5-1 DPR - Project Development and DPR

Power Finance Corporation Ltd.

(A Govt. of India Undertaking)

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Project Development, DPR Preparation, Appraisal and Schemes ImplementationDistribution Reform, Upgrades and Management (DRUM) Training Program

Project Development and DPRSource: MECON

A. INTRODUCTION

01 Objectives In order to improve the Sub-transmission and Distribution (ST&D) system for reducing Transmission and Distribution (T&D) losses and improving reliability and quality of power supply to consumers, it is necessary to take up strengthening and improvement of the system in a scientific and methodical manner. Planning studies may cover a distribution circle/ or an urban area as may be required. The objectives of formulation of project report for up-gradation of ST&D system are as under:

Planning and design of distribution system to meet load growth and to ensureo Voltage conditions to be within permissible levelso Optimum energy losseso Least overall cost system

Improvement in reliability / security of power supply Improvement in quality of power supply Safety of operation Evolving a scientific automation and load management system Better customer service

02 Strategy

The scheme for improvement and strengthening of system should be based on detailed study. Planning for system improvement is data intensive. With the availability of computer based tools and software, it is possible to study a number of alternatives to evolve optimum system development plans.

However, considering the present general data status, it becomes imperative that initially the improvement and strengthening of system may be taken up in two phases – Short Term and Long Term. During the implementation of short term measure, data base for long term studies is to be built up.

In the short-term, priority attention needs to be given to the objective of loss reduction, especially the commercial losses. For this, to begin with short-term report may be formulated. While short term measures are under implementation, for strengthening the system to meet future load demand, long term plans may be formulated.

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03 Tasks for Short Term Plan

The tasks to be taken up in short-term plan are as under : Energy Accounting/ Energy Audit Network Documentation – Single line diagram/ geographical map upto 11 kV

level Estimation of T&D losses/ Segregation of losses Technical Power Loss reduction (short term) Commercial Power Loss Reduction Improvement of voltage profile Preparation of Cost estimates Financial Analysis Preparation of Short Term Report

04 Tasks for Long Term Plan

The tasks involving long-term plan are : Mapping of the system, data collection and validation of data Analysis of existing system Voltage variation/ regulation study Technical losses in the system Load forecast Up-gradation of network/ expansion Technology option including integration of features of modernization of system

such as

Less LT System – High Voltage Distribution System (HVDS) Installation of shunt capacitors Technology option for containing theft such as Aerial Bunched Cables

(ABC), Automatic Meter Reading (AMR) etc. Demand Side Management (DSM) Communication Facilities Management Information System (MIS) Consumer Interface Automation Distribution Automation Customer Relationship Management Systems Reliability Analysis Training of Personnel

Evaluation of various alternatives for least cost optimal system Firming up of scope of works and their prioritization Preparation of Cost Estimates Phasing of works and their cost Financial Analysis

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Preparation of Long Term Report

05 Anticipated Achievement

The expected benefits from the study are: Reduction of technical and commercial losses in the system Strengthening of the system to meet the future load growth with least cost Improvement of quality and reliability of power supply Improvement of metering, billing and revenue collection Development of management information system Customer Satisfaction through improvement in power supply and access to

on-line information of the energy consumption/ billed

B. SHORT TERM PROJECT REPORT

The short term project report apart from covering the general features of the project i.e. executive summary, description of the circle, objectives etc. should include the following main activities.

01 Energy Accounting and AuditBefore taking up the formulation of plan for up-gradation of system, it would be necessary to estimate the T&D losses in the circle and segregate these losses into losses due to commercial as well as technical factors and identify high loss areas. For this, the utility should establish an Energy Accounting System to estimate the losses on a continuous basis. This activity should cover review of the existing energy accounting system and replacement of defective meters, installation of meters at appropriate locations for proper energy accounting. The suggested metering plan is to provide meters at Electrical Circle / town input point All sub-station and feeders upto & including 11 kV level Distribution transformers feeding pump sets as well as selected distribution

transformers feeding loads other than pump sets. Design methodology for estimation of unmetered energy consumption. Prepare energy balance sheet Estimate the total energy losses in the network Segregate technical and commercial losses by computing technical losses Validate segregation of losses with sample studies on distribution

transformers provided with meters

02 Network DocumentationSingle Line Diagram and Geographical Map upto 11 kV shall be prepared. In case of low voltage network emanating from distribution transformers, the sample map for typical high, medium and low load density areas covering various category of consumers may be prepared.

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03 Estimation of Technical LossesThe technical losses in distribution network may be estimated by computer aided system studies through simulation of the network. The difference between the total losses and technical losses is considered as commercial losses in the circle. The essential input for estimation of technical losses are : Network map with length of conductor and sizes used in lines/ cables Equipment data Load Data Power factor at critical buses of the Network Load flow analysis for complete 66/33 kV network emanating from 220/132

kV grid substation(s), 11 kV lines and distribution transformers Load flow analysis for low voltage network emanating from distribution

transformer under typical 11 kV feeder(s) covering high, medium and low load density area of the circle. The results of this typical low voltage network may be extrapolated for the complete low voltage network of the circle.

04 Technical Power Loss ReductionThe reduction of technical losses at base load level is pre-requisite for development of least cost network expansion plan. The technical loss reduction programme may include the following: Network reconfiguration including installation of new/ augmentation of Primary

and Secondary Substation (The transformer capacity to be installed in the new/ augmentation of 66/11 kV or 33/11 kV sub-stations should be adequate for meeting future load growth as per long term plan).

Network reconductoring Installation of 11 kV and LV capacitors New distribution sub-stations/ augmentation of existing sub-stations capacity Reducing the length of LT lines by installation of additional distribution S/s

(less LT System) Load balancing on all three phases of distribution feeders Improvement of joints in electrical network Refurbishment/ replacement of old and obsolete equipment

05 Commercial Loss ReductionProper monitoring and reduction of commercial losses is the main key for improving the financial performance of the utility. The huge investment proposed to upgrade the sub-transmission and distribution system with a view to reduce technical losses may not result in overall reduction of T&D losses unless an action is initiated simultaneously for reduction of commercial losses. The utility should work out and formulate the strategy of reduction of commercial losses. For this, the suggested steps are: Estimate the total commercial losses in the circle and also category-wise tariff

details

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Formulates a scheme for classification of consumers based on ABC analysis Comparison of consumption of high value consumers Provide check meters outside the high value consumer’s premises Computerize the billing of energy sale and analyze the billing data Regularize unauthorized connections Simplified procedure for release of new connection to consumers Implement on-line Billing/ Revenue Collection system for High Value

Consumers Prepare a strategy plan for liquidation of arrears Crash procurement and installation of good quality energy meters Adoption of Time of Day (T.O.D) metering coupled with incentive for

consumers to utilize off-peak energy Action plan for tackling theft/ pilferage of energy through legislative and

governance reforms Set up Vigilance Squad (where these have not been set up) Launch prosecution against persons indulging in theft of energy to secure

convictions in the courts The LT feeders should be inspected periodically by the special vigilance

group for tracing the unauthorized consumers and direct tapping from line Severe penalties may be imposed for tampering with metering seals etc. Initiate publicity to depict theft of electricity as a social and economic crime

and inform regarding provisions in electricity laws in this regard. To improve customer relations, consumer billing should be based on scientific

approach and record of energy consumed provided through Internet to consumers.

o Establishment of computerized complaint centero Meter checking for accuracy and detecting of tampering/ by passing

06 Cost Estimate & Financial AnalysisPrepare cost estimates based on prevailing market rates for each items of work. The utility shall then prioritize the works to be taken up under short term plan with the objective of minimization of losses so as to maximize the net benefit.The short term project report apart from covering the network and consumers’ load details, total peak and energy loss in the circle, estimated technical and commercial losses, should include measures to reduce technical losses and minimize commercial losses as well as other administrative measures proposed to be taken to eliminate pilferage of energy and organizational changes for creation of profit centers and fixing of individuals accountability and responsibility.

C. LONG TERM PROJECT REPORT

The long term plan will cover all the measures for improvement of quality and reliability of power supply and reduction of T&D losses in the circle / town by up-gradation, strengthening and improvement of the Sub-transmission & Distribution

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system to meet the load demand for next 5 years. The plan will be prepared by scientific planning of the system on the basis of detailed system studies.

01 Brief Description of the Circle/ Project AreaThe scheme should cover a brief description of the area covered under the circle. The various physical and demographic features, which could be included are: Name of Utility Name of Distribution Circle District/ Town(s)/ Village covered Location Latitude and Longitude Area Population Boundaries Climatic Conditions Status of Development Access to Electricity Economic Structure – Socio Economic features Predominantly Urban and RuralThe existing organization set up of the circle in respect of administration, planning, construction, operation and maintenance etc, may be given.

02 Data Collection/ Compilation of Existing SystemFor convenience in operation and administration, the area covered by a circle will be divided into divisions and sub-divisions while the electrical network in the circle remains one single connected entity. It is likely that some feeder(s)/ substation(s) may get interconnected to other circles through switch(s)/ metered point(s) that may be provided for the purpose. The existing power system may be detailed in respect of the following: Category wise number of consumers and connected load including the Bulk

Consumer’s details such aso Contract Demando Maximum Demando Energy Consumptiono Supply Voltage

Peak demand MW/ MVAR – simultaneous and non simultaneous Annual Energy Consumption – Energy balance sheet Geographical Map (to scale) of the area depicting Transmission and Sub-

transmission System Source(s) of power supply/ Grid sub-station(s) supplying power to the area

o Existing Substationso Existing lines

Sub-transmission Systemo Existing 66-33/11 kV Sub-stations & Existing 66-33 kV lineso Under Construction Sub-stations

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o Under Construction 66/33/11 kV lines Distribution System

o 11 kV lineso Distribution Transformerso LT lines

Operational Parameterso Substation equipment statuso 66/33 kV Feeder breakdownso Failure of distribution transformerso Tripping on 11 kV Feeders/ lineso Consumer outages

Electrical Network detailsFor carrying out studies, the sub-transmission and distribution system and its back up system from Grid sub-stations to the consumers’ level would have to be detailed. The data requirements for analysis of the existing power system are :

o Electrical network details – single line diagrams with conductor sizes, lengths, transformer locations, transformation capacities, capacitors, consumer location and load etc.

o Parameters of equipments, devices and conductorso Load data-peak load, diversity factor, power factor etc.

Sub-transmission & Distribution NetworkElectrical network mapping will in the first phase generally be prepared as single line diagram showing the network layout. Sample electrical network diagrams for Sub-transmission and Distribution System. The network diagrams will be prepared for each and every sub-station and line section up to LV bus of the distribution transformer

LV NetworkThe LV network starts from the low voltage terminals of the distribution transformer. The following information is essential for modeling of the low-voltage network.

o Section Lengtho Conductor size of each sectiono Connected load for each group of consumero Number of consumers in each groupo Total connected load on the transformer

Sample LV network emanating from distribution transformer located in high, medium and low load density pockets of the circle and covering different categories of consumers may be modeled which can form the basis for determining the improvement in the entire LV network.

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Equipment Parameter DataThe schematic diagrams for existing sub-stations are to be prepared with information of power transformer ratings and numbers, impendence values, bus bar scheme, isolators, circuit breakers type e.g. minimum oil/ bulk oil/ SF6/ Vacuum and type of installation (indoor/ outdoor), no. of incoming and outgoing feeders, CTs and PTs., details of taps and normal tap position, spare bays etc.

Load DataThe load data should cover the monthly, daily and hourly details of energy/ peak power in the electrical system of the circle. The various operational and load data required are :

o Peak load on each transformer/ feeder and corresponding actual voltage

o Diversity factor at various voltage levelso Power factor at various voltage levelso Load factor and loss load factor at various voltage levels

The load data could be obtained from the log sheets maintained at each 33/11 kV sub-station. The data could also be obtained more accurately from logging type electronic energy meters, if available in the system.

The planning studies should be based on actual feeder load conditions and measurement taken at various points in the system. Load data in respect of distribution transformers may be compiled by using tong-tester and/ or by installing meters on LT side of distribution transformer.

The 33/11 kV and 66/11 kV Sub-stations and 11 kV feeders are to be fitted with Electro-static meters with data logging facilities. The daily, monthly and annual load curves considering the seasonal variation will have to be analyzed from the logged data on these meters to compute the system peak and average demands.

System Load Factor and Loss Load Factor (LF & LLF)The annual load duration curve for the circle may be derived by aggregating the typical hourly spot reading of system power demand at grid substation(s) feeding the Distribution circle for typical working days and holidays in each month during the year so as to take into account the seasonal variations as well.

The system power losses are proportional to the square of the system load. An annual loss load duration curve may accordingly be derived from the load duration curve by squaring the ordinates.

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The load factor and loss load factor for the system may be computed from load duration and loss load duration curve respectively.

Data ValidationThe data compiled for existing system has to be validated for correctness and consistency especially in respect of load and network data. In the case of meters supplies, metering deficiencies in the form of non-functioning / defective meters have an impact on the correctness of loading / consumption figures. The proportion of non-working and defective meters should be identified. Check metering has to be done periodically on random sample basis. In case of unmetered supplies, the data would have to be worked out by sample metering and field studies. These measures would help in evolving suitable mechanisms for data validation.

03 Analysis of Existing SystemThe study of the existing system should be carried out to assess the following:

Voltage variationo Voltage at each node / bus sectiono % voltage variation with respect to rated input voltageo Whether Voltage variation within permissible limits

Peak power loss / Energy loss of each system element for arriving at total technical losses in the circle

Computation of commercial losses

Assessment of inadequacies of the existing ST&D system along with the identification of

o Overloading of transformerso Overloading of lineso Requirement of reactive compensation

Inadequacy of the back up transmission system

Security and reliability of power supply

The above analysis is to be carried out through system studies. The analysis of existing system will be done for:

I. Sub-Transmission Systemi) Sub-Transmission Sub-stationsii) Sub-Transmission lines

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II. Distribution Systemi) Distribution transformersii) 11 kV feedersiii) LT feeders

Existing T&D LossesFrom the total losses obtained from the energy balance sheet, the technical losses as obtained above will be subtracted to find the commercial losses of the area under study.

04 Load ForecastThe Distribution system planning involves siting of sub-stations, routing of feeders and many other decisions relating to both locations and amounts of capacity additions. Therefore, the Distribution load forecast refers to forecast of geographical location as well as quantum of future load growth. The Distribution load forecast of urban areas is relatively more complex due to high-density, high growth rates, variation intensity in a small geographical area and rapid transition of suburban are form rural to urban characteristics. The three step procedure involved in Distribution load forecast is:

Analysis of past trends of growth in electricity demand and energy consumption.

System load forecast viz. Forecasts of load for the entire study area. Spatial or small area load forecast viz. Divide the utility service area into

sufficiently large number of small areas and forecast for each small area.

05 Planning of Future System

05.01 Planning ObjectivesThe objective of strengthening and improvement of Sub-Transmission and Distribution system is to ensure quality and reliability of supply to the consumers, bring down technical losses to an optimal value and phase the system expansion to match the growing power demands in the time horizon of the study.

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05.02 Planning PhilosophyThe approach for planning of distribution system should be based on the following: Delivering bulk supply of electricity as near to the load centres as possible. Consumers affected due to outage to be few in the area, if at all it becomes

inevitable. Formation of ring circuit and radial circuit or combination of both depending

on the technical and economic requirement of the system to enhance reliability of power supply.

05.03 Planning CriteriaTo achieve the objectives set out, the following criteria may be adopted for planning the Sub-Transmission and Distribution System:

1. The voltage variations in 33 kV and 11 kV feeders should not exceed the following limits at the farthest end under peak load conditions and normal system operation regime.

Above 33 kV (-) 12.5% to (+) 10%Up to 33 kV (-) 9.0% to (+) 6.0%Low Voltage (-) 6.0% to (+) 6.0%

In case it is difficult to achieve the desired voltage especially in Rural areas, then 11/0.433 kV distribution transformers (in place of normal 11/0.4 kV DT’s) may be used in these areas.

Adequate power supply at normal voltage shall be available at main grid sub-stations to meet the system demand. The transformation capacity at the grid sub-stations shall be such that the system demand shall be met even with the outage of the largest capacity transformer.

2. Every Primary Receiving Sub-station, subject to space constraints shall be provided with at least two transformers having either sufficient cyclic loading capacity to supply the sub-station maximum demand or sufficient 11 kV system inter-connection to enable the maximum demand in the area to be met in the event of outage of single largest capacity transformer.

3. Every 33/11 kV substation should preferably have at least two incoming feeders from two different sources from reliability consideration. If both the 33 kV incoming feeders to 33/11 kV substation emanate from the same source (sub-station) then each feeder should supply independent sections of the 33/11 kV sub-station, the two sections being isolated from each other by bus coupler or isolators. This results in increasing reliability. However, if one of the 33 kV, feeders has much longer route, the shorter feeder may normally feed

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the 33/11 kV substation and the other one may be called upon to supply in emergency.

4. The sitting of Primary substation i.e. 33/11 kV substation should be on the basis of load forecast, demographic factors, space availability, right of way considerations, existing network configuration etc.

5. Power Transformer: The preferred transformer capacities for Primary Sub-stations (i.e. 66/11 kV or 33/11 kV) should be of 6.3, 8, 10, 16 MVA for Urban areas and 1, 1.6, 3.15, 5 MVA for Rural areas.

6. Distribution Transformer: The Distribution transformers to be installed in the circle should preferably have standard rating of 25, 50, 63, 100, 250, 315, 400, 500 and 630 kVA. The higher capacity (i.e. larger than 250 kVA) shall be used for concentrated loads or area with high load density and lower capacity (less than 100 kVA) may be used for Rural areas. In high rise building having concentrated loads, higher capacity distribution transformers such as 1000 kVA may be used. 33/0.415 kV distribution transformers of appropriate rating 630 kVA, 1000 kVA, 1600 kVA, 2000 kVA, may also be used based on techno-economic considerations. Lower ratings could be used for rural areas/ far flung urban areas. Standardization of ratings would help in achieving reduction in inventory for purposes of Procurement & Maintenance and reduction in price on account of bulk purchase.

The distribution transformers in urban areas should operate at an initial capacity factor of about 65%-75% of their rated capacity and would have to be augmented when the maximum demand on the transformer is near its rating. In case of Rural areas, a higher loading based on the assessment of load growth could be considered for adoption.

7. Choice of Conductor: Standard conductor sizes should be adopted for 66 kV, 33 kV, 11 kV and LT lines. ACSR and AAAC conductors for overhead lines and XLPE and PVC/ PILC cables can be used. Most power utilities use ACSR on account of price considerations although AAAC conductors are lighter in weight, have a longer life an account of higher resistance to corrosion.

Rated System Voltage

Conductor Type

33 kV ACSR Panther, Wolf, Dog or equivalent AAAC. Core XLPE cables of 150, 185, 240, 300 and 400 sq.mm

11 kV ACSR Dog, Racoon, Rabbit or equivalent AAAC. Equivalent Aerial Bunched Cable (ABC) 3-core XLPE cables of 120, 150, 185, 240 and 300 sq.mm

LT ACSR Dog, Racoon, Rabbit AAC, Ant, Grasshopper, Wasp or equivalent AAAC. Equivalent Aerial Bunched Cable (ABC) 3½ core or 4 -core PVC cables of 95, 120, 150, 185, 240 & 300 sq. mm

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In the choice of conductor size, the parameters to be considered are the thermal limit, voltage regulation and economic loading based on capitalized cost of losses. The first two parameters are technical requirements and have to be ensured. The loading of the lines should preferably be kept as near to the economic loading level of the conductor as feasible. This approach could lead to requirement of huge capital cost. Therefore optimization of conductor size after ensuring voltage regulation and thermal limits has to be done considering the cost of decremental losses vis-à-vis the incremental cost involved.

It would be desirable to limit length of LT feeder to a minimum. Based on the experience and conditions prevailing in our country, the length of LT feeder should not exceed about 400 meters. For higher voltage levels, feeder length should be decided based on studies.

8. The 11 kV feeders shall generally not be long under normal conditions and shall as far as possible feed only local areas. The 11 kV feeders shall be so planned that wherever the size of the conductor is inadequate or the voltage drop exceeds the prescribed limit, the existing conductors shall either be replaced by higher size conductor or load on the feeder shall be reduced by addition of new feeders. Existing line should be utilized to the maximum extent.

9. Selection of Voltage vis-à-vis size of conductor: 0.4 kV, 11 kV and 33 kV are selected as distribution voltages depending upon quantum and location of load. The higher the voltage more expensive is the system in terms of investment cost. However, it would be less in terms of total owning cost by way of capitalization of losses. The most economic voltage level would have to be determined through techno-economic studies from voltage regulation considerations, loading limits of conductor, cost of losses and investment cost considerations.

10.The Power factor of the system would preferably be not less than 0.95 at 11 kV level.

11. The level of security of supply to be provided is a matter of subjective judgment for the power utility. Higher the level of security, higher would be the cost. The highest degree of security is obtained when a sub-transmission system is operated in closed ring but this method requires an expensive protection system. Operation is more complicated and this system should be restricted to very densely loaded city center or VIP areas where security of supply is essential. More common arrangement requiring less of investment would be open ring system.

For industrial consumers, it may be appropriate to provide an alternative source of supply by using an open ring circuit for 66/33 kV and 11 kV consumers with the least possible restoration time. In case of improvement

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low voltage consumers, it may be proposed to provide alternate source of supply from adjacent Distribution transformer.

12. Technical loss levels: - Acceptable technical loss levels are subject to the economic factors such as costs of power and energy, cost of equipment and discount rates rather than purely on technical factors.

However target levels and maximum tolerable loss levels for each voltage level on the system with a view to meet the economic loss performance may be taken as shown below:

PROPOSED TARGETS FOR ECONOMIC LOSS LEVELSSystem Component Levels for peak power losses

Target level %

Maximum tolerable %

(i) Step-up transformer and EHV transmission system

0.50 1.00

(ii) Transformation to inter-mediate voltage level, transmission system & step-down to sub-transmission voltage level

1.50 3.00

(iii) Sub-transmission system and step-down to distribution voltage level

2.25 4.50

(iv) Distribution lines and service connections 4.00 7.00Total Power Losses 8.25 15.50

13. Maximum Fault Levels : The three phase fault levels may not exceed the following except where the system is nearer to the generating source where actual short circuit value may be used to decide switchgear specifications:

i) 33 kV Systems 750 MVA ii) 11 kV Systems 350 MVA (Urban Area)

250 MVA (Rural Area)

05.04 Up-gradation / Strengthening of the Sub-Transmission and Distribution Systems

With increase in load demand, the system would need strengthening and augmentation to ensure delivery of power to this consumers at proper voltage and for reduction of losses to a reasonable level. For the development of the system, the spatial load demands are worked out and imposed on the existing system to assess the inadequacy of the system for meeting the demand in the horizon year. This system augmentation / strengthening is then worked out to cover the inadequacy of the existing system to meet the proposed demand.The strengthening of sub-transmission system would involve:

a) Augmentation of sub-stationsb) Establishment of new sub-stations

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c) New sub-transmission linesd) Re-conductoring of sub-transmission lines

After finalization of sub-transmission system, the up-gradation requirements of distribution need to be worked out. The peak demands on each sub-station need to be disaggregated to each feeder and then to the distribution transformers.Voltage regulation & power losses on each feeder section up to DT are to be worked out using computer software / km – kVA method; requirements of reconductoring / addition of new feeders has to be worked out to ensure voltage regulation within limits. It may also require installation of additional Distribution Transformers.

The proposed distribution system would involve

a) New 11 kV linesb) Reconductoring of 11 kV linesc) New distribution transformers / augmentation of distribution transformersd) Reconductoring of LT lines e) New LT lines

The requirement of LT lines may be worked out based on extrapolation of results of typical distribution transformers.

05.05 Reactive Power Compensation Shunt capacitors are the simplest and cheapest way of managing the reactive power Agricultural pumpsets & LT motive load are operating at very low power factor (0.6 to 0.7) causing reactive power management and voltage profile problems in the system and thereby increasing system losses. It has been realized that the installation of LT capacitors close to the consumer load would – (i) reduce load current in the LT feeders (ii) reduce overloading of distribution transformers and 11 kV lines & back-up system.

As LT consumers do not ensure the working of capacitors even if these are provided at the time of release of connections. This problem can be taken care of by the power utilities by providing LT capacitors on distribution transformers.

As changing load demand characteristics pose problems in deciding on the level of compensation. It would be worthwhile to provide minimum level of fixed compensation of LT level to meet the average demand conditions and prescribing for higher nominal voltage (+10%) to ensure safe operation under possible adverse conditions. The balance requirements could be met by placing capacitors on 11 kV feeders where ever the site conditions permit.

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While deciding the optimal location of the capacitors, considerations like maintenance of capacitor & feasibility of monitoring & maintaining have to be kept in view.

The requirement of additional switched reactive compensation at 66 / 33 / 11 kV level may be decided based on system studies. Adequate capacitors at 66/11 kV level may be provided on 220 / 66 kV and / or 132 / 33 kV S/S.

05.06 Evaluation of Technical Losses

The studies by simulation of the proposed system would facilitate in identifying the element wise losses in the system. The total technical annual average energy losses of the proposed system, would be computed using appropriate load factors at different voltages in the system and corresponding load loss factors.

05.07 Reliability Analysis

In order to demonstrate the improvement in quality and reliability of supply with the implementation of project, reliability indices of power supply in the circle shall be estimated before and after ‘implementation of the project’. The reliability indices can be assessed as under:

Customer Interruption Frequency Index =

Total Number of Customer Interruptions

Total Number of customers Served Total Number of customer Interruptions = Sum of No. of Customers having no power supply in each interruption

Customer Interruption Duration Index =

Sum of Customer Interruption Duration

Total No. of customers served

Sum of Customer Interruption Duration = Sum of No. of Customers not having power supply Duration of Interruption

The supply interruption of customers may be due to

Grid supply failures

Breakdowns of 33 kV, 11 kV or LT lines

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Rostering of 11 kV rural feeder

Failures of distribution transformer

Blowing of transformer fuses

Individual fuse off

06 Cost Estimates

The detailed cost estimates for each item of work has to be prepared. The estimates shall be prepared based on prevailing market rates.

07 Phasing of Works & Their Estimates

The works have to be phased year-wise as per the capability of the utility to execute the works and the finances available. The phasing of works shall be decided on the priority accorded to various sub-works depending on the benefits from each sub-work. Higher priority should be given to those activities that are especially effective in loss reduction.

08 Financial Analysis

The design and sustainability of project is to take into account the level of incentive for undertaking and maintaining a project investment. The financial incentive takes the form of the increased income the investment generates with the execution of project.

A financial statement can be drawn up by showing the net income generated by the project investment after allowing for loan inflow and loan payment etc.

The works proposed for strengthening, up-gradation and improvement of substations and distribution system shall help in bringing down the technical and commercial losses by the horizon year. The system shall also be able to meet the load demand in the Horizon year with resultant increase in sale of energy. The up-gradation would also enable larger amount of energy to be delivered to consumers, which will result in higher sales. This approach however, assumes that the existing network would continue to operate at the present level of efficiency (and inefficiency) without any up gradation. That is to say that without any network up-gradation, the prevailing level of technical losses would not increase and / or the capacity to deliver energy would not diminish in (i.e. in the horizon year).

It would also be reasonable to distinguish between technical losses vs. commercial losses. So, careful consideration should also be given to determine whether the ‘administrative’ actions needed to reduce commercial losses could

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be effectively implemented without up-gradation. For instance, metering a various input / output points and at consumer levels is a pre-requisite for launching a successful program of reducing commercial losses. In such a situation it may be appropriate to consider apportioning a part of the credit for reduction of commercial losses to an up-gradation project.

There shall be many other indirect benefits, which cannot be quantified in monetary terms viz. improvement in quality and reliability of power supply, fewer break down increased customer satisfaction etc.

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5-1 DPR - Project Development and DPR

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