During outages or grid disruption, it is essential to have a robust voice communications system in place. Mike Norfield explains how a UK company tackled this issue
Utility companies around the world are facing more demands than ever.
As energy resources continue to diversify to include a range of traditional and renewable technologies, there is also a need to manage this widening portfolio in a smarter, leaner and more efficient way.
Increasingly, companies that are striving to deliver the dream of smart grid technologies are finding that they are faced with major communications challenges when it comes to providing the information and control required for insight into grid performance and issues when outages occur.
In addition to these growing demands, there remains the constant pressure of keeping the lights on. Utility companies face major fines if power is not restored quickly after an outage so need to be able to respond quickly using reliable communications systems.
During outages or grid disruption, it is essential to have a robust voice communications system in place. However, the increasing demands of smarter grid systems mean data is also becoming an equally important part of the mission critical mix. And while there are a growing number of applications run on smartphones, tablets and other connected devices which exchange large amounts of data over broadband networks, it is typically reliable low-band telemetry data that becomes essential for diagnosing problems in the event of outages.
Despite this, many companies are using a mix of telemetry interconnecting technologies that each have limitations. This includes the use of cellular systems, such as GPRS, which are often patchy and unreliable. There are also a number of other unlicensed radio frequencies, such as 446 MHz, which are prone to interference and overcrowding and could leave companies exposed in emergency situations.
UK utility company Western Power Distribution (WPD) provides electricity to 7.8 million customers across a 55,300 square kilometre service area which covers the Midlands, South West England and South Wales.
The WPD network, which spans the width of the country from Penzance on the tip of Cornwall all the way to Skegness on the North Sea, consists of 220,000 km of overhead lines and underground cables, and 185,000 transformers.
Since 2007, Simoco has worked closely with WPD to install one of the largest analogue MPT1327 private mobile radio (PMR) voice networks in Europe, based on the Simoco Xfin system. The network was expanded in 2012 and WPD strategy has been to enhance this core network and introduce services such as SCADA (supervisory control and data acquisition) technology.
WPD asked Simoco to consider using the PMR systems in the Midlands to carry secondary SCADA telemetry data owing to poor coverage, interference and reliability issues. WPD was looking to move away from its current GPRS solution, used in this area to connect some 8000 devices.
Following a number of lab- and field-based trials, Simoco developed a solution that uses a digital mobile radio (DMR) network to transmit mission critical low-band data. It utilizes the available VHF spectrum but adopts an architecture design similar to the existing UHF solution currently deployed in the Midlands. WPD describes this alternative solution as licensed VHF open channel.
|Robust voice cummunications are vital during an outage|
Surf Telecoms, a wholly-owned subsidiary of WPD, is responsible for monitoring and maintaining the utility network. The company operates two network management centres 24 hours a day, 365 days a year. Maintenance teams have an immediate response time and four-hour fix targets for all bandwidth service affecting faults.
Simoco Pulse installation at WPD
Surf Telecoms Manager Kevan Scott says: “WPD operates a ‘Target 60’ initiative, which aims to restore power within 60 minutes in the vast majority of cases.
“If lengthy power outages occur, utility companies can be fined heavily by the industry’s regulator if it is not possible to fix them in a quick and cost-effective manner.”
WPD was provided with Simoco Pulse, a DMR Tier III trunked solution, which uses a fully-integrated IP network to connect information sent from data modems or RTUs to SCADA masters. This functionality makes it easy to scale the solution to include more modems, RTUs or even voice transmission to the same network. It means DMR becomes a practical way of managing a large and complex amount of information, with operators and maintenance teams having constant insight into grid performance and any locations where issues have occurred.
As WPD already had existing RTUs in place, it was supplied with the Simoco Pulse Air data modem. The solution uses the widely-adopted DNP3 protocol when communicating across the DMR network. The modem provides a robust connection to the SCADA master using reliable digital radio over licensed VHF and UHF radio channels and is also capable of directly interacting with any RTU that uses this standard telemetry protocol.
Licensed channels are more effective in mission critical environments as they do not suffer from interference, data call collisions or variable usage. The system is designed to connect tens of thousands of devices and, with low operating costs thanks to its inherent reliability, it can be quickly scaled to provide a solution across wide geographical areas.
A further feature of using DMR to transmit telemetry data is its ability to carry voice communications over the same infrastructure. This means Simoco Pulse can cost-effectively be scaled to co-exist with voice on a full mission critical solution capable of meeting the voice and data needs of utility companies in the smart grid age.
The three-year programme to upgrade the current WPD network and introduce 100 new sites with DMR infrastructure will include an initial rollout of 8000 data modems across the Midlands region. Delivery of the infrastructure and first 2000 Pulse Air Data Modem units was completed in November 2015, with the first sites going live early this year. On completion of the rollout in the Midlands, the solution will be expanded into the WPD South West and Wales regions.
Saving time and costs
Simoco’s Pulse solution has enabled WPD to add smart grid management and control functionality to its operations. This includes real-time monitoring, network optimization, delivery of proactive maintenance programmes and the remote implementation of commands and updates.
If a problem on the network occurs, WPD saves time and costs by knowing exactly where the problem is located rather than having to dispatch teams to manually search areas of the grid. Before the introduction of telemetry data this involved physical visits to the site in order to locate the source of an outage.
Setting up a communications infrastructure to support reliable low-band data transmission can be challenging for utility companies like WPD, where cellular coverage can be patchy and intermittent, and installing wired networks has significant cost implications. However, the Simoco Pulse solution provides a stable path for the limited but critical amounts of data associated with SCADA communications as a result of the use of robust DMR.
While larger amounts of data can be carried across overlaid broadband networks, providing connections to wide bandwidth devices such as smart phones and tablets, it remains an unreliable and sometimes insecure way of transmitting mission critical data.
|Data from modems is connected to SCADA masters|
In contrast and by their very definition, PMR networks are ‘private’, less open to security threats and less congested than unlicensed radio alternatives or broadband networks. The latest digital radio standards include the necessary levels of security demanded by public safety services and government agencies.
Private Radio systems also provide a predictable cost of ownership. WPD’s system has been designed to its exact requirements and, once installed at the budgeted cost, there are no further call charges or unexpected upgrades as new technologies are rolled out.
Finally, the Simoco Pulse DMR Tier III trunked solution also has the benefit of being able to offer WPD and other users a flexible way of migrating voice communications from analogue systems to a DMR network. By using DMR to transmit both voice and low band data, mission critical communications can be unified on the same, reliable and cost effective licensed network.
Kevan Scott explains: “DMR is a standard that has a proven track record for mission critical communications. While voice transmissions remain an essential part of this mix, low-band telemetry data is just as critical if you are a utility company in 2016.
“By moving SCADA to DMR we have a secure and reliable picture of our network and the ability to react quickly when issues occur.”
He adds that WPD’s target of restoring power within 60 minutes of an outage “is well on the way to being achieved, meaning we are well placed to meet the demands of today and the future”.
Mike Norfield is Chief Executive of Simoco Group. www.simocogroup.com