Power management systems are installed at four of Wescast Industries Inc.'s plants at Brantford and Wingham, Ontario.
Wescast Industries is the world's largest supplier of cast exhaust manifolds for passenger cars and light trucks. They design, develop, manufacture and machine, high-quality iron and steel exhaust manifolds for automotive OEMs. Wescast operates seven production facilities in North America and three sales and design offices in North America and Europe. The company is recognized worldwide for its quality products and innovative design solutions.
Their power management system is a real-time management system allowing Wescast plant management to reduce operating costs through the automatic control of plant furnace loads with minimum interference to production levels. Experience with this system has proven that the overall energy cost can be reduced while improving productivity and energy consumption efficiency. The system is fully integrated with the Wescast local and wide area networks permitting multiple users to access the system's real-time and historical data from their existing desktop computers.
There are four Wescast plants that have management systems installed.
Brantford Installation
The Brantford plant was built in 1991 and covers approximately 168,000 square feet. The plant produces Ferritic Ductile Iron and High Silicon Molybdenum Ductile iron cast as exhaust manifolds. The plant has an installed potential load of 20 MW, the major loads being comprised of 5 furnaces and one holding furnace. The plant is supplied by one 27.6kV line and is billed by the utility on the Ontario RTPll rate structure. The E2MS RealTime system monitors the main incoming utility meters and the sub-meters installed on each of the furnaces and the plant substation transformers. The E2MS system is complete with a fully automatic load control software module which issues raise and lower load signals to the furnaces. The control signals are issued in accordance with a calculation of the plant's predicted load and its difference to an operator set target. The control output signals turn on or off optically isolated output modules which are interfaced to the individual furnace controls via the plant's PLC equipment. The system is shown in Figure 1.
The RTU panel contains the data acquisition equipment and is mounted alongside the computer cabinet. The data acquisition equipment is manufactured by Opto22 and provides optically isolated input and output modular interfaces. KWh, kVARh and time synchronizing pulses from the utility metering are connected to the input modules together with kWh and kVARh pulse signals from Multilin PQM transducers on each of furnaces 1,2 and 3. Furnaces 4 and 5 are equipped with Multilin MTM+ transducers which are mounted on each furnace power supply equipment and provide local readout of electrical parameters. The PQM and MTM+ units supply kWh and kVARh energy data and are interrogated by the data acquisition computer via an RS485 two wire communication highway.
An additional 5 MTM+ units, mounted on a panel in the plant's main substation are also monitored on this highway. Control outputs on the Opto22 data acquisition equipment are connected as inputs into the plant's PLC system. These outputs signal the PLC to raise or lower individual furnace loads in accordance with the plant's predicted load and desired hourly target. The operators can select the order of furnace control through their PLC logic pushbutton interface.
Wingham Castings Plant Installation
The Wingham Castings plant was built in 1901 and covers approx. 165,000 square feet. The plant produces Ferritic Ductile Iron and High Silicon Molybdenum Ductile iron cast as exhaust manifolds. The plant has an installed potential load of 20 MW, the major loads being comprised of 7 furnaces. The plant is supplied by one 44 kV line and is billed by the utility on the Ontario RTPll rate structure. The E2MS RealTime system monitors the main incoming utility meters, the transducers installed on each of the furnaces and the plant substation transformer loads through Multilin PQM sub-meters. The system is complete with a fully automatic load control software module which issues raise and lower load signals to the furnaces. The control signals are issued in accordance with a calculation of the plant's predicted load and its difference to an operator set target. The control output signals turn on or off optically isolated output modules which are interfaced to the individual furnace controls via the plant;s PLC equipment (see figure 2).
There are three RTU panels containing the data acquisition equipment at the Wingham Castings plant. RTU panels 1 and 3 are located beneath the control room while RTU #2 is mounted on the far side of the plant. The equipment in the panels has to operate under high electrical noise conditions and is subjected to high temperatures and vibration. The computer equipment is mounted in a cabinet located in a controlled environment.
The data acquisition equipment is manufactured by Opto22 and provides optically isolated input and output modular interfaces. KWh, kVARh and time synchronizing pulses from the utility metering are connected to the input modules in RTU panel #1 together with kWh and kVARh pulse signals from the transducers on each of furnaces 1, 2 and 3. The kWh signals from transducers on furnaces 4, 5, 6, and 7 are connected to RTU panel #2. RTU panel # 3 is equipped with the output modules to control furnaces 1, 2 and 3 while RTU panel #2 has the output modules for furnaces 4, 5, 6, and 7. Multilin PQM meters supply kWh and kVARh energy data for the plants auxilliary loads and are interrogated by the E2MS data acquisition computer via an RS485 two wire communication highway.
Control outputs on the Opto22 data acquisition equipment are connected as inputs into the plant's individual furnace control systems. These outputs raise or lower individual furnace loads in accordance with the plant's predicted load and desired hourly target. The operators can select the order of furnace control through the E2MS control configuration.
Wingham Machine Shop Installation
The Wingham Machine Shop was built in 1991 and covers 103,000 square feet. The plant has an installed potential load of 2 MW and machines product produced by the Wingham Castings plant. This plant is sub-metered from the Wingham castings plant and is also billed on the RTPll rate. The machine shop substation load is monitored by a Multilin PQM meter which is interrogated by the E2MS system located at the Wingham Castings plant, using the plant's wide area network. From the data supplied by this sub-meter the plant can allocate the machine shop portion of the overall bill. The system is shown in figure 3.
A Multilin PQM meter is installed on the secondary side of the machine shop substation incoming supply. This meter provides kWh and kVARh aux pulses which are connected to Opto22 input modules contained in an E2MS RTU mounted in the substation. The PQM internal registers can also be interrogated by the E2MS computers using an RS485 connection.
An IP addressed, dual channel, Ethernet to serial interface, is mounted in the RTU panel and provides a transparent serial connection through the use of TCP/IP. The E2MS computer software, in the Wingham Castings plant, uses the data obtained from the PQM in the machine shop as a sub-metered load and tracks the energy used by the machine shop along with the energy used in the Wingham Castings plant.
North Huron Castings Plant Installation
The Wescast North Huron Castings plant was built in 1999, covers an area of 105,000 square feet and produces SiMo Iron which it casts into exhaust manifolds. The plant has an installed load of 20 MW and is on the large user Time of Use rate (TOU) with on-peak demand penalties.
The E2MS RealTime system monitors the main incoming utility meter, the Multilin PQM sub-meters installed on each of the furnaces and the plant substation transformer loads through Multilin PQM sub-meters. The E2MS system also issues raise and lower load signals to the two furnaces and holding furnace in accordance with an E2MS calculation of the plants predicted demand and its difference to an operator set target. The E2MS output control signals are interfaced to the individual furnace controls via the plants PLC equipment. The system is shown in figure 4.
There are three RTU panels containing the data acquisition equipment at the North Huron Castings plant. RTU panel #1 is located at the end of the plant closest to the utility metering location. RTU panel #2 is located at the opposite end of the plant in the plant's substation and RTU panel #3 is located close to the variable frequency power supplies for the two furnaces and holding furnaces. The equipment in RTU #3 has to operate under high electrical noise conditions and is subjected to high temperatures and vibration. The computer equipment is mounted in a cabinet located in a controlled environment in the plant's server room. All the data acquisition equipment is manufactured by Opto22 and provides optically isolated input and output modular interfaces. KWh, kVARh and time synchronizing pulses from the utility metering are connected to the input modules in RTU panel #1.
Multilin PQM meters supply kWh and kVARh energy data for the plants aux loads and for each furnace and holding furnace. The RTU panels are interrogated by the E2MS data acquisition computer via a dual fiber optic highway using RS485 and RS422 serial communications. Control outputs on the Opto22 data acquisition equipment in RTU panel # 3 are connected as inputs into the plants individual furnace PLC control systems. These outputs raise or lower individual furnace loads in accordance with the plants predicted load and desired demand target. The operators can select the order of furnace control through the control configuration.
Overview of the systems
Figure 5 shows an overview of the plant application as described in the previous sections. The present system allows an authorized user to view real-time and historical data from all plants from anywhere on the network. The existing system as installed can also be extended to provide aggregation of each of the plant's profiles, and real-time data, into a format suitable for purchasing power under a deregulated market.
System Operation
The following description is applicable to each of the Wescast Castings plants using the E2MS system.
The computer system continuously obtains electrical information from the plant's main utility meters, and from the transducers and meters on the furnaces and aux loads. At each plant the E2MS control software module monitors the energy being used at the plant and forecasts the plant's demand in accordance with the power utility billing algorithm used at the plant.
For the North Huron plant, on Time of Use rates, the control program compares the forecast demand with the desired set point demand, as determined by plant management, and issues control commands to raise or lower furnace loads.
For the Brantford and Wingham Castings plants, on RTPII rates, the control program operates slightly differently. The plant management sets the desired hourly demand target in accordance with the hourly kWh rate, issued daily by OPGI, and with the desired production schedule. The melt department shift leader enters the prices into the software and sets the hourly targets based on the production schedule. The system control module automatically changes the target each hour in accordance with the preset requirements. As the hourly pricing is generally lower at night and on weekends, the melt department will melt as much as possible during the night and build an inventory of molten iron in the holding furnace. The plants will then run at a lower load during the daytime when costs are higher, the load being restricted by the control program.
In all plants the output signals are sent to the appropriate RTU panels where they operate digital output modules which in turn signal the process control PLCs to make the appropriate adjustments in load.
The system operators are provided with a real-time graph of overall plant load versus time, with the set target load displayed, together with full analysis tools for historical and cost analysis. In addition to the overall plant total, the load on each individual furnace is also shown. The control of demand is smooth and is applied in stages to the furnaces in a set order in accordance with the plant production requirements. Reloading of the furnaces is automatic after the load has fallen to the restart level as defined in the system configuration. Every time a control operation takes place, the activity is written into a control log together with the time, date and demand at that time.
The load target is password protected and may be changed at any time by authorized users when on the control screen. The output control levels are computed on a minute by minute basis using the utility metering signals. The system has several major communication routines. These routines are:
(a) The one minute read, on the minute, of all RTU metering counter registers. This information is used for real-time load prediction calculations and for load control and is saved for future analysis.
(b) The five minute read and filing of all RTU metering counter registers. This 5 minute information is used for bill verification purposes in the deregulated markets.
(c) The 15 minute read and clear, on the 15 minute mark, of all RTU metering counter registers. This information is filed in a database using Access, Oracle or SQL and is used for historical billing analysis purposes.
(d) The one minute control signal to update the outputs in the various RTU panels in accordance with the load forecasts.
Menu driven routines provide access to the stored data and logs for analysis purposes. All E2MS systems are network enabled allowing authorized multiple users to access data from across the Wescast network.
System Software
The SYSTEM software, as installed at Wescast industries, consists of the following major modules.
(a) Communications module: This module provides the data acquisition functions and interface with the control equipment via the plant RTU.
(b) Display module: Provides the user interface with the system both in graphical and spreadsheet format using Windows 98/NT system software.
(c) Analysis module: Provides graphical and spreadsheet analysis of the stored data including maximums, minimums, coincident demand data, energy use and load factors.
(d) Report module: Provides reports on power use and plant running costs including bill verification by generating utility bill.
(e) Database filer: Stores the data and configuration parameters in ODBC compliant database.
(f) System and cost configuration module: This module allows the number of points to be entered, identified and utility metering algorithms assigned together with energy and demand costs. Both RTPII and Time of Use (TOU) rates are provided.
(g) Automatic demand control module: This module uses the E2MS load prediction calculation to determine the demand and rate of energy use in accordance with the rate setup in the system configuration.
Plant experience with the system
The systems at Brantford and Wingham Castings were first introduced in the mid 1990's. Over the years modifications and enhancements were made to cater to advances in computer technology and changes in billing tariffs.
The introduction of the RTPII tariff was a challenge to the system programmers as the tariff was very complex and required a great deal of development and testing. There have been savings made with the system through the limiting of demand and identification of operating opportunities.
Current work involves enhancements to the products to make them ready for the deregulated market. In this respect hourly prices will be downloaded directly from the IMO into the E2MS software without the need to enter them manually.
T. Thoma is Director of Technology, Wescast Industries Inc. and L. E. Crossley P.Eng, is Executive Vice President, Engineering, E2MS Inc. ET