Wide-Area Backup Protection in Power Systems with High Penetration of Renewable Energy Sources

Due to the unique fault behaviours of renewable energy sources (RESs), the growing integration of RESs poses new challenges to the effectiveness of conventional protection systems. Additionally, protection schemes must contend with typical issues such as hardware failures, deficiencies in logic, and measurement errors. One significant benefit of PMUs is their ability to facilitate wide-area backup protection (WABP) to address the shortcomings of local protection schemes. Ensuring the reliability of protection systems in the presence of RESs requires a comprehensive understanding of the unique fault behaviour of RESs as per their various control strategies. This, however, has not been well addressed in the WABP methods in the literature. In this work, this understanding is combined with taking advantage of PMUs for the design of effective WABP methods. This work proposes robust WABP methods for transmission systems with high penetration of RESs. The methods are aimed at addressing practical challenges such as temporary loss of the time-synchronisation signal (LTSS), sparse PMU coverage, and communication failures and latencies without placing any rigid constraints on PMU locations.
Novel formulations with low computational burden are proposed to identify the faulted line in near real-time based on the superimposed-circuit methodology and the weighted least-squares method. The main contributions of the present thesis can be summarised as follows: (i) A technique is proposed for reducing the computational complexity of WABP methods that are based on the superimposedcircuit methodology; (ii) A rigorous derivation of the equation weights is proposed based on the statistical distributions of the superimposed errors to be used in the weighted least-squares method; (iii) Non-linear fault behaviours of RESs are captured while maintaining the linearity of the WABP formulation and accounting for any penetration level, locations, and control strategies for RESs; (iv) A new methodology is proposed that can work well with unsynchronised and delayed measurements without imposing a significant computational burden.
Simulation studies conducted on the IEEE 39-bus test system verify the superiority of the proposed methods over existing methods and the robustness of the proposed methods against influential factors such as measurement and parameter errors and other practical challenges, e.g., LTSS, sparse PMU coverage, and communication failures and latencies.