Frequency Support Functions in Large PV Power Plants With Active Power Reserves

The total installed capacity of photovoltaic (PV) power, within each year, constantly pressures transmission system operators to continuously upgrade their network codes (NCs) moving their focus to grid stabilization features. The NCs started to demand large-scale PV power plants (LPVPPs) to synthetically inherit frequency support functions from the conventional generation-frequency sensitive mode (FSM) and encourage the use of inertial response (IR) along with a minimum supply of active power reserves (APRs). This paper investigates the impact of LPVPPs supplying mandatory FSM enhanced with high-sensitivity IR over the frequency quality parameters. Moreover, the paper performs a time-domain evaluation combined with a statistical analysis of the generated synthetic frequency. The main purpose is to demonstrate the short-term and midterm benefits brought by the added ancillary services and to prove their need with increased levels of PV penetration. This paper realizes a complete representation of a power system having modeled the generic IEEE 12 bus system evaluated over a real-time digital simulator platform. The power system model is enhanced with an automatic generation control system and subject to a realistic Danish winter load profile to create the synthetic frequency of the grid. LPVPPs with APRs and frequency support functions share part of the control responsibilities and show their contributions for short-term and midterm frequency stability once the penetration level reaches higher levels.