Dynamic Traffic Light Controller

Introduction

This project is to design a dynamic traffic light controller, which adopts according to real time traffic flow and then control the switching of signals according to the traffic condition. In this design, induction loops are used as vehicle detectors and the control of traffic lights is done dynamically by a fuzzy logic controller in such a way to get a smooth flow of traffic. The control signals from main controller to the controllers at each traffic light is done through wireless communication which is another significant feature in this design.

Project Scope

There are three main sub sections in the project as in names, detection, controlling and communication. Under the first section vehicles has to be detected to get a proper idea of real time traffic situation. Therefore one objective of this project is to build a system to detect vehicles in order to get information about traffic flow to implement next sections. As a vehicle detection system, induction loops have been used which is one of the most commonly used methods for vehicle detection with higher accuracy and higher durability compared to other commonly used methods.

The real time vehicle count is an important fact in analyzing the current traffic condition at a particular junction and as in this case a four-lane junction is basically considered, there are eight induction loops that are been placed as two per each lane as shown in the figure. Two of the loops of one lane are placed at a pre-determined distance based on data collected about the traffic condition of particular lanes. However fundamentally one induction loop sensor is been placed near to the intersection while other one is been placed at a pre-determined distance from this. That distance is determined according to the maximum possible traffic condition of each lane so that at all times, traffic queue is in between the two loops. The difference between the information through two induction loop sensors at one lane is been used to calculate the traffic density at a particular lane. 

Next section in the project is to build up a proper controlling methodology. For that analyzing the traffic condition at real time may pose the optimum solution for traffic congestion problem. In that case fuzzy logic is used in this project as it gives a mathematical version for representing human knowledge and experience involving indistinct concepts and also it is an effective mechanism to systematically formulate a solution to complex uncertain problems.In main controller there are separate fuzzy units for each lane and the waiting time of vehicles and traffic density at respective lane has considered as two main inputs to the unit in this project. As stated earlier queue length or traffic density is determined by the induction loop data while the waiting time is the incremental time which started from 0 at the moment red light is ON of respective lane. Then from the each fuzzy unit variable number gives as an output, after considering the inputs. And send those four variable values from each lane to the fuzzy comparator which is also in the main comparator from which gives out the most suitable next phase to be opened and also whether current green phase should terminate or continue. Using those two outputs final phase selector decide the phase which should have green light ON. Communication between detectors and the central controller will be done using wireless technology.

Conclusion

In Sri Lanka most popular method which has been used to control the traffic congestion problem in many urban cities are conventional traffic light controllers. These are incorporate with pre-determined program which is based on chronological data at particular junctions. Since traffic congestion are random and non-linear matter, those pre-programmed method have not been able to achieve the most effective signal timings which in order to get a smooth flow of vehicles at the multilane junctions. But in application this method will solve the problem in most optimum way.

Project Supervisor: Dr.Satish Namasivayam

Group members: I.L.Kumarasinghe | K.J.Lakmewan | G.P.S.Lakshan | K.A.T.Lasagani

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Posted in: Researches and Projects

VEGA - Towards a new era with super speed

Crude oil reserves are rapidly diminishing. Therefore the prices of the petroleum are rising. Further the burning of petroleum oil causes deadly effects towards the environment with millions of vehicles in the world. That number is enough to have a clear image about the amount of the petroleum burnt per second in the world. These clues give us the evidence to switch our energy sources currently used in vehicles to a clean energy source.

Timely necessity of an Electrical vehicle………

Electricity can be generated with less or no effect to the environment. There are plenty of non-conventional renewable methods to generate the electricity. Therefore it is foreseen that there will be an optimistic future for electricity generation which can be matched with demand using more environment friendly methods which are to be revealed. This will be a good sign to change the energy source of the vehicles from petroleum oil to the electricity. At the present it is being brought into action all over the world in different scales. In the Sri Lankan context, "Codegen International" has taken up the responsibility of producing the 1st super car driven by the electricity. They hope to identify possible technological barriers for making the electrical car a reality which will be a major advancement of technology in Sri Lanka.

Minds behind Innovation

Dr.Harsha Subainghe, CEO of Codegen has invested for the research and development of the project of producing a super car named “VEGA” with the collaboration of group experts of different fields in initiating this project. Dr. Beshan Kulapala who has specialized in Electrical Engineering from Arizona and possessing 13 years of career experience at Intel is leading this project. Thilak Dissanayake; an Engineering Consultant specialized in Aerodynamics with long term experience at Boeing, Pabassara Karunanayake; Project Manager at Codegen, Sasiranga De silva an Engineering Consultant and a Lecturer of University of Moratuwa   are some of the experts involved in the project VEGA.. The design of the VEGA super car was a result of the innovative outlook of Dashantha Gunarathne. Varuna Ruwan Maduranga, Ruwan Seneratne, Rashiga Walallawita, Shiranga Ariyasinghe, Supun Amarasinghe, Senal Devasurendra and Dilshan Prageeth Siriwardhana are among the eight full time staff. The three Army personnel Chinthaka Srinath Wijesekara, Buddhika Jayaranga and Nihal Kumara Thebuwana also contribute to this project.

Design Features……..

This super car is designed such that it has an acceleration of 0-100km/h in less than four seconds and the top speed being 220km/h with the capacity of 300 km with one charge. In order to meet the required specifications; all the components are designed and manufactured in Sri Lanka except the two motors and the battery cells.

Two permanent magnet synchronous motors (PMSM) with nominal torque of 210 Nm at 4400 rpm are used for traction in VEGA. PMSMs, a hybrid of brushless DC motors and induction motors, are widely used for traction purpose in hybrid vehicles because of their high power density. Unlike traditional vehicles, the gear mechanism in VEGA consists of fixed ratio gear sets. Speed and torque is controlled by changing the power input to the motors. Motion of the car is manipulated by controlling torque since it is more relevant to the dynamics of the vehicle. VEGA will have a capability of accelerating to 60 miles/h from still within less than 4 seconds. Advance power electronics technologies are highly utilized for motor controlling and charging mechanisms.

VEGA is equipped with an electronic differential braking system for steering purposes. Two rear wheels can be controlled separately using this braking mechanism. VEGA contains over 25 processors connected through a Controller Area Network (CAN) for its computing tasks. There is no doubt that complex software is essential for real time signal processing of an electric super car. Engineers of VEGA project exhibit their technical capabilities by developing their own software required for computations.

Design of Battery system

Battery is the most important component that comes into consideration when designing an electric vehicle. Engineers of VEGA project use the most advanced battery technology in the world to make VEGA a reality. Currently one of the most efficient battery technologies, Lithium Ferro Phosphate is used as the battery cells. Each battery cell supplies 3.3V and it is proposed that there will be 600 battery cells in the car.  Battery heats up to around 600C while operating therefore an efficient cooling mechanism is essential especially for a super car. Water and Ethyl Glycol mixture will be utilized as the coolant of batteries. An intelligent battery charging mechanism is used for charging these batteries to the exact same amount every time it is being charged to avoid any excess burden on few battery cells. Condition of each and every individual battery cell is important for an efficient performance of battery system. VEGA is equipped with a battery management system to increase its efficiency further. Three levels are available for the charging mechanism of VEGA.  In the first 2 levels, battery is fully charged within 3 to 6 hours after connecting to 230V AC supply. It has 300 km mileage after fully charged. Third level, supercharging has been designed for emergency charging purposes. Battery is charged to 80% of total capacity within 20 minutes.

Body of the car is designed with carbon fiber, light weight, high strength material which is used in sport car manufacturing in most of the developed countries. The mould of the body has being built with a foam material. First the plug of the car will be built and then will be finished with carbon fiber. Much consideration is given to the mechanical stability of the car. Aerodynamic and other mechanical stabilities were analyzed using computer simulations.

The design work of the car will be completed by December reflecting the world that Sri Lankans are capable in producing advance technological product. In the future Sri Lanka might prove to be the leading electrical vehicle Manufacturer in the world with a super electric car coming under a purely Sri Lankan brand. This will contribute towards maintaining an environment friendly transportation system and further to maintain uniform load curve throughout the day since vehicle owners can be encourage charge their batteries during the off peak enhancing the electricity consumption which will result in a healthy load curve.

Team VEGA

Article By:Lahiru Sasintha
                Indoopa Manamperi

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Posted in: Electrical Industry

Design and Build a Real Life Power System Model

Introduction

It is important for an Electrical Engineering undergraduate to know about power systems in theoretical as well as in a practical approach. Thus, a power system simulator is ideal to understand practically the theories learnt in class. Commercially available models though are in existent, the endeavor was taken to design and build a power system simulator, as a final year project. The simulator is a scaled down model of the actual power system prevailing in the Sri Lankan context. Though it is a scaled down model, all electrical components such as generators, relays, circuit breaker panels are all actual industry used components. As a continuing project many aspects are being developed piece by piece under the guidance of the supervisors and with financial support from the industry. This project provides the basis for the fulfillment of the aspiration by the Department of Electrical Engineering, University of Moratuwa, to give a firsthand experience for the undergraduates before they encounter industrial training.

Project Scope

Figure 1: Power System Model

When completed the model will consist of,

•     A synchronous generator/transformer unit with voltage control   
•     A prime mover (an induction motor) with governor control (VSD drive)
•     Manual synchronizing facility with the grid (mains supply)
•     4 Transmission lines, a grid substation and a distribution system
•     Variable resistive and inductive loads
•     An integrated protection system to detect and clear the faults
•     Instrument transformers (Current Transformers and PotentialTransformers) to provide information    to the protective and metering systems
•     Metering facilities at various points in the system
•     Vacuum Circuit breaker Panels and Facilities for remote operation of circuit breakers.
•     A fault creation facility for the application of faults on transmission lines
•     Laboratory practical’s on power systems, fault clearance and protection schemes

Project Objectives for 2013 

This year embarks the 4^th phase and the following objectives are initiated for the completion of the project.

Fault & Load flow study and current transformer specification

A thorough load flow analysis was done to understand the system in operation. A fault study was done to determine the fault currents in different instances. The nominal current and fault current was taken from the study. The relay burdens were found by the manuals and other official documents. The knee point voltage was then calculated. By the parameters it was concluded that current transformers with a ratio of 60/5 and burden of 7.5VA would be best for implementation as they were commercially available.

Implementation of donated mechanical and numerical relays

Several numerical and mechanical relays have been donated by numerous contributors and these are being appropriately implemented onto the circuit breaker panels in the power systems laboratory. Due to the diverse nature of the relays, they were studied individually and extensively, ultimately learning how to program and operate. The relays which were donated will simulate the following protection schemes.

1. Transformer protection (Over current, Differential)   
2. Line Protection (Differential, Distance, Overcurrent, Directional overcurrent)
3. Generator protection ( Overvoltage, Negative sequence, Overcurrent, Differential)

Implementation of load

It was decided that for the start, a resistive load of 3.3kW would be implemented to complete the distribution segment of the power system model. Implementation of inductive loads will be facilitated in the expansion of the project in the future.

Laboratory practical’s

Currently laboratory practical’s are being designed to be tested among the undergraduates as a pilot project before establishing it in the curriculum.

Generous donations have been made by LTL Holdings (Pvt) Ltd, Ceylon Electricity Board, Balfour Beatty engineering services Ceylon (Private) Limited,Hayleys Industrial Solutions (Pvt) Ltd, ABB Sri Lanka, FDK Lanka (Pvt) Ltd and by Lanka Electricity Company (Pvt) Ltd.

Project Supervisors: Professor J.R.Lucas | Eng. J. Karunanayaka
2009/2010 Group members: G.B.Alahendra| A.C.P.Aluthgama| P.G.L.Arachchi | G.U. De Silva
2010/2011 Group members: S. V. Herath| K. S. Hettiarachchi| W. J. M. L. Himal |C. Ileperuma
2011/2012 Group members: T.G.R.Lalitha | K.D.S.Kuruppu | L.L.U.J.Lenaduwa|   D.R.Liyanage
2012/2013 Group members: A.R Devinda| D.M.S Dissanayaka| C.L Fernando | M.H.M Fernando


For further information please feel free to contact us by energyzee.projects@gmail.com

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Posted in: Researches and Projects

Development of a prototype of vehicle active suspension system

Introduction

The aim of the project is to develop an active suspension system for vehicles. In this project, the main objective is to suppress the vibrations caused due to the imperfections of the road surface and give a better stability to the sprung mass. In order to achieve this goal, the suspension system changes its characteristics and suppress the vibrations according to the vibration level of the road and applied disturbances.

Project scope

The proposed method consist of a controller, linear motor driver, linear motor acting as an actuator and feedback sensors are used to complete the control system. The controller will accumulate suppressed vibration performance details of the system and takes position feedback of the motor using a linear encoder and motor current feedback using a current sensor to provide desired output signals to the motor driver. The desired output is calculated using motor disturbance observer technique. The response of the suppressed vibration is transferred to controller using a 3D accelerometer and the controller save them for analysis.

Figure 1: Block Diagram

The control signal then transferred into the motor drive module which provides power to linear motor USING PULSE WIDTH MODULATION. The actual current if the linear motor is measured by a current sensor using shunt resistance current measurement method. Current sensor used in between driver and linear motor to calculate the exact current transferred to motor. This measured value then used in DOB to calculate load torque.  The Linear motor acts as the actuator of system, providing required dynamic suspension response to suppress vibration experienced by motor body itself. The linear motor is capable of delivering required torque and speed response directed by controller through motor driver.The Linear encoder measures the motor position and sends the position measurement to controller for system response measurement. These systems are connect as described above and as in above block diagram to provide a viable solution to our problems.

Conclusion

The effectiveness of the active suspension system with respect to prevailing passive suspension system can be observed by comparing the vibration suppression capability of the both systems in different vibration levels. The effective usage of the active suspension system can be implemented to improve the control, contact and comfort of the motor vehicles.

Project Supervisor: Dr.Harsha Abeykoon
Group members: P.A.M.M.B. Abeyrathna | W.A.S.P. Abeysiriwardane | S.W. Amarasinghe | W.M.S.L. Ariyasinghe

For further information please feel free to contact us by energyzee.projects@gmail.com

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Posted in: Researches and Projects

E-waste - A national issue to be considered...

Electronic waste (e –waste) is one of the major environmental issues which are currently faced by the developing countries as well as the developed countries all around the world. With the rapid technological development, many innovative products arrive to the market. The demand for those innovative products is growing day by day and those innovative products replace the existing ones. Thus, that will create a hazardous situation regarding the disposal. In our country – Sri Lanka too, the current consumption of the new technological equipment is increasing in a considerable rate with respect to the past and the disposal of waste will be a huge issue, in the near future. So, it’s very much convenient to be aware of e – waste, its impact and the e – waste management system in Sri Lanka.

E –waste …

Discarded electrical and electronic appliances such as computers, mobile phones, batteries, bulbs etc…, can be considered as e – waste.
These e – waste consist of various harmful substances such as Lead (Pb), Nickel (Ni), Antimony (Sb), Arsenic (As), Cadmium (Cd), Mercury (Hg) etc…  Therefore, many environmental and health impacts can be occurred with the e – waste.

The main environmental issues associated with the e – waste are, most of the waste is not decayed, addition of harmful substances to the soil and emission of harmful gasses to the atmosphere because of the burning of the waste. The most common health hazards engaged with the e – waste can be described as follows.

How can we minimize e – waste?

In order to overcome the problem of e-waste, there exist several possible approaches as follows.
•    Use only the essential electrical and electronic equipment.
•    Get the maximum use of the equipment, throughout its entire life-time.
•    Forbid the transfer of used electronic and electrical equipment from developed countries.
•    Recycle the waste which is not suitable for usage.

If the consumers such as domestic, commercial etc use only the most essential electrical and electronic equipment, the contribution towards reduction of e-waste is enhanced. On the other hand, by getting the maximum use of equipment throughout its entire life time, consumers will not switch to the new equipment immediately. This fact will also be helpful to minimize e-waste. Most of the developed countries export their own e-waste to the developing countries for a cheaper price in order to get rid of those. Because of this action many developing countries have faced a huge problem in disposing e-waste. Therefore forbidding the transfer of used equipment is a must.

Recycling is the main step of reducing the impact of e-waste. In the process of recycling, the waste is sent for the extraction of substances. And those extracted substances can be used in manufacturing processes which contribute towards saving natural resources. Therefore recycling will reduce the air pollution, water pollution and emission of greenhouse gases.

Approach to waste management in Sri Lanka…

Sri Lankan government has already established the acts for e-waste management under the Central Environmental Authority (CEA). There are some companies who have engaged in e-waste collection and recycling under the inspection of CEA.

Though there exists an e-waste management concept in Sri Lanka, most of the people are not aware about that, as it is only limited to the Colombo city area. But as a result of technological development the usage of electrical and electronic equipment has spread all over the country. Therefore it is very much essential to implement a national level waste management program.

When considering the current situation, it is very much clear that people don’t have a proper knowledge on the harmfulness of e-waste. The foremost action of this e-waste management is to make people aware regarding this matter and impact on their lives. Then as an approach, establishment of waste collection centers in each area is a must. Also recovering and recycling material by safe methods are essential. If we can conduct such a national level e-waste management program from today itself, we will be able to win the battle of e-waste disposing which will appear in the near future.

Article By:  Harshani Bendarage
                  Tharangi Gunarathna

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Posted in: Sustainable Energy and Policy

What is so special about Inverter type Air Conditioners….

Have you ever tried hiding the remote controller of the air conditioner simply to get rid of the extensive current bill? If so, inverter type air conditioners are just the thing for you!

This particular strategy of energy saving is suggested in a popular TV advertisement, nowadays. As it suggests, with this inverter type air conditioners energy saving up to 60% can be expected.  Therefore, it is worth to have a look, how this new phase of technology accounts for the energy efficiency and the performance of the air conditioners.

The basic operation of the air conditioners is to extract the heat energy from a compartment area and release it to the outer environment.Therefore, when maintaining the air conditioned space, at a lower temperature, air conditioner has to extract heat energy from a lower temperature medium, and release it to a higher temperature medium. From the second law of thermodynamics (Clausius statement), for this to happen, there should be some external work done somewhere in the cycle. The work needed for this thermodynamic cycle is done by the compressor of the air conditioner.

Operation principle schematic

Thermodynamic cycle in Air conditioners

The point of the cycle, where air conditioning can be easily controlled, is the compressor motor.  In conventional air conditioners, on off control of compressor is used to maintain the temperature of the air conditioned space around the set value. That is, if the temperature of the room is below the ‘set value-some tolerance’, compressor will completely turn off, whereas if the room temperature rises above the ‘set value + some tolerance’, compressor will completely turn on. A dead band is there to avoid rapid fluctuations of the response around the set point, which would occur otherwise.

On- Off control operation

In inverter type air conditioners, in contrast, the conventional on- off type control is replaced with a wide range of speed control technology. That is, with this new technology, the speed controlling of the compressor is possible rather than just turning on and off. To control the speed of the compressor motor (which is an induction motor), over a wide range, a variable frequency motor drive is used.

Control block diagram of the compressor

Operation block diagram of the inverter

At stating of the air conditioner powerful cooling is required to reach the set temperature.When the set temperature is reached,only a little power is sufficient to maintain the achieved temperature when it comes to inverter type air conditioners. This is achieved by controlling the compressor speed. In contrast, with conventional air conditioners, only the on-off control of high the speed compressor is possible.That in turn results in large fluctuations of temperature.Subsequently this leads to a wasteful consumption of energy.

How much of this wasted energy you can save by replacing the old air conditioner with an inverter type one mainly depends on the factors such as, environmental conditions, thermal insulation of the compartment area, set temperature, rate of change of the room conditions, etc. 

Another major plus point with inverter type air conditioners, over the conventional type is its ability to reach the set temperature smoothly and quickly. And also it is capable of maintaining the air conditioned space around the set temperature with a lower tolerance. Due to more precise temperature control, enhanced room comfort can be expected. 

With the conventional type air conditioners, sharp fluctuations of voltage which would disturb the other electricity consumers and appliances could occur due to frequent on/off of the compressor. But with inverter type air conditioners, that issue is completely eliminated.

Anyway, with the added complexity due to the introduction of power electronics, production cost tends to increase proportionately. Moreover repairing and troubleshooting of this new inverter, is neither simple nor easy as it is with the conventional one.

Whether you like it or not, conventional air conditioners are now being rapidly replaced by this newly introduced member!

References:

http://www.airintelligence.co.uk/cooling-air-conditioners/  

http://slideplayer.us/slide/245200/

Article By: Thisandu Kahingala 

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Posted in: Utility and Social