FROM MAY 2004 TO SEPTEMBER 2005, A WASHINGTON UTILITY BUILT A COMPLETE SCADA SYSTEM. In addition, Lakeview Light & Power (LL&P; Lakewood, Washington, U.S.) also replaced every protective relay on its system, and upgraded controls for all transformer load-tap changers (LTC) and voltage regulators. And, just for good measure, LL&P completed a major renovation to its central office/customer service center, adding an operations center with a mosaic-tile map board.

With a list like that, you might expect LL&P would swear to never, ever again undertake so much in such a short time. However, the projects went remarkably well, and the operational and customer-service benefits to its 10,000 electric consumers in the Lower Puget Sound community of Lakewood have been substantial. The utility says it would definitely do it all again.

CHALLENGES AND OPPORTUNITIES

The LL&P system consists of three distribution substations with four transformers, serving 16 radial feeders. The distribution system is predominantly urban, with a mix of overhead and underground construction. Sectionalizing switches allow LL&P to remove any one transformer and its associated bus and feeder breakers without interrupting service to customers.

Until 2004, two substations were equipped with original-issue electromechanical protective relays, while the third, Lake Grove, was equipped with 20-year-old analog relays. LL&P did not have any form of SCADA (supervisory control and data acqusition), nor were there any digital instruments in the substations. The utility performed all meter reading, switching and post-fault target collection manually and locally. In recent years, analog relay failures exhausted the utility's spare supply, and additional failures would have made it difficult or impossible to safely keep all the equipment in service.

LL&P entered into discussions with vendors to explore options for relay replacement. At the same time, remodeling work in the utility's central office was ready to begin. LL&P had included an operations center in the remodel plan and, while it was possible to maintain the planned new map board manually, the utility hoped to identify a protection upgrade path that would support an affordable SCADA system to integrate with the map board and provide remote access to the new substation intelligent electronic devices (IEDs).

POSSIBILITIES AND PROMISE

LL&P talked to several vendors that would supply either new substation protection or a traditional remote terminal unit (RTU)-based SCADA system, or both. One vendor, System Protection Services (SPS; Lewiston, Idaho, U.S.), proposed to install new protective relays and use them as the data acquisition and control front end of a SCADA system. Further, SPS was developing a new approach to the hardware installation that it claimed would reduce the length of construction outages. The unified approach to protection and SCADA, coupled with the reduced outage length, made SPS's proposal extremely competitive.

In May 2004, LL&P awarded SPS the contract to upgrade all protective relays in the Lake Grove Substation and develop a SCADA system that would support the single substation. By that time, the central office remodel was well under way and would be complete by the September construction outage, providing a home for the new SCADA Master PC. Figure 1 shows a portion of the new operations center.

THE LAKE GROVE PROJECT

For the protection upgrade at the Lake Grove Substation, LL&P requested the replacement of every protective relay for 12.5-kV feeder breakers, bus main breaker, transformer differential and transformer backup overcurrent. The utility took advantage of the built-in breaker controls offered by the selected SEL-351S-7 relay and removed the existing pistol-grip breaker control switches. Feeder-tagging toggle switches for recloser disable and ground-element disable were replaced by front-panel control push buttons on the new relays. Integrated this way, substation and remote SCADA controls were designed to fully control the relay without risking disagreement between the field and SCADA switch positions. Table 1 lists the key protection capabilities provided by the new relays.

Demolition, construction and commissioning were performed during two weeks surrounding Labor Day weekend in 2004. The replacement protection module approach worked as advertised: two electricians removed the existing relays, then installed and commissioned the new relays and communication equipment in less than eight workdays. Much outage time was saved because each protection module included a new relay prewired to its test switches. Figure 2 shows the new switchgear lineup after the protection module installation was complete.

SCADA SYSTEM CAPABILITIES

The SCADA system was installed and commissioned at the same time as the protective relays. The SCADA system architecture offers us a great deal of flexibility in the communication channel and protocol selection. Figure 3 illustrates the major components in the SCADA system.

In conversations with SPS, LL&P requested a SCADA interface that would be simple to operate and provide basic control and real-time data-presentation features. Along with what it requested, LL&P also got some novel features that have turned out to be quite valuable. Table 2 lists the SCADA system capabilities provided in the initial project.

The SCADA Master PC runs an Object Linking and Embedding for Process Control (OPC) server that handles real-time data and control with the substation communication processor and makes the data available to OPC Client software packages for several functions. The channel and software flexibility are the most attractive features of this system. Real-time data on the Master PC is in an OPC format and is available to any properly configured OPC Client on the network. The Master PC runs OPC Clients for the SCADA interface, event paging and map board control. In addition, LL&P has installed the SCADA interface client on a laptop PC that can then be connected to a network jack in the substation. All of the real-time data acquisition and control capabilities available in the control center are also available in the substation using the network-connected laptop.

Table 1. New protection capabilities.

Feeder phase and ground overcurrent protection

Feeder reclosing

Bus main phase and ground overcurrent protection

Transformer primary differential protection

Transformer backup overcurrent protection

Recloser enable/disable

Ground protection enable/disable

SCADA remote control enable/disable

Local breaker trip/close]

Feeder alternate relay settings (enabled under certain switching conditions)

Table 2. Initial SCADA system capabilities.

Single-line display of all breaker positions, tag application and essential metering, including substation battery voltage

Detailed display of relay targets, AC meter quantities, breaker and relay controls, by feeder

Apply and remove reclosing and ground element tags

Select active relay setting group

Automatically update map board display with real-time breaker positions

Provide manual interface for map board display of unmonitored switch and breaker positions

Indicate control-house door positions

Display most recent event data (fault type, date, time, location and current)

Automatically generate text messages (including alarm type or fault type and current) for feeder and substation outages and critical alarms

Log inception, acknowledgement and clearance of substation alarms

Automatically retrieve and archive event reports from all new relays

Provide remote engineering access for nonroutine data acquisition and setting maintenance

Provide backup telephone-line-based access via secure modems

Table 3. Second-round protection additions.

Replace transformer load-tap changer controls

Add transformer tap position monitors]

Add substation satellite-time clocks for event data synchronization

Develop fast-bus tripping, automatic bus restoration and automatic load-shedding scheme for Roy Miller Substation (double-ended sub)

Table 4. Second-round control additions.

Add remote manual tap position and voltage regulator control

Incorporate transformer top-oil temperature, winding temperature and substation ambient temperature measurement, display and alarms

Monitor and control transformer cooling fans

Monitor transformer nitrogen pressure and LTC oil-filter alarms

Monitor 115-kV disconnect switch positions

SYSTEMWIDE COMMITMENT

LL&P was pleased with the system performance and quickly requested an upgrade to the protection in its Tyee and Roy Miller substations, and had them added to the SCADA system. LL&P also expanded the upgrade to include new transformer load-tap changer controls at its Lake Grove and Roy Miller substations, as well as integration of the voltage regulator controls it had installed at the Tyee Substation. Tables 3 and 4 list the protection and control capabilities that LL&P added in the second round of upgrades.

Like the Lake Grove outage in 2004, the Tyee and Roy Miller outages (three total) each lasted less than two weeks. Figure 4 shows the Roy Miller switchgear lineup after the final installation outage.

Figures 5 and 6 show two of the most frequently used SCADA interface screen styles. Screens for each substation provide an overview of the present substation breaker positions, meter quantities, and active alarms or tags. The feeder management screen displays relay targets, tag positions, more detailed meter readings and a summary of the most recent event data. Screen controls are presented in a fashion that represents the substation controls as closely as possible. This presentation is an aid to understanding and reduces the already short learning curve of the system.

RESULTS, BENEFITS AND LESSONS

The results of these projects are almost overwhelmingly positive, though LL&P has learned a few lessons it wants to share for the benefit of others who may be considering this type of project.

LL&P's responsiveness to electric outages has improved dramatically. In the past, like most utilities its size, LL&P needed to wait for customer calls to recognize the scope of an outage. Today, key staff receive page messages from the SCADA system for nearly any fault. Using the pager information, LL&P can immediately dispatch a line crew, sometimes before the first call comes in at the call center. Since it knows the nature of the fault, the crew is better prepared for what they will find, and LL&P is able to restore power more quickly than before.

LL&P has a better understanding of the electrical properties of its system. After experiencing a feeder relay trip due to sustained high current imbalance, the utility used meter quantities presented by the system to rebalance its feeders. LL&P was able to maintain reasonable sensitivity in its ground protection because its loads were better balanced.

System switching operations are performed more efficiently. Using a laptop PC in one substation, the utility can control reclosing, ground element enables, circuit breakers, transformer load-tap changers and voltage regulators in all three substations. The ability to immediately see the feeder and transformer loads during switching operations and to control substation apparatus from a single site makes switching operations go smoothly, predictably and quickly. This can be a real money saver when line crews are on overtime responding to a system event.

The best way to learn the usefulness of a new tool is to have it suddenly taken from you when you need it. Presently, a retail communication vendor supplies network drops into each of the three substations. One of those drops is served by the vendor's own repeater, powered by a feeder from Roy Miller Substation. The repeater has a battery-backed uninterruptible power supply (UPS) designed to serve the repeater after loss of AC service from Roy Miller. LL&P learned about the repeater when the 115-kV line into Roy Miller Substation faulted out for nine hours during a recent storm. The utility lost SCADA communication with Roy Miller approximately an hour after the fault when the repeater UPS battery expired earlier than the communication vendor had intended. LL&P's long-term goal is to acquire direct control of the communication drops into the substation.

The utility's operations staff adapts more easily than most get credited. There was some initial concern about the change in breaker control switches and feeder-tagging methods that these upgrades brought. Once the Lake Grove upgrade was complete, acceptance was nearly universal. The new controls are clean and easy to understand. Furthermore, safety is improved because most energized breaker switching is done remotely over the SCADA system. Staff can be clear of the switchgear aisles when breakers close, reducing arc flash hazards. And everyone appreciates the ability to serve customers better by reducing the length of outages.

FUTURE OPPORTUNITIES

As LL&P works with the SCADA system, the utility has naturally thought of additional things for which to use it. By June 2006, LL&P intends to have the following new capabilities operational:

• Cold-load pickup scheme

  Following the long outage of the 115-kV service to Roy Miller Substation, LL&P discovered that cold-load pickup could make it difficult to restore service to some of those feeders. The utility is implementing a cold-load pickup function that can be enabled at each feeder relay front panel and is using the SCADA system to simplify service restoration the next time it has a long outage.

• Breaker and substation maintenance data

  The new relays are configured to track breaker operations for maintenance purposes. The SCADA system monitors transformer, LTC and battery-charger performance alarms. LL&P's goal is to incorporate these data sets into a simple substation maintenance scheduler to automatically keep track of maintenance to-do lists by substation and by equipment type.

• Logbook entry automation

  The SCADA system supports a simple logbook function to allow the utility to make operational entries. The system also tracks inception, acknowledgement and clearance of selected system alarms. LL&P has requested that these functions be modified to automatically make a logbook entry when certain system control actions are performed using the SCADA system.

• Automatic load profile and system historian

  LL&P used to download feeder load profile data from each relay on a monthly basis. Since the system is already collecting this data in real time, this seemed like a redundant step. So, the utility is now automatically archiving selected data on the SCADA Master PC and using a web interface to turn the collected data into graphical and textual reports. The report generator e-mails preconfigured reports to management automatically each month, and can also be used to generate special-purpose reports on demand. Since breaker and sectionalizer switch positions will be stored with the analog data entries, LL&P expects the data archive to deliver useful insights into system loading over the years, which may allow the utility to postpone future capital investments through system configuration changes.

To successfully advance your protection and control technology by approximately 30 years — in the space of about 17 months — and systemwide requires a big commitment by utility management and a lot of open-mindedness on the part of everyone from the line crews to utility directors. It also can take the support of quality vendors if a utility does not have the in-house time or experience to tackle the job alone.

LL&P has found that making the leap to new protection and SCADA has transformed the way it operates its system and serves its customers. LL&P expects these investments to yield tangible benefits for many years to come.

ACKNOWLEDGEMENT

The authors would like to thank LL&P's General Manager Robin Rego and the board of directors for making these projects possible.

Tony Rusin is a meter and substation technician for Lakeview Light & Power (LL&P). He has been with LL&P for 27 years, acquiring journeyman cards as lineman, wireman and meterman. He has extensive knowledge in personal computing and networking, and holds the titles of network administrator and purchasing agent for the utility. arusin@lakeviewlight.com

John J. Kumm is principle engineer and owner of System Protection Services (SPS). SPS provides protection engineering; system integration; and relay coordination, fault and arc-flash hazard studies to the electric industry. The company invented the EasiLinc protection modules, which simplify the application, installation and integration of high-performance protective relays. Kumm is a licensed professional engineer. jkumm@systemprotection.com