Design and Operation Optimization of a Solar Collector System

This thesis introduces the concept of Concentrated Solar Power utilization for the production of Electrical Energy. As the world economy grows and the technology growth booms, the dependability on more robust, ingenious and cost effective ways of generating electricity becomes essential. Solar Energy is currently striving to become a major player in fulfilling the energy needs of the modern world with environmental aspects guaranteeing a safer future for our generations. There are two main ways through which solar energy from sun is employed to produce electricity i.e. Photo-voltaic cells and Concentrated Solar Power. Little work has been carried out in the field of Concentrated Solar Power (CSP) but there is still room for significant improvement. Concentrated Solar Power has a lot of potential in our country considering the abundance of solar radiation throughout the year particularly in the southern region. The proposed design will be scalable to industrial level. This research project is one of its kind considering not much work has been carried out previously in this regard in Pakistan. The following report contains detailed design strategies for making a Heliostat. We carried out work on Heliostat design in our institute and significantly improved the previous designs of any such tractable heliostat thus enhancing the efficiency of the system.

Heliostat Design

1        Heliostat Design

The Design of the heliostat is a very important task. A good design can enhance the efficiency of the system significantly. It is also necessary in order to effectively withstand various static & dynamic loads that the heliostat will face.

Following are some of the aspects of Heliostat design and other parameters associated with or related to the design of heliostat.

•      Field Selection for Heliostats/Polar Field

•      Selection of Frame Arrangement/Horizontally rectangular main frame

•      Shape and design of the Mirror/Slightly tilted mirrors

•      Wireless And autonomous control

•      Tracking of primary axis

•      Wind Protection

•      Hail protection /Rain protection

Design Features of A Heliostat

1        Heliostat Field Selection

From case studies of different mega projects involving SCSs (solar tower) we observed that the heliostats were arranged in one of the following configurations

1.      Surround Field

2.      Polar Field

1.1      Surround Field

In this configuration the solar tower is completely surrounded by heliostats on all sides. This configuration has an added advantage that the total insolation remains relatively more uniform throughout the day. When the sun moves from one side of the tower to the other side then the heliostats on the opposite side start to reflect the sun rays more effectively hence maintaining a uniform profile.

It has been experimentally observed that the efficiency of the heliostats nearest to the tower is maximum & it decreases as the distance increases. In surround field configuration more heliostats can be placed inside this high efficiency region.

This type of field is used in Ivanpah (392 MW).

1.2      Polar Field

In this type of field all the heliostats are placed on one side of the tower.

This characteristic can be utilized in medium to large sized solar tower systems(STS). If the same number of heliostats is arranged in polar field instead of surround field then due to their increased efficiency more energy will be generated with the same initial cost

Due to above mentioned reasons we are going to use “Polar Field”.

1.2.1    Mechanical Design

The mainframe of the heliostat is designed to be rectangular with its length greater than its height. This arrangement will give us following benefits

1. Due to smaller height, the heliostat will cast a smaller shadow on the mirrors behind it as opposed to a vertically erect rectangular heliostat.
2. The distance between consecutive rings can be decreased due to smaller shadow of front row heliostat which will result in increased system efficiency.
3.   The center of gravity will be lower to the ground which will increase stability of the mechanical system while facing wind.
4.      Smaller height will result in smaller moment arm so the assembly can bear high forces without being overturned.
5. The frame will be rotated along the horizontal axis while the mirror will rotate along the vertical axis.

Mirror Manufacturing for Solar Concentrator

Selection of Reflective Mirror

In almost all of the STSs plane mirrors are used. The reason is that the cost of manufacturing curved mirrors is enormous which results in an increased amount of capital required to install the plant.

Despite the higher cost, curved mirrors were selected for this project due to following reasons

1.      Through literature survey we came to know that in terms of “Levelized Cost of Electricity” (LCOE) reduction, a design improvement that results in 1% performance improvement is equivalent to a design improvement that reduces solar field cost by about 2.3% i.e. the leverage of performance vs. cost on LCOE is better by a factor of about 2.3x

The exact improvement in efficiency due to this decision is unknown at this stage & it is possible that this improvement might not be able to balance out the increase in capital cost. Any and all results will be reported at the end of the project including the impact of this decision.

2.      There is another factor that inspired us to use curved mirrors. As the distance from the solar tower increases, the effect of scattering from dust particles becomes more and more pronounced. Thus the advantage of using a converging beam of light become more evident as this kind of reflected beam will be able to transfer a considerably more amount energy to the solar tower even after scattering.

3.      As the beam is converging therefore the area of the “wave front” formed at the receiver will be of small size. This enables us to design a receiver of smaller size which will reduce cost.

4.     Higher concentration of light due to converging beam will result in increased temperature which will result in increased efficiency of the system.

5.     Very high precision tracking is usually not feasible. The decreased wave front area of the reflected beam gives us an increased margin of tolerable error in our tracking.

Heliostat Tracking Techniques and Control Mechanism

1.1      Solar Tracker

The solar tracker is a device and a mechanism for orienting the solar concentrator in such a way that it reflects maximum sunlight on the receiver directly from the sun and the deviation angle is minimum throughout the tracking time. A highly efficient Solar tracking mechanism drastically enhances the efficiency of the solar concentrator since it can collect more sun light as compared to a passive mechanism.

Solar trackers are implemented using Astronomical equations, light dependent resistors, sun pointing sensors etc. coupled with other devices such as Stepper motor, Dc Motors, Servo motors, gas filled piston etc.  

1.1.1    Dual Axis Trackers

The dual axis tracker has both horizontal and vertical axis and hence can track the position of the sun and its apparent motion anywhere in the sky throughout the day. Dual axis tracker track the sun through both East to West and North to South, which gives it an added benefit of capturing more sunlight directly from the sun, which increases the added power output and the theoretical efficiency by approximately 40%.

It can be implemented with the help of sun pointing sensors or light dependent resistors, astronomical data or predicted trajectory of sun throughout the day.

1.1.1.1  Disadvantage

Dual axis tracking comes with greater complexity for the system. More motors are to be used to dual track which increases the difficulty level. It is also argued that it can be less reliable considering greater number of devices used in this mechanism which increases the maintenance and down time.

Design of Uninterruptible Power Supply/UPS

Problem Statement:

Design a 1kVA UPS powered by a single phase 220V/50Hz AC. You may consider one of the following design options:

a.         A rectifier as battery charger+ DC-DC Boost converter + Sinusoidal PWM Inverter

b.         A rectifier as battery charger + Full bridge DC-DC converter using pulse power transformer+ Sinusoidal PWM Inverter

c.         A rectifier as battery charger + Sinusoidal PWM Inverter + Step up transformer

Charging current of battery must not exceed 15A and you must take care of input power factor.

What is an Uninterruptible Power Supply?

An uninterruptible power supply, also uninterruptible power source, UPS or battery/flywheel backup is an electrical apparatus that provides power to the system which it is connected to i.e household assembly of electricity run devices, offices, computer run etc when the power from the main grid gets disrupted or cut off and it can also provide emergency power to a load when the input power source, typically mains power, fails.

UPS is a device that provides battery backup when the electrical power fails or drops to an unacceptable voltage level. Small UPS systems provide power for a few minutes; enough to power down the computer in an orderly manner, while larger systems have enough battery for several hours. In mission critical data centers, UPS systems are used for just a few minutes until electrical generators take over.

Traffic Control System based on PLC and SCADA Techniques

This smart traffic control system uses Programmable Logic Controllers (PLC’s) and SCADA HMI for monitoring and controlling of traffic signals. This system is quite useful in high-traffic-density areas, toll gates and other high-end-parking areas.

Wikipedia quotes " A programmable logic controller (PLCPLC SCADA, or programmable controller is an industrial digital computer which has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high reliability control and ease of programming and process fault diagnosis.

They were first developed in the automobile industry to provide flexible, ruggedized and easily programmable controllers to replace hard-wired relays and timers. Since then they have been widely adopted as high-reliability automation controllers suitable for harsh environments. A PLC is an example of a "hard" real-time system since output results must be produced in response to input conditions within a limited time, otherwise unintended operation will result."

This is a centralized control of traffic system where it collects the several places traffic conditions remotely through communication medium and this information is monitored using SCDA HMI. Therefore, synchronizing the traffic at different junction roads is possible with this system. And, also depending on the traffic density at different junctions, it controls the traffic light through remote operation.

Radio Frequency Identification for Library

Background

CE 1.1) RFID (Radio frequencyIdentification) technology is one of the most evolved technique in our contemporary time with huge potential ranging from applications as simple as implementation a gate security system to as complex and exigent as automatic money transfer system. The project for designing and implementing a RFID system for libraries employs the broader use of radio frequency technique along with PLCs in algorithm for security control, access control and tracking system of the library.

CE 1.2) RFID technique is an upgrade from bar-code technique which has been previously employed for realizing the same task. The bar-code consist of images of lines affixed with varying spacing against which there is information stored for the particular product to which the specific barcode has been assigned. Unlike RFID, bar-code technique uses light transmission for communication between the ‘reader’ and the bar-code. The reader in this case gather the information from the barcode and converts it into digital data for practical use.

Design of a vibration isolation system

Vibration isolation is very important for advanced production and high-resolution measurements; these include semiconductor chip manufacturing, scanning probe microscopy, holographic interferometer, co focal optical imaging, etc.

Conventionally, an arrangement of springs and dampers is used as isolator and the objective is selection of spring and damper parameters to optimally reduce

(i)  Vibrations transmitted from ground through the suspension and

(ii) Vibrations caused by disturbances acting on an isolation table directly. A suspension with less stiffness is better for reducing the former because dynamic coupling between the vibration source and the isolation table is weakened; thus, zero stiffness is ideal in this case. However, higher stiffness is better for suppressing the latter because it reduces displacement of the isolation table from its desired position; thus, infinite stiffness is ideal in this case. In conventional spring-damper arrangement, the two conflicting requirements cannot be simultaneously achieved. However, recently, a novel approach has been presented to achieve both the requirements by incorporating the concept of negative stiffness.

This project will aim at designing a vibration isolation system utilizing the concept of negative stiffness. Mechanical hardware will be fabricated, necessary sensors and electronics will be implemented. A control algorithm will be implemented.

Functional Brain Mapping of EEG Signals

Due to the dynamic and multiprocessing nature of a brain functioning with billions of Neurons, monitoring of a brain activity is a challenging task. This project is aimed to functionally map a brain activity on an anatomical brain template. This will enable to detect the occurrence of that brain activity in contrast to the rest or other activity states.

The student will get a significant knowledge of instrumentation with brain, EEG obtainment, and DSP of EEG data sets for brain activity monitoring.

• Develop an understanding of the EEG signals
• Understand the protocols for EEG experiments
• Analyze available EEG datasets with Matlab
• Target  an  experiment  for  EEG  data  and  design  its experiment
• Obtain EEG data
• Basic validation of EEG data
• Report writing
• Develop DSP scheme to classify the brain activity underneath the EEG data
• Validation of the results
• Improvements in the scheme, if any
• Submission of results in a conference
• Writing of thesis

FPGA based Tremor Sensing and Minimization Using Non-Invasive Techniques

Tremor is a neurological disorder which causes unintentional, rhythmic muscle movement involving to-and-fro movements (oscillations) of one or more parts of the body. It is the most common of all involuntary movements and can affect the hands, arms, head, face, voice, trunk, and legs. Most tremors occur in the hands.  Tremor is generally caused by problems in parts of the brain that control muscles throughout the body or in particular areas, such as the hands. Different types of tremor are Essential, Parkinsonian, Dystonic, Cerebellar, Psychogenic and Physiologic tremor. Deep brain simulation is the most common invasive technique  used  for  tremor  surgery  but  this  project  focus  on  non-invasive techniques for tremor control using multichannel sensors terminated on FPGA. Moreover the sensing is based on tremor occurrence at rest not during action. Understanding of different techniques used for tremor minimization (i.e. SVM)

• Literature survey on tremor occurrence and causes
• Non-invasive techniques used for sensing and acquisition
• Component selection for brain computer interface
• Implementation on FPGA based development platform
• Hardware interfacing with FPGA
• Development of a tremor model based on selective case study
• Selection of tremor minimization Algorithm and their implementation
• Validation of the results
• Thesis writing

Investigation of Economic Aspects of Solar Energy

Energy demand is increasing day by day due to which it’s not enough to produce electricity only from conventional sources. The major drawback of conventional sources is that the production unit is far from the load so extra burden is put on economy due to transfer of energy till load point. Moreover these sources are limited so world is looking towards renewable energy sources. Solar is one of a renewable energy source and the main focus of this project is to investigate this sources in terms of economy and to make a comparison between solar energy cost per unit and the cost of energy getting from other sources. It covers both installation and operational costs.

• Investigate working to solar panels.
• Real time i-v curves for 30 days of a month for a solar panel.
• Investigation of MPPT on economy.
• Study of dry cell batteries and single phase inverter
• Calculate cost involved for producing dc power over entire guaranteed period of solar panel.
• Calculate cost involved for producing single phase AC from solar panel.
• Calculate costs involved in conventional sources.
• Make a comparison between per unit cost that WAPDA charges and per unit cost that solar panel offers.

Automatic Voltage Regulator Design for a Synchronous Generator

Synchronous Generator or alternator is the most prevalent and important component in a power system.  Most types of generating stations working as base load power plants use this type of generator to generate electrical power. It is requirement from all types of generating plants to provide an electric supply which has excellent voltage regulation. Due to this constraint it is essential to ensure a nearly constant voltage profile at the terminals of synchronous generator under all load conditions.

The objective of this project is to design an automatic voltage regulator for a synchronous generator, which controls the terminal voltage automatically by varying the excitation voltage of the generator in response to change in terminal voltage.

• Review of Basic concepts of Synchronous generator working and control.
• Study of existing schemes for excitation control based voltage regulation of synchronous generator.
• Simulations to demonstrate the working of synchronous generator and excitation control based voltage regulation.
• Open loop excitation control of an actual synchronous generator
• Circuit design of an AVR (Automatic voltage regulator) for synchronous generator.
• Simulation studies of the proposed circuit design.
• Hardware Implementation
• Thesis writing

Optimal Placement of DGs and Capacitors in a local Distribution network for Power loss Minimization

In Distribution systems, the voltage at the buses reduces as we move away from the substation, and the losses increase. Moreover with distribution systems becoming more and more complex the losses are increasing leading to poor voltage regulation. The Most common way to improve voltage profile, power factor and reduce losses is to introduce DG sources and Capacitors in the distribution network. In order to maximize the benefits achieved by connecting DGs and Capacitor banks, it is essential to identify the optimal locations in the distribution network for their connection leading to minimization of line losses and operating cost.  In this project the student will develop novel technique for optimal placement and sizing of DGs and Capacitor banks for a distribution network.

• Literature review for Basic concept of DG.
• Investigation of impact of DG and Capacitor bank placement on line losses in the power system.
• Analyze the Impact of size and location of DG source and capacitor banks on line losses and Voltage profile in the Distribution network in a IEEE standard system.
• Literature Review for exploring existing techniques for optimal sizing and location of DG and Capacitor banks in a distribution network.
• Report writing

A Medium Power High voltage Pulsed Power Generator

This project focuses on literature survey of pulsed power supplies for medium power RF applications. The literature survey would identify different design options for different applications. Moreover a medium power (few kW) pulsed power generator for microwave applications would be designed and demonstrated.                    

• Literature  survey  of  applications  and  design  option  for pulsed power supplies
• Design  of  a  pulsed  power  supply  for  medium  power
• Microwave applications 
• Implementation of pulsed power generator
• Testing and validation

Integration of a Cascaded Multilevel Inverter (CMLI) with AC Mains

This project focuses on integration of a CMLI with 220V AC mains. In this regard, individual stages of a CMLI have already been implemented and tested. Another group will be working on cascading of multiple stages and resolving issues of switches noise through filter design. So this project considers a working CMLI with controllable frequency and amplitude and addresses the problem of integration with AC main.

• Understanding and formal description of the problem and identifying issues associated with integration of CMLIs with AC power distribution system
• A comparative study of solutions in the literature
• Selection of a suitable design for integration of a 4kVA CMLI      
• Design Analysis and circuits Simulation Implementation of required hardware Controllersimplementation synchronization and power flow
• Operational testing for demonstration of integration
• Thesis Writing    

Integration of Multiple Inverters and Filters to Form a 15-level Cascaded Multilevel Inverter (CMLI)

This is the second phase of the project of development of a CMLI. Previously, multiple Inverter circuits were implemented and tested and a couple of them were cascaded to form a 5-level CMLI. It was observed that switching noise is a major issue in cascading multiple stages and require properly designed filters between the stages and at the output. The objective of this project is to extend the work on CMLIs to integrate up to 7 stages to form a 15-level CMLI with filters between the cascaded stages and output filters to suppress switching noise. Moreover, THD analysis will be performed.               

• Understanding the problem and identifying issues to be resolved
• Getting familiar with already developed hardware
• Design of filters to integrate multiple stages of a CMLI
• Implementation of required filters
• Integrating a 15-level CMLI
• THD analysis against the switching angle control
• Demonstration   of   4kVA   power   output   with   THD minimization and control over modulation index
• Thesis Writing

Inductive Power Transfer

This project focuses on exploring the potential of inductive wireless power transfer for different applications. After comprehensive literature survey, requirements analysis for different applications, a prototype system will be designed and fabricated for a particular application.     

1. Literature survey of applications and design option for inductive power transfer systems
2. Requirements analysis for different applications
3. Design of inductive power transfer system for a particular selected application
4.  
5. Implementation of inductive power transfer system
6. Testing and validation
7. Thesis Writing

Integration of Distributed Generation into Power Networks

The generation of power from Distributed Generation (DG) is increasing day by day as this technology is not only becoming cheaper relative to other resources but is also environmentally friendly. However, DG can also have an adverse impact on operation of the existing power network. For example, issues related to power system (PS) stability, power quality and protection coordination can occur due to connection of DG to the grid. The project will focus on the impact of DG (base d on different power generation resources-conventional, wind, an d solar, etc) on voltage profile, s ability and protection coordination of a conventional power network.

Selection of Suitable Type and Place of a Fault Current Limiter in a Power Network with embedded DG

The generation of power from Distributed Generation (DG) is increasing day by day as this technology is not only becoming cheaper relative to other resources but is also environmentally friendly. However, DG can also have an adverse impact on operation of the existing power grid. For example, issues related to power system (PS) stability, PS quality and protection coordination can occur due to connection from DG to the grid. Fault current limiters (FCL) are employed to reduce the negative impacts of DG in power networks.  The purpose of this project is to investigate the impact of a fault current limiter on the fault current level, losses and stability of a power network with DG connection. The research will also focus on finding the suitable type and location of a FCL for fault current reduction and increasing the system stability in the presence of DG.

Smart Antenna

In order to minimize the wasted energy and traffic collisions in transmission of signals what can be improvised is the use another type of antenna called “smart antenna”. These antennas can use select able radiation patterns depending on the situation and thus drastically minimize the unnecessary energy waste. Smart antennas also provide the ability to sense the direction of incoming signals which is favorable for physical layout mapping such as orientation. Research now a days is focusing on the prototyping of a new type of smart antenna called the SPIDA smart antenna. This antenna is used to produce smart antenna designed for the 2.4 GHz frequency band. The SPIDA smart antenna can use sixty-four different signal patterns with the control of six separate directional modes, amidst these patterns are six single direction patterns, a unidirectional signal pattern and fifty-six directional patterns.