Power Management Systems for Hybrid Power Plants to Provide Ancillary Services

(HPPs), which combine renewable IBRs with conventional synchronous generators and energy storage systems, emerge as a promising solution to address these challenges. By aggregating and coordinating diverse generation assets, HPPs can behave as a dispatchable and controllable resource at the grid interconnection point, while simultaneously supplying local loads and providing ancillary services to the grid.

However, the coordinated operation of HPPs remains a challenging task, as it requires managing multiple heterogeneous agents with distinct dynamic behaviors, time scales, and operational constraints that may be inherently conflicting. Synchronous generators, renewable sources and Battery Energy Storage Systems (BESS) pursue different control objectives, such as inertia provision, SOC management, renewable maximization, and power dispatch compliance, making unified operation nontrivial, especially in the context of providing ancillary services as a single aggregated unit.

This work proposes a Power Management System (PMS) algorithm for an HPP based on

Supervisory Control Theory (SCT), providing a structured coordination framework that enables the plant to behave as a single entity from the grid perspective. The proposed PMS main objectives are to ensure voltage support and constant power dispatch while maximizing renewable energy utilization through SOC-based coordination of the BESS and synchronous generators. In grid-connected mode, the PMS enables the HPP to regulate its active power exchange with the grid following a defined reference, including Grid Zero operation, with no active power exchange with the grid. Through continuous SOC monitoring and coordination with conventional generators, the HPP can operate as a flexible grid-supporting resource, providing active and reactive power control or voltage and frequency support as required. The PMS based on the SCT is also responsible for the interlock between conflicting operating modes, avoiding undesirable operation.

The proposed PMS is validated through a detailed case study using electromagnetic transient simulations of an HPP comprising multiple synchronous generators, PV and wind plants, a

BESS, and local loads. Two operational scenarios are analyzed: Grid Zero operation under highly variable renewable generation, and voltage support during a grid transient. Validation is done through a Controller Hardware-in-the-Loop (CHIL) setup using two Digital Real-Time

Simulators.

Results demonstrate accurate active power regulation, effective voltage support, and enhanced utilization of renewable energy. The SOC-based coordination strategy proves essential for reliable and resilient HPP operation, confirming the PMS’s capability to provide both local supply and valuable ancillary services to the grid.