Electrical and Computer Engineering

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This is the collection for the University of Waterloo's Department of Electrical and Computer Engineering.

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Browsing Electrical and Computer Engineering by Author "Ahmed, Mohamed"

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    Demand Response and Battery Energy Storage Systems in Electricity Markets: Frameworks & Models
    (University of Waterloo, 2019-08-09) Padmanabhan, Nitin; Bhattacharya, Kankar; Ahmed, Mohamed
    Ensuring a balance between the generation and demand is one of the most challenging tasks in power systems because of contingencies, sudden load changes, forecasting errors and other disturbances, occurring from time to time. The peak demand, which occurs only for a short duration, has always been a concern for independent system operators (ISOs), as it leads to high market prices and reliability concerns. Furthermore, in recent years there have been significant increase in the penetration of renewable energy sources (RES) to address the challenge of significantly reducing carbon dioxide (CO2) and other greenhouse gas (GHG) emissions and the system's dependence on fossil fuels based generation resources. However, the high penetration of RES, because of their intermittency and uncertainty, poses operational and reliability issues and thus necessitates an increase in the procurement and deployment of primary and secondary regulation reserves, as well as spinning and non-spinning reserves. In recent years, demand response (DR) and battery energy storage systems (BESS), because of their characteristic features such as fast response time, high ramp rate, and the ability to provide flexible upward and downward response as compared to conventional generators, have been considered as promising and viable options by the ISO to reduce the peak demand, facilitate RES integration and for the provision of ancillary services, such as regulation and spinning reserves. Despite the benefits and the growth opportunities of DR and BESS, there are still many challenges associated with their market participation. To address the challenges pertaining to DR and BESS participation in electricity markets, this thesis proposes appropriate models and frameworks, which can efficiently integrate these resources into the day-ahead and real-time electricity markets, and at the same time effectively address the aforementioned challenges of ISOs. This thesis first presents a new bid/offer structure for DR provisions, simultaneously through price responsive demand (PRD) based bids and load curtailment based DR offers from customers. Thereafter, incorporating the DR offer structure, a novel day-ahead, co-optimizing market auction framework and mathematical model for DR-energy-spinning reserve market, based on LMPs, which includes transmission loss representation within the dc power flow constraints is proposed. The impact of DR on both energy and spinning reserve market prices, market dispatch, line congestions, and other economic indicators, is studied using the IEEE Reliability Test System (RTS), by considering various scenarios and cases. In the next stage, the thesis considers the BESS participation in the day-ahead markets. First, a novel BESS cost function model, considering Degradation Cost, based on depth of discharge (DOD) and discharge rate, and Flexibility Cost, in terms of the battery power-to-energy (P/E) ratio, is presented. A detailed bid/offer structure based on the proposed cost functions is formulated. Thereafter, a new framework and mathematical model for BESS participation in an LMP-based, co-optimized, day-ahead energy and spinning reserve market, have been developed. Three case studies are presented to investigate the impact of BESS participation on system operation and market settlement. The proposed model is validated on the IEEE RTS to demonstrate its functionalities. Finally, the thesis considers BESS participation in the real-time operations. Firstly, a novel framework for simultaneously procuring primary and secondary regulation reserves alongside energy, in a BESS integrated electricity market, by taking into account probabilistic scenarios of contingencies, is proposed. Thereafter, an appropriate mathematical model is developed considering BESS alongside conventional generators to determine the optimal real-time primary and secondary regulation reserves and energy market clearing, in a co-optimized, LMP based market, taking into consideration the a priori cleared day- ahead market schedules. Lastly, the impact of participation of BESS in day-ahead and real-time energy and reserve markets on prices, market clearing dispatch, and other economic indicators are investigated using the IEEE RTS, for various scenarios and cases.
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    Impact of Demand Response and Battery Energy Storage System on Electricity Markets
    (University of Waterloo, 2017-12-19) Ibrahim, Haytham Raafat Gamal; Salama, Magdy; Ahmed, Mohamed
    The calls for the reduction of carbon dioxide (CO2) and other greenhouse gases emissions from conventional electricity generation have been dramatically growing in the recent years owing to their negative environmental impact which became evident in climate change. The penetration level of Renewable Energy Sources (RESs) in the electrical power system is promptly increasing as they provide a cleaner and a cheaper solution to generate electricity. The main impediment to the spread of these RESs is that they are not dispatchable due to their intermittent nature. For example, the photovoltaic arrays output depends mainly on the solar insolation level. As for wind generation, the output is primarily affected by the wind blow. Hence, their coincidence with demand is not guaranteed, and this affects system reliability. Distributed Energy Resources (DER), such as Energy Storage Systems (ESSs) and Demand Response (DR) can play a major role to overcome the operational challenges with RESs, especially in the context of Smart Grid (SG). The main aim of this research is to assess the effect of using DR service and utilizing an existing Battery Energy Storage System (BESS) with the objective of minimizing the costs from the utility point of view. This is carried out by solving a constrained Optimal Power Flow (OPF) problem in three different cases (i.e.: Base Case, DR Case and BESS Case) to get the total incurred costs, conventional generation commitment and Locational Marginal Costs (LMCs) in each case to highlight the impact of DR and BESS on the electricity market. The results obtained for the IEEE 14-bus system show that either the application of a DR program or the employment of an existing BESS with the objective of cost minimization can be beneficial in terms of reducing the running costs vis-à-vis operating the system with neither.
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    Impact of Second-Life Batteries on Enhancing the Integration of Renewable Energy Resources
    (University of Waterloo, 2019-08-02) Hassan, Engy; Salama, Magdy; Ahmed, Mohamed
    The current distribution systems are typically not designed to accommodate a high level of renewable sources. Customer impact assessment studies are usually required by the distribution utility prior to the connection of DG. In these studies, the impacts of Distributed Generator (DG) on the system voltage profile, reverse power flow, short circuit level, and the system voltage unbalance are evaluated. If the DG failed to fulfill the distribution system technical requirement, the DG project application might be rejected. In some cases, the DG capacity may be reduced to fulfill the technical constraints. In other cases, the renewable based DG power may be curtailed (especially at peak generation). The reduction in DG capacity, as well as the DG active power curtailment, will badly affect the DG project investment. In order to eliminate the DG active power curtailment, the investor may connect a battery at the same point of the renewable DG. The battery can dispatch the DG generation; therefore, the peak DG power, that causes the violation to the system technical constraints, is shaved. However, the high capital cost of the batteries may negatively affect the investor profit. In such cases, the usage of second life (SL) batteries represents the most useful solution. SL batteries have significantly cheaper capital costs compared to new batteries. Thereby, the major driver for using SL batteries is the possibility of reducing costs and maximizing the DG investment by avoiding the utilization of new Li-ion batteries. The main aim of this research is to use batteries, which have lost part of their original performance during their first life, with the distribution system applications. The general objective is to utilize the SL batteries for smoothing the photovoltaic based DG power to increase the DG penetration while fulfilling the utility technical constraints. Another objective is to use the SL batteries connected at the same bus of the DG to maximize the DG project investment. Towards the execution of the proposed research work, some ancillary studies are presented in chapter (3); the results of these studies are used to solve the main problems under study presented in chapter (4). The studies presented in Chapter (3) comprises a probabilistic model for the PV DG, a long-term forecasting technique for the system load, a load flow study to determine the maximum allowable injected DG power, and an economic assessment study to determine the best PV DG capacity that increases the net present value of the profit of the PV DG project. The results of the aforementioned studies are integrated with the main problems under study that were formulated and solved in Chapter (4). Two main objectives were presented in this chapter; i.e. the first objective is to obtain the optimal size of the SL batteries that achieve zero curtailment while minimizing the battery cost, the second objective is to obtain the optimal schedule of the batteries that maximize the net present value of the profit. The results obtained show that the SL batteries are adequate for the application, and they have superiority over the brand-new batteries in terms of cost. SLB batteries give a chance to the investor to purchase batteries at low prices at later years of the project rather than purchasing all the required batteries at the beginning of the project. Thus, the SL batteries offer a competitive solution for the cost problems associated with the battery integration with the distribution systems.