Decentralized Load Frequency Control for a Power System with High Penetration of Wind and Solar Photovoltaic Generation
Author: Sergio A. Dorado-Rojas (sergio.dorado.rojas@gmail.com)
Supervisors: Prof. Sergio Rivera and Prof. Eduardo Mojica-Nava
The results of this work have been presented in the 2018 IEEE PES PowerTech Milano.
Dorado-Rojas, S. A., Cortés-Romero, J., Rivera, S., & Mojica-Nava, E. (2019, June). ADRC for Decentralized Load Frequency Control with Renewable Energy Generation. In 2019 IEEE Milan PowerTech (pp. 1-6). https://ieeexplore.ieee.org/document/8810873
Non-conventional renewable energies represent a significant challenge for electric grids due to the technicalities associated with their implementation. Integration of such energy sources requires revisiting the grid structure and operation paradigm. The most relevant difficulty is that such a transformation must be carried out while keeping the system operational.
In a conventional power system, synchronous machines are widely used as traditional electricity generators. These rotating machines store kinetic energy in their rotors. Rotor kinetic energy can be released or captured to compensate for load or generation disturbances, thus keeping the system's frequency constant (inertia characteristic). Large-scale renewable integration reduces the grid's inertia significantly since they interface to the network through inertia-less power converters.
Several control strategies have been proposed to enhance the inertia capability of renewable generation units such as solar photovoltaic plants or wind turbines. However, this control loop does not guarantee frequency restoration to the nominal value. For this reason, it is critical to consider a secondary control loop to drive the frequency back to the desired steady-state operating condition.
This work considers a system with high penetration of solar photovoltaic and wind energy. The main objective is to evaluate a decentralized linear controller's performance for a secondary control loop with the active contribution of renewable units. The resulting controller is benchmarked against conventional alternatives such as a linear quadratic regulator. The document focuses mostly on designing a secondary load frequency controller under the active disturbance rejection paradigm using a linear technique such as an extended-state observer.