Advanced control of large-scale power systems with integration of renewable energy sources

• Main Author: Jiang, Hao
• Other Authors: Wang Youyi
• Format: Thesis-Doctor of Philosophy
• Language: English
• Published: Nanyang Technological University 2020
• Subjects: Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/144266
• Institution: Nanyang Technological University

In the past few decades, the world becomes more concerned about environmental protection and climate change. The same concern is shared within the electric industry. Conventional thermal power plants burn fossil fuels as energy sources to generate electricity. On the other hand, Renewable Energy Sources (RES) such as wind, solar, tidal, etc., produce less CO2 and are less contaminating. However, RESs usually rely on VSC-based converters to connect to the power grid and are usually considered as lacking inertia/zero-inertia. Therefore, the integration of a large amount of RESs affects the transient stability of the existing power system, and researches should be carried out to investigate the influence of RES on transient stability and propose new control methods to enhance the transient response. Based on the global control principle, controllers are designed for both Single Machine Infinite Bus (SMIB) and multi-machine systems with the integration of RESs. The nonlinear power system models are re-described by multiple nonlinear partial models. Then the nonlinearity is handled by direct feedback linearization. Robust controllers are designed for each of the partial models and are synthesized via membership functions to provide global control over all operating regions. The resulting closed-loop control shows improved transient responses from a simple system to multi-machine systems. With more and more RESs integrated, the system transient stability should be dependent on both conventional synchronous generators and RESs. Proper control methods should also be designed for RESs by utilizing the properties of RESs’ structure. When load changes or faults occur, imbalances of power between energy generation and consumption is the fundamental cause of system instability. Hence, controllers based on the power balancing principle is proposed on various RESs-side during transience. For steady-state operation, RESs operate to provide optimal economic benefits. The steady-state controller and proposed transient frequency controller are synthesized by membership functions to provide weighting and smooth transition. The proposed controller is tested in multi-machine systems with various RESs integrated, and the results show promising performance.