ABT meters

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ABT meters

Text of ABT meters

DIN E ISO 9001: 2000

MAHARASHTRA STATE ELECTRICITY TRANSMISSION CO. LTD.PUNE PRESENTATION BY

S.M. BAKRE , M.E. , M.M.S.EXECUTIVE ENGINEER400 KV R.S. , Jejuri

ON ABT METERS

WELCOME

Basic Concepts Historical Preview Principle of working Meters Generations First - Ferrari or Electromechanical Second - Static Third - Numeric

Electromechanical or Ferrari Meters The First Generation meters based on rotation of Aluminum disk within current coil and pressure coil.

Static Meter Advantages High Accuracy Low cost

Limitations Not intelligent Tamper can not be detected. Magnetic Theft

ABT Meters ABT means Availability based Tariff .

The term Availability of ABT Indicates that the power MW should be available. It may specifically be noted that energy charge (at the specified plantspecific rate) is not based on actual generation and plant output, but on scheduled generation.

Availability as a base For example if the rated capacity of generator is 50 MW out of which 30 MW generation is available , the base for billing would be 30 MW and not 50 MW. 30 MW would be scheduled generation for calculating deviation if any. If 20 MW power is generated instead of scheduled 30 MW , the penalty of 30-20 = 10 MW would be imposed as UI charge.

ABT Concept Traditional Concept :dw / dt Modern Concept :dw/df . df/dt dw/df :- ABT Meters df./dt :- Frequency Trend

Underfrequency Relay (UFR) UFR Settings 48.8 Hz 48.6 Hz 48.2 Hz

Frequency Trend Relay ( FTR )

df/ dt Relay

Implementation of ABT was recommended initially at Central Generating Stations in the year 1994 by M/s ECC of USA under the study sponsored by World Bank and Asian Development Bank .

ABT tries to improve a quality of power and curtail the following

Unacceptable rapid and high frequency deviations Frequent grid disturbances which result in generator tripping , power outages and grid instability. The pricing of power is made frequency dependent by ABT.

ABT Operation and Billing & Payment Mechanism The SEBs give the LD its requirement in 15-minute blocks for the next day. At the same time the CGS stations also provide the LD their 15-minute availability positions.

ABT Operation and Billing & Payment Mechanism

Based on the declared demand and available supply, the LD provides a schedule to the SEBs and the CGS for drawl and generation in 15-minute blocks.

ABT Operation and Billing & Payment Mechanism

Based on the drawl and generation positions of the SEBs and the CGS stations, the UI bill is computed.

The Three-part ABT Tariff

Fixed Charge : This is

payable by the beneficiary states based on the capacity allocated to them, and is irrespective of the amount of power they draw or schedule to draw

The Three-part ABT Tariff

Energy Charge: All the

scheduled energy that is drawn is charged as per the variable energy charge of the station from which power is being drawn.

The Three-part ABT Tariff UI Charge : The UI(Unscheduled Interchange) charge is levied on those units of energy that are a deviation from the schedule. This UI charge is frequency dependent.

Billed Amount Billed Amount = Fixed Charge + Energy Charge + UI Charge

The energy is metered in 15-minute time blocks, since frequency keeps changing (and the UI rate with it). The metered energy is then compared with the scheduled energy for that 15minute time block, and the difference (+ or -) becomes the UI energy. Corresponding UI rate is determined by taking the average frequency for the same 15-minute time block into account.

ABT Meters Intelligent meters Based on polled approach

Principle of working of ABT meter The energy is recorded in terms of pulses per kWh . The principle of working of static ABT meter is sampling . The voltage and current singles are received from PT and CT respectively .The samples of these signal at a particular instant are collected by Sample and Hold circuit . The phase difference between voltage and current is also found out . These values are analogue values .

Principle of working of ABT meter The CPU [ Central Processing Units ] only accepts digital signals . Therefore , the analogue signals are converted to digital by the circuit called ADC [Analogue to digital converter].The CPU processes these input signals for finding KVA [VI] , kWh [ VI cos ] , RKVA [ VI sin ] and other parameters . In order to measure the energy in terms of units , the circuit Energy to frequency converter is provided. The energy is converted into pulses . The counter counts number of pulses .

Sampling of a sinusoidal wave IRMS = ( I1 2+ I2 2 + I3 2 +I4 2 .. +In 2 ) -----------------------------------------------------n

VRMS

( V1 2 + V2 2 + V3 2 +V4 2 .. +Vn 2 ) = -----------------------------------------------------n

V1 I1 + V2 I2 + V3 I3 +V4 I4 .. +Vn In W = ------------------------------------------------------n W cos = ----------------VRMS IRMS

Functional Block Diagram of ABT Meter

3 Phase , 4 Wire Meters [ 3 wattmeter method ]

3 Phase , 4 Wire Meters

W = W1 + W2 + W3 = VI cos + VI cos + VI cos = 3 VI cos

General Arrangement

General arrangement Keypad - 12 numeric plus * and # keys. LCD Display 4 row X 20 characters Optical Port RS232 electrically apart Metering Module with sliding guides. Calibrated LEDs for dial test. MD Reset button sealable RJ-11 Port - RS-485 interface with MODBUS.

METER TESTING LAB SETUP Program the AC Power Source to generate a particular waveform. Configure the reference meter. Set the pulse counter to zero. Turn ON / OFF the switch I at the beginning / end of the test. Record results and make calculations.

METER TESTING LAB SETUP

ZERA

ABT Meter Testing Dial Test - No. of blinkings per kWh Accuracy Test 0.2 Min. Current test Max current test

Test Terminal Block (TTB)

Testing of ABT Meters

Manufacturers of ABT meters

Status of ABT meters at 400 KV Jejuri SSFeeder / ICT 400 KV Lonikand 400 KV Stg IV ICT HV Side ICT LV Side 220 KV Baramati 220 KV Jejuri I 220 KV Jejuri II 220 KV Phursingi Type MFM MFM ABT ABT MFM MFM MFM MFM Category T2T T2T T2T T2T T2T T2T T2T T2T

Advantages of ABT Meters These meters are capable of storing data . Therefore , the features such as load survey , energy history , tamper data etc is available. If the meter is stopped or tampered , the evidence is recorded .

Advantages of ABT Meters

These meters

have higher accuracy of the order of 0.2 .

Advantages of ABT Meters

These meters are capable of displaying energy as per applicable tariff I.e. TOD and ABT tariff.

Advantages of ABT Meters In the advent of load survey data , it is possible to monitor the consumption pattern.

Advantages of ABT Meters Using polled approach , the CPU detects abnormality in the metering system.

Advantages of ABT Meters

The starting current of is very less i.e. 0.1 % of base current. Thus 1 A meter will record 1 mA consumption.

Advantages of ABT Meters The ABT meters have self diagnostic feature by which any error developed in the inside component can be detected. This feature checks that the data stored in the meter is safe and not corrupt.

Advantages of ABT Meters These meters are

friendly.

user

The display parameters are easy to understand. Push button operation to read display parameters is easy. Data retrieval through MRI [ Meter Reading Instrument ] is simple .

Advantages of ABT Meters MD can be reset through any of the modes : MRI Manual Laptop Auto

Advantages of ABT Meters

Remote data retrieval possible through internet and mobile. Can be used in AMR [ Automatic Meter Reading ]

OPEN ACCESS, WHEELINGOpen 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.

OPEN ACCESS, WHEELINGSuppose party - A has contracted to supply 10 MW round the clock to party B (in the same State) at a certain price (which need not be disclosed to others), through the State grid. Suppose the transmission loss apportioned to this transaction has been determined as 0.5 MW. Party - B would then be entitled to receive 9.5 MW, provided party - A is actually injecting 10.0 MW into the State grid at its end. In actual operation, both injection by A and drawl by B may fluctuate over the day and the differential may vary from 0.5 MW. Who would pick up the commercial liability arising on account of these deviations? Since A and B are physically apart and operationally independent, a pragmatic solution for commercial treatment in such a case would be to meter the actual injection of A and actual drawl of B in 15-minute time blocks, and separately compute their deviations from their respective schedules (10.0 MW / 2.5 MWh for A and 9.5 MW / 2.375 MWh for B).

4 Quadrant Import Export Meter

Q2 Q1 Export Import Lag Lead Q3 Q4 Export Lag Import Lead

ABT SpecificationsParameter ValueStandard

IEC 687 , CBIP 88Billing Energy

DefinitionVoltage RatingTemperature

Type of meter 3 phase , 4 Wire400KV to 11KV/110 /3 V27 0C

ABT SpecificationsParameterCurrent RatingMaximum Current [ 200 % of Ib ] Minimum Current [ 0.1 % of Ib ] Class Of Accuracy

Value1 Amp

2 Amp 1 mA 0.2

Frequency

50 Hz [ +- 5% ]

ABT SpecificationsDisplay Parameters 1