ES3_H_Shakya

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TITLE :TITLE :

Isolated MicroIsolated Micro--Hydro Plants and Hydro Plants and Distributed Generation Distributed Generation

Problems and Benefits of Grid Problems and Benefits of Grid InterconnectionInterconnection

HITENDRA DEV SHAKYAHITENDRA DEV SHAKYA

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Isolated MicroIsolated Micro--Hydro Power Plants (MHP)Hydro Power Plants (MHP)Micro-Hydro = Size - less than 100kW ( Pico-hydro - <10kW)

Isolated Micro-Hydro = At least 5 years away from national distribution network (Grid) at the time of construction/operation.

Characteristics – Remote, Far from Road access, small villages, small river, tiny but growing economy, Villagers’ Initiative

Subsidy essential– Government and International agenciesNo. of households – 100 to >1,000

Primitive technology – indigenous turbine, induction generator, manual spindle-type inlet valve, manual intake gates, diversion weirs, simple load and freq controller, Low efficiency

Need and necessity in mountainous and under-developed regions with plenty of annual rain such as Nepal

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Isolated MHP Isolated MHP –– facing gridfacing grid--connectionconnection

Gradual expansion of national Grid and distribution networkRoad access – nearest road-head coming nearer to villagesCommunication and Radio/TV technology – access is creating accelerated demand for electricity but load growth is halted.

Local pressure for efforts to bring the gridAt the cost of the MHP operators –MHP operators –• .Mostly Public (owned by National Utility Nepal

Electricity Authority NEA) but which are leased to private – Gorkhe, Chame, Manang, Helambu etc

• .Community-owned ( Handed over from NEA or international agencies) – Timure, Ghandruk etc

• .Private – few but growing trend – Barpak

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Isolated MHP Isolated MHP –– facing gridfacing grid--connectionconnection

After grid connection, Govt./NEA owned MHPs went into disrepair and shutdown – Thansing, Gajuri, Dhading and many others

Typical cases –• These were nearer to highways• Load grew fast• Resulting in Insignificance of the MHP. • When Grid was connected, these were not synchronized. • Crude synchronization without proper equipment for

protection, control etc. With neglect for maintenance, soon they were shutdown.

No reason for continuation – employment in NEA assured elsewhere, power supply being more reliable and cheaper, neglected by NEA due to small size.Presently, many isolated MHP are being leased to private firms.

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Isolated MHP Isolated MHP –– facing gridfacing grid--connectionconnectionReason for Continuation

Community-owned MHPs –Source of income for communityEmpowerment and self-reliance of villages – decision making, development issuesRepayment of bank loans, projected incomes

Private MHPs -Similar reasons Avoid loss of profitDistribution rights

Result – Resistance to grid connection , resistance to opportunity.

No reason for resistance – provided the problems are solved.It can be solved. The MHP are profitable – no fuel costs, no royalties – Only Operation and Maintenance costs

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Isolated MHP Isolated MHP –– facing gridfacing grid--connectionconnectionThe MHP are profitable – no fuel costs, no royalties – Only Operation and Maintenance costsBefore

Subsidy for construction and expansionNRs 70,000 / kW + transport subsidy (Project cost appx. 150,000 /kW)After five years of operation, most bank loans paid.High O&M costs – electro-mechanical spares, repairs- remote, so costlyElementary protection and control equipment installedOperation times and tariff – Flexible. Tariff at par or higher than UtilityNo energy meters in most cases, monthly charge on no. of lamps, appliances (TV, Rice cooker etc.), Load control based on MCBs 2A,5A

Fixed income – enough for fixed costs plus certain savingsPoor load factor- Mostly lighting load in evenings, Few cottage industry eg flour mill or carpentry etc.

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Isolated MHP Isolated MHP –– facing gridfacing grid--connectionconnectionFacing now

Distribution network will be overtaken – Energy meters to be installed.Sell energy to the Utility. Hurdles of Power Purchase AgreementRules and regulations not established. Each deals on its ownTwo options1. Form a Community electricity group (CEG) – bulk purchase from NEA at low tariff NRs 3.60/ kWh ( national Average Rs. 6.50/kwh), Excess generation at off-peak to sell at the same rates.2. Sell to Utility at its delivery point – At a higher rate (Rs. 3.55 / kWh in wet months and Rs 5.95 in dry months) Suitable for Private-owned, but not applicable in areas taken by CEG (Rs 3.60/kwH)

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Isolated MHP Isolated MHP –– facing gridfacing grid--connectionconnectionPotential BenefitsOperator – Improved load factor – Maximum generation and export to grid Tariff may go down, but total revenue is increased, Equipment last longer due to stable operation provided Protective relaying is there.

Consumer - Power supply is more reliable, cost / unit is lower, no load restriction, room for growth

System Operator - distributed generation, less spinning reserve, less transmission and distribution burden

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Isolated MHP Isolated MHP –– facing gridfacing grid--connection : connection : Technical constraintsTechnical constraints

Facing now Increased fault level – Protective relaying required.Modification in control equipmentSynchronizing equipmentAnti-islanding protection and Island detectionEnergy meter installation at consumer endAccounting and administrative complexity – PPA, meter reading, billing,

For the UtilityAdministrative burden of small power purchasesChanges in radial distribution feeders – metering and auto-reclosuresIf it becomes numerous, the information gap as to operation and availability of these MHPSystem loss – Remote, so Off-peak losses will be higher

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Isolated MHP and Distributed Generation : Case Study Isolated MHP and Distributed Generation : Case Study --33

Grid

ChilimeV MHP 20 kW

BemdangSHP 450kW

ChhedingmoSHP 500 kW

66 kV

400V

11 kV

Timure MHP 20 kW

Chilime P/S 20 MW

Isolated MHP Isolated MHP TimureTimure -- 20 kW20 kW

Distributed Distributed Small Hydro PowerSmall Hydro PowerChCh--500kW Be500kW Be-- 450kW450kW

Distributed MHPDistributed MHPChilimeChilime-- 20 kW20 kW

Timure – Isolated, nearest road-head 5 hours walkCommunity owned, subsidized, 150 householdsSingle impulse turbine, belted coupling to 3-ph induction motor-generator, manual inlet valve, no controller for prime moverElectronic Load Controller (ELC) – thyristor firing to dump-load (water tank heating) based on Generator voltage, No excitation controlNo energy meters, 2A MCBs, charge according to no. of lamps, Operation in the evening only for lighting. Demand is growing

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Isolated MHP and Distributed Generation : Case StudyIsolated MHP and Distributed Generation : Case StudyTimure (20 kW) –Grid connection <15 kilometers away - Upgrade or shutdown?Technical upgrades

Electronic Load Controller –Modify ELC using contactor – Normal frequency band where ELC is disconnected. No dump load, all power is exported. Above 52.5 Hz, contactor switching to dump-load, disconnection from grid.Adjustable reference Pot. for speed control during synchronizingSwitching equipment –Air Circuit Breaker or Contactor with Overcurrent relaysVariable inductor for voltage control, to be cut off after synchronizingThree-lamp method for synchronizingProtection –Earthing reinforcement of the transformersIslanding –Use of Load Break Switch and Synchro-check relay at the interconnection point for Isolated operation during long Outage.

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Tariff and meteringTariff and metering ––Import/Export Import/Export -- CEG installed biCEG installed bi--directional directional metering at connection point metering at connection point –– import/export import/export tariff sametariff sameMetering at all consumers’ endMetering at all consumers’ endAccounting of the meterAccounting of the meter--reading, billing, reading, billing, revenue collection etcrevenue collection etc

Training of staffTraining of staff--Better understanding of electricity and high Better understanding of electricity and high voltage equipment, and Operation voltage equipment, and Operation Procedures, Island operation etc.Procedures, Island operation etc.

Isolated MHP and Distributed Generation : Case StudyIsolated MHP and Distributed Generation : Case Study

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Isolated MHP Isolated MHP -- SummarySummaryPreparing for Grid Connection requiresPreparing for Grid Connection requires

Hardware upgrade package Hardware upgrade package Clear definition of rules and procedures with UtilityClear definition of rules and procedures with UtilitySubsidy and tax exemption packageSubsidy and tax exemption packageTraining of personnelTraining of personnelA Package deal is necessaryA Package deal is necessary

Understanding of the benefits is requiredUnderstanding of the benefits is requiredIncrease in Profit – Revenue increase covers expenses in 2 years, but lack of confidence, understanding of the process, and lack of facilitation by the Utility can obstruct / generate local MHP resistance Unnecessarily

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Distributed generation with MHP Distributed generation with MHP –– case studycase study

ChilimeChilime village MHP (20kw) village MHP (20kw) -- Grid is already thereGrid is already there

Development of small river into MHP and operation by local peoplDevelopment of small river into MHP and operation by local peopleeGeneration and connection at Low voltage (400 v)Generation and connection at Low voltage (400 v)

Technical requirements Technical requirements –– Control, Switching, Protection and Control, Switching, Protection and Synchronizing devices necessary Synchronizing devices necessary –– SimilarSimilar

Training, Administration, Subsidy, Operational procedures Training, Administration, Subsidy, Operational procedures -- SimilarSimilar

Bi-directional meter at power plant for sale of power at declared rates to Utility directly. Higher rate of energyBi-directional Time-of-Day meters can be used for high proliferation of such MHPs (From Utility poin-of-view)

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Local concentration of such small and micro hydro plants create a mini grid

Be-450kW and Che-500kW Small Hydro Power plants along with Chilime village MHP and Timure MHP create a minigrid with possibility of Isolated operation of local load.

High outage of >300 hours/year due to long 11kV lines in remote mountainous region - To avoid losses during outage of grid connection, Isolated mini-grid operation is necessarySuch minigrids are possible in many regions, requiring a definite Operation strategy.

Frequency control, re-synchronization by Lead generator in mini grid–

The lead generator is normally the largest and near to the synchronization point (Bemdang 450 kW)– frequency and voltage control devices need to be installed, as well as communication with the System Operator and the connection point (Chilime 20MW)

Additional investment necessary for communication and control device at the Synchronization point of the mini-grid.

The investment and the loss of generation by the Lead generator during Isolated runs has to be compensated by participating generators

Distributed generation Distributed generation –– mini grid with more of MHP and SHPmini grid with more of MHP and SHP

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Conclusion from the casesConclusion from the casesOperation of MHP are profitable to run even after Grid connectioOperation of MHP are profitable to run even after Grid connection, and n, and beneficial to System operators also.beneficial to System operators also.

Understanding of the typical problems in bringing the distributiUnderstanding of the typical problems in bringing the distribution on network of such MHP under the grid and facilitating the switchnetwork of such MHP under the grid and facilitating the switch--over by over by technological and financial subsidy is necessarytechnological and financial subsidy is necessary

Rules, procedures should be simplified with the Utility so the Rules, procedures should be simplified with the Utility so the MHP’sMHP’sinterests are safeinterests are safe--guarded.guarded.A general package deal policy will encourage smooth switchA general package deal policy will encourage smooth switch--overover

Proliferation of MHP and SHP can result in miniProliferation of MHP and SHP can result in mini--grids. Management of grids. Management of such minisuch mini--grids is necessary for the System Operator and the grids is necessary for the System Operator and the MHP/SHP operators.MHP/SHP operators.Lead generator and synchronization point equipment necessaryLead generator and synchronization point equipment necessarySeparate arrangement within each miniSeparate arrangement within each mini--grid for Isolated operation.grid for Isolated operation.

In deregulated regime, instead of participating in the market, TIn deregulated regime, instead of participating in the market, Timeime--OfOf--Day biDay bi--directional meters can be used with all available energy to be directional meters can be used with all available energy to be produced and sold to the Grid Operator or Distributing companyproduced and sold to the Grid Operator or Distributing company

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Growing trend of MHP in remote villagesGrowing trend of MHP in remote villagesAddition of MHP in Nepal is a need and a necessityAddition of MHP in Nepal is a need and a necessityRemote areas can not wait forever for gridRemote areas can not wait forever for gridMHP with govt. subsidy are proliferatingMHP with govt. subsidy are proliferating

50 nos. of Micro50 nos. of Micro--hydro plants totalling 1140 kW hydro plants totalling 1140 kW benefiting 10100 households are being added with benefiting 10100 households are being added with subsidy from Alternative Energy Promotion Centre subsidy from Alternative Energy Promotion Centre (AEPC(AEPC) this year.) this year.Larger nos. of PicoLarger nos. of Pico--hydro plants with locally made hydro plants with locally made peltricpeltricsets are added every year.sets are added every year.

These MHP/PHP help to These MHP/PHP help to create loadcreate load centers. As centers. As demand grows, and grids come nearer, Grid connection demand grows, and grids come nearer, Grid connection of MHP is unavoidable.of MHP is unavoidable.

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RecommendationRecommendationThe switch-over from Isolated to Grid-connected system should be painless, and rather profitable.

Policies should be made to facilitate the process and afterwards

A policy with a package deal specifying technological upgrading and financial subsidy, tariff and metering should be developed for MHP

Identified technical requirements should be incorporated in new MHPs with subsidy for such extra investments –for eventual grid-connection

Minigrid with three or more MHP/SHP should arrange for Lead generator and Isolated operation

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general observationgeneral observation

Due to the inherent characteristics of Nepalese geography and economy –

Many Isolated MHP will continue to be constructed, and eventually connected to grid.

A solution with a view for long term operation is required and proposed

Small is beautiful !

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