Contributions

This dissertation deals with the concept of the effect of integrating EVs within a microgrid and applying a hierarchical management applicable to microgrid network application. In particular, the thesis addresses the management of the microgrid, which has a variety of distributed generators and a fleet of EVs connected to a charging station system with hybridization forming the dual resources of an EV. This thesis considered the practical applicability and implementation methodology of managing microgrid components as a holistic, working

system. The majority of the published work is mainly focused on the optimisation of microgrid operation or optimisation of EV operation, as an offline computation and non-physical connection method to obtain the minimum operation cost from the view of optimisation issues. Other researchers limited the research to operating the converter system of the EV to either obtain the optimum power arbitration of dual resources over a predefined load profile, or proposed a topology and switching modulation function to obtain high power quality. Minor researches considered management and control of the microgrid, including the integration of EVs, as a holistic working system. As a result, the contradicting objectives that arise when modifying a distribution network to a microgrid network can be listed as follows:

1- Find the effect of the EVs on the microgrid network.

2- Find the optimum operation of the microgrid that has different characteristics of distributed generators, different kinds of loads, and EVs.

3- Manage and control the centralised charging and discharging operation of the EVs as a supporter of the distributed generator.

4- Compensate the decentralised operation of the EV to manage and control the power flow through energy storage units,including the associated power electronic topology and switching modulation that facilitates the integration of EV into a microgrid. As a holistic system approach, this thesis contributes to constructing, describing, integrating, and operating the key processes involved in microgrid power and energy management. This thesis presents the following novelties:

 The positive impact of voltage stability enhancement on the operation of microgrid concept compare with conventional grid.

 The impact of integrating aggregated EV at specific bus bar on the microgrid voltage profile and voltage stability characteristic at discharging operation mode.

 Design a unified systematic framework to implement the power decomposes into modular blocks in chronological execuation for three operators: Microgrid Operator (MGO) to ececute long term desition of management and control couple of distributed generators with loads, Charging Station Operator (CSO) to mange and control aggregated EVs connected at specific bus bar on the microgrid through charging station system, and Elictric Vehicle Operator (EVO) to mange and control operation of duel resources of EV within microgrid in term charging and discharging activity. The holistic Moduler Power Energy Management System (M-PEMS) execuation proceeds to demonestrate a reconsetraction of the power management problem.

 Modified space vector pulse width modulation to do switching an eighten swithes of modified H-bridge multi-level inverter for controlling duel resources of EV.

 Interconnecting the operation of vriaty different dynamic response elements of microgrid at different level to provide reseliance operation of microgrod including EVs through various execution time operators of the modular framework structure, which then makes all the microgrid elements collaborate each other to operate as one compleate system. The EVs integrated into microgrid based on a set of equations to calaculate the power flow and regulate the power level of charging or discharging.

Operating of the M-PEMS has been structured into modular hierarchical process operators. The MGO handles the long-term decisions to optimise minimum cost and minimum pollution of the power usage in the distributed generators at the microgrid. The process within CSO, however, handles medium-term decisions to optimise minimum charging cost or maximum discharging cost of fleet EVs connected at the microgrid. Finally, the EVO handles the short- term decisions that facilitate the power and energy management of EV.

The modified multilevel inverter proposed in this thesis is suitable for EV application that is powered by a dual energy storage system, consisting of the battery connected to a three-phase bridge inverter and three supercapacitors connected in series with each leg of a standard three- leg inverter through an H-bridge converter.

The modular structure approach is oriented to ensure the reliable and stable operation of the microgrid with the objective of contributing completeness of the control and management of the operation of the EVs within the microgrid problem description.

The key contributions as a result of this thesis in order of presenting inside thesis can be summarised as major and minor; the major contributions are as follows:

1- The thesis presents a fresh perspective to operating the EVs within the microgrid research arena by introducing a novel approach that provides a modular structure with three distinct hierarchical processes resulting in the following key benefits: A- Balancing the energy sources and electricity demand within MGO. B- Managing and controlling the centralised charging and discharging aggregated EVs

connected to charging station within CSO.

C- Managing and controlling power flow between the resources of the EV and the microgrid as well as switching to a decentralised charging operation in case any failure happen in the centralised charging station within EVO.

2- The thesis distinguishes the voltage stability enhancement of the smart grid at two modes: i.e. (a) connected and (b) disconnected microgrid operation over the conventional power grid.

3- This work identifies the optimisation requirement and considers all the constraints of the distributed generators and electrical demands to implement and achieve minimum cost operation and minimum cost pollutant treatment for maintaining a balanced operation between the supply and load.

4- The dissertation presents a formulation for the charging and discharging power management with scheduling equations incorporating fleet EVs connected to the charging station at the microgrid to achieve minimum charging cost or maximum discharging cost without a congested power flow. The charging formula constraint is based on several factors: the initial state of charge, a period of connection to the microgrid, desire to leave the state of charge, rated power of the converter, and capacity of the energy storage. The discharging formula is based on owner acceptance, the state of charge of a predefined limit, frequency and/or voltage deviation, in addition to charging formula constraints.

5- It provides a modular structure for decomposing the power and energy management for charging or discharging EV powered by dual energy storage resources within the hierarchical process.

6- The thesis presents a novel formulation of the reference power management by understanding the mathematical equation of integrating EV into the microgrid and the physical constraints of the energy storage technology. The energy management operation illustrates, based on the sequential decision process of control, the power fluctuations at the connection node of the EV to the microgrid to accommodate the process of the management energy shell (EVO-EMS).

7- The method of determining power-split ratios to charge or discharge the battery and the supercapacitors is made using the controlled signal of the EMS to accommodate the process of the power management shell (EVO-PMS).

8- It describes the numerical design and practical validation based on CompactRIO devices and LabVIEW software to modulate SVPWM for operating the multi level inverter under research, and provides technical insight information on the hybridization of the battery and the supercapacitors to accommodate the process of the power electronic shell (EVO-PES).

9- The thesis presents the flexibility of charging or discharging the EV by merging the centralised and decentralised operations of the EV, based on the owner of the EV requirement. The EVA at centralised smart charging implements the instruction of the CSO, whereas a smart agent of the EV is responsible for controlling the charging or discharging intervals of the EV in decentralised smart charging.

The minor contributions are as follows

10- It presents a clearly constructed microgrid from an existing distribution system in the form of choosing a suitable type and location of distributed generators and all necessary power electronic equipment. This assists towards reconstructing the existing distribution network into the microgrid concept.

11- It defines clearly the construction of a centralised charging station to connect each EV to its recharging socket, which collects the state of the vehicle and addresses it to the bidirectional power flow meter. The state of the vehicle transfer to the process of the charging station is to apply the optimisation function.