A Novel Structure of the Future Generation of the Electricity System

load by using an intelligent controller supported by information and communication technology to monitor the generation of the system and load. The smart controller promotes management and control as players (bidirectional or unidirectional) connected to the grid, whereas the communication link monitors the grid using an advanced metering infrastructure to connect the equipment of the grid to the intelligent controller. The operation of the transmission system and distribution networks ensures a fixable power transfer with a secure and stable operation. Distributed energy resources (DERs) and EVs, which are connected at the distribution level, are expected to participate actively in the functioning of the smart grid. Thus, the players (DERs and EVs) connected on the distribution networks would support the transmission system in the grid. Therefore, the deployment of management and control strategies requires extending the monitoring and data acquisition capabilities downstream to the distribution level of the grid, thus, changing the concept of centralised management and control to a decentralised concept and handling the data processing capability of all the control variables and consequent communications. The decentralised management and control network organise the distribution network in small controllable networks called microgrids. Each microgrid operates as a single controllable system that handles and controls the generation units and loads in a coordinated way in grid connected mode and islanded mode. The microgrid is considered to have a self-healing capability which works autonomously to disconnect from the grid, deliver power to its local area, and recover the supply and demand conditions in emerging electricity markets, such as natural disasters, demand congestion, or grid outage. It is possible to restore the service of the smart grid by reconnecting the microgrid to the smart grid in case the demand exceeds the local generation of the microgrid.

Microgrids are small areas of the smart grid paradigm to provide the flexible and controllable operation of low voltage networks, which then changes the distribution network operation philosophy from passive to active. The microgrid is a single controllable network, combining distributed energy sources and controllable loads, connected by a communication system, ensuring the management and control of interconnected elements at autonomous operation mode. The microgrid philosophy improves the system robustness and provides a resilient operation as well as an adequate framework to fully integrate EVs as a new player to the network. Since the largest microgrid problem is maintaining the stability of the system with low inertia and intermittency of microgeneration units, a widely-accepted solution is to use EVs’ resources to keep voltage stability, in the short term, in voltage stability oscillation. Extensive deployment of the integration of EVs into microgrids will impose many challenges to the operation and management charging demands of EVs but will assist in avoiding the stability issue.

The EVs will play a major role in microgrid operation. The EVs are new, flexible load or mobile storage devices that are capable of being represented either as a normal load to charge the resources as G2V mode, or providing its power back to the microgrid as a V2G mode. The EVs are often provided with two resources for short operation time storage: seconds to minutes – such as supercapacitor and medium operation time storage; minutes to hours – such as a

battery to meet the performance expectation of the vehicle operator. The energy to power ratio for short operation time storage is less than one second whereas it is between one and ten for medium operation time storage [63]. The energy to power ratio is defined as a division of energy capacity by the power rating to get the operation duration time of the device while delivering its rated power, which is also called discharge time with unit of second. The high- power ratio source (battery) works as a primary energy source while the low power ratio source (supercapacitor) operates as a primary power source. An important feature for short operation time storage is the ability to recapture energy during regenerative braking. Power and energy management of the EV is required to meet the power quality and the stability of the vehicle at running mode and connecting mode.

Hybridization of the battery and the supercapacitor become necessary to achieve high performance and efficiency of EV operation. However, hybridization of multiple energy resources with different characteristics to generate the proportional amount of power and split between them is a big challenge for EV research. Configuring the battery and supercapacitor electrically within the EV power system and within the microgrid network forms the power electronics scope of this research. The multilevel inverter is a good approach to coordinate the multiple resources of the EV in bidirectional operation. This operation requires a high-level control and management scheme to be incorporated by using the battery and supercapacitor in a synergetic way. The charging infrastructure is an essential part of the interfacing between the microgrid and EV. The charging activity could take place at home, work, or through public access as single or aggregated EVs. A CSS could be on board with each EV based on the hardware and energy storage system capability, or outboard when integrated to the microgrid. The outboard charging station is divided into standard charging and fast charging based on the capacity of the charging station and waveform characteristics of the grid. The charging behaviour of the EV depends on:

 The ability of the resources of the EV.  Period of connection.  The state of charge of the resources.  Charging strategies.

 Location and time of connection.  Microgrid power availability.  Driving distance and style requirements.

Widespread integration of the charging stations in the microgrid is a key pillar to reap the wide deployment of EVs and the achievement of their large-scale development. Management of the role of the charging station to mitigate the congestion operation of EVs, apply microgrid constraints, and sophisticate the requirements of the microgrid and owner of an EV, are considered to be the biggest obstacles to the widespread adoption of EVs by customers. According to complexity of the microgrids’ elements, the control system of the microgrids distributes between several operators:

 Distripuation Network Operator (DNO) to mange and control many micorogrids within distribution network.

 Microgrid Operator (MGO) to mange and control balancing the generation and loads of the microgrid.

 Charging Station Operator (CSO) to centralize manage and control aggragated EVs connected at specific bus bar within charging station system on the microgrid.

 Privet-Home Operator (PHO) to mange and control charging and discharging home or private CSS.

 Electric Vehicle Operator (EVO) to either apply the CSO or PHO instructon for charging or discharging the resources of EVs or decentralize mangment and control the resources of EVs.

This new operation increases the reliability, efficiency, and sustainability of the system. The general structure of the CPS and the smart grid system is shown in Figure 1-12.

Microgrid_N Microturbine Diesel engine Fuel cell Fixed storage energy Photovoltaic cell Wind turbine Smart building Electric vehicle operator (EVO) Platform_A Recharging socket (RS_A) Platform_N

Recharging socket (RS_N) Electric vehicle operator (EVO) Local controller (LC) Local controller (LC) Local controller (LC) Local controller (LC) Local controller (LC) Local controller (LC) Charging station operator (CSO_A) Charging station operator (CSO_B) Electric vehicle operator (EVO) Platform_A Recharging socket (RS_A) Platform_N Recharging socket (RS_N) Electric vehicle operator (EVO) Local controller (LC) Smart meter Microgrid operator (MGO_A) Smart home Market operator (MO) Distribution network operator (DNO) Distribution management operator

The Past

The Future

Single failure point could leave us in the dark

Centralised generation

units Transmission system

Substations

A microgrid is a single controllable network that works as a cluster of micro sources which deliver power locally to loads and act as a transceiver with other networks by ensuring communication, management, and control of interconnected elements to achieve autonomous operation mode.

Local controller (LC) Point of common coupling (PCC) Centralised generation units Transmission system Substations Electrical demand Hour Microgrid Operator (MGO_A) (Strategy)

Top level long-term decision frame Minutes Charging Station Operator (CSO_A) (Policy) Middle level medium-term decision frame seconds Energy Management Shell (EMS_A) (Regulatory) seconds Power Management Shell (PMS_A) (Advisory) milli-seconds Power Electronic Shell (PES_A) (Instructive) micro-seconds Electric Vehicle Operator (EVO_A) (Process)

Lower level short- term decision

frame

Smart meter _{operator (PHO)}Private-Home

Private-Home operator (PHO)