The Project

Project Summary

Large PV power plants need to ensure a smooth injection of the generated renewable power into the grid where they are connected, while providing the required ancillary services to such a grid. Depending on the grid nature, such requirements can differ considerably, ranging from frequency or voltage support for PV power plants connected to power systems based on conventional synchronous generators, to grid-forming capability in systems or microgrids where PV is the main generation source.

The project aims at developing relevant control architectures and control algorithms to ensure optimal performance in different kinds of systems. Such control schemes will take into account the distributed nature of the different elements and the necessity of control coordination. The option of using or not communication systems in different control layers will be analyzed, suggesting appropriate architectures depending on given requirements.

The interactions between power converters and different system elements will be investigated in order to develop methodologies and tools that ensure the overall system stability. The potential resonances and instabilities will be carefully analyzed and the key quantities and elements that can trigger them will be identified. The developed methodologies will be applied to selected realistic case studies.

The project aims at developing and implementing tools to allow PV power plant engineers to design the controllers of large PV power plants in a systematic way.

Types of PV power plants

Type 1: Large PV Power Plants

Large PV power plants are systems dominated by power electronic converters. Power plant controllers, coordinated with lower level converter controllers can be adjusted to provide the required services to the main grid where the power plant is connected, according to the relevant grid code. The project aims at defining advanced algorithms to optimally dispatch the different set-points of active and reactive power inside the PV power plant, while taking into the account the risk of interactions and dynamic instability problems between converters.

Example of power plant control of a large PV power plant

Type 2: Microgrid dominated by PV Generation

Microgrids dominated by PV generation require coordination between PV generators, energy storage devices and conventional diesel generators. Different layers of control need to be coordinated to ensure the optimal frequency and voltage control (especially for islanded operation) while optimization the energy management in the overall system. Furthermore, the fact of having a grid potentially dominated by power electronic converters raises the need to carefully study the risk of interactions and dynamic instability.

Example of control structure for a microgrid based on PV power

Objectives and Targets

The main objective of the project is to develop methodologies and tools to optimize the controllability of PV power plants of different nature, including large PV power plants connected to the grid and microgrids dominated by PV generators.

Specific Objectives

  • Analyze large PV power plants, considering collection grid, transformers, energy storage units, fixed capacitors, statcoms, diesel generators and other equipment.
  • Define control architectures to ensure the system controllability and performance in different operating points. Define tuning methodologies.
  • Integrate power plant controllers and energy management systems.
    Study interactions between converters. Propose methodologies and tools to mitigate oscillations.
  • Build a tool to calculate the controller parameters for given applications.
  • Apply the developed methodologies and tools to relevant practical cases.