Deregulation is forcing energy suppliers and consumers to pay close attention to the metering of energy at every exchange point in the power system than ever before. Simple metering at the point of consumption is no longer enough.
Today, independent generation, transmission and distribution companies, as well as independent system operators, power brokers and energy services companies all have an unprecedented need to measure the contractual performance or compliance at the interfaces between these entities. Corporate entities that expects to survive in the deregulated energy market are developing plans for a Performance Metering system.
Performance Metering systems measure and analyze the delivery of goods and services. It is also a business tool -- and sometimes a lawyer's tool --and it is indispensable in a deregulated energy environment.
The Performance Metering Challenge
In the energy market, the exchange of goods and services for money is becoming increasingly difficult to define, measure and manage. We now have concepts like cogeneration, wheeling, interruptible rates, time of use rates, and real time pricing. In response to consumer demand, progressive power utilities are implementing contractual commitments to power reliability, power quality, and even "green power."
Unlike conventional EMS and SCADA systems, there must be a Performance Meter to verify delivery at every supplier/consumer exchange point where energy goods and services are exchanged. These Exchange Points exist throughout the power grid, and define the point of supply and the point of consumption. Exchange points exist between the generating company (GenCo) and the transmission company (TransCo), between the TransCo and the distribution company (DistCo), and between the DistCo and the End User.
At each exchange point, the performance meter has to satisfy the information needs of the supplier and of the consumer. That is, the information must be able to satisfy both parties that the contracted goods are being delivered, and to provide proof if a dispute arises over the performance of the supplier.
Performance Metering for the End User
The exchange point that services the end user is the most common metering point for performance metering in a deregulated market. In addition to providing the ability to display traditional energy and demand values in real time, the performance meter must be able to:
- generate billing and financial data, and to display historic energy, demand and cost data.
- aggregate energy and demand for all -sites belonging to the End User.
- broker power purchase contracts and display costs in real time. Real-time Pricing requires up-to- the-minute information for the price of goods.
- negotiate interruption requests in real time and display interruptible rate compliance.
- view and analyze power quality data for the plant (type, magnitude, direction, and cause of disturbances), and correlate the disturbance to production problems and other system events.
Performance Metering for the DistCo
From the perspective of the DistCo, performance metering must be able to provide all the information that the End User is expected to want, and then some. As a distributor, it will be your responsibility to keep all your customers satisfied, which means more than traditional energy and demand metering. As a customer to the TransCo, you will want to have access to the kind of information that the End User wants, as described above. In addition, the performance meter must be able to:
- determine the source, cause, magnitude and ripple effect of any power quality disturbance
- determine the compliance of major customers to demand limits and interruption requests.
- compute network energy and power demand losses
Performance Metering for the TransCo
Going further up the supply chain, the exchange points between the DistCo and the TransCo are a direct result of deregulation. As a transmission service provider, you must keep all your customers (DistCo's) satisfied, which means you need access to all their information. As a customer of the GenCo, you will also want to have access to the kind of information that the End User wants, as described above. The performance meter must be able to:
- analyze capacity utilization in real time
- analyze power quality data, energy flow and efficiency.
- broker supply / delivery contracts from GenCo's and to DistCo's in real time.
Performance Metering for the GenCo
If you generate electricity, you will need to have access to the same information available to your customers (TransCo's, etc.). You will also need up-to-date information to decide the prices that should be posted in real time pricing schemes. Performance meters must be able to:
- determine available capacity based on anticipated and contracted loads, and compliance with existing supply contracts.
- determine cost to produce (including losses).
- determine level of power quality to determine the source, cause, and magnitude of any disturbance which affected its ability to deliver power as contracted.
Versatile Performance Meters
The difficulty for utilities is finding a performance meter that can measure the delivery of goods and services at the exchange points, and satisfy the whole spectrum of needs of each entity in the system.
Most vendors offer conventional meters that have very restricted configurability, which in turn makes it difficult to extract performance metering information from the standard energy and demand readings. If the meter cannot be adapted to filter the data for new kinds of information, it usually means "out with the old and in with the new" when your metering needs change. Obviously, this is a very expensive approach to the problem of implementing a maintainable performance metering system.
The only Intelligent Electronic Devices (IEDs) that begin to address this problem have the ability to be reconfigured for specific applications: e.g. some level of programmable logic for waveform recording and signaling based on setpoint conditions. The most advanced performance meters offer object modularity within the device that allows you to select operating modules needed for specific applications.
This approach takes advantage of the most powerful aspect of object technology: a network of objects that can be easily linked to create exactly the system you need. An intelligent Performance Meter with object technology can be configured to monitor exactly the conditions that are most critical in your power system, interpret the data in the field, and send very carefully focused information to the host computer system.
Networked Information Management
The performance meters in the field comprise only a part of the complete performance metering system. It also requires an information management infrastructure that makes all information available to the right people, in the right format and at the right time.
The physical information network that meets this information management challenge requires that every meter is connected over a communication backbone to a network of computers and software that can be used for information management, as well as analysis and control.
The information needs to be in a format that is useful to the customer. The user interface, for example, should support system diagrams with easy access to fine details as well as general overviews of the system operation.
Individual companies and user groups must be able to protect and secure data which is confidential and proprietary to them, and at the same time share data which is of mutual interest with others.
Information management systems based on low-cost desktop workstations using the Windows NT operating system and conventional networking are rapidly becoming commonplace. Using non- proprietary components allows you to take advantage of best-in-breed technologies as the system grows with your needs, and to connect to wide area information sharing systems that are required by real-time pricing and independent system operators.
Application of Performance Metering
TransAlta Utilities in Alberta is one of the first Canadian utilities to deploy a performance metering system in response to deregulation of the electricity market. The system is based on over 400 intelligent performance meters, distributed performance metering software, and interfaces to existing MV-90 billing systems.
Each of the 7700 ION performance meters, manufactured by Power Measurement Ltd., is used to monitor the delivery of the goods between the generating companies and the grid, or between the grid and the distribution companies. The PEGASYS software is connected through the corporate information system Intranet, giving easy access to all users that need it.
There are many applications that can and will be met with TransAlta's Performance Metering System (see T&D Automation Expo, 1996 Conference Proceedings). In addition to the engineering and operational uses (real-time data, disturbance monitoring, load research, etc.), the stated intention is to use the system for power quality monitoring and real-time pricing, and to position TransAlta as a recognized vendor of high-quality electricity and services.
Summary
Deregulation of the electricity supply industry is causing fundamental change in the way electric utilities operate. To thrive and prosper in this new market, utilities are offering new electrical energy products, new value-added services and new performance-based contracts to their large and valued customers.
With these changes, the exchange of energy goods and services is becoming increasingly difficult to measure
Performance Metering Systems provide the fundamental tools to accurately and securely meter the performance of suppliers and consumers.
Rudi Carolsfeld is a Marketing Applications Engineer with Power Measurement Limited of Victoria, Canada. He is a member of the IEEE. He can be reached by E-mail at: rudi_carolsfeld@pml.com. ET