AMR using GSM Network

Abstract:-

Automatic Remote Meter Reading is the process of measurement through digital communication techniques & bring “intelligence” into the revenue cycle and manage it:  The main objective of the project is to develop a wireless energy meter. The micro-controller takes the reading from the energy meter and displays the reading on the LCD. The reading of the energy meter is also sent to the cell phone of the user by a message through GSM modem. This project is powered by an on-board power supply takes the ac power and converts it into dc power that is fed to on-board devices and integrated circuits. Utilizing an existing cellular network for data transportation requires no additional equipment or software, resulting in a significant savings in both time and capital.

  1.    Issues With Stand Alone Metering:-

Way back in 70s to 90s, stress was on generation of more and more power and energy, and distribution network was under evolution with the concern of providing energy to masses. Later in 90s, developed nation soon realized that one may need to incorporate management issues related to energy for managing the growing demand for energy i.e., Demand Side Management has to be in place for proper energy management, conservation, utilization, efficiency and environment. It was soon realized that the true bottleneck in demand side management is in effective Automatic Meter Reading. Thus to carry out demand side management, an effective AMR is required.

Demand Side Management:

As mentioned in background, economical issues, growing market changes, and

technological discontinuities drive changes, and subsequently opportunities get created. In

context to economics, higher construction cost and investor concerns forces better

utilization of generation and distribution system, resulting in real time pricing based on

demand, supply and cost. Interestingly, market competition always puts downward

pressure on the price and margin, and thereby threatens the market share, customer

loyalties and requires consolidation, there by open possibilities high margin, faster growth

and unregulated business. Technological innovation patches the discontinuities, there by

drive the integration of networks -PSTN, PLC, WL, Internet, control, data, audio, video –

internet connectivity etc. The confluence of these forces puts pressure on all parties, seemingly on conflicting goals.

Utilities: Need way to reduce cost, charge realistically, to increase customer base, identify

new revenue sources, satisfy customer and shareholder and ultimately remain viable entity

in the market.

Generation companies: Need way to have effective utilization of produced power, reduce

no load and peak load losses effectively and efficiently match the dynamic demand.

Consumer: Needs low cost, dependable system, economical, ecological sound energy

source.

Technology companies: Need to bring solution to market in time. Time to market

determines leadership, growth and survival.

Govt. Institutions: Need trust of its constituents, economic climate conducive for growth with Adherence to the myriad laws.

The other main issues with the current stand-alone meter reading system are as below:

•         Highly Person dependent.

•         Human errors cannot be avoided.

•         Accessibility of meters in rural/ Agricultural zones.

•         Energy Audits performed based on bill collection which is highly inaccurate.

•         Billing done mainly on estimated/ monthly average basis.

•         Inability to monitor and control discrete loads.

•         Billing cycle requires excessive time.

•         Meter data used only for billing, cannot help in analysis like demand analysis, energy audit, pinpointing losses, etc.

  2.    Smart Metering and IT: An opportunity to Leapfrog:

Purpose of Automatic meter reading system:

Way back in 70s to 90s, stress was on generation of more and more power and energy, and distribution network was under evolution with the concern of providing energy to masses. Later in 90s, developed nation soon realized that one may need to incorporate management issues related to energy for managing the growing demand for energy i.e., Demand Side Management has to be in place for proper energy management, conservation, utilization, efficiency and environment. It was soon realized that the true bottleneck in demand side management is in effective Automatic Meter Reading. Thus to carry out demand side management, an effective AMR is required.

   3.    Effective Automatic Metering System:-

 Automatic metering can be carried out in many ways. One of the intermediate solutions that customers may have seen is reading meter using palm devices, hand held computer, wireless drive by systems etc.. The effectiveness in automatic metering system can only be established if the ground for demand side management of energy is laid on the daily basis and is scalable as per the hierarchy of customer and participating business entities.. The only compelling mechanism that can lead us with metering data on the desktop is by having an active network of meter. Thus one of the prime requisites for carrying out demand side management is to have metering devices on network.. Creating a cost effective network itself a big challenge for effective AMR. Architecting the networking and sub-networking sphere of this domain for more challenges like bringing different types of meter on to network and also the topological distribution of meters. Topological distribution of meter poses a big challenge on choosing medium of communication for bringing metering system onto network. The other challenge posed is related to the data transmission from the meter. Different types of customer have different type of metering systems. Say for example, a residential customer has a metering system which is 1 phase and 3 phase type and meter reads only KWhr as a parameter for energy consumption and where as an industrial consumer have a metering information consisting of KWhr and maximum demand, and some of them trivectors meters installed for carrying out metering for all the three energy vectors of importance. Apart from this, meter needs a periodic check as well from the remote location and should also have theft prevention mechanism along with the encryption. If we consolidate the above mentioned challenges, then it broadly means that AMR on the meter side should have :

1. A Choice of communication interface that can latch to network

2. An interface with the meters of different type and is scalable.

3. A standard interface that can cater to vast class of meters in the field.

And should answer these questions:

1. How a meter reading and communication device at meter layer is of low cost?

2. What is strategy of acquiring meter data at the host sub system?

3. What are intermediate sub layers that need to be established for cost effective communication to the data center?

4. How do one make a judicious choice of communication medium?

  4.    Critical Benefits From AMRS:-

•         Ability to detect tamper events and outage occurrences.

•         Remotely Connect/ Dis-connect power supply through meter.

•         Calculate transformer loading and sizing from interval data

•         15 minute interval data gives accurate load information for supply scheduling, switching operations, planning etc

•         Monitor voltage at each premise to know conditions when to operate capacitor switches or regulators

•         Consistent and granular data for improved accuracy

          The factors that governs the implementation of AMR selectively are:

•         Maximum demand of the consumer

•         Consumer past record or intelligence accumulated for his power consumption and payments

•         Grouping and sub grouping of the consumers with common metering and low consumption sub metering

•         Services, end consumer wants to subscribe

•         Willingness for multiple tariff system for the consumer, etc.

  5.    Definition: Of AMR:-

–        Automatic Remote Meter Reading .

–        Automating the process of measurement through digital communication techniques.

–        Bring “intelligence” into the revenue cycle and manage it:

 

Metering    >      Billing     >    Operations       >  Customer    >     Service

  6.    AMR Network Architecture:-

§  Connectivity in AMR Architecture:-

1. GSM Based Communication

§  Single stage communication between Meter and central station through GSM Modem

2. Hybrid Communication

§  Two stages of communication in AMR System

·        GSM Based Communication :-

 

·        Hybrid Communication :-

Two stages of communication in AMR System

·         Meters and Data Concentrator Unit (DCU):

Communication channel used between meters and DCU is Power Line.

·         DCU and Host Central Station (HCS):

Communication channel used between DCU and HCS is the standard GSM, CDMA, RF or PSTN Network.

  7.    Primary Components:-

1.      Meter Interface Module

2. Communication System
3. Central Office Equipment

1.     Meter Interface Module:-

–        The AMR system starts at the meter. Some means of translating readings from rotating meter dials, or cyclometer style meter dials, into digital form is necessary in order to send digital metering data from the customer site to a central point.

–        Electro - optical interface

–        Signal Processing Electronics

–        RAM & Program Memory

     A. GSM Based Communication

•         GSM modem

•         Antenna

      B. PLCC Communication

Data Concentrator Unit (DCU)                 

•         The Data Concentrator sits on the loop of secondary of the distribution transformer. Collects meter readings from all the meters using Power Line Communication System at predefined intervals.

•         The DCU and all the  meters connected to it can be considered as a sub-system of the HCS.  The sub-system is set up with a DCU monitoring the low voltage power zone downstream of a Distribution Transformer. 

                    Retrofit Card:-

                                                                                                                                                                  

•         Consists of a single PCB, which converts CF pulses of Electronic Energy Meters to Electrical pulses, accumulate them and generate a meter reading with help of Microprocessor.

•         Microprocessor converts this data into Power Line Modulation.

•         Existing Meter Reading, Meter Constant and Meter ID is stored in NV RAM of Micro controller, before Retrofit is made operational.

•         One unit is incremented when Retrofit senses the pulses equal to Meter constant.

•         The incremented unit are stored in the NV RAM of the Micro controller.

                     Power Line Carrier Communications:-

•         Most economically viable technology for transferring Meter data to DCU.

•         Uses the technique of communicating the data over existing Electrical Lines which carry LT power to the site.

•         Employs an ASIC, which accepts digital data & converts it into FSK modulation and transmits it over the power line by sensing a zero crossing of 220V sine wave.

•         Typical frequency used for frequency modulation is 132KHz.

PLC Schematics:-

     C. AMR Enabled Meters:-

·         Collect, process and record power consumption data and transfer it to DCU over existing Power Lines.

·         Monitor electrical load in real time.

·         After receiving a set of commands from DCU, meter process energy consumption data according to pre-set time intervals.

·         Data received from different meters are stored in corresponding Load Data Records in Flash memory of DCU.

·         The MIU is built-in, no separate Interface Unit is required.

2.     Communication System:-

–        Used for the transmission, or telemetry, of data and control send signals between the meter interface units and the central office.

•         GSM Network

•         Power Line

GSM Network In AMR:-

·         Utilizing an existing cellular network for data transportation requires no additional equipment or software, resulting in a significant savings in both time and capital.

·         Cellular technology utilizes an encryption technique to prevent an outside source from receiving the transmitted data.

·         The cellular network provides full two-way communications, allowing scheduled reads, demand reads, alarm and event reporting, power outage reporting and power restoration reporting.

Why Power Line / Hybrid Communication?

·         PLCC Best Suited for LT 440 V network for detecting outages, tamper events and performing remote disconnect

·         Uses same power lines as communication media, so ideally suited for rural/ agricultural connections

·         Communication on HT side can be implemented via a choice of GSM, CDMA, RF or PSTN

3.     Central Office Equipment:-

•         Central office systems equipment includes:

–        Modems

–        Central server

–        Client Software for data acquisition and data analysis

Meter Data Analysis & Energy Accounting:-

•         Network Schematic Modelling: Modelling the physical network structure (substation, HT Feeder, Transformer, LT Feeder) & keeping it updated as changes occur.

•         Handle Feeder Switching scenarios for Energy Accounting:

–        From One LT feeder to another on the same transformer

–        From One distribution Transformer to another distribution transformer, but with the same LT feeder

–        From One HT feeder to another HT feeder but through the same DT and LT feeder

•         Reports/Analysis

–        Identifying customers with tampered meters or zero readings.

–        Monitoring the energy consumed /supplied and energy accounts /reconciliation over a particular duration

•         by customer category

•         by network device (LT Feeder, transformer, HT Feeder, Substation)

•         by geographical area (zone, circle, division, subdivision)

–        Monitoring the maximum demand, voltage levels, current, power consumption/ load on each meter.

•         Can calculate Max demand of LT / HT feeder, Transformer & Substation

–        Abnormal consumption report

–        Ability to build ad-hoc reports without having to know any programming language or query language.

•         Energy Balance Report

•         Areas of High Loss Report

•         Consumption trends Report.

  8.    GSM Modem:-

•         Dual Band or Triband GSM GPRS modem (EGSM 900/1800MHz) / (EGSM 900/1800 / 1900 MHz )

•          Designed for GPRS, data, fax, SMS and voice applications

•          Fully compliant with ETSI GSM Phase 2+ specifications (Normal MS)

•          Interfaces

•          RS-232 through D-TYPE 9 pin connector

•          Power supply through Molex 4 pin connector

•          SMA antenna connector

•          Toggle spring SIM holder

•          Red LED Power on

•          Green LED status of GSM / GPRS module

  9.    Inbound & Outbound Dialing:-

 

–        This supports both outbound and inbound communication modes. In the latter mode, the modem passes the commands sent by the data acquisition server to the meter and directs the meter response as-is back to the server. The meter manufacturer specific APIs running on the server will send the necessary commands to collect the meter data.

–        In the inbound mode, the modem will initiate communication to send reading or event data to the data acquisition server. It will again invoke manufacturer specific meter commands to collect data from the meter reading and tamper registers.

–       This server comprises the following modules::-

–        Data Acquisition: The server holds the APIs for enabling outbound dialing to various makes of HT meters. MeDAS’ outbound scheduler schedules automatic dial out to respective meter-end modems.

–        Data analytics:

–        Raw reading/tamper data retrieved is first stored in flat files. This also applies to the data obtained from inbound dialing or downloaded from MRIs.

–        The data analytics module then validates the raw data and stores it in the Oracle Database so that it can be used for further analysis.

–        Alarms and Notification: Sends notifications to the users via email/SMS/GUI for preprogrammed parameters like demand violation, abnormal power factor, tamper conditions, missing data and other preset conditions that the user might need alarms for.

–        Interfaces to existing KESCO systems to exchange consumer indexing information and billing data.

10.                       Advantages:-

a.     ELECTRIC COMPANY BENEFITS :-

–        Smart automated processes instead of manual work.

–        Accurate information from the network load to optimize maintenance & investments.

–        Customized rates & billing dates.

–        Streamlined high bill investigations.

–        Detection of Tampering of meters.

–        Accurate measurement of transmission losses.

–        Better network performance & cost efficiency.

–        Demand & distribution management.

–        More intelligence to business planning.

–        Better company credibility.

b.    CUSTOMER BENEFITS:-

–        Precise consumption information.

–        Clear & accurate billing.

–        Automatic outage information & outage recovery.

–        Better & faster customer service.

–        Flag potential high consumption before customer gets a high bill.

Conclusion:-

An economical prototype of Wireless Automatic Meter Reading System (WAMRS) has been developed, in which wireless communication is based on IEEE 802.15.4 ZigBee standard and security has been implemented by following the Direct Sequence Spread Spectrum (DSSS) protocol. Bill generation software has been programmed using Visual Basic/Macromedia Flash MX, interfaced to a SQL database server. Successful implementation and demonstration of WAMRS has made it possible to be implemented on a large scale in Oman and efforts are already underway to achieve this objective.