Retail Supermarket Energy Management System

PROJECT BACKGROUNDA retail supermarket chain identified huge potential overhead savings in store electricity usage. The savings could be gained through :

  • Ensuring the electricity billing for each store each month was correct through an auditable check metering system
  • Ensuring a good power factor at each store by installation of capacitors and implementing a monitoring and alarming system on power factor
  • Identifying and correcting supply voltage problems to protect shop floor equipment
  • Monitoring the daily and monthly electricity consumption profile at all the stores and correcting problem areas through benchmarking and alarming of inefficient use.

A low cost, reliable check metering system which could monitor and alarm energy usage and provide accurate account checking and convenient reporting for over 450 stores distributed all over Sub-Saharan Africa was required. After considering a number of proposals the retail chains consultants appointed WSP Energy Management to manage all the stores electricity usage and costs using technology and tools designed, installed and commissioned by NC Automation.

AUTOMATION SYSTEM DESIGN

The system was designed around NC Automation’s PowerSmart software  which accomodates large scale automatic meter reading into an open ODBC database and all SCADA systems from a number of different manufacturers’ meters via Ethernet networks, GPRS/ GSM/landline modems and/or RS485 networks.

A Central Energy Server PC resides at one of the chains regional headquarters and is connected to all 450 stores via the chain’s existing wide area network (WAN)

An Elster Kent A1700 3-Phase billing energy meter is installed on the incomer to each store and connected to the store’s Ethernet network via an Ethernet/RS232 converter which via a unique static IP address and Port number facilitates communications to/from the A1700 meter’s RS232 serial port over the WAN.

AUTOMATION SYSTEM DESIGN (CONT)Branches not on the WAN are accommodated using GSM modems with scheduled dialup from the central server.

A number of branches already had Netelek DM200 meters installed and working , so rather then replace existing equipment or purchase, learn and operate different software for different branches, a driver for the Netelek DM200 meter was written for PowerSmart OPC Server which enabled all these stores to be integrated transparently into the analysis and billing software system.

Low cost approved Energy billing meters store timestamped kWh, Lagging kVarh and Leading kVarh half hourly load profile and billing data for last 360 days and measure instantaneous pf, kw, kvar and phase voltages and currents, frequency, voltage dips.

Meter’s recorded half hourly kWh and kVarh profile data and events logged automatically and reliably into central SQL SERVER database by Powersmart OPC Server. PowerSmart EM software on any networked PC facilitates billing reports using rlevent municipality/supplier tariff and detailed analysis on profile data stored in central database.

Current meter measurements (kW, kVA, Volts, Amps, pf, voltage dips etc.) and billing accumulators (monthly kWh consumption, maximum demand) are made available via OPC server to Adroit 5.0 SCADA long term trending and alarming via email or SMS.

KEY SYSTEM BENEFITS

The Switched Ethernet network provides robust and high speed access between the SCADAs and the PLCs and between the SCADAs and the Server while facilitating access to both PLCs from the maintenance PC and access to the Intranet from any PC on the network

Information entry, such as recipe design, dispatch details, stock takes, maintenance reports and the results of laboratory tests are logged through to a central  SQL database from any PC on the network via custom designed web pages making up the site wide intranet

Production floor information obtained via the sensors connected to the PLCs is logged through Adroit 4.2 via it’s new DBAccess agent to a SQL database. In addition the advanced VB scripting features of Adroit 4.2 allowed easy fetching of recipe and production schedule information for SCADA display and PLC set up.