GOOD MORNING ! HITENDRA DEV SHAKYA TITLE :
Isolated Micro-Hydro Plants and Distributed Generation Problems and Benefits of Grid Interconnection
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Isolated Micro-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 agencies No. 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 – facing grid-connection z
z z
z z z
Gradual expansion of national Grid and distribution network Road access – nearest road-head coming nearer to villages Communication and Radio/TV technology – access is creating accelerated demand for electricity but load growth is halted. Local pressure for efforts to bring the grid At 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 – facing grid-connection z
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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.
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No reason for continuation – employment in NEA assured elsewhere, power supply being more reliable and cheaper, neglected by NEA due to small size. ¾ Presently, many isolated MHP are being leased to private firms. 5
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Isolated MHP – facing grid-connection Reason for Continuation ¾
Community-owned MHPs – z z
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Private MHPs z z z
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Source of income for community Empowerment and self-reliance of villages – decision making, development issues Repayment of bank loans, projected incomes
Similar reasons Avoid loss of profit Distribution rights
Result – Resistance to grid connection , resistance to opportunity.
No reason for resistance – provided the problems are solved. ¾ It can be solved. ¾ The MHP are profitable – no fuel costs, no royalties – Only Operation and Maintenance costs 7
Isolated MHP – facing grid-connection ¾
The MHP are profitable – no fuel costs, no royalties – Only Operation and Maintenance costs ¾ Before z z z z z z z
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Subsidy for construction and expansion NRs 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 costly Elementary protection and control equipment installed Operation times and tariff – Flexible. Tariff at par or higher than Utility No 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 savings Poor load factor- Mostly lighting load in evenings, Few cottage industry eg flour mill or carpentry etc.
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d poss ible so lutions
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Isolated MHP – facing grid-connection
Facing now z z
blem a n
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Identif ying P ro
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Distribution network will be overtaken – Energy meters to be installed. Sell energy to the Utility. Hurdles of Power Purchase Agreement Rules and regulations not established. Each deals on its own Two options 1. 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 – facing grid-connection Potential Benefits Operator – 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 – facing grid-connection : Technical constraints ¾
Facing now z z z z z z
Increased fault level – Protective relaying required. Modification in control equipment Synchronizing equipment Anti-islanding protection and Island detection Energy meter installation at consumer end Accounting and administrative complexity – PPA, meter reading, billing,
For the Utility z Administrative burden of small power purchases z Changes in radial distribution feeders – metering and auto-reclosures z If it becomes numerous, the information gap as to operation and availability of these MHP z System loss – Remote, so Off-peak losses will be higher 12
Isolated MHP and Distributed Generation : Case Study -3 Grid
Chilime P/S 20 MW 11 kV
66 kV
Bemdang SHP 450kW
Chhedingmo SHP 500 kW
400V ChilimeV MHP 20 kW Timure MHP 20 kW
Isolated MHP Timure - 20 kW
Distributed Small Hydro Power Ch-500kW Be- 450kW
Distributed MHP Chilime- 20 kW
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Timure – Isolated, nearest road-head 5 hours walk
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Community owned, subsidized, 150 households Single impulse turbine, belted coupling to 3-ph induction motor-generator, manual inlet valve, no controller for prime mover Electronic Load Controller (ELC) – thyristor firing to dump-load (water tank heating) based on Generator voltage, No excitation control No energy meters, 2A MCBs, charge according to no. of lamps, 13 Operation in the evening only for lighting. Demand is growing
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Isolated MHP and Distributed Generation : Case Study ¾
Timure (20 kW) – ¾ Grid connection <15 kilometers away - Upgrade or shutdown? ¾ Technical upgrades z z
z z z z z z z z z
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 synchronizing Switching equipment – Air Circuit Breaker or Contactor with Overcurrent relays Variable inductor for voltage control, to be cut off after synchronizing Three-lamp method for synchronizing Protection – Earthing reinforcement of the transformers Islanding – Use of Load Break Switch and Synchro-check relay at the interconnection point for Isolated operation during long Outage. 14
Isolated MHP and Distributed Generation : Case Study
Tariff and metering – z Import/Export - CEG installed bi-directional metering at connection point – import/export tariff same z Metering at all consumers’ end z Accounting of the meter-reading, billing, revenue collection etc Training of staffBetter understanding of electricity and high voltage equipment, and Operation Procedures, Island operation etc. 15
Isolated MHP - Summary Preparing for Grid Connection requires ¾ Hardware upgrade package ¾ Clear definition of rules and procedures with Utility ¾ Subsidy and tax exemption package ¾ Training of personnel ¾ A Package deal is necessary
Understanding of the benefits is required ¾ Increase 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 16
Distributed generation with MHP – case study ¾
Chilime village MHP (20kw) - Grid is already there
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Development of small river into MHP and operation by local people Generation and connection at Low voltage (400 v)
Technical requirements – Control, Switching, Protection and Synchronizing devices necessary – Similar Training, Administration, Subsidy, Operational procedures - Similar
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Bi-directional meter at power plant for sale of power at declared rates to Utility directly. ¾ Higher rate of energy ¾ Bi-directional Time-of-Day meters can be used for high proliferation of such MHPs (From Utility poin-of-view)
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Distributed generation – mini grid with more of MHP and SHP ¾
Local concentration of such small and micro hydro plants create a mini grid
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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.
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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 necessary Such minigrids are possible in many regions, requiring a definite Operation strategy.
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Frequency control, re-synchronization by Lead generator in mini grid– z
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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 19 Isolated runs has to be compensated by participating generators
Conclusion from the cases ¾
Operation of MHP are profitable to run even after Grid connection, and beneficial to System operators also.
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Understanding of the typical problems in bringing the distribution network of such MHP under the grid and facilitating the switch-over by technological and financial subsidy is necessary
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Rules, procedures should be simplified with the Utility so the MHP’s interests are safe-guarded. A general package deal policy will encourage smooth switch-over
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Proliferation of MHP and SHP can result in mini-grids. Management of such mini-grids is necessary for the System Operator and the MHP/SHP operators. Lead generator and synchronization point equipment necessary Separate arrangement within each mini-grid for Isolated operation. In deregulated regime, instead of participating in the market, Time-OfDay bi-directional meters can be used with all available energy to be produced and sold to the Grid Operator or Distributing company 20
Growing trend of MHP in remote villages ¾ ¾ ¾ ¾
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Addition of MHP in Nepal is a need and a necessity Remote areas can not wait forever for grid MHP with govt. subsidy are proliferating 50 nos. of Micro-hydro plants totalling 1140 kW benefiting 10100 households are being added with subsidy from Alternative Energy Promotion Centre (AEPC) this year. Larger nos. of Pico-hydro plants with locally made peltric sets are added every year. These MHP/PHP help to create load centers. As demand grows, and grids come nearer, Grid connection of MHP is unavoidable. 21
Recommendation ¾
The switch-over from Isolated to Grid-connected system should be painless, and rather profitable.
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Policies should be made to facilitate the process and afterwards
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A policy with a package deal specifying technological upgrading and financial subsidy, tariff and metering should be developed for MHP
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Identified technical requirements should be incorporated in new MHPs with subsidy for such extra investments – for eventual grid-connection
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Minigrid with three or more MHP/SHP should arrange for Lead generator and Isolated operation 22
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general observation
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Due to the inherent characteristics of Nepalese geography and economy –
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Many Isolated MHP will continue to be constructed, and eventually connected to grid.
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A solution with a view for long term operation is required and proposed
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Small is beautiful ! 24
THANK YOU !
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