Road Map for Electricity Distribution Reforms

Road Map to Electricity Distribution Reforms

 

SUDHIR KUMAR SRIVASTAV

Addl. GM - RAPDRP

NTPC LIMITED, NEW DELHI

Sudhirksri1@gmail.com

Reasons for adoption of Distribution Reform

1. Poor Commercial Performance:
• Very poor Metered Energy : Input Energy.
• Very poor billing efficiency & collection efficiency.
• Complicated Metering, Billing & Collection (MBC) System.
• High Aggregate Technical & Commercial (AT&C) Loss
• Average Revenue Realised (ARR) is much below than Average Cost of Supply (ACS).
• Inadequate Anti Theft Measures.
• Lack of accountability/responsibility in officers.

2. Poor Reliability: 
• Unplanned expansion.
• Poor condition monitoring of equipments.
• Unreliable protection.
• High DT failure.
• High feeder outage.
• Low HT:LT Ratio.
• Low Power Factor.
• Poor Record Keeping.

3. Old Technology & lack of IT intervention 

4. Non-importance to capacity building and technical up-gradation.

 
 

Road Map

For improvement in commercial Performance:

1. GIS based Consumer Indexing and Asset Mapping should be done along with preparation of feeder wise and DT wise consumer books. Policy should be formulated for new connection so that no new connection should be allowed before allotment of Consumer Indexing Number (CIN). Monthly report on category wise new connection should be prepared.

2. Ring fencing of energy at interface points should be done.

3. MBC should be made transparent and linked with Consumer Indexing data base. All the three activities should be done by single agency. Metering efficiency should be around 90%, billing and collection efficiency should be more than 95%.

4. Energy meters with digital interface should be installed on all industrial and commercial consumers. Metering of these consumers should be done through MRI, without any human interference. Automatic Meter Reading (AMR) can also be adopted for above consumers.

5. Consumer meters should be brought out of the premises of consumer. Preferably the meters should be installed on pole mounted meter boxes. Distinctly visible joint less overhead service connection should be provided to avoid the chances of theft of electricity. In case of any difficulty on bringing out the consumer meter on pole, check meter should be installed on the pole to counter check the consumed energy by consumer.

6. Stringent checking of contracted load of each consumer w.r.t. Supply Code provisions for calculating contracted load. Annual verification of the same shall be strictly monitored.

7. Feeder managers should be made responsible and accountable of 11 KV feeder for energy audit/accounting, profit/loss accounting and outage of the feeder. One feeder manager should not have more than 03 feeders in his jurisdictions.

If sufficient feeder manager is not available, the O&M and MBC of feeder should be out sourced on individual feeder wise with fixing of benchmark targets on reliability index and ARR on flow of energy on the feeder. If possible the complete Primary Sub Station (PSS) can be out sourced for all the electricity distribution activities with fixing the benchmark target and formulating penalties on non-adherence of benchmark/agreed targets.

8. SDO/AE should be made accountable and responsible for energy audit / account, profit/loss account and outage of each 33 KV feeder and connected PSS. He should also be made responsible for adherence of Supply Code in his area.

9. Executive engineer should be made accountable and responsible for energy audit/account and profit/loss account of the energy received in the division. He should be made responsible for adherence of Supply Code & Electricity Act.

10. CEO/DGM should be made responsible and accountable for profit/loss of whole circle, which includes cost of power purchase, O&M expenditure, establishment expenditure etc. Complete balance sheet and profit/loss account should be prepared at circle level and the same should get audited on yearly basis. He should be responsible for all Acts & Regulations.

11. Bimonthly billing of domestic consumers should be converted to monthly billing and status report/techno-commercial report should be prepared within 20 days so that timely corrective action may be taken. Breakup of 20 days schedule shall be as below:
• Preparation of bills                                          :           03 days
• Distribution of bills                                         :           05 days
• Realisation of bills                                          :           10 days
• Preparation of techno-commercial report        :           02 days

12. High Voltage Distribution System (HVDS) should be adopted for Private tube well consumers and rural consumers if any.

13. HVDS along with Arial Bunched Conductor (ABC) shall be adopted for theft prone area.

14. Un-metered consumers should be identified, provide meters for them and all the energy flow to consumers should be metered.

15. Anti theft measure should be made more stringent. Anti theft police squad may be increased. Analysis should be done on effectiveness of police squad by reviewing the expenditure on the squad and realization of theft energy.

16. Condition monitoring & routine checking of DTs and Sub-Station equipments should be done to reduce DT failure rate and improve reliability.

·         Format for the condition monitoring for PSS equipment is as per annexure A.

·         Checklist of distribution transformer & power transformer is as per annexure B.

17. Locations and capacity of Distribution transformers should be re-arranged considering the present loading of DTs and analyzing load center.

18. Policy should be formulated for installation of DT capacitors to achieve the power factor >= 0.95.

19. Data logging & computerisation work of electricity disdtribution business should be done in true spirit to derive the benefits for system analysis and minimize human intervention.

20. Business plan re-engineering and Integrated IT implementation shall be adopted to improve:

Ø  Record keeping

Ø  System analysis and fault finding

Ø  Transparency in system

Ø  Accountability in human resource.

 

For improvement in technical Performance:

Preventive maintenance, condition monitoring & proper documentation of sub-station equipments shall be done in following way:

Switchgear

1. All the 33KV & 11 KV incomers, Bus Couplers, Outgoing feeders and Power transformers should have dedicated circuit breakers with healthy protection system. Name of feeder, code, etc. should be properly painted on all the panels in a uniform manner.
2. All 33 KV & 11 KV panel covers should be properly closed and gland hole should be properly sealed.
3. All the breakers should be able to trip electrically both on manual operation and under fault conditions.
4. Ammeters, Voltmeters, Wattmeter and P.F. Meter should be available on all the feeders, incomers and bus coupler panel and should be in order.
5. Electronic energy meters with digital interface should be available on all the incomers and feeders. Energy accounting of the Sub-station should be done through MRI or AMR.
6. System should be connected with computerized data logging for proper analysis of data and generation for exception report without any human intervention.

Batteries & Battery charger: 

1. The batteries should be well insulated & supported on wooden structure/frame.
2. Periodical check up of electrolyte specific gravity and cell voltage should be done and recorded.
3. Battery charger should be in working order and connection with battery should be firm and properly dressed.

Power Transformer:

Common causes of Power transformer failure are:

·         Inadequate protection.

·         Absence of Lightening Arrestor.

·         Deteriorating condition of oil & insulation.

·         Frequent switching.

·         High level of harmonics.

·         Improper repair (for repaired transformers).

·         Overloading & unbalance.

Preventive measures:

·         Lightning arresters should be available on all the three phases near the transformers.

·         Power transformers should be free from any oil leakage.

·         Oil level should within the range indicated in the level gauge on the conservator.

·         Protective relays, tripping status and alarm system of the transformer should be healthy.

·         Better quality of transformer repair should be ensured with stringent checks.

·         Routine check and test should be done on power transformers. (Checklist at Annexure-B).

·         Yearly testing of Power Transformer should be done for following minimum test:

Ø  No load current / Magnetising current for observation of core loss.

Ø  Short circuit test.

Ø  Transformation Ratio test.

Ø  Magnetic balance test.

Ø  Winding resistance measurement.

·         Condition monitoring tests of transformer oil should be done for following minimum test on yearly basis:

Ø  Transformer oil Break Down Voltage (BDV) test

Ø  Moisture content in transformer oil.

Ø  Oil resistivity and Tan Delta test

Ø  Dissolve Gas Analysis (DGA) test.

·         Silica gel in the breather should be dry and blue in color. The oil cup in the breather should be filled with oil.

·         Winding and oil temperature indicators should be in order.

·         Transformer rating & diagram plate should be in order.

·         Transformer grouting and earthings should be in order.

Distribution Transformers:

      Common causes of distribution transformer failure are:

·         Inadequate protection, absence of LA, MCCB, HT fuse etc.

·         Lack of condition monitoring.

·         Overloading & unbalance loading.

·         Poor earthing.

·         Deteriorating condition of oil & insulation.

·         Frequent switching.

·         High level of harmonics.

·         Improper repair (for repaired transformers).

Preventive measures:

·         Identification code to be marked on each Distribution Transformer.

·         All the Distribution Transformers should have Electronic energy meters with digital interface. MRI based reading of DT meters should be done for energy audit, load current, neutral current, unbalance current etc and take corrective action after analyzing above data.

·         Distribution Transformer should be mounted either on plinth or poles and should be properly fenced. Danger plates should be provided on each DT.

·         All Distribution Transformers should have LA, MCCB, TPMO with HT fuses of proper rating.

·         Routine check and test should be done on Distribution transformers as per checklist at annexure-B.

·         If possible, harmonic suppressor should be installed at LT side of Distribution Transformer.

·         Distribution Board with proper fuse ratings should be provided on LT side of the DT.

·         Maximum LT current for different Distribution Transformers are:

v  250 KVA        :           350 Amp

v  400 KVA        :           550 Amp

v  630 KVA        :           880 Amp

v  1000 KVA      :           1390 Amp

Maximum permissible current on different conductors are:

v  Weasel             :           150 Amp

v  Raccoon          :           250 Amp

v  Dog                 :           310 Amp

Considering above permissible currents, the LT lines with different distribution transformers should be as below:

Ø  DTs of 100 KVA & below can run with single LT circuit of Weasel conductor.

Ø  250 KVA DT should be connected with 02 Nos. LT circuit of Raccoon conductor.

Ø  400 KVA DT should be connected with 03 Nos. LT circuit of Raccoon conductor OR 02 Nos. LT circuit of DOG conductor.

Ø  630 KVA DT should be connected with 04 nos. LT circuit of Raccoon conductor or 03 Nos. LT circuit of DOG conductor.

Ø  1000 KVA DT should be connected with 05 Nos. LT circuit of DOG conductor.

33 KV and 11 KV Lines:

1. Periodical patrolling and inspection of HT lines should be carried out such that every HT line is inspected at least once in a month. Hot spots, sparking, if found should be attended immediately.
2. Preventive maintenance of HT lines should be carried out thrice a year (pre- summer, pre-monsoon & autumn). All loose connections, blackened lugs, clamps etc. and damaged/leaky insulators should be replaced. All the trees fouling with the lines should be trimmed out. All the foreign material e.g. kites, strings etc. falling on the line should be removed.
3. Earthing & earth resistance of the poles should be checked once in a year.
4. Ensure the availability of earth guard wire and its healthiness at vulnerable points like road crossings, vicinity of LT lines, etc.
5. Poles, cross arms etc. should be painted with red oxide and aluminum paint.
6. Routine checks on healthiness of stay wires.

LT Lines: 

1.      Feeder combing should be carried out on regular interval and un-authorized service connections should be removed or regularized.

2. Trees fouling with the lines should be trimmed out and garbage like kites etc. should be removed regularly.
3. Proper conductor spacers should be provided in LT feeders and the same should be repaired / replaced if defective.
4. Minimum distance between two LT feeders should be 100 meters.
5. All the service connection in one premise must be from one LT feeder only.
6. Preferably use ABC for LT feeder in theft prone area.  
7. Earth resistance of the poles should be checked on regular basis.
8. Routine checks on healthiness of stay wires.
9. Some LT feeders are running in parallel with overhead HT feeders as composite main. These LT feeders should be removed under HVDS scheme with mounting of small transformers & metering cubicle on HT poles. Consumer meters should be installed in the metering cubicle & service connection should be provided directly from HT pole through metering cubicle.

Extra cost required for installation of small transformers on HT poles can be compensated by recovered LT conductors and associated DTs.

Service Connection:

1.      Periodic inspection of service connection should be carried out.

2.      Load carrying capacity of the service connection should be double than the contract load.

3.      Service connection should be properly supported with GI wire to avoid any break down due to storm etc.

4.      Service connection should be joint less and distinctly visible from pole to consumer meter to avoid the chances of any theft.

5.      Service connection cable should be provided by the utility so that the quality and uniformity can be maintained. If required the utility can load the cost of service connection to consumer.

6.      Meter reader / linemen should be made responsible for maintaining the healthiness of service connection.

New connection:

1.      No middleman should be allowed for new connection.

2.      Transparent guideline should be formed for required documents on application of new connection.

3.      Consumer should have liberty to apply for new connection through Internet, through telephone or through physical application at different location. Consumer should get registration no. and date of registration immediately on application.

4.      Designated executive should approach the consumer for required documents.

5.      No new connection should be released before allotment of Consumer Indexing Number.

6.      Designated executive should be held responsible for allotment of consumer indexing number and release of new connection within 07 working days after application.

Substation Logging & Records:

Following data should be regularly recorded and properly registered:

1. Hourly readings of all feeder & incomer currents, bus voltages, etc.
2. Monthly energy accounting/auditing through MRI.
3. Feeder tripping status / power reliability.
4. Fault tripping register: To record feeder wise number of tripping, duration of tripping, relay indications, duration of outage, fault identification etc.
5. Test result register: To record test results of all the equipments, e.g. Switchgears, Transformers, Transformer oil, WTI, OTI, relays, energy meters, CBs etc. (including the tests carried out by testing group)
6. Shift register: Chronological record of shift events and shift handing/taking over.
7. Maintenance register: To keep record of all the maintenance activities      
8. Defect Register: To record all sorts of defects observed by the operating staff, etc.
9. Computerised Data logging along with AMR shall be better option for substation logging & Records.

General Requirements:

1. A single line diagram of the substation should be displayed in the switchgear. Feeder wise DT details should also be mentioned in SLD.
2. Do’s & Don’ts regarding substation equipments.
3. Fire extinguisher at proper place in switchgear. Periodical checking and refilling.
4. Fire escape door should be available in switchgear.
5. Fire buckets (sand filled) should be available near Power transformer.
6. Electrical Shock Treatment Chart should be available in switchgear.
7. 33 KV yard should be free from grass & weeds.
8. Healthy house keeping should be maintained in sub-stations.
9. All cable trenches in control room/switchgear room should be covered with concrete slabs or chucker plates.

 

Mobile Service Van:

Mobile Van should be equipped to attend following problems:

Technical:

1. Fuse of call.
2. Low voltage, high voltage, fluctuating voltage, floating neutral etc.
3. Poor earthing / No earthing.
4. Distribution box fuse failure / burnt component.
5. Pole shock
6. Service connection wire broken, wire damaged, wire loose etc.
7. Streetlight not glowing.
8. DT related problems.
9. Short circuit / burning complaint.
10. LT & 11 KV line related problem.

Commercial:

1. Defective meter, meter jumping, defective sealing etc.
2. Shifting of meter.
3. Checking of meter on complaint.
4. Wrong bill, non-delivery of bill, NA/NR/IDF/RDF bill.
5. Long pending dues settlement.
6. Realisation of bill and issue of money receipt.
7. Customer Queries.

Service connection related:

1. Application for New connection.
2. Extension / reduction of load.
3. Change / Transfer of name.
4. Change of category.
5. Dismantling of service connection.
6. Disconnection / re-connection.

The Mobile Van should have following minimum equipments / items:

To Attend Technical Problems:

1. Earth discharge rod of 11 KV withstanding voltage. (02 Nos.)
2. Hand gloves of 11 KV withstanding voltage. (02 sets)
3. Safety belts. (02 sets)
4. Collapsible type aluminium ladder. (01 No.)
5. Hand / battery operated Megger: 0.5 KV (02 Nos.)
6. Hand / battery operated Megger: 1 KV & 2.5 KV  (01 each)
7. Multimeter. (02 Nos.)
8. Search light
9. Torch cell (as per local requirement)
10. Tool kit / toolbox. (02 set)
11. LT and 11 KV insulators.
12. LT power cable / LT wires for service connection replacements.
13. DT bushings (HT & LT both)
14. Conductors of each type for repair of LT & 11 KV over head conductors.
15. Transformer oil for top up in DTs.
16. HRC fuse of each type.
17. Earth wire and wire fuses of each type.
18. Come along clamps / PG clamps for stringing work.
19. Any other item as per local requirement of utility.

To attend commercial problem and customer queries:

1.      One PC / Laptop having wire less connectivity with billing data server and GIS based customer data server.

2.      One printer for printing of duplicate bills on standard format / stationary.

3.      One printer cum scanner for generating customer related queries.

4.      One UPS to avoid data loss on power failure.

5.      One mobile phone for voice communication if required.

6.      Different type of consumer meters.

7.      Aqua check meter for checking consumer meters.

8.      Meter sealing system.

9.      Sealing certificates.

PC / Laptop along with wireless connectivity with central server should be able to perform following duties:

1. PC should be capable of interfacing with MRI for uploading meter reading & should provide data validation checks to minimize data entry error.
2. Able to generate duplicate bill on demand and should have the provision for accepting the payment. Necessary money receipt with unique identification number can be issued against payment. All the bill generation and payment realization should be associated with the login-id of the personal and mobile van code.
3. Should be able to generate daily reconciliation statement on bill realization.
4. Should also allow different mode of payment like cash, cheque, draft, credit card, debit card etc.

7. Should be able to generate and issue different application forms for new connection, Extension / reduction of load, Change / Transfer of name, Change of category, re-connection.
8. Should be able to accept forms along with registration money and issue unique registration number for future follow up. System should check before accepting a form that all mandatory details as mentioned in the forms is filled.
9. Should be able to generate daily reconciliation statement on collection of registration money.
10. Should be able to ledgerise the sealing certificate in case of new meter or meter replacement.
11. In case of termination of connection requested by customer, the system should be able to accept the terminating meter reading for generating the last bill.
12. Should be able to generate customer related queries like different mode of payments, different promotional schemes, tariff rates, process of new connection, Extension / reduction of load, Change / Transfer of name, Change of category, re-connection etc.

Other Requirement:

1. Mobile van should have closed encasing with proper ventilation and one or two security guard to protect the collected cash.
2. Two linemen, one cashier cum computer operator, two-meter reader along with officer in-charge should always be available with Mobile Van.
3. First Aid box along with first aid instruction manual should be available with the Mobile Van.

 

Load growth & future planning:

1. Data should be collected for load growth of last five years and future planning should be done for capacity expansion.
2. Full fledge planning and engineering department should be established in the organization to study the load growth and plan for future expansion.

Adoption of change in technology and IT intervention:

Implementation of business process re-engineering and adoption of integrated IT approach. All the activities of the distribution business should be interlinked through IT interface.

Capacity Building and Technical Up-gradation of employees:

   Human resource of the corporation should be developed & enriched through regular training, seminars, workshops etc.

 

ANNEXURE-A

Base Data of Sub-station

Name of Sub-station:

33 KV System

Length of 33 KV feeder:

Source of 33 KV feeder:

33 KV Breakers

Name of Breaker	Capacity	Make	Year of manufacture	Sl. No.
Breaker No.1
Breaker No.2

Power Transformer

Name of Transformer	Capacity/ voltage ratio	Make	Year of manufacture	Sl. No.
Transformer No.1
Transformer No.2

11 KV Breakers

Name of Breaker	Capacity	Make	Year of manufacture	Sl. No.
Incomer – 1
Feeder No.-1
Feeder No.-2
Incomer - 2
Feeder No.-3
Feeder No.-4
Feeder No.-5

11 KV Feeders

Name of Feeder	Length in Km	Current Capacity	No. of DTs with capacity	No. of LT lines	No. of Consumers

 

Monthly monitoring parameter of Sub-station

Status of 33 KV Breakers:

33 KV breaker	Breaker No.-1	Breaker No.2
Closing status
Tripping status
Protection status
Max. current
No. of Tripping
Total trip Duration

Status of Power Transformer:

Power Transformer	Transformer No.-1	Transformer No.2
Oil level
Oil Leakage
Oil condition
Silica gel condition
Alarm Status
Earthing Status

Status of 11 KV Breakers:

11 KV breaker	Name of 11 KV Circuit Breaker
	Incomer-1	Feeder-1	Feeder-2	Incomer-2	Feeder-3	Feeder-4	Feeder-5
Closing status
Tripping status
Protection status
Maximum current
No. of Tripping
Total trip Duration

Techno commercial Status of 11 KV feeder:

11 KV breaker	Sub - Station	Name of 11 KV Feeder
		Feeder-1	Feeder-2	Feeder-3	Feeder-4	Feeder-5
Input Energy
Billed Energy
Metered Energy
Billed Amount
Revenue Realised
No of DT Failure

 

Monthly monitoring parameter for Distribution Transformer of Each 11 KV feeder

Name of 11 KV feeder:

Name/Rating of Distribution Transformer	Date	Oil Level	Cable box Status	Earthing Status	R-Phase Current	Y-Phase Current	B-Phase Current

 

                                                                                                            ANNEXURE-B

Daily Check List of Power Transformer
Name :		Location :
Capacity:
							Remarks
1	Oil Leakage	O.K.			Not O.K.
2	Oil Level	Normal			Low
3	HT & LT Connection	O.K.			Loose
4	Status of LUG	O.K.			Not O.K.
5	Winding Temperature	<90' C			>90' C
6	Oil Temperature	<80' C			>80' C
7	Status of Buchholz relay	O.K.			Not O.K.
8	Status of circuit breaker	Healthy			Unhealthy
9	Status of Earthing	Healthy			Unhealthy
10	Status of LA	Healthy			Unhealthy
11	Alarm Status	O.K.			Not O.K.
		R-Phase	Y-Phase		B-Phase
12	Transformer LV current
13	Transformer LV voltage

Check List of Distribution Transformer
Name :		Capacity:			Sub-Division:
							Remarks
1	Oil Leakage	O.K.			Not O.K.
2	Oil Level	Normal			Low
3	HT & LT Connection	O.K.			Loose
4	Cable Box Status	O.K.			Not O.K.
a	Position of fuse base	O.K.			Not O.K.
b	Status of LUG	O.K.			Not O.K.
c	Status of Fuse wire	O.K.			Not O.K.
d	Condition of Box	Healthy			Unhealthy
5	Status of Earthing	Healthy			Unhealthy
6	Status of MCCB	Healthy			Unhealthy
7	Status of Capacitor	Healthy			Unhealthy
8	Status of LA	Healthy			Unhealthy
9	Status of TPMO & fuse set	Healthy			Unhealthy
		R-Phase	Y-Phase		B-Phase
10	Transformer LV current
11	Transformer LV voltage
12	Power Flow ( Calculated )