M. Bhaskar Naik M. Bhaskar Naik

This is to certify that the thesis entitled "The Solar Assisted Smart Public Transportation System and it's Coordination with the Grid", submitted by me to the Indian Institute of Technology Guwahati, for the award of the degree of Doctor of Philosophy, under the supervision of Dr . This is to confirm that the thesis entitled "The Solar Assisted Smart Public Transportation System and it's Coordination with the Grid", submitted by M.

Introduction

Tram systems for urban transit
Trolleybus systems for urban transit
Supercapacitor based bus systems for urban transit
High capacity energy storage systems in the smart grid technology
Role of the supercapacitors in the smart grid technology
Contactless power transfer
Solar energy in the smart grid systems

Next subsection explains the importance of supercapacitors in the public transport systems and their technological growth. VRB is called as 'the green battery' (the material used in it is environmentally friendly).

Motivation

Energy flows from renewable energy sources (solar systems/other renewable energy sources/standalone solar systems) to the grid when the 'belt is used as a hub' (ref. The energy transfer between electric cars and ESD is also beneficial to the grid during peak load periods.

Fig. 1.4 Layout of the literature review and thesis plan

Aim of the thesis

A suitable algorithm should be required to determine ONB for different types of days in all seasons of a year. Verification of the response of smart public transport networks should be required for all seasons of a year and also for the uncertain situations encountered in the system.

Main contributions of thesis

SPTS network expansion has been carried out using CBs and EVs along with e-buses in Guwahati's urban transport network. The SPTS network response to uncertain situations in the system has also been verified.

Thesis organization

The response of the SPTS network has been verified for three seasons of the year, with ESD only and with 'ESD together with CB and EV'. A specified EBS is considered in the SPTS network to charge CBs and EVs along with e-buses.

Small-scale Solar Plants coupled with Smart Public Transport System and its Coordination

Modeling of the SPTS

The structure of EBS
ESD sizing
Solar irradiance availability determination
SP sizing
Assumptions

The electronic bus receives power from the ESD located in the current EBS through the inductive charging system (ICS) and switches to the next EBS (the stopping time of the electronic bus in the EBS is considered as 2 minutes and the electronic bus is charged within this duration The amount of power it receives e -bus from ESD in duration 2 minutes is 39.7 kW). E = E (2.8) ETSP is the total energy produced by the SP in a day and 'c' is the number of hours of sunshine. E = E E (2.11) ETSPSH is the total energy produced by SP in sunny hours and EESDSH is the remaining energy in ESD in sunny hours.

Table 2.1: The ESD specifications and EB energy requirement [113]

Minimization of SPTS dependence on the grid

Favorable energy utilization from both, the grid and SP for SPTS support
SPTS response for three seasons of a year
The Fuzzy logic controller

ESD acts as a load on the network during the off-peak period (filling the valley of the network load profile) and acts as a resource on the network during the peak load period (the peak of the reduction of the network load profile). Favorable use of energy from the network and SP for smooth operation of the SPTS. Send power from ESD to grid and also from SP to grid Send power from.

Fig. 2.6 shows an algorithm for the favorable energy utilization from both, the grid and SP for SPTS support

Results and discussion

Case-1: SPTS response with only ESD and with both, the ESD and SP
Case-2: SPTS response for three seasons of a year

Winter (W) season
Summer (S) season
Rainy (R) season

The energy behavior with ESD only and with both ESD and SP after integration with the electricity grid is shown in figure. The Vpu profile has remained below the peak period from 07:00 to 13:00, so that both the ESD and SP signals transmit energy to the grid. The Vpu profile remains below the peak period from 09:00 to 18:00, so that both the ESD and the SP send energy to the grid.

Fig. 2.21 The energy behavior with only ESD and with both, the ESD and SP after integrating with the grid

Summary

The intelligent energy utilization of both ESD and SP reduced the SPTS dependence of the network. The intelligent energy utilization of both, ESD and SP reduced the SPTS dependence of the network. In [113], the energy storage devices were used to combine the transport system with the grid.

Structure of the SPTS network

The bus stop structure
Assumptions

At each EBS, the passengers get off/in time from/to the e-bus is considered to be 2 minutes. The e-bus maximum energy (EBT max) is considered as 2 times of EBT min to avoid the emergency situations in SPTS. The communication channels (CC) have been provided between each EBS and also, under the Central Transport Authority (STA) and the bus stops, to handle the failure situations in SPTS.

Fig. 3.2 The electric bus stop structure

The ONB determination and failure analysis in SPTS

The ONB determination
Failure Analysis in SPTS

ONB is the average of NB1 (NB relative to NP), NB2 (NBs relative to EESD) and NB3 (NBs relative to ESP) for ND/SD during the off-peak/peak period (3.5). Therefore, ONB during off-peak period (ONBOPP) and on-peak period (ONBPP) can be expressed as. 3.1) If the network stays in the off-peak period, then the ONB is determined in the following way. NBs related to EESD (the total ESD capacity (EESDT) is considered as 300 kWh) [133] is expressed as.

Fig. 3.3 ONB determination for ND and SDs in SPTS

Failures from hardware side: Four types of failures have been considered under this category

The Fuzzy logic controller
Results and discussion

Case-1: SPTS performance for normal and special days
Case-2: SPTS response in failure situations

ESD receives/sends more/less energy from/to the grid during off-peak/peak periods. ESD receives/sends less/more power from/to the grid during off-peak/peak periods. K-ti EBS receives/sends more energy from/to the grid during the off-peak/peak period.

Fig. 3.6 The communications required in the electric bus stop

Failures from software side

Summary

Determining the optimal number of e-buses and fault analysis in the SPTS shows the self-sustainability of the SPTS for failure situations that exist in the system throughout all seasons. The next chapter presents the expansion of the smart public transport network (using capa-buses and electric vehicles together with e-buses) and its interaction with the network. Note: This work, "Optimal number of e-buses in a solar powered smart public transport system and its failure analysis" is published in the IET Journal under the topic "Electric Systems in Transport".

Smart Public Transportation Network expansion and its interaction with the grid

Structure of the smart public transportation network

MEBS structure
ESD sizing
Solar irradiance availability determination
Assumptions

This section explains the structure of the smart public transport network, including the MEBS structure, the availability of solar radiation and the size of the solar plant. The inputs are: energy status of the ESD (EESD), energy status of the solar power plant (ESP), the number of e-buses (NEB) and the per unit voltage of the network (Vpu). The size of the ESD is determined based on the energy requirement of the electric bus (to travel between the successive EBSs) (EEB) and the total number of electric buses traveling from an EBS for 24 hours (EBd).

Fig. 4.1 Structure of the smart public transportation network

Smart public transportation network expansion using CBs and EVs

The capa-buses (CBs)

CB’s energy requirement calculations
Algorithm of CB controller

Electric vehicles (EVs)

EVs energy requirement and the algorithm of EV controller
Aggregator

Smart public transportation network response for three seasons of a year
Fuzzy logic controller

Maintaining the power quality in the grid by improving the voltage profile of the grid. EVs and CBs amplify the ESD to receive/send more energy from/to the grid during off-peak/peak periods. So the Vpu limit of the electricity grid has been taken into account and is expressed as.

Fig. 4.3 The basic model of the smart public transportation network at the MEBS

Results and discussion

Case-1: The smart public transportation network response for three seasons of a year

Winter season
Rainy season
Summer season

Case-2: The smart public transportation network response for uncertain situations

If CB fails to receive energy from ESD
EVs behavior when the grid is under peak period during sunshine hours

The Vpu response of the grid with 'ESD only' and ESD with CBs and EVs for the rainy season is shown in Fig. The Vpu profiles of the grid with 'ESD only' and 'ESD with CBs and EVs' for the summer season are shown in Fig. The energy behavior of ESD, the solar plant, ESD with EVs and the electric bus, when the grid remains below the peak period in sunshine hours, is shown in Fig.

Fig. 4.16 Vpu profile of the grid with ESD only and ‘ESD with CBs and EVs’ for the winter season

Summary

The Vpu response of the grid and the energy behavior of ESD are not shown for this case. Note: This work, 'Smart Public Transportation Network expansion and its interaction with the grid' has been submitted to the ELSEVIER Journal on 'Sustainable Energy, Grids and Networks'.

Conclusion and future works

Summary of the present work

An algorithm is developed for the favorable energy support from both grid and SP to SPTS. An algorithm is developed for CB controller to control the power flow between ESD and CB. Also, an algorithm is developed for the EV controller to control the power flow between the ESD and the EV.

Contributions of the present work

SPTS network expansion has been done using CBs and EVs along with the e-buses in Guwahati city. SPTS responses have been verified in three seasons of a year, with 'ESD alone' and with 'ESD together with CBs and EVs'. The SPTS response is also verified for the uncertain situations that exist in the SPTS.

Scope for the future research work

The Vehicle dynamics and the e-bus energy requirement calculations

The vehicle dynamics calculations

The rolling resistance (F R )
The aerodynamic resistance (F AD )
The acceleration resistance (F A )

Gradual deformation exists between the tire and the road surface (more at the bottom and low at the entry and exit points). Slip of the tire on the road causes a loss of energy and consequently resistance) [123]. The tractive force required by the e-bus (FT e-bus) to overcome all these resistance forces is expressed as. Regenerative braking energy produced by the kinetic energy of the e-bus (ER e-bus) [146] during deceleration/.

Fig. A.3 The tractive, regenerative and actual energy of the e-bus

The working principle and equivalent circuit of the supercapacitor

Introduction

The definitions of the basic terminology used in supercapacitor/battery are given as follows [149]. It plays a major role in determining the size (necessary to achieve the given target) of the supercapacitor/battery. It determines the size (necessary to achieve the given electrical range) of the supercapacitor/battery.

The working principle of the supercapacitor

The activated carbon electrodes are impregnated with an electrolyte where the positive and negative charges are formed between the electrodes and the impregnation as shown in Fig. At the interface between the electrode and the electrolyte, there exists a series of charged particles. The supercapacitor performs the charge/discharge operation with a rapid rise in voltage at constant current as shown in Fig.

Fig B.2 The electrochemical action (double electric field) in the supercapacitor

The equivalent circuit of the supercapacitor

Discharging mode

The above equations indicate the energy loss caused by the series resistance in the supercapacitor. E V I dt V C dV CV (A.13) The above equation shows that an increase in the supercapacitor voltage increases the stored energy of the supercapacitor. The specific energy and energy density of various storage devices, along with the supercapacitor, are given in Table B.3.

Table B.1: The specifications of the supercapacitor cell

The working principle and equivalent circuit of Vanadium redox flow battery (VRB)

Introduction

Batteries for electric vehicles
Batteries for stationary storage applications

In the first category, the sodium-beta high-temperature battery and the sodium/sulfur batteries were developed. These batteries are used in the electrochemical systems (oxidation and reduction take place in the solution of ionic species and the reactions take place on the inert electrodes). The components involved in the VRB model are: the electrolyte (electrolyte remains in different valence states of vanadium sulfate in the positive and negative electrode components of VRB. The sulfuric acid is the supporting electrolyte for this solution and remains at a concentration of 2 molar), the electrolyte storage tanks, cell stacks (electrodes), control unit and the converter unit.

The equivalent circuit model of VRB

I (C.7) The parasitic losses include fixed power loss (Pfixed) modeled as fixed resistance (Rfixed) and variable power loss (Pvariable) modeled as controlled current source (Ipump). The electrode capacitor is represented by measuring battery cell capacitor and is based on the connection type of the cell. The calculations of the VRB equivalent circuit parameters are based on the total losses of 21%, where the parasitic losses are 6% in worst operating conditions and the 15% loss is due to internal resistances.

Solar energy and the solar irradiance availability determination

The solar irradiance availability determination

TGMT is the hourly difference between local time (LT) and Greenwich Mean Time (GMT) and is expressed as D.6) The equation of time (in minutes) (EOT) is used to correct for the eccentricity of the Earth's orbit and the Earth's axial tilt [125]. Therefore, the hour angle of sunrise is given as. D.14) The radiation (B0) received by the unit of horizontal area, outside the Earth's atmosphere is therefore. Therefore, ra depends on the cloud fraction (CT) and is expressed as. D.33) The quadratic polynomial is used to approximate the function f(SCI) and is included in (D.29).

Solar energy calculations

The solar cell’s equivalent circuit

Iph is the photo current (proportional to solar radiation), ID is the diode current and Ish is the current flowing through Rsh. ISC is the short-circuit current (full current photo current capacity), ki is the short-circuit current temperature coefficient (ki=0.0017 A/0C) of the solar cell, and G is the solar radiation (W/m2).

The working principle of Fuzzy logic controller

Introduction
The working principle of FLC
Example for the working principle of FLC
The procedure to build FLC in MATLAB

The fuzzy set values (input values) are converted to language variables in the fuzzification process. The contributions from the corresponding results of all identified rules for P± are shown in Fig. The contributions from the corresponding results of all the rules for SP± are shown in Fig.

Fig. E.1 The structure of the fuzzy system

Bibliography

Krein, “A Review of the Impact of Vehicle-to-Grid Technologies on Distribution Systems and User Interfaces,” IEEE Trans. Kar, “Vehicle and Network Scenario Compatible Electric Vehicle Charging Station Model,” IEEE Int. Kar, “Coordination of multiple charging stations for electric vehicles and its application to a vehicle-to-grid scenario,” IEEE Conf.