T H E E R N A K U L A M

POWER SCENEMONTHLYNEWSLETTEROF THE KSEBENGINEERS’ASSOCIATION,ERNAKULAM UNIT

Vol. X Issue : 107 February 2013 Ernakulam For Private Circulation Only

Edited, Printed and Published by Er: Haseena P.S. for and on behalf of KSEB Engineers’ Association, Ernakulam

We know that our lives are passing through a somewhat tricky socio-political and climatic scenario. Thesecircumstances have put great responsibilities on us demanding our active involvement in certain areas.Most important among them is the in depth review and analysis of the draft document of tripartite agreementplaced before us, and presenting the views of our association to safeguard the best interests of the utility, itsemployees and its consumers along with the welfare of our society as a whole. Another powerful initiativeeach of us has to take is for encouraging those in our neighbourhood to avoid misuse or squandering ofelectricity. We may train our fellow citizen in becoming a conscious user of electrical energy thus preventinga disastrous blackout or brown out.The diminishing water levels in our reservoirs are sending shock waves to us, but recently while deliveringthe keynote address associated with the inaugural function of a new electrical section, Sri.C.N.RamachandranNair, an eminent jury and highly respected scholar, (presently serving as chairman of Dam Safety Authority)opined like this… ""]›naL´w tIcfØn\p In´nb hcZm\amWv, DbcØn¬\n∂v hogp∂ Hmtcm

Xp≈n Pehpw aebmfnbpsS Du¿÷ t{kmX mWv.'' - We may expect that such words shall persuadethe ‘die hard opponents’ of proposals for new hydel power stations to go for a rethinking.Recession, inflation and ever increasing fuel costs… the whole world is going through a tough period .Thistime also, the new budget has left the salaried class in an unfriendly tax landscape. Anyhow, each of uswill have to exercise caution and control in our spending pattern both at home and in our offices.In spite of the acute power position, KSEBoard has temporarily lifted the load shedding to help the studentcommunity, and I take this opportunity to wish all the students best of luck for the upcoming Board/University/competitive examinations.

With warm regards TENSON M.A.

Chairman SpeaksDear Engineers,

Among the 9 groups of students from various Engineering colleges in andaround Ernakulam, following are the winners.First place - Arjun Unni.A.S & Minu Maria Tom - Model EngineeringCollege, Thrikkakkara.Second place - Mohammed Saheer P and John Joy Chiramel - SCMSSchool of Engineering and Technology.Third place - Ashmi Mani M and Gowtham Anand K A - Toc-HInstitute of Science and Technology.

A talk on ‘Relevance of Energy Conservation’ was heldat Toc-H Institute of Science & Technology on 18.2.2013.

Modern trends and global power position was explainedby Er. Simon A Akkara, Joint Director, MIS.

Tips for energy conservation was provided byEr. Kenny Philip, AEE, ESD, Central.

The class was well attended by the students and washighly interactive.

Activities of Ernakulam unit for the month of February 2013

Er. Gayathri Nair R., Chief Engineer (System Operation),Kalamassery, inaugurating the Special Seminar Series 2013

at Productivity Hall, Kalamassery on 16/2/2013.

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Grid Connectivity of RenewableEnergy - Issues and Solutions

Ashmi Mani M., Gowtham Anand K. A.B-Tech. EEE, Toc–H Institute of Science and Technology

Abstract - Economic, technology and environmentalincentives are changing the face of electricity generationand transmission. By introducing the term gridconnectivity of renewable energy to common man’s lifewe can meet the energy demand to a large extent. Thereare several issues in grid integration.In this paper, wediscuss the technical and economic feasibility of a low-cost distributed solar-thermal-electric powergeneration technology.Our proposal utilizes invertertopology to convert the direct current from the batteryor the solar panel to alternating current in the samevoltage and phase angle of the grid. This in turn requirehigh power solid state switch, typically MOSFETs.

I. IntroductionEnergy is the cornerstone of our modern

society. It permits services and opportunities thatrange from the simple to the profound, fromcooking meals to education. Without electricity weare denied healthcare, sanitation services, and thesocial, educational, economic, scientific, andagricultural progress that characterizes life.Theeconomic development of a country is often closelylinked to its consumption of energy. Although Indiaranks sixth in the world as far as total energyconsumption is concerned, it still needs much moreenergy to keep pace with its development objectives.The currently electricity sector in India has aninstalled capacity of 211.766 GW as of January 2013.Captive power plants generate an additional 31.5GW. Non Renewable Power Plants constitute88.55% of the installed capacity and 11.45% ofRenewable Capacity.India generated 855 BU (855000 MU i.e. 855 TWh) electricity during 2011-12fiscal.India’s projected economic growth rate is slatedat 7.4per cent during the period 1997-2012.

This would necessitate commensurate growthin the requirement of commercial energy, most ofwhich is expected to be from fossil fuels andelectricity. India’s proven coal reserves may last formore than 200 years, but the limited known oiland natural gas reserves may last only 18 years to26 years, which is acause of concern. The continuedtrend of increasing share of petroleum fuels intheconsumption of commercial energy is bound

to lead to more dependence on importsand energyinsecurity. To meet the crisis India Govt. has takenlot of initiatives to harvest Renewable Energy byvarious incentive/subsidy schemes. Initially we arethinking of off-Grid systems and now it is time tothink of Grid tied systems. Renewable energy(RE)grid connection enables customers to use grid likea large battery, drawing energy when they need itand sending it out when they have an excess.

Economic, technology and environmentalincentives are changing the face of electricitygeneration and transmission. Centralizedgenerating facilities are giving way to smaller, moredistributed generation partially due to the loss oftraditional economies of scale. When powerdemand is foreseen to rapidly increase in nearfuture, the need to upgrade the electrical system/equipment becomes apparent. When operationmust proceed while any change is in progress, therevision is very difficult. Now it’s becomingcommon that consumers providing power backto the grid. Utilities have concerns about employeesafety and system reliability regarding wideparticipation in power generation byinterconnected non utilities. By utilizing renewableenergy sources we can meet the electricity demandto an extent.

Installing a solar electricity system is one waythat householders can support renewable energyand reduce their greenhouse gas emissions. In urbanareas, most householders prefer a grid-interactive

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system—solar panels connected to the mainselectricity grid via an inverter—so they can drawpower from the grid during lean solar times andsell surplus power to the electricity retailer whenthe sun is shining. But householders who have gridconnected solar systems warn that the process isn’tas simple as it could be. Like all emergingtechnologies, it can take some time for regulators tounderstand the challenges involved in gridconnecting and to provide the guidelines, codes andregulations to simplify the process.

II. Necessity

Among renewable energy sources we prefersolar energy. Solar power has plenty of advantagesover other types of energy. It has viableapplications, from the smallest home solar powersystems to large, centralized power plants.Solarpower is also very diverse. It’s used to charge yourcell phone or laptop, power cell phone towers, andprovide electricity to your home and the entireelectric grid. It can be used in a field, on a rooftop,as home siding and in outer space to powersatellites and space stations - not to mention heatand cool home water supplies and living spaces.

Solar power ’s most obvious and hypedadvantage is its cleanliness. While nonrenewableenergy sources like coal, oil and gas are contributingto global climate change and poor air quality, solarpower represents a clean, renewable solution tothose problems. Solar power is also beneficial toboth developed and developing countries, allowingaccess to clean electricity and clean water for poorand rural residents around the world.

In relation to other renewable resources, suchas wind, geothermal, tidal energy and arguably,nuclear power, solar power is the most scalable forsmall-power generation. While geothermal powercan be used to heat and cool the home, solar powercan do that and more, providing hot water, HVACand electricity. Wind power is a very beneficialenergy source but is still difficult to use in an urbanenvironment due to the size of wind turbines.Other renewable energy sources simply do notapply to home energy production.

In spite of several advantages provided byconventional power systems, the followingtechnical, economic and environmental benefitshave led to gradual development and integrationof Distributed generation systems:

(1) Due to rapid load growth, the need foraugmentation of conventional generation bringsabout a continuous depletion of fossil fuel reserve.Therefore, most of the countries are looking fornon-conventional/renewable energy resources asan alternative. (2) Reduction of environmentalpollution and global warming acts as a key factorin preferring renewable resources over fossil fuels.As part of the Kyoto Protocol, the EU, the UK andmany other countries are planning to cut downgreenhouse gas (carbon and nitrogenous by-products) emissions in order to counter climatechange and global warming. Therefore, they areworking on new energy generation and utilizationpolicies to support proper utilization of these energysources. It is expected that exploitation of DERswould help to generate ecofriendly clean powerwith much lesser environmental impact. (3)Distributed generation provides better scope forsetting up co-generation, tri generation or CHPplants for utilizing the waste heat for industrial/domestic/commercial applications. This increasesthe overall energy efficiency of the plant and alsoreduces thermal pollution of the environment.(4) Due to lower energy density and dependenceon geographical conditions of a region, DERs aregenerally modular units of small capacity. Theseare geographically widespread and usually locatedclose to loads. This is required for technical andeconomic viability of the plants. For example, CHPplants must be placed very close to their heat loads,as transporting waste heat over long distances isnot economical.This makes it easier to find sitesfor them and helps to lower construction time andcapital investment. Physical proximity of load andsource also reduces the transmission anddistribution (T&D) losses. Since power is generatedat low voltage (LV), it is possible to connect a DERseparately to the utility distribution network or theymay be interconnected in the form ofMicrogrids.TheMicrogrid can again be connected to the utilityas a separate semi-autonomous entity.(5) Stand-alone and grid-connected operations of DERs helpin generation augmentation, thereby improvingoverall power quality and reliability. Moreover, aderegulated environment and open access to thedistribution network alsoprovide greateropportunities for DG integration. In somecountries, the fueldiversity offered by DG isconsidered valuable, while in some developingcountries, the shortage of power is so acute that

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any form of generation isencouraged to meet theload demand.

Application of individual distributedgenerators can cause as many problems as it maysolve. A better way to realize the emerging potentialof distributed generation is to take a systemapproach which views generation and associatedloads as a subsystem or a “microgrid”. Duringdisturbances, the generation and correspondingloads can separate from the distribution system toisolate the microgrid’s load from the disturbancewithout harming the transmission grid’s integrity.This ability to island generation and loads togetherhas a potential to provide a higher local reliabilitythan that provided by the power system as a whole.

III. Issues and SolutionsIn order to best integrate PV and other

renewable into the grid we need to approach theproblem from several angles. We look to solve oreliminate the negative effects that can be broughton by adding a lot of intermittent generation withoutthe appropriate hardware and/or controls. We alsolook to increase the amount of power delivered tothe grid from solar generators by increasing theefficiency and reliability of the generation systems.We do this by employing advanced technologies thatcan help us to integrate locally high penetrations ofPV while simultaneously maintaining, and evenimproving, the quality and reliability of the powerdelivered by our electrical grid.

(1) Primary issues (2) Secondary issues1) Primary issues

Voltage, frequency, waveform and phasesequence of the generated voltage and grid voltageshould be same ie, both should be synchronized.2) Secondary issues

A grid consists of 3 stages: generation,transmission and distribution. Transmission stageis made efficient using separate feeder.These arethe major issues that come across while we go forgrid connectivity of renewable sources.Solutions:(1) Voltage: We should attain the condition:Grid voltage-generated voltage=0.

Grid voltage and generated voltage shouldbein same phase. If grid voltage is greater than thegenerated voltage, the grid current flows to theinverter system and the system will get damaged.

Vice versa will also happen. So to avoid that bothshould be in same phase.

(2) Frequency: Same as in the case of voltage, aslight variation in frequency will not allow attainingthe condition. As the no of cycles increases, thisvariation increases and results in same case asabove.

(3) Waveform: Waveform of the both should besame otherwise what that take place in the case ofvoltage that same will occur, short circuit / systemfailure will occur.

(4) Phasesequence: Both generated voltage andgrid voltage should be in phase. If not what thathappens in voltage will take place.

(5) Secondary issue: TransmissionThese areseveral problems that would arise in thetransmission of the generated voltage. Such as:

• When we use the same feeder for supplyingpower to the grid through distribution transformerand to the same grid, generated voltage is suppliedthrough the step up transformer. The distributiontransformer both windings get energized. As theboth windings get energized flux will flow to thecore and thus result in leakage of flux and wastageof power.• The distribution transformers as well as anytransformer have rating. By feeding the generatingpower back to the same grid distributiontransformer core would come across a substantialamount of voltage and current which cannot bewithstand by the transformer core.• When the application of microgrid isfound profitable by the society. There is a chanceof expansion of generation by each consumersalong with this rating of distribution transformeris also increased. In such case paralleling oftransformer is made.• When the grid supply is made off for anymaintenance, the feedback voltage to the gridshould also be zero. Otherwise this will lead toserious hazardous situations to the persons workingon the transmission and distribution line.

So to provide synchronization of voltage,frequency, waveform and phase sequence. We onlyneed to synchronize the generated voltage and gridvoltage because by synchronizing the voltage otherparameters will get synchronized too. As allparameters depend on voltage. In the case of

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transmission stage, feed backing the generatedvoltage to a separate feeder other than the incomingfeeder. We can avoid all the problems that arise intransmission stage.

IV. Our Proposal

Figure 1: Methodology

Taking both inputs such as 230V, 50 Hz supply(reference line) and generated PV voltage into agrid tracking inverter .Which synchronizes boththis inputs. For a parallel storage battery isprovided. The synchronized output 230V, 50Hz ofgrid tracking inverter is taken out through aseparate grid to step up transformer .which stepup to 11KV and given to the substation. Switchingto different feeders is done by substation. Byimplementing this system we can commercializethe concept of grid integration of renewable energy.

Block diagram explanation

Solar panelis one of the power generating units inour system. This section contains an array of photovoltaic cells that absorbs the energy in the photonsand converts it into electric potential. The voltagegenerated by the solar panels is bypassed to batteryin order to store the energy.The charging circuitmonitors the battery voltage and controls thecharging action. It prevents over charging andleakage of the battery to the solar panel in absenceof light.The selector switchdetermines the directof current flow. The battery will be connected tothe charging circuit as far as the sunlight is availableand the battery voltage is less that the solar panelvoltage. The output of the solar panel is directlyconnected to the inverting transformer once thebattery is fully charged and the sunlight is available.

Figure 2: Block diagram

In night and in absence of light the battery will beconnected to the circuit. All these connections aremade by this selector switch under control ofmicrocontroller.Battery is the storage media ofpower. This battery can be either rechargeablebatteries or super capacitors. There different typesof rechargeable batteries like lead acid, nickelcadmium, nickel metal hydride, lithiumthynolchloride etc.Our proposal utilizes inverter

topology to convert the direct current from the batteryor the solar panel to alternating current in the samevoltage and phase angle of the grid. This in turnrequire high power solid state switch, typicallyMOSFETs or IGBTs. However cutting edgetechnologies in electrical and power electronicindustries provide highly reliable high powerintegrated power switching modules. The low voltageinverted current is stepped up to the magnitude ofthe grid supply by the step uptransformer.PowersensorWe have to measure both input power andoutput power from and to the grid. For this, we haveto calculate input voltage, input current, input powerfactor, output voltage, output current and outputpower factor. All these actions are done by four blocksin the block diagram. They are

• Grid voltage sensor-tomeasure voltage.• analog to digital converter - to convert

analog output from the sensor tohexadecimal from

POWER SCENE February 2013

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Members are requested to give the articles to the Power Scene, to the Editor or the Area Representatives.Articles from family members are most welcomed. Articles may be e-mailed to haseena.ps@gmail.com

NEXT MONTHLY MEETINGDate : 7th March 2013, ThursdayTime : 05.30 p.m.Venue : Transmission Club, KalamasseryAgenda : Normal Business Session

Power point presentation - Autism -Early intervention - by Punarjani,a Charitable Society

WELCOME1. Rithesh P. R., Assistant Engineer, has been

transferred and posted to BDPP Brahmapuram2. Baby paul, Assistant Engineer, has been

transferred and posted to 220 kV SubstationBrahmapuram

KSEB Engineers’ Association Ernakulam unit offersa hearty welcome to both of you

• Output voltage sensor - to measure outputvoltage.

• Zero crossing detectors - to detect andmeasure the phase difference betweenvoltage and current to calculate powerfactor and control switching.

Since we are playing with the high voltage highcurrent grid supply, care must be taken to avoidcatastrophes. The relay provide in between the girdsupply and inverter output helps us to reduce thechance of accidents, losses since it is possible to isolateboth in case of emergency by switching off thisrelay.However the microcontroller cannot drive thisrelay since it is an electromagnetic switch that requireshigh voltage and high current than the sourcingcapacity of the microcontroller. Thus a relay driver isindispensable to integrate relay in this system.

For adequate control a human machine interfaceis provided. The key board unit helps the user togive commands and data to the system and thedisplay unit helps us to read the commands fromthe system. An array of push to on switches can beutilized as key board while an alpha numeric LCDwill be the best suit for display.

V. ConclusionBy implementing this low cost,highly efficientmarketable product .which is not yet available inthe market.We can commercialize theconcept”gridconnectivity of renewable energy “all overIndia.Our proposal is the only solution up to datebecause of the following reasons:

• Solar energy is renewable and is availablealmost 8 hrs every day. It is free

• It is green energy, non-polluting and echofriendly

• No byproducts or waste• Cheap and can be implemented by every

electricity consumers• Maximum energy production in peak load

timeWe can save our planet by saving fossil fuels andwater during day time.The consumer can buyelectricity as well as sell it.Consumers need to payif and only if his consumption is greater thanproduction. Otherwise the power distributionagencies will credit his account for his excessproduction. Thus focusing to renewable energysources we can reduce the ongoing energy crisis toa large extent.