Energy Monitoring: A Foundation for Effective Energy Management
Author: Dennis Stewart, Centric Design May 2008 / Whitepaper
Energy Monitoring: A Foundation for Effective Energy Management
Contents CONTENTS .................................................................................................................2 EXECUTIVE SUMMARY .............................................................................................3 INTRODUCTION..........................................................................................................4 THE INITIAL SOLUTION .............................................................................................5 ADDING NATURAL GAS AND STEAM.......................................................................5 MANAGING ELECTRIC ENERGY CONTRACTS .......................................................6 GENERATION AND NET METERING.........................................................................7 OPC CONNECTIONS..................................................................................................8 HEAT TREATING FURNACE ......................................................................................8 ENVIRONMENTAL SUSTAINABILITY ........................................................................9 SYSTEM RESULTS.....................................................................................................9
Whitepaper on Energy Monitoring & Control - 2
Energy Monitoring: A Foundation for Effective Energy Management
Executive Summary Energy Monitoring: Modern manufacturing processes run on energy. Electricity and natural gas are common inputs to all manufacturing. Other fossil fuels such as oil and coal are also widely used. Instability among global energy suppliers and increasing environmental impact concerns are causing many manufacturers to reevaluate their use of energy. In order to control energy use and the associated environmental impacts it is necessary to understand how and when energy is used. This paper describes a monitoring and control system that allows one major manufacturer to both understand and control their energy use. This has resulted in cost savings and understanding and control of greenhouse gas emissions associated with the manufacturing processes. The paper describes some details of a particular system, but the methodologies described have been used in multiple locations with similar success.
Whitepaper on Energy Monitoring & Control - 3
Energy Monitoring: A Foundation for Effective Energy Management
Introduction Modern manufacturing processes run on energy. Instability in energy supply and pricing and increasing concerns about environmental impacts are causing many manufacturers to reevaluate their energy use. In order to control energy use and associated impacts it is necessary to understand how, when, and why energy is used. One major manufacturer commissioned an energy monitoring system as a tool to understand electrical use in multiple buildings on their large manufacturing campus. The facility has a 13kv distribution system consisting of multiple feeders that provide electricity to multiple buildings. Most feeders on the system feed multiple transformers, so the building load cannot be determined simply by reading individual feeder loads. Furthermore, the complexity of the distribution system and the building transformers is such that most building loads could not be defined simply by installing meters on a limited number of connection points. The client had a business requirement to track electrical energy consumption and demand for each building. To determine building loads, it was necessary to add or subtract multiple meter readings together into a collection of total readings. Early meetings with the client defined planned meter locations and the necessary combination of readings to achieve the desired totals. The client had already chosen an electrical meter manufacturer and was installing their meters at the start of the system project. This made it necessary that the system provide an open architecture and support for multiple protocols. The client also required access to the system from multiple locations around the facility so that key personnel to check electrical system conditions in real-time from their daily work locations.
They chose Citect Integration Partner (CIP) Centric Design as the system designer/integrator as a result of the long history of positive experience and trust with Centric Design representatives. This white paper describes how a Citect system was applied to the customer’s requirements and how that system has evolved over time, keeping pace with every
Whitepaper on Energy Monitoring & Control - 4
Energy Monitoring: A Foundation for Effective Energy Management
requirement to enhance the customer’s business operation and simplify their management of energy in the facility.
The Initial Solution The initial system was designed using CitectSCADA 5.41. Communications to I/O devices was achieved through a combination of Ethernet and serial channels. The system initially connected 20 advanced electrical meters and 2 electric utility billing meters to the power monitoring system. Most of the advanced electrical meters were Electro Industires/Gaugetech Nexus 1250 meters. The electric utility billing meters were TransData Mark V energy meters. The advanced electrical meters were installed on each of the 13kv feeders in the facility’s electrical substation and at selected locations around the plant to provide the ability to calculate individual building usage. The original system design included the following:
Active plant electrical system graphic displaying electrical conditions and breaker (switch) status in the facility’s electrical substation Electric energy consumption for each building (achieved by adding and subtracting various electric meter kwh readings) Electric demand for each building (calculated from individual building consumption data) Power flow, energy, and demand through the two power transformers that feed the plant Alarms on breaker (switch) status Alarms on high current and low/high voltage around the facility Trending of power and demand for the plant and buildings Tracking electric energy delivered through the electric utility billing meters Two Internet Display Clients were installed to allow engineering personnel to access system data from various locations in the facility
The electric utility billing meters provided energy pulse outputs. Those pulses were totalized and used to calculate energy use, demand and power flow. These calculated numbers were compared to the composite numbers for all the feeders connected to the main facility electric substation. As a result of the initial system installation, facilities engineering, operations, and management personnel began to see benefits and identify improvements in operations that would provide additional value. Shortly after the system was installed, operations personnel identified a need to add free-form text fields for each monitoring location. These notes pop-up boxes allow users to enter operational notes regarding the electrical circuitry at each monitored location. This allows them to maintain a central repository for important information regarding the operation of the electrical system.
Adding Natural Gas and Steam In 2004 facility energy managers decided to add gas and steam monitoring to the energy system. The addition was complicated by the desire to use available transducers to minimize installation cost. Steam lines had flow transducers. Gas lines had only pulse outputs from the gas utility billing meters. The client desired to have
Whitepaper on Energy Monitoring & Control - 5
Energy Monitoring: A Foundation for Effective Energy Management
consumption, demand, and flow data for high and low pressure gas connections and various steam lines feeding the plant. Sixnet I/O devices were connected to the various inputs to collect raw data. This data was processed in a Sixnet PLC to calculate the required consumption, demand, and flow data. This approach saved the client thousands of dollars which would have been required to take shutdowns and install the necessary metering devices which would have been required to have collected the raw data directly. The calculation methods applied have provided sufficient accuracy to meet the client’s monitoring requirements.
Similar to the pattern developed in the earlier electrical deployment, the system provided consumption and demand data and current flow for each measured location. Consumption is provided in month-to-date numbers. Monthly totals are stored in a system database for historical retrieval. The system includes active single line diagrams showing current operational status and data for all steam and gas usage by the plant.
Managing Electric Energy Contracts Changes in the electrical energy market resulted in additions to the system in 2005 when the facility changed their energy supplier. The new energy contract included several provisions that made it advantageous to improve the facility’s understanding of their daily energy use. To improve their ability to stay in compliance with the new energy contract, the facility energy manager decided to make two major changes to the energy system. First the system was modified to automatically report energy usage to the energy supplier every fifteen minutes. Total electric and gas energy consumption for each 15 minute interval is captured. At the end of each interval, the system automatically connects to the energy supplier’s servers via an Internet connection and downloads the consumption data. For each interval the system reports total imported electric energy, total on-site electric generation, and total gas consumption.
Whitepaper on Energy Monitoring & Control - 6
Energy Monitoring: A Foundation for Effective Energy Management
The second change to the system was much more complex. The energy contract has a specified monthly limit in kwh. In order to ensure that the facility’s total monthly energy does not exceed the contract limit, the system calculates a daily energy budget based on the monthly limit. On the billing date each month a new budget for the entire month is calculated. The new daily limits calculated are based on prior usage patterns.
Throughout the month, the system tracks energy consumption for each day and month to date. A calendar screen displays the daily and month-to-date energy use and percent of budget. The screen also provides visual warning when daily or monthto-date usage is higher than the calculated budget. This change gave impetus to make another change. It soon became apparent that in some months the facility would buy energy on the spot market. As a result, the system was further modified to allow a daily entry of spot purchases. These spot purchases have to reflect into the budget so that the system still presents an accurate representation of the month-to-date performance against the contract limit. The system changes to manage the energy contract have proven to be extremely valuable in controlling total energy cost.
Generation and Net Metering The facility had installed two large co-generation units in 2002. However, changes in their electrical supply contract in 2007 resulted in changes to the method of operation of those generators and an associated change to the system. Prior to 2007, the co-gen units had been used to supply internal energy needs. During those first years, generation was used to offset energy purchases from their electric supplier. A new contract for 2007 resulted in the company having the ability to sell generation onto the electrical system. As a result, the facility needed to be able to track energy into and out of the plant. To achieve the desired goal, the system was modified to gather pulse outputs from the billing meters for energy flow in both directions, rather than only incoming energy. The system tracks energy in each demand interval and calculates demand and peak
Whitepaper on Energy Monitoring & Control - 7
Energy Monitoring: A Foundation for Effective Energy Management
demand in each direction. The usage numbers are tracked monthly and stored to provide a record of energy use and sales.
OPC Connections In 2007, facility management determined that there was a need to integrate additional data from existing systems into the energy system. The customer site has a Wonderware system that was originally installed to monitor and control the cogen units that were installed in 2002. Additionally, the site has a Honeywell EBI system for facility management. The customer specified selected data from both the Wonderware and Honeywell systems that were to be pulled into the Citect Energy System. The intent of this addition was to replicate selected system views from the external systems inside the Energy System. Successful OPC connections have been installed to both external systems. The data pulled from the Wonderware system enables plant management to better monitor the conditions of the cogen facility and the load-shed control system. As a result of this addition, plant management has identified a problem with the load shed system that prevents it from fully protecting the plant for the loss of the utility feed. The data pulled from the Honeywell system will be used to provide plant floor views of electrical use. The new views will provide real-time access to electrical conditions at machine tools located throughout the facility. The connectivity capability of the Citect Energy System coupled with the ease of access to the system through the web clients made it the ideal platform to expand plant management access to the critical operating data from the external systems. These OPC connections further improve the ability of facilities and plant operations personnel to view and understand the real-time condition of energy use and to assess the accumulated impact of energy use decisions on daily and monthly intervals.
Heat Treating Furnace In 2008, the facility added a new heat-treat furnace. This furnace is fueled by natural gas and electricity. Plant and corporate management desired to track both energy inputs and the results of inputs for the furnace. As a result, the Citect Energy System
Whitepaper on Energy Monitoring & Control - 8
Energy Monitoring: A Foundation for Effective Energy Management
was connected to an EIG Shark electrical meter and a Mercury Instruments gas meter. Data from both meters has been added to the system. The system collects energy inputs to the furnace and calculates daily and monthly energy use. The system also connects to the PLC that controls the furnace. Furnace temperatures and batch data are collected from the PLC.
With the combined data, the energy system correlates energy inputs with temperature results and tons of material treated. The real-time temperature changes that result from incremental energy inputs are calculated. This allows plant managers to see the real-time performance of the furnace and compare it to prior performance. Plant managers expect to be able to detect very slight performance degradations that occur over time as burners and other components age. This will allow timely maintenance and repair to ensure that they are getting the highest possible return on energy costs and are having the minimum possible environmental impact from operation.
Environmental Sustainability The company that owns this facility has elected to be proactive in addressing greenhouse gas emissions and has adopted a policy of sustainable manufacturing. As a result, there is a high level focus on greenhouse gas impacts of energy use. Late in 2007, in response to the corporate sustainability policy, plant managers decided to attempt to track greenhouse gas impacts of plant operation. In 2008 the first additions to the system to address greenhouse gas were added. The system tracks greenhouse gas impacts of electrical consumption and of selected natural gas uses. The corporation has established greenhouse gas emission targets for coming years. The energy system additions allow plant managers to track greenhouse gas emissions and tie them directly to the energy requirements of specific production activities. The system is designed to track direct Scope 1 emissions and Scope 2 indirect emissions. They are now able to take specific steps that will enable them to meet future greenhouse gas targets.
System Results The system started as a fairly simple monitoring system to help plant management understand their electrical system and electric energy usage in each building. Over
Whitepaper on Energy Monitoring & Control - 9
Energy Monitoring: A Foundation for Effective Energy Management
the years, the system has grown into a large and complex total plant energy system. It provides not only usage information for each building in the facility but also assists operations managers in controlling energy consumption and costs and contract compliance. Users of the system universally agree that the system has been an operational and financial benefit to the facility. They are confident that the system will continue to meet their energy monitoring and management needs because of the inherent capacity of the system and its demonstrated ability to change in response to changing business requirements.
About Citect: Citect is a global provider of industrial and facilities automation, realtime intelligence, and next generation manufacturing execution systems (MES). Leveraging open technologies, CitectSCADA, CitectFacilities and Ampla connect to multiple plant and business systems. Its products are complemented by Professional Services, Global Customer Support and Educational Services. Distributed in more than 80 countries worldwide, Citect solutions are installed in numerous industries: mining, metals, food and beverage, manufacturing, facilities, water/wastewater, oil & gas, power generation/distribution and pharmaceuticals. Citect has offices in Oceania, Africa, the Americas, China, Europe, India, Japan and Southeast Asia. © 2008 Citect Pty Ltd ABN 88 001 158 854
About Centric Design: Centric Design is a Citect Integration Partner specializing in monitoring and control of site utilities. Based in Boise, Idaho (USA), Centric Design provides Citect system solutions to support clients’ efforts to understand and control their energy use. Centric Design’s founder, Dennis Stewart, is an electrical engineer with over 25 years of experience in electrical systems. Centric Design’s clients include manufacturers, service companies, and institutions and are located throughout the United States.
Whitepaper on Energy Monitoring & Control - 10
