abstract: The presence of distributed generation in high renewable energy penetration system increases the complexity for fault detection as the power flow is bidirectional. The conventional protection scheme is not sufficient for the bidirectional power flow system, hence a fast and accurate protection scheme needs to be developed. This thesis mainly deals with the design and validation of the protection system based on the Future Renewable Electric Energy Delivery and Management (FREEDM) system, which is a bidirectional power flow loop system. The Large-Scale System Simulation (LSSS) is a system level PSCAD model which is used to validate component models for different time-scale platforms to provide a virtual testing platform for the Future Renewable Electric Energy Delivery and Management (FREEDM) system. It is also used to validate the cases of power system protection, renewable energy integration and storage, and load profiles. The protection of the FREEDM system against any abnormal condition is one of the important tasks. Therefore, the pilot directional protection scheme based on wireless communication is used in this thesis. The use of wireless communication is extended to protect the large scale meshed distributed generation from any fault. The complete protection system consists of the main protection and the back-up protection which are both presented in the thesis. The validation of the protection system is performed on a radial system test bed using commercial relays at the ASU power laboratory, and on the RTDS platform (Real Time Digital Power System) in CAPS (Center for Advanced Power System) Florida. Considering that the commercial relays have limitations of high cost and communicating with fault isolation devices, a hardware prototype using the interface between the ADC (analog to digital converter) and MATLAB software is developed, which takes advantage of economic efficiency and communication compatibility. Part of this research work has been written into a conference paper which was presented by IEEE Green Tech Meeting, 2017. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2017

This thesis has proposed two types of real time System Integrity Protection Schemes(SIPS) using Emergency Single Machine Equivalent (E-SIME) and Model PredictiveControl (MPC) approaches respectively. They are aiming to resolve the transientstability problems in power systems. Synchronous measurements, fast communicationnetwork and FACTS are deployed in the two SIPSs. The Thyristor Controlled SeriesCompensation (TCSC) is applied as the control action in both SIPSs.In the E-SIME based SIPS, the SIME approach is used to evaluate the transient stabilityof the system and then a decision is made about the control actions needed to stabilizethe system. During emergency conditions, a fast response time is very important andthis requires a security guideline to be used in the decision making process. Theguideline is developed by analyzing offline multiple fault scenarios using an automaticlearning approach. This ensures appropriate control actions can be performed withoutcompromising the response time required on a real system.The MPC based SIPS optimizes the control action at every discrete time instant byselecting the control action that leads to the minimized cost function value. Automaticlearning (AL) is utilized to predict power system dynamics by assuming each controlaction has been taken. Furthermore, a feature selection technique, that chooses themost relevant variables, is used to improve the performance of the AL prediction. Themodel predictive control (MPC) technique is performed every discrete time interval, sothe optimal control action is always selected.Two types of SIPS are tested and verified in the benchmark systems. Simulation resultsshow they can effectively protect the system from loss of synchronism in the aftermathof a large disturbance. This thesis also compares the two SIPSs and concludes thebenefits and shortcomings of each approach.

The increasing volume of renewable and intermittent generation that is being connected to power systems means that system operators need more advanced dynamic control tools to manage the increase in congestion and the resulting pressure on system constraints. The introduction of synchronised measurement technology provides the wide area real-time measurements that are essential to develop and implement adaptive online solutions for current network issues. The objective of the research presented in this thesis is to design intelligent system integrity protection schemes (SIPS) that protect transmission lines and power transformers from thermal overloading. An intelligent protection scheme should be able to identify the fault severity, predict the post disturbance trend of system states, continue monitoring specific vulnerable system variables and propose an accurate solution that is tailored to the actual system conditions and the specific contingencies that have occurred. The intent of this research is to contribute to the development of adaptive protective schemes that are enabled by modern synchronized measurement technologies for future power systems. The research presented in this thesis focuses on the creation of novel Operational Tripping Schemes (OTSs) that explicitly satisfy both the functionality and economical requirements by integrating an improved assessment of thermal behaviour of the monitored assets. Novel OTSs are proposed for both transmission lines and transformers and they can be considered to be intelligent, adaptive and efficient SIPS for the thermal protection of system assets. A novel functional block is proposed that be included within the OTS and that uses optimization theory to determine the lowest cost solution to overheating in the time available. Furthermore, case studies have been conducted to verify the performance of each novel OTS using simulations of a full GB system model.

The main objective of this thesis was to develop appropriate system protection schemes against two important causes of failure in power systems, namely, long-term voltage instability and cascade tripping of overloaded transmission lines, mainly due to overloading. To this purpose a distributed undervoltage load shedding scheme against voltage instability, and a centralized protection meant to alleviate line overload are proposed. The former, through the chosen system protection scheme characteristics, has the ability to adjust its actions to the disturbance location and severity. This behavior is achieved without resorting to a dedicated communication network. The distributed controllers do not exchange information, but are rather informed of their respective actions through voltage measurements. Neither do the controllers require a model of the system. This and the absence of communication makes the protection scheme simple and reliable. The other protection scheme, inspired of model predictive control, is aimed at bringing the currents in the overloaded lines below their limits in the time interval left by protections, while accounting for constraints on control changes. Its closed-loop nature allows to compensate for model uncertainties and measurement noise. In order to tune the proposed system protection schemes parameters and validate their performance it was preferred to detect plausible cascading event scenarios. To this purpose, an algorithm meant to identify such complex sequences has been developed. It encompasses hidden failures and the resulting system response. The tests performed on small systems as well as on a real-life one confirm not only that proposed protection schemes appropriately deal with the problems for which they were designed, but also that they cooperate satisfactorily for combined voltage and thermal problems that are beyond their individual capabilities.