Deregulation of the electric power industry is radically changing the way
utilities function. Today, industry and manufacturers are increasingly automated, thus more sensitive to power quality. This comes at a time when utilities have less control over power quality due to wheeling interdependence.
And yet, in this new era of competition, improving power quality is indeed one of the most important actions utilities can take. Improving power quality not only differentiates utilities by adding value to their service, but also avoids possible million-dollar customer lawsuits from service interruptions.
Idaho Power is a progressive utility that has come a long way in a short time. Only a few years ago, the utility was manually recording meter readings for distant agricultural customers on paper charts. Today, Idaho Power remotely monitors the quality of power supplied to high tech industrials through state-of-the-art client-server software linked to digital meters.
Idaho Power knows the increasing importance of meeting high customer expectations of price, power quality and reliability. To this end, the utility is installing more distribution automation capabilities to increase efficiency and reduce costs. An infrastructure of digital metering is also being integrated into its existing SCADA and EMS systems.
Idaho Power realized that new, advanced metering technology was required to adequately measure performance at the interfaces between the utility and its customers. This metering system consists of a network of instrumentation, computers and software. The meters not only perform traditional revenue metering, but also analyze the power quality and reliability of the delivered product.
The metering system can correlate power quality events with their effects and share the information with customers. Many of Idaho Power's customers have also installed advanced metering systems in their plants to both verify the quality of power they receive and identify the source of power quality problems.
Integrated SCADA and Metering System
Idaho Power Company's territory covers some 20,000 square miles, from snow-capped Rockies to butte prairies. It encompasses southern Idaho, eastern Oregon and northern Nevada. But this vast service area roughly equal to New Jersey, Rhode Island, Delaware and Maryland combined consists of 79 towns and a dispersed population of only 700,000.
Idaho Power's 2,400 MW summer peak energizes the seasonal irrigation pumps in a large number of far-flung farming enterprises. Idaho Power also counts cheese, potato and ore processors among its customers, as well as an increasing number of computer and semiconductor manufacturers. These high tech plants many running non-stop, power sensitive, computer-controlled processes depend on clean, reliable power.
Generating most of its own electricity from 17 hydro and 3 coal-fired plants, Idaho Power delivers energy to these diverse customers through some 234 substations in a radial distribution system. Distribution is controlled by a SCADA system in which master workstations poll Harris remote transducer units (RTUs).
The utility reaches out to its dispersed customer base through box and mobile substations. The tiny agricultural box substations have all the necessary equipment encased in low-cost aluminum boxes.
About six years ago, digital power meters from Victoria, B.C.-based Power Measurement Ltd. (PML) were installed in these box substations. This was a marked improvement over earlier paper charts when data had to be manually recorded, then converted into digital form and, finally, integrated with other databases.
Once a month, during the growing season when the box stations operate at nameplate capacity, the data accumulated by the box stations' meters is transferred onto a laptop PC and brought to the distribution and planning department.
There, the data is analyzed to prevent the utility from overloading its equipment. We also use the data in formulating procedures to help irrigators increase the efficiency of their water pumps, said Kent Venosdel, Idaho Power engineer .
In addition to box stations, Idaho Power also has mobile substations. The two newest of these self-contained substations on wheels rated at 40 MVA with on-load tap changing capabilities are ready to roll in an hour as a convoy of three tractor-trailers.
These mobiles are deployed in remote areas when a substation must be upgraded or brought back on-line after a failure. Instead of working around the clock to patch a problem, a mobile's transformer can carry the downed substation's load until the utility has the parts to correctly perform the job.
While a mobile is on-line at peak load, equipment temperatures and the mobile's voltage output are measured by a digital power meter and a RTU, the latter measuring transformer temperatures. Weekly, the data is transferred from the meters' memory to a laptop PC.
It's a convenient way to collect date/time-stamped alarm information based on setpoints we've activated in the meters, Venosdel said.
If the mobiles are in service longer than two weeks, the meters can also be linked to the utility's
central SCADA system through its communications or dial-up modems.
Modbus and Transducer-Less Operation Cut Costs
Idaho Power is installing power meters in all newer permanent substations that distribute via secondary feeders. These meters communicate with its SCADA system over a network via the Modbus protocol.
The Modbus compatibility allows meters to communicate with other substation systems despite the lack of industry standard protocol.
Programmable meters also offer a range of information to choose from, including harmonic data.
Idaho Power is acutely aware that harmonics can generate problems in its distribution system. It shields its own equipment, and that of its industrial customers, from harmonics disruptive effects.
Harmonics can heat the core of our substation equipment and potentially create havoc with our manufacturers' sensitive, solid-state machines, Don Angell, engineering supervisor said. We've also had industrials, in the past, generating harmonics that caused problems for our other customers.
Instead of the earlier one-way C-Code, Idaho Power today has two-way communications between dispatcher and the substation RTUs and the power meters. Now, more than merely receiving alarm information, dispatchers can actually perform some control functions.
Power meters can also eliminate the need for additional transducers to collect voltage, current, watts and VAR information. Its a neat installation since we no longer have to daisy chain voltages around different types of transducers, which never gave us the option of getting any harmonic information, Angell said.
This reduces the amount of equipment, such as test switches and cables, needed to commission a substation. "Rather than evaluate a number of different gear, we now only need to test one device," he said. The RS-485 nework lets us connect several meters together in a substation. We now collect the data directly from the remote panel-mounted meters using Modbus. These meters, through our SCADA system, give us more consistent data and control.
The meters help Idaho Power control transformer loads while trending load cycle data. According to Angell, the utility improves reliability by correcting any problems it finds. Bottom line, transformers that are not overloaded and have a longer life . Power failures are avoided which is an improvement in power quality.
Idaho Power brings information from the meters into its SCADA master stations where specially created screen icons warn of alarm conditions. Collected data can now be sent to several different places. For example, information can be sent to the EMS master and to several different engineering groups in Boise for analysis.
Sharing the same data helps the utility to quickly correct the cause of alarms. This information
also helps the utility project loading conditions in planning future expansion.
On-Site Power Quality Audits
As presently integrated with the SCADA system, the digital power meters provide a broad range of setpoints that the utility can trigger on any selected values.
We can set the meters to trigger on abnormalities and then analyze that data to determine whether power irregularities were caused by us or our customers in their plants, Angell said.
From its newly-created power quality department, the utility uses PML's PEGASYS Windows NT-based client/server software to remotely monitor advanced new meters installed at larger semiconductor manufacturers and food processors.
This analytical/forecasting service is now staffed by power quality engineers. Helped by PEGASYS and the remote meters, Idaho Power engineers perform the power quality verifying process at the customer's interface.
As a value-added service, engineers from Idaho Power's wholly-owned subsidiary, Stellar Dynamics, go into these plants to help solve customer power problems. Based on analyses of power system and control processes, Stellar Dynamics engineers can design optimum power monitoring for customers and install the components to form an integrated, industrial control automation system. Once a system is installed and operational, either the customer or Idaho Power can remotely monitor power quality.
Power quality studies are usually triggered by a customer telephone call or letter indicating concern that its process is not operating at maximum efficiency and, therefore, the company could be losing money, said Vernon Padaca, Stellar Dynamics project engineer.
This applies not only to companies in the high tech sector, but most large industrials because of the automation built into their facilities. Padaca said.
Customers often don't know why, for example, PLCs or adjustable speed drives are coming off-line in their processes. Some high tech manufacturers have in-house facilities engineers who, unfortunately, are spread so thin they have to be experts in everything.
I can communicate with them easier because they know what voltage, current and a transient is, Padaca said. But even they get lost when we go deeper into power quality.
In other companies Padaca must deal with plant personnel lacking an engineering background.
Just explaining why machines are coming off-line, in other words how their own machines work, is at times fairly difficult, he said.
Padaca believes that part of the power quality investigation is educating himself by sitting down with customers and learning their plant processes.
It's also educating the customers that a disturbance may not be caused from right outside their door. In fact, the electrical disorder may originate hundreds of miles away, even from another utility.
Once Idaho Power understands the manufacturer's processes, one if its engineers may meter some
parameters to see if starting any motors cause voltage dips, thus possibly crashing the plant's
processes. It could be a utility-supplied disturbance causing the problems. If so, Idaho Power will
perform a system study to see what disturbances will affect this customer when the utility
experiences faults or switching in its power system.
Remote Monitoring of High Tech Customers
Idaho Power also monitors power-sensitive customers remotely to determine which disturbances affect plant production. Data is collected by the PEGASYS system, via dial-up modems and meters at technology-based businesses, and fed to the main computer in Boise.
For example, Zilog Semiconductors, located 20 miles from Boise in the city of Nampa, has a unit metering a transformer secondary. The transformer is the common point affecting two manufacturing buildings. The meter continuously monitors the power system for any disturbances that may affect Zilog's production.
In this case, a disturbance means a variance from an established setpoint. An under-voltage, for example, could be 90 percent of nominal voltage. Should the voltage fall below that setpoint, the meter takes a high-speed waveform recording of all voltages and current, calls up the Boise computer, and downloads the data that is logged by PEGASYS.
At work in the morning, the utility's engineers can immediately see that a disturbance struck because, on PEGASYS' screen, the Zilog plant changed color. The number of disturbances that may have happened are also registered on a counter.
On-screen, Idaho Power engineers will see graphically-displayed information, including recorded disturbance waveforms, current, voltage, min/max values, harmonics, and symmetrical components. From this main screen engineers can open other windows to see more details on the disturbances or any other related data they want to analyse.
Engineers may also check Idaho Power's transmission outage reporting system running on a mainframe connected to the utility's SCADA system to see if any disturbances occurred on the utility side, such as a fault, trip close or switch.
They'll look for any date/time correlation of data between what was downloaded from a customer's meter and what was monitored by the SCADA system. This informs the engineers whether it was a locally-caused anomaly, it originated from elsewhere through the grid or was an internal plant disturbance created by the customer.
Until PEGASYS and the digital power meters, we had no hard data to verify the validity of customer complaints, Padaca said. It's possible that customers were maybe overly sensitive to power fluctuations or perhaps created the problems themselves.
Padaca said the new system has proven so successful in finding the source of a disturbance, he plans to install digital meters throughout Idaho Powers service territory.
However, the utility's power quality function goes beyond assigning responsibility for power problems. "
Our primary mission is service, Padaca said. With deregulation and retail wheeling entering the industry, we're seeing opportunities to service our customers beyond our traditional bounds.
A customer already requested that Idaho Power perform power studies outside the utility's service area. Of course our industrial customers, headquartered elsewhere, may well have another utility come into our turf to conduct studies, Padaca said. It's becoming quite competitive.
Idaho Power sees power quality surveys and monitoring as possible revenue generators. The utility now monitors only its largest consumers, doing what it takes to retain them. However, smaller customers soon could have monitoring equipment installed on their premises by Stellar Dynamics and remotely monitored by Idaho Power.
Industrial customers need the ability to determine the magnitude, type, direction and source of disturbances. And they need to correlate any disturbance to other electric distribution system events.
In today's competitive atmosphere, Idaho Power is aggressively applying state-of-the-art
technology to meet customer expectations of the cleanest possible power. This not only helps
retain present customers, but also interests other companies to move their manufacturing
operations to Idaho's attractive business climate and lifestyle.
Power Measurement Ltd. (PML) is a manufacturer of advanced, multi-function digital power meters.
For more than two decades, PML has provided comprehensive, cost-effective power monitoring, analysis, and control systems to power utilities, and institutional, commercial and industrial facilities.
Today, the company provides local support through representatives and distributors in more than 50 countries.
Ralf Edler is a writer for TeleComputer Communications located in British Columbia.