Capacity remuneration mechanisms (CRMs) are “climbing” regulatory agendas in all liberalised power sectors, especially in the European Union. CRMs are introduced to improve system reliability and to minimise power shortages to an economically efficient extent. These schemes will have a central role in future power systems. This PhD thesis provides an in-depth review of CRM design elements and recommendations to increase their efficiency and effectiveness, particularly in view of the challenges that these mechanisms have to confront in the current power sector environment, characterised by the pursuit of decarbonisation. The attention is focused here on the interaction with regional market integration, the need for properly-designed performance incentives, and the interaction with renewable technologies. The research is based on empirical evidence collected from international experiences, which is complemented, where applicable, by a model-based analysis to examine specific design elements. The outcomes of this PhD thesis can be summarised as follows. The participation of cross-border resources in national CRMs must be guaranteed in order to fully seize the benefits of regional market integration. However, this participation requires a strong commitment from power systems (and governments) in the regional market and the implementation of network codes and market rules that deter system operators from blocking exports when the latter are the outcome of an efficient market clearing. Where short-term markets are coordinated through market coupling, the algorithm must include a conditional nomination rule that ensures that, during regional scarcity conditions, available resources are assigned to those consumers that paid for them in the CRM market. CRMs must rely on robust performance incentives that foster the actual delivery of the committed capacity. High penalty rates may increase the cost of the capacity market, but the overall cost of electricity supply may decrease. Renewable technologies should be allowed to participate in CRMs and should be exposed to the market signals provided by these mechanisms. If renewable and conventional technologies must compete in the same markets, they should do it subject to the same rules. Obviously this participation must be coordinated with renewable support schemes, discounting CRM revenues. / <p>QC 20160411</p>

Fossil fuel is presently a major source for electricity production, but it contributes significantly to Green House Gas emissions. Wind is a promising alternative, and can potentially become a major power resource in future power systems. Wind power installations are growing significantly for producing clean energy in electric power systems. As the wind penetration continues to increase to relatively high levels, it can significantly affect the overall performance and reliability of the power system. Hence, it becomes very important to accurately model the behaviour of wind, its interaction with conventional sources and also with other wind resources connected to the power system in order to conduct a realistic assessment of system reliability and benefits from wind energy utilization. When the wind penetration levels are low, all the wind energy generated is utilized to serve the load. However, at higher wind penetration levels, wind energy is spilled due to limitations in the operating reserve or ramping capability of the scheduled generating units. The system reliability and the wind energy benefits are reduced as the wind energy spillage increases due to wind curtailment. Hence, accurate wind models should be researched and developed to include wind energy curtailment in the reliability modelling, considering factors such as the system load level, priority loading order of the generating unit and response rates of the generating units. Researchers have not incorporated these factors in wind power modelling and in the adequacy evaluation of wind integrated power systems. A new analytical technique is developed in the subsequent chapters to carry out a comprehensive wind absorption capability evaluation of the power system, and also to incorporate this characteristic in reliability modelling of the system. Wind curtailments can take place not only due to generation constraints, but also due to transmission line constraints depending on the capacity and location of the wind energy resource in the power system, and the power transfer capacity of the transmission lines connected to the wind farm bus. Therefore, reliability modelling of the power system considering wind curtailments due to both generation and transmission constraints should be carried out to assess the impact of wind farms on bulk system reliability and the wind energy benefits. Wind curtailment is incorporated in the composite power system reliability evaluation by modelling the wind resource both as generation and as negative load. The techniques can be utilized to conduct system adequacy and wind energy benefit assessment both at the capacity planning stages and composite generation/transmission planning stages, incorporating wind power curtailment due to generating unit response limitations. As the wind penetration in a power system increases, the wind farms connected to the system are distributed at different geographical locations. Both analytical and Monte Carlo Simulation based techniques have previously been used by the research group at the University of Saskatchewan to include the cross correlation between the wind characteristics of different wind farms in the wind modelling for reliability evaluation of power systems. However, the combined effect of wind diversity and wind curtailments due to both transmission and generation constraints on the system reliability and wind energy benefit assessment has not been considered. The techniques developed for system adequacy and wind energy benefit assessment considering wind curtailment due to generation and transmission constraints are further modified and presented in this thesis to include wind diversity in the analysis. The developed techniques for adequacy evaluation of wind integrated power systems considering wind power curtailment and diversity should be extremely useful for system planning engineers and policy makers as wind power penetration in power systems continues to increase throughout the world.

There are presently worldwide targets for decreasing anthropogenic greenhouse gases (GHGs) emissions owing to global climate change concerns. Here in the United Kingdom, the government has committed to reduce its GHGs emissions by at least 80% by 2050 relative to 1990 levels. In order to achieve the ambitious 2050 targets and minimise cumulative emissions along the way, modern power systems are facing a series of great challenges. These challenges include extensive utilisation of renewable generation, diverse demand--side participation in power system operation and planning, as well as considerable application of emerging smart devices and appliances. All of these challenges will significantly increase the complexity of future power systems in terms of both operation and design. Regardless, the primary objective of power systems remains the same. That is the system must supply all the customers (responsive ones and non-responsive ones) with electricity as economically as possible and with an adequate level of continuity and quality. With the widespread utilisation of smart meters and appliances as well as the large-scale installation of different storage technologies, the services that demand response (DR) and electrical energy storage (EES) resources can provide will cover a wide range of ancillary services. More importantly, the grid-scale penetration of DR and EES resources is able to provide energy management and capacity support services, which can be considered as the alternative to generation resources. In this light, considerable amount of research has been done focusing on engaging particular types of electricity users with different kinds of incentives and/or tariff schemes, so that the economic benefits to both utilities and customers are optimised. However, no general framework for systematic assessment of the contribution to power system adequacy of supply from potential grid-scale penetration of DR and EES resources is available up till now, particularly taking specific consideration of DR's flexibility and payback characteristics as well as EES's operational parameters. The research work in this thesis therefore emphasises exclusively on the potential of grid-scale DR and EES resources to serve as alternative resources to electricity generation within the context of power system adequacy of supply. More specifically, based on literature survey of existing studies in similar topics, this thesis has made some substantial contributions and innovations, such as developing novel models of these emerging demand-side resources, implementing a systematic adequacy of supply assessment with new aspect to measure the level of adequacy of supply (new indices), proposing a novel and comprehensive framework for evaluation of the capacity credit of DR and EES, and analysing the economic value based on power system fundamental long--term costs of interruption and supply. Ultimately, this thesis has established a comprehensive framework for assessment of the contribution of DR and EES to power system adequacy of supply. Additionally, the numerical studies carried out in this thesis have enabled the inference of general adequacy of supply implications in terms of deploying DR and EES resources to provide capacity support to power systems.

Renewable energy sources have received increasing attention in electric power systems around the world due to growing environmental concerns. Wind and solar are among the most promising alternatives to conventional energy generation. There has been a rapid growth of wind and solar energy integration in power systems in the last decade, and is expected to grow further in the years to come. The main concern with wind and solar energy sources is the uncertainty and the intermittency of power generation, which leads to problems in maintaining the overall system reliability. The impacts of these sources on bulk system reliability depend on a large number of factors. The strength of the wind or solar resource at the installation site, the existing renewable power penetration level in the system, the points of connection of these sources to the power grid, the correlation in resource availability between multiple installation sites, and the correlation between the load and the renewable power are key factors that are analyzed in this thesis. These factors are considered in evaluating the bulk system reliability and reliability benefits of wind and solar power sources, and the reliability worth to the electricity customers from the addition of these energy sources. The IEEE-RTS test system is utilized throughout the thesis to evaluate the effects of these factors on bulk system adequacy. Swift Current and Saskatoon wind resources are modeled and utilized in this thesis. The Swift Current area has a strong wind resource and provides better reliability benefit and reliability worth than the Saskatoon wind resource. The benefits from wind and solar power integration, however, also depend significantly on the location where it is connected to the grid network. Wind farms that are diversified in multiple regions with independent wind speed profiles provide superior reliability benefits and worth than wind farms located in one region. The incremental benefits of adding wind or solar power decreases as the renewable power penetration is increased in the power system. Wind power at practical locations provides higher reliability benefits than photovoltaics. However, the daytime contribution of photovoltaics to system reliability is relatively high. The reliability benefits and reliability worth of solar power are significantly different for different seasons. A comparison study on reliability benefit and worth between a wind integrated bulk system and a solar integrated bulk system is also done in this thesis in order to identify the best option for bulk system reliability.

Large interruptions of power supply in the transmission system have considerable impact on modern society. The goal for the transmission system operator (TSO) is to prevent and mitigate such events with optimal decisions in design, planning, operation and maintenance. Identifying critical power components for system reliability provides one important input to this decision-making. This thesis develops quantitative component reliability importance indices applicable for identifying critical components in real transmission systems. Probabilistic models with component failure statistics are combined with detailed power system models evaluated with the AC power flow technique. In the presented method each system component is assigned three importance indices based on outage events expected probability and consequence to (i) reduced system security margin, (ii) interrupted load supply and (iii) disconnected generation units. By ranking components by each of the three interests, a more complete view of the risks to system reliability can be assessed than if, as traditionally, only (ii) is modelled. The impact on security margin is studied in well established critical transfer sections (CTS) supervised by the TSO. TSOs set the CTSs limits [MW] based on deterministic security criteria, with regard to thermal, voltage level, and system stability limits, and the CTSs' condition at post-contingency state is in the method used as an indicator of the system security margin. The methodology is extended with three indices modified to quantify the component importance for common-cause events initiated by acts of sabotage. The developed methods are applied on a significant part of the Great Britain transmission system, modelling 7000 components and 107 substation layouts. The study includes several load demand scenarios, 200 million initiating outage events and non-functioning protection equipment. The resulting component ranking provides an important input to the TSO's decision-making, and could be implemented as a complement to the existing deterministic N-1 criterion. With the methods applied a TSO can perform further and more detailed assessments on a few critical components in order to enhance system reliability for equipment failures and strengthen the system vulnerability against sabotage. / QC 20110920