Search

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. N/A N/A

In recent years, with the rapid development of solar energy and other renewable energy, PV grid connected power generation technology has more and more attention. Grid connected inverter is the core of grid connected power system. When grid connected inverter operated in grid, the current control mode is essentially a voltage source input and current source output of the inverter. At present, a lot of work has been carried out in the aspects of filter selection, grid connected control strategy and controller design in the domestic and abroad, aiming to improve the power quality of grid connected current. In this paper, the reactive voltage control strategy of grid connected photovoltaic system is studied in order to increase the penetration rate and improve the stability of grid voltage. Grid connected PV system generally consists of a number of inverters, so it is necessary to analyze the control strategy of a single inverter and the reactive power output constraints.

In order to improve the efficiency of photovoltaic array, which need maximum tracing power. Perturbation and observation method has become one of the algorithm of the wide range research because of its simple and easy. But the traditional P&O will be oscillation in near the maximum power point due to its fixed step disturbance and leads to some loss of power and in certain circumstances and incorrect judgment will be in steady state. In order to overcome these shortcomings, a variety of improved methods are proposed, and the main improvements of those are summarized. Some simulation experiments have been done for these methods, and these methods are proved to be feasible.

Micro-grid is a kind of new organization and structure of distributed energy, It integrates the advantages of distributed generation and weakens the adverse impact of the distributed generation on the grid. It makes the distributed power generation units, power grid and the end users to be connected as a whole, so the structure and configuration can be optimized easily. At the same time, the operation of micro-grid can improve energy efficiency, reduce the effect of energy power systems on the environment, solve the serious problems of lacking of energy, lead the use of energy to green and environmental protection.