection with an increasing demand for dynamic reactive power compensation. Results emphasise that the coupled determination of steady-state and dynamic reactive power demand identifies suitable portfolios of different compensation devices using synergies for voltage control during steady-state operation, disturbances and power-flow shifts.