Training Report NRLDC

Infrastructural Analysis of Load Dispatch Centre

ABSTRACT

Electricity is a widely used entity by each human being though it is divided by different types of consumers. It is used by each and every consumer daily like a breath. Without electricity our life will be in dark. To provide electricity up to our doors each & every component of a power system is working very efficiently & continuously. If there is malfunctioning at any stage of operation of a power system component, our switchgear is always ready to repair it again & present that component for our service. Load dispatch center is a coordinating agency for state electricity boards for ensuring a mechanism for safe and secure grid operation. Load dispatch center is an important links between generation and transmission, which co-ordinates the power requirements of consumers of electricity. Load Dispatch center which is the nerve of our power system is used to perform various functions. This paper explains the details of LDC, its functions, its importance in a power system & its future scenario as it is a very important factor of a power system. Terms and Keyword used:

LDC – load dispatch center

SLDC – state load dispatch center

RLDC- regional load dispatch center

DCC – distribution control center

Act - The Electricity Act, 2003

CEA - The Central Electricity Authority

CERC - The Central Electricity Regulatory Commission

DAS- Data Acquisition System

IEGC- Indian electricity Grid Corporation

1. INTRODUCTION

Power sector is reforming day by day to give us the uninterrupted & continuous supply up to our homes. No. of new equipments are coming forth for fulfilling the above purpose along with the simulation studies like load flow, economic load dispatch, control units, tariff measurements etc.Power sector is a key infrastructure sector & is the backbone of Indian economy. Installed power generation capacity in India has grown to 87 times since independence.Until 1980’s Indian power sector was in growth phase with many achievements to its credit. But by late 1980’s almost all SEB’s (state electricity board) started showing signs of financial technical & governance failure. But after the mergence of private companies SEB’s were restructured with financial support like IPP’s (independent power producers).Before knowing about Load dispatch center it is important to know about what is about electricity and how the electricity is related with countries economy.Today electricity plays a key role in a society. In house, offices, factories or farms electricity powers so many gadgets. It is the most versatile form of commercial energy & it has been a key input to economic growth in turn improving quality of life. It can be economically transported over long distances & easily converted to heal, light, or shaft power. It does work for us, cannot be seen, heard, smelt but still it is always with us without polluting the atmosphere.

The Indian Power System was demarcated in early sixties in five regions for the purpose of planning, development and operation with a view to optimally utilize the unevenly Distributed power resource in the country, as well as to achieve economy, reliability and Security of supply. Five Regional Electricity Boards, viz., Northern, Southern, Eastern, Western and North-Eastern were constituted to ensure integrated operation of regional grids formed with progressive interconnection of contiguous state power systems. Five Regional Load Dispatch Centers were also set up to coordinate the operations of the Regional girds in real time. The regional grids were strengthened with the establishment of large thermal, hydro and nuclear stations in the Central Sector in which the states of the concerned region have shares. Central Sector transmission system was constructed for Evacuation of power from these central projects to the beneficiary states. The contiguous Regions have also been interconnected through AC and HVDC back-to-back systems with the ultimate objective of achieving a National Grid. Eastern & Northern-Eastern Regions operate in synchronous mode while other regions operate independently and exchange power asynchronously through HVDC back to back systems or through AC lines in radial mode.

2. EFFECT OF ECONOMY ON POWER SECTOR

In our country 70% of population living in villages. India is country of villages, on the other hand India has many cities with excellent infrastructure ,good industrial base $many R & D centers & excellent academic institutions. All these needs electricity continuously in villages plus in cities which shows our economic aspects.

Everyone needs energy in some or other form like agriculture, homes, industries, government offices, commercial buildings, transport facilities, different operating machines etc. It is also true that half of the population of India depends upon non commercial sources of energy as they are not using any appliance or advanced equipment for their daily routines eg. Use of gobar gas in rural places, hand operated water lifting pulley etc. The main users of commercial energy are industries, agriculture, domestic users & transport sectors. Different power stations are in work to supply energy to us like Hydro, Nuclear, thermal, diesel, bio gas, bio mass, solar stations, wind farms, tidal powers etc. Following diagrams shows the Overview of commercial energy supply by sources, consumption, & consumption by different loads.

We know that power is the backbone of Indian economy and power sector is also Doubling every 10-15 years like other infrastructure sectors. Before looking actually towards the LDC it is important to know about the power system, its Structure & the main components taking part to make its flow successful.

3. POWER SYSTEM AND ITS FUNCTIONS

Right from generation to distribution or up to our premises power is not directly coming but it has to go through ups and downs the whole journey. Main wonder is how electricity generated reaches up to our homes thousands of miles away. The main contribution is by the thing called power system and to know about the power system it is essential to know its block diagram and each component.

Power system

Network of generating stations, substations, and power lines is called as power system It spans a large area. It has a 5 major blocks which are efficient in transforming power to End user.

Electrical power production is the very important part of the complete electrical power system. Once it is produced it must be distributed to location where it will be used. Controlling of power is done by using no. of devices and equipments. To convert it to different forms particular types of loads are used and the last block is for measurement of energy without which control & conversion is difficult. Power system may be a huge or a small network.eg. a small generating station operating on a waterfall at the edge of village with power lines running to village square from where they branch off to village homes a small power system or a system like Niagara falls. The whole power system also uses different devices for different functions like data loggers, data acquisition devices, SCADA, security monitoring systems etc. monitoring of power quality is another issue which decides the thing that whether the provided power is of harmonic free or not.

Loads which are creating harmonics are many so the harmonic mitigation is of utmost importance. Hence quality monitoring is essential. For this purpose many computer based measurement & automation products aid scientists and engineers in research, design, valid production testing and field monitoring of industrial power sectors. Other things like data transmission logging, acquisition, receiving, and economic load Dispatch, load forecasting and load allocation is also important for power system.

Sub systems of the power system

The summarizations of 3 major blocks of a power system are

Generation :- production of a power (fuels or inputs are different) Transmission and distribution :- produced power is transmitted or

distributed as per the consumers need.(underground or overhead) Utilization: - use of electricity for different purposes.

Following are the block diagrams of the typical power system

For the healthy operation of a power system G, T, D, and U must work in close Co-ordination. As per the requirement the generated voltage can be lowered or raised for transmission purposes. In case of a distribution levels are decided for different users like 33, 22, 11, 415 etc. It may be AC or DC hence distribution system is a 1st inter phase of utility with consumer. So power system is like a drama with many actors & director calling the tune. Power system performs smoothly if all actors dance to same tune. Any abnormality may lead to grid collapse as this drama is going all over the country , spread over thousands of kilometres.

SCENARIO OF POWER SYSTEM BEFORE THE SETUP OF LOAD DESPATCH CENTRES:

No Grid Discipline.

Low voltage, low frequency.

Frequent Grid failures.

Non optimum utilization of available resources.

No real time availability of data/ events occurring.

Inefficient Power System Operation & Load Management

Wide gap in Demand - Supply position (no regulation).

Low voltages at Consumer end.

High per Unit cost.

NECESSITY/OBJECTIVES:

To Provide Secure operation and Control of the Power System in the country leading to ‘GRID DISCIPLINE’.

To provide Reliable , Uninterrupted and Quality power to the consumers.

For running the power system at maximum economy.

For getting real time information for speedy and efficient decision-making.

For meeting the demands of the ABT regime.

4.LOAD DISPATCH CENTER

At state level minute to minute operation of a power system is Co-ordinated from a LDC which at the receiving end or load side. In one way LDC is a Wonderland as it is handling no. of changes, demand supply irregularities daily.It gives safe and secure grid operation. It is located in state capital. It is further connected to 3/4 sub LDC’s which in turn are connected to major substations and generating stations, hence LDC will get information about major changes in generating station plus whether condition information from different locations in the state. In earlier days it was only with few telephones and few engineers to keep the record.

State LDC is connected to regional LDC (RLDC), where RLDC monitors a whole region eg. Southern RLDC in Bangalore monitors A.P. tamilnadu, Karnataka, Kerala and Pondichery. RLDC also gets information from generating station & substations of central utilities (NTPC,NPC, POWER GRID etc). LDC at state plus regional level is connected to all these locations using reliable communication media that can carry information and voice.

LDC must be equipped with essential facilities:

*Reliable and far reaching communication network

*Accurate SCADA system

*Fast data processor and data formatting system

*Reliable power supply for LDC equipment for all the time

*Visual display of important system data

*Integrity of operating engineers

*Basic amenities, utilities and logistics.

Typically LDC prepares:

*An hourly generation schedule for each generating station in advance.

*Also the maintenance schedule (prepared for the year in

*Advance for any equipment failure.) Which needed relative power gen. cost.

*Contractual agreements.

*Water/fuel availability

*Irrigation requirement and load requirement forecast.etc.

Power System in India

• Electricity is a concurrent subject

– Both State and Central Govt. responsible for development & management of this sector

• State Electricity Boards (SEBs)/STU responsible for development of intra-state transmission system

• POWERGRID – the Central Transmission Utility for development of inter-state & inter-regional system

• Power distribution responsibility is with State Govt. and Private owned utilities

• 3 levels for Grid management system namely State, Regional & National

Hierarchy of Indian Power System:

1010

National Grid

33

Regional Grid

State Utilities

1

5

DISCOMS

NATIONAL POWER SCENARIO:

Installed Capacity in 1947 1,300MWInstalled Capacity as on 31.08.2007 1,35,000MW

Demand Estimates (FY2012) 16th EPS*

Energy Demand (Billion Units) 750

Peak Demand 155,000

Installed Capacity required to 195,000

meet peak demand (MW)

Additional Capacity Required (MW) 71,000

• Present Energy Shortage 8.2%

• Peak Demand Shortfall 13%

* Energy Survey by GOI

Transmission Network:

• Synchronous Grid interconnecting four(4) regions of 90 GW capacity geographically spread over 2.6 million sq. kms.

• South(SR) is asynchronously connected

• Transmission Grid$ (as on 30th September 2007)

– 765 kV / 400 kV Lines - 82089 ckt. km

– 220 kV Lines – 116745 ckt. km

– HVDC Bipole (3 nos.) - 2389 ckt. Km, 5 GW

– HVDC back-to-back - 7 nos., 3 GW

– FSC – 18 nos.; TCSC – 6 nos.

• Inter-regional capacity – More than 16 GW

Present Power Scenario

Installed Capacity (IC)– 135 GW

Peak Demand (PD)– 107 GW

Growth rate – 8-9% per annum

Installed Capacity & Inter Regional links:

Inter Regional Link MW Capacity

NER-ER 1,850

ER-NR 2,500

ER-SR 1,200

ER-WR 1,650

SR-WR 1,200

WR-NR 900

Talcher Kolar HVDC Bipole 2,000

Synchronous Operation of ER & NER:

Synchronous Operation of ER + NER & WR:

Synchronous Operation of ER + NER + WR & NR:

National Grid:- Present

Inter-regional capacity: 16.2 GW

NORTHERN REGIONAL LOAD DESPATCH CENTER

NRLDC is the apex body to ensure integrated operation of the power system in the Northern Region.

The main responsibilities of NRLDC are:

To ensure the integrated operation of the power system in the Northern Region.

Monitoring of system parameters and system security. Daily scheduling and operational planning. Facilitating bilateral and inter-regional exchanges of power. Analysis of tripping/disturbances and facilitating immediate

remedial measures. System studies, planning and contingency analysis. Augmentation of telemetry, computing and communication

facilities. Computation of energy despatch and drawal values using SEMs. Load generation balance and quality of supply Maintenance scheduling of generating units and

transmission lines Economic load dispatch Grid discipline Load forecasting or demand estimation System security and islanding facility Black start preparedness Energy distribution and load pattern study Communication and SCADA management Event analysis and preventive measures Coordination with neighbor grids Public relations and consumer interaction

Dispatchers study for load patterns:

*Industrial category of consumers (industries working in all 3 shifts)

*Industries working in day time with high power demand.

*Commercial category consumers like shops , offices ,show rooms operates during day time (9 to 20.00 hrs. )

*Railway traction load have generally steady nature whole day.

*Water works require power for pumping drinking water for urban and rural areas during early morning hours.

*Farmers also requires power for irrigation during day time .

400 KV GRID DIAGRAM OF NORTHERN REGION:

Zones and Flow gates in Northern Grid:

Significance of Unscheduled Interchange Mechanism in the Indian Electricity Supply Industry:

The two fundamental characteristics of power delivered to a customer are frequency and voltage. The short run supply-demand balance is indicated by frequency. Frequency is a ‘public good’ having large external effects. Stable operation of the interconnected power system, requires that frequency be maintained within a certain tolerance as defined by the standards adopted in a country.

Power systems all over the world have to make provisions for achieving a balance between real time demand and supply. Power markets generally have control areas that are prohibited from deviating from scheduled interchange. Concept of Area Control Error (ACE) used to measure these instantaneous deviations takes into account of both frequency and net excess flow out of a control area. Control areas are required to keep their ACE near zero for maintaining a constant frequency in the interconnection. This model for load frequency control used in developed countries may be a good practice but given the techno-economic and socio-political realities prevailing in India, it is currently incompatible with Indian power system.

Operating Frequency: 49 to 50.5 Hz

Pre ABT Settlement system:

• The payment to Central Generating Station by a constituent - proportion to total energy drawal -Recommendation of K.P.Rao Committee Report.

• Both Fixed and Variable charge was payable as per energy drawal

• Based on Monthly Regional Energy Account- REA

• Conventional Meter Readings

• Fixed cost recoverable with deemed generation ( generation not made available)

• Incentive payable after accounting for deemed generation

Although a two part tariff- Single part for constituent

Inadequacies:

• Non-utilization of Utilities’ Surplus Power

– No incentive for Maximization of own/ IPP/captive generation within a State as the cost of power paid is based on pooled rate of ISGS stations.

– No effective commercial mechanism for pricing deviations from schedule.

• Dumping of surplus power at High Freq

– Forced Backing down/ Reserve Shut down

– Deemed generation for backing down

• Non-utilization of embedded IPP/Licensee surplus Power.

– Administrative problems and no commercial arrangements for utilization of this power. Any surplus remains unutilized.

• Non-utilization of Pumped Storage Scheme

– No commercial mechanism to draw cheap off peak power for pumping. Bhira PSS/Kadamkadai is not being utilized in the pumping mode.

• Inability to Despatch Generation according to Grid requirement.

– Generation of Licensees cannot be despatched as per Grid requirements due to commercial problems.

• Curtailment of Bilateral Transactions due to Grid Indiscipline.

– Overdrawing State(s) deliberately increase drawls and cause frequency to dip below 48.5 Hz so that inter-regional transactions are terminated.

• Absence of Merit Order Operation

– As payments are based on drawls and not on shares/schedules, fixed cost are not perceived as sunk costs.

Inherent Disadvantage:

• No incentives for generators /utilities to respond to dispatch orders for issues like frequency control

– No Incentive for helping the grid

– No disincentive for hurting the grid

• No signal to generators to match availability with system needs

• Did not promote Grid Discipline

• No signal for trading of power.

Overall economy was lost.

Ultimate Effect:

• Grid Indiscipline-

• Low Frequency during peak

• High Frequency during off peak

• Control Instructions

• Subjective decisions

• Not based on overall economy

• Perpetual Operational & Commercial Dispute amongst Utilities/Central Generators

• Poor Supply quality to consumers/industries

• Damage to equipments

• Shifting of Industries/Investments

The comprehensive solution:

ECC Report , NTF & RTF Proceedings

• Availability Tariff for Bulk Power- Appropriate incentives

• Plant Availability to replace PLF-Capacity ownership

• Dispatch guidelines to Improve System parameters

• Frequency

• Voltage

• Each SEB

• to maintain its sovereignty.

• Regn Grid : to operate as a loose pool-Option C

• Increase in Trading Opportunities & Harnessing of Captive Generation

• ABT (self controlled mechanism)

Availability Based Tariff

Capacity Ch. + Energy Ch. ± UI

A + B ± C

Links commercial mechanism & Grid Operation Promotes grid operation ABT Structure – 3 parts of tariffs

A. Capacity charges

– Proportionate to entitlements (not actual drawals)

– Full recovery at target availability (not PLF)

– Incentives linked to Availability (80%) and PLF (77%)

– Incentives half of per KWh fixed charges at target availability / capped at 21 p/u.

B. Energy charges

– Payable for schedules (not as per actual drawals)

C. Unscheduled Interchange

– Payable for deviations from schedules

– Linked to average frequency for 15 minute time block (graph enclosed)

UNSCHEDULED INTER-CHANGE RATE

Average frequency of 15 minute time block

UI Rate (Paise / KWh)

50.5 Hz & Above 0.0

Below 50.50 Hz & upto 49.80 Hz @ 8 paisa / .02 Hz

Below 49.80 Hz & up to 49.02 Hz @ 18 paisa / .02 Hz

Below 49.02 Hz 1000

UI RATE Vs FREQUENCY

0.00

2.00

4.00

6.00

8.00

10.00

12.00

49.00 49.16 49.32 49.48 49.64 49.80 49.96 50.12 50.28 50.44

Ru

pee

s

The term Availability Tariff, particularly in the Indian context, stands for a rational tariff structure for power supply from generating stations, on a contracted basis.

The Indian version of Availability Tariff comprises of three components: (a) capacity charge, towards reimbursement of the fixed cost of the plant, linked to the plant's declared capacity to supply MWs, (b) energy charge, to reimburse the fuel cost for scheduled generation, and (c) a payment for deviations from schedule, at a rate dependent on system conditions. The last component would be negative (indicating a payment by the generator for the deviation) in case the power plant is delivering less power than scheduled.

How do the beneficiaries share the payments:

The Central generating stations in different regions of the country have various States of the Region as their specified beneficiaries or bulk consumers. The latter have shares in these plants calculated according to Gadgil formula, and duly notified by the Ministry of Power.

The beneficiaries have to pay the capacity charge for these plants in proportion to their share in the respective plants. This payment is dependent on the declared output capability of the plant for the day and the beneficiary's percentage share in that plant, and not on power / energy intended to be drawn or actually drawn by the beneficiary from the Central station. The energy charge to be paid

by a beneficiary to a Central station for a particular day would be the fuel cost for the energy scheduled to be supplied from the power plant to the beneficiary during the day. In addition, if a beneficiary draws more power from the regional grid than what is totally scheduled to be supplied to him from the various Central generating stations at a particular time, he has to pay for the excess drawl at

UI RATE Vs FREQUENCY

0.00

2.00

4.00

6.00

8.00

10.00

12.00

49.00 49.16 49.32 49.48 49.64 49.80 49.96 50.12 50.28 50.44

Ru

pee

s

a rate dependent on the system conditions, the rate being lower if the frequency is high, and being higher if the frequency is low.

How does the mechanism work:

The process starts with the Central generating stations in the region declaring their expected output capability for the next day to the Regional Load Dispatch Centre (RLDC). The RLDC breaks up and tabulates these output capability declarations as per the beneficiaries' plant-wise shares and conveys their entitlements to State Load Dispatch Centres (SLDCs). The latter then carry out an exercise to see how best they can meet the load of their consumers over the day, from their own generating stations, along with their entitlement in the Central stations. They also take into account the irrigation release requirements and load curtailment etc. that they propose in their respective areas. The SLDCs then convey to the RLDC their schedule of power drawl from the Central stations (limited to their entitlement for the day). The RLDC aggregates these requisitions and determines the dispatch schedules for the Central generating stations and the drawl schedules for the beneficiaries duly incorporating any bilateral agreements and adjusting for transmission losses. These schedules are then issued by the RLDC to all concerned and become the operational as well as commercial datum. However, in case of contingencies, Central stations can prospectively revise the output capability declaration, beneficiaries can prospectively revise requisitions, and the schedules are correspondingly revised by RLDC. While the schedules so finalized become the operational datum, and the regional constituents are expected to regulate their generation and consumer load in a way that the actual generation and drawls generally follow these schedules, deviations are allowed as long as they do not endanger the system security. The schedules are also used for determination of the amounts payable as energy charges, as described earlier. Deviations from schedules are determined in 15-minute time blocks through special metering, and these deviations are priced depending on frequency. As long as the actual generation/drawl is equal to the given schedule, payment on account of the third component of Availability Tariff is zero. In case of under-drawl, a beneficiary is paid back to that extent according to the frequency dependent rate specified for deviations from schedule.

Why was Availability Tariff necessary:

Promote competition, efficiency and economy- Merit order dispatch.Competitive market based system.Possibility of trading on a non-firm basis- selling of capacity entitlement.Facilitating Grid discipline- Incentive and disincentive for deviation.

How does it benefit everyone:

The mechanism has dramatically streamlined the operation of regional grids in India. Firstly, through the system and procedure in place, constituents’ schedules get determined as per their shares in Central stations, and they clearly know the implications of deviating from these schedules. Any constituent which helps others by under-drawl from the regional grid in a deficit situation, gets compensated at a good price for the quantum of energy under-drawn. Secondly, the grid parameters, i.e., frequency and voltage, have improved, and equipment damage correspondingly reduced. During peak load hours, the frequency can be improved only by reducing drawls, and necessary incentives are provided in the mechanism for the same. High frequency situation on the other hand, is being checked by encouraging reduction in generation during off-peak hours. Thirdly, because of clear separation between fixed and variable charges, generation according to merit-order is encouraged and pithead stations do not have to back down normally. The overall generation cost accordingly comes down. Fourthly, a mechanism is established for harnessing captive and co-generation and for bilateral trading between the constituents. Lastly, Availability Tariff, by rewarding plant availability, enables more consumer load to be catered at any point of time.

OPEN ACCESSAvailability Tariff is primarily meant for long-term supply from generating stations on a contractual basis and is not directly applicable for transactions under “open access” and “wheeling” provisions in the Electricity Act, 2003. However, its third component (UI) has a great relevance. “Open access” and “wheeling” generally involve two parties, one supplying a certain quantum of power to the other through the regional / State grid. Any such transaction involves a number of parties, and disputes could arise in scheduling, energy accounting and commercial settlement, unless an appropriate framework is in place.

Evolution of Power Market in India

IEGCFeb.’2000

ABT 2002-03

Open Access 2004

PX 2008

Capacity Market

Ancillary Market

DEFINITIONS:

Section 2(47) of Electricity Act 2003

“Open Access” means the non-discriminatory provision for the use of transmission lines or distribution system or associated facilities with such lines or system by any licensee, or consumer, or a person engaged in generation in accordance with the regulations specified by the Appropriate Commission”

“Bilateral transaction” means a transaction for exchange of energy (MWh) between a specified buyer and a specified seller, directly or through a trading licensee or discovered at power exchange through anonymous bidding, from a specified point of injection to a specified point of drawl for a fixed or varying quantum of power (MW) for any time period during a month.

“Short-term open access” means open access for a period up to one (1) month at one time.”

Short-Term Open Access in Inter-State Transmission

(Bilateral Transaction)

Procedure for Scheduling

As per CERC Open Access Regulations, 2008 (dated 25.01.2008) &

Subsequent (Amendment) Regulations, 2009 (dated 20.5.2009)

GENERAL CONDITIONS/APPLICATION SUBMISSION:

As per OA regulations Dtd. 25/01/08 w.e.f 01/04/08 &

OA Amendment Regulations Dtd. 20/05/09 &

as per order-amendment to CTU procedure Dtd.28/10/09

RLDC will check if connectivity with CTU/ ISTS or STU system (as the case may be) is established, necessary metering, protection, communication are in place, transfer capability upto the CTU network for power flow of the quantum of injection/drawl applied for is available on the date of application and whether the applicant has undertaken to abide by the Central Electricity Authority (Technical Standards for Connectivity to the Grid) Regulations, 2007.

Application to be submitted to::

– Nodal RLDC where point of drawl is situated

– & also to all RLDCs involved in the transaction

Application Contents

– Details:: Buyer / Seller / Point of injection/ point of drawl / Contracted power at supplier interface/ date/ time period (as per (Format-I-Application for scheduling) along with application fee

SUBMISSION OF APPLICATION:

• SLDC concurrance

– Concerned SLDCs concurrence in advance (Format - II-Concurrance from SLDC)

– In case of deemed concurrance the applicant alongwith the aplication shall submit duly notarized affidavit (Format-IIA-Affidavit-Deemed concurrance from SLDC

– RLDC concurrance

Bilateral Transaction having a State Utility or an intra-state Entity as a Buyer/Seller in other region:: concurrence of the concerned Regional Load Despatch Centre(s).

Nodal applications to be considered first before giving other concurrance

ADVANCE SCHEDULING:

• Advance Scheduling – 3 months in advance

• Separate Application –

– Month wise - each transaction

• Time Line for submission

– Last date for submission ( -10 / -5 / 0 days prior to end of current month MO – for transaction in M1, M2, M3)

– Cut-off time of application: 17:30 Hrs. of last day (Day 0)

– Request for concurrence (RLDC) – by 12:00 Hrs. next day (Day 1)

– Concurrence - by 20:00 Hrs (Day 1)

– Congestion Information to Applicant – next day 12:00 Hrs (Day 2)-Format-IV(Congestion information-Advance scheduling)

– Revised Request – next day 11:00 HRs. (Day3)-Format-V-Request for revision due to congestion)

– E-bidding – in case of Congestion (Day 4)

– Acceptance/Refusal of Scheduling Request – (Day 5)-Format-VI-Acceptance for scheduling.

e-Bidding Procedure:

• Invitation of Bids from the concerned applicant

– period of congestion

– RTS/IR corridor – expected to get over stressed

• Only Registered Users

– User ID & Password

– Electronic submission – website of CTU

– Bid Closing time as specified

– Single Price Bid

– No Modification/withdrawal once submitted

• Bid Price

– In addition to Open Access Transmission charges

- Multiples of Rs. 10/ MWh . ( Min. Rs. 10/MWh)

• Mandatory - Non-participation – Rejection of Application

• Acceptance - Decreasing order of Price Quoted

• Equal Price Bids – Pro-rata

• Applicant getting approval < request à Charges as quoted

• Applicant getting approval=request à Charges as paid by last applicant getting approval = request

“FIRST-COME-FIRST-SERVED” BASIS:

• Scope

– FCFS shall be considered only when transactions are commencing & terminating in the same calender month.

• Separate Application for each month

• To be submitted 4 days prior to date of Scheduling

• Processing time – 3 days on FCFS basis

• Applications received during last 10 / 5 days of month of M0 would be considered only after complete processing of Advance transactions for M1 & M2

• Application Received upto 1730 hrs in a day to be processed together – same priority

• Application Received after 17:30 Hrs. - to be considered as received next day

• Congestion Management – pro-rata.

DAY-AHEAD BILATERAL TRANSACTION:

• Applications received within 3 days prior to the day of Scheduling and up to 15:00 Hrs. of the day immediately preceding the day of scheduling shall be treated as same priority

• Processing only after processing of the Collective Transactions of the Power Exchange (s)

• Congestion Management – Pro-rata

SCHEDULING OF BILATERAL TRANSACTION IN A CONTINGENCY:

• Buying Utility/Trader on its behalf to make an Application to the Nodal RLDC

• To be considered after 1500 hrs of the day immediately preceding the day of scheduling

• In case of intra-day/same day – scheduling from 6th time block

• Congestion Management – Pro-rata.

INCORPORATION IN DAILY SCHEDULES:

• Incorporation in Daily Schedules of the Regional Entities

• Average energy losses - estimated on weekly basis

– RLDCs – ISTS (Inter Control area)

– SLDC – (Intra-State/Control area)

• Resolution of 0.01 MW at each State/inter-Regional boundaries.

• Losses on the system to be compensated by Drawing utility (net drawal schedule after deducting losses)

• Ramp-up- commencement of the transaction

• Ramp-down- at the time of termination of the transaction

REVISON OF SCHEDULE:

• Only in case of “Advance Scheduling” or “First-Cum-First Served basis”

• Accepted schedule for Day-Ahead & Contingency transaction shall not be revised or cancelled.

• For period of revision/cancellation upto two days:: Original transmission/operating charges

• For period of revision/cancellation > two days:: Transmission Charges and Operating Charges for the period beyond two (2) days shall be payable as per the revised accepted schedule and for the first two (2) days as per the original schedule.

• Margin Available – could be utilized for scheduling of other Open Access Transactions.

Example:

• Applicant has been scheduled for 10 days from 21st day of a month to 30th day of a month for 100 MW on round the clock basis (i.e. for 2400 MWh per day). If this Applicant, on or before 18th day of that month, submits request for revision of schedule to 50MW on round the clock basis (i.e.1200 MWh per day), the revised schedule will get implemented from the beginning of the transactions (i.e. 21st day of the month). The Applicant shall pay the Transmission Charges for 2400 MWh per day for the period from 21st to22nd day of the month. Whereas for the period from 23rd day to 30th day of the month, Transmission Charges shall be payable for 1200MWh per day.

However, if the Applicant requests for such revision on 20th day of the month, his request will be implemented from 23rd day of the month. He shall pay Transmission charges for 2400 MWh per day for 2 days i.e. from 23rd to 24th day of the month and for the remaining period he shall pay the Transmission Charges based on 1200MWh per day.

CURTAILMENT IN CASE OF TRANSMISSION CONSTRAINTS:

• In case of reallocation of GOI share leading to corridor constraints

• Transmission constraint or to maintain grid security

• Curtailed in the manner, which in the opinion of RLDC, would relieve transmission constraints/ enhance grid security

• For cancellation or curtailment of any transaction, among short-term, medium-term and long-term transactions, short-term transactions shall be cancelled or curtailed first, followed by medium -term and long term–transactions:

• Within Short Term transactions bilateral would be curtailed first followed by the Collective Transactions

• Rerouting allowed without curtailment

• Pro-rata refund of Transmission Charges.

DEFAULT IN PAYMENT OF OPEN ACCESS CHARGES:

• Nodal RLDC, at its discretion

– may not schedule the transaction or

– may cancel the scheduling of already scheduled transaction or

– may not entertain any Application of such Applicant in future until such time the default is cured

• Simple interest at the rate of 0.04 % for each day of default from the Due Date of Payment

• Cheque has been dishonored

– No cheque payment - next three (3) months

– Payment to be made by electronic transfer/demand draft

GENERAL CONDITIONS:

• Entities which are making Application for the first time must submit the “One- Time” information as per enclosed format (FORMAT-VIII: “Registration Form) to the concerned nodal RLDC.

• Application - through Post / fax

• Any amendment/modification

– fresh Application

• Applications not been accorded the Acceptance

– stand disposed off with suitable intimation to the concerned Applicant(s)

• All costs/expenses/charges associated with the Application, including Bank Draft, shall be borne by the Applicant.

• Incomplete / vague Application

– summarily rejected

• No charges payable for a transaction shall be adjusted by against any other payments/charges.

• The Applicant shall abide by the provisions of The Electricity Act, 2003, Indian Electricity Grid Code and CERC Regulations, as amended from time to time

• Applicant shall keep each of the SLDCs/ RLDCs indemnified

Role of SLDC:

1) As per the Electricity Act, 2003, the State Load Dispatch Centre (SLDC) shall be the apex body to ensure integrated operation of the power system in a State.

2) SLDC shall exercise supervision and control over the intra-State transmission system.

3)SLDC will be responsible for carrying out real time operations for grid control and dispatch of electricity within the State through secure and economic operation of the State grid in accordance with the Grid Standards and the State Grid Code.

4) The SLDC shall comply with the directions of the RLDC.SLDC shall keep accounts of the quantity of electricity transmitted through the State grid.

5.USE OF SCADA IN LOAD DESPATCH CENTER

There are multiple agencies within a state engaged in generation, transmission, and distribution of electricity. State Load Dispatch Centre monitors these operations and keeps the account of quantity of electricity transmitted through the state grid. SCADA is a part of it. Supervisory Control And Data Acquisition System (SCADA) is a high tech computer system with associated communication network that enables supervision and control o f power system network. SCADA is the technology that enables a user to collect data from one or more distant operator to stay or visit frequently to the work locations. It includes the man machine interface.It allows an operator to make set point changes on distant process controllers, to open or close valve or switches, to monitor alarms to collect measurement information SCADA is best applicable to processes that are spread over large areas and it is suitable for

1. groups of small hydroelectric generating stations that are turned on and off .

2 .oil and production facilities, pipelines for gas, oil, chemicals, water which are located at far distances.

3. Electric transmission systems irrigation system etc.

The direct benefits of a modern SCADA system are:

Constant access to Real Time picture of entire network showing power system voltage, frequency, MW, MVAR, etc.

Supervision, monitoring and control of power in Real Time.

Optimal operation of power system, i.e. generation and associated resources.

Minimum of outage and faster restoration of the system in the event of Grid disturbances.

Improvement in the quality of supply through better control of frequency, voltage and other parameters.

Less dependence on basic telephone system. When it comes into existence.

6.FUTURE SCENARIO

Source: Integrated Energy Policy, Govt. of India

2006-07 2011-12 2016-17 2021-22 2026-27 2031-320

100200300400500600700800

107158

226323

437

592

135220

306425

575

778

Projected Peak Demand and Installed Capacity at 8% GDP growth

Pead Demand Installed Capacity

GW

Perspective National Grid

CHANDRAPUR

U.SILERU

NAGJHARI

SR

KOLHAPUR

PONDA1000MW

BELGAUM

MW1000

GAZUWAKA

RAIPUR

VINDHYACHAL

WR POOLING

GORAKHPUR

WR

GWALIORUJJAIN

NAGDAZERDA

MALANPUR

AGRA

KANKROLIRAPP

KOTA

AURAIYA

FATEHPUR

NR

BIRPARA

ERMALDA

SILIGURI

NAGARPURI

BALIMELA

SIPAT

KORBA

ROURKELARANCHI

TALCHER

DEHRI

SAHU

BALIAMUZAFFARPUR

PATNA

BARHB'SHARIFFNABI

NERBONGAIGAON

SALAKATI

NARENDRA

1000MW

500MW

BUDHIPADAR

SASARAM

GAYA

National Grid by 2012

Time Line

The main things are make load dispatch center operations more complex than earlier years are changes in system network, growth in consumer population, mix of fuel used etc. also problems related to security , integration of various grids, forces the load dispatcher to attain new dimensions. Load dispatch center has to handle and face no. of problems regarding the electricity changes. In earlier days the methods used to communicate oral instruction and manual intervention were somewhat unreliable in critical situations.And this thing make necessary to adopt the new methods and

1)techniques like automatic control on generating units as well as important load centers. This is for effective and timely control to avoid the major occurances of black out.This aspect will also require the foolproof arrangement of reliable interlocks and back up protection to ensure safe grid working.

2)Also the transmission switchyard will be properly equipped and no interference of local staff except the experts.

3)Control actions taken by load dispatcher can not be bypassed.

4)The remote control of generation should be done through the governor controls to improve generation. In recent years it is done by the automatic governor control.

Grid Management outlook:

• Need for infusion of Intelligence in the Grid for

– Growing demand for digital quality power

– Increasing number of interconnections

– Economic dispatch

• Features of Intelligent Grid

– Phasor measurements for Wide Area Monitoring

– Adaptive islanding

– Self-healing

• Establishment of Power Exchange

7.CONCLUSION:Day by day the technology is changing , new trends are emerging which are definitely beneficial for utility side, power players and consumers too. In early days communication was done by the telephones only. All the changes, information transfer, fault data, generation and demand side requirement and all other data transfer depends upon the means which were not adequate but somehow it was very difficult to keep the records of all the above said things second to second as in many cases some information may gets lost.

Hence a new technique named SCADA originates which helping the power sector a lot by taking the form of load dispatch center. A real-time expert system now dergoing considerable fault case for restoration guidance. The progress so far indicates a hopeful future for a quick and accurate fault restoration support system. The system will continue to be thoroughly tested in the field until it can be introduced into practical service. Also automation in communication process gives quick information and response and all this happens at Load dispatch center.Hence this presentation conclude that Load dispatch center is a very important and most useful factor of a power sector in all sense.

Grid Management – The Need

We need a a smarter Electrical Grid , one that is prepared for real-time information, innumerable choices, quick decisions, and fast response. We’ve already seen the benefits of this in other industries. we file our taxes electronically, order books, clothes and even food online. We communicate around the world at nearly the speed of light via email. But, we still generate and deliver electricity much the same way we have for over a century.

CONTENT

S.NO TOPIC1 ABSTRACT2 INTRODUCTION3 EFFECT OF ECONOMY ON POWER SECTOR4 POWER SYSTEM AND ITS FUNCTIONS5 LOAD DISPATCH CENTER6 NORTHERN REGIONAL LOAD DESPATCH CENTER7 Significance of Unscheduled Interchange8 Availability Based Tariff

9 (i) OPEN ACCESS (ii) Short-Term Open Access in Inter-State

Transmission(Bilateral Transaction)

10 ROLE Of SLDC11 USE OF SCADA IN LOAD DESPATCH CENTER12 FUTURE SCENARIO13 Grid Management outlook14 CONCLUSION