By: IntelligentUtility |
Answer this SAT-style analogy: Land line is to cell tower as power line is to _____ ?
If you said, “smart grid,” CenterPoint Energy agrees. The transmission and distribution utility is bringing electricity in Houston, Texas into the digital age. In less than four years, the company has completed installation of 2.2 million digital smart meters across the nation’s fourth largest city and made significant progress in building an intelligent grid (IG) of distribution automation equipment to improve power reliability and restoration. At the heart of these transformative projects is a robust, two-way telecommunications network.
Before installing their first smart meter, CenterPoint Energy and a strategic alliance of vendors had designed and begun building a proprietary wireless radio frequency (RF) communications network. Customers’ electricity usage data collected by smart meters is transmitted wirelessly to 5,434 cell relays mounted on power distribution poles on to 140 radio tower Take Out Points (TOPs) and then by microwave and fiber optic cable to the company’s data center, which processes 219 million meter readings per day. Current successful read rates of 99.91 percent on daily register reads and 99.65 percent on 15-minute interval reads testify to the reliability of the network.
As a result, over 600,000 Texans get more frequent, detailed information on their electricity use, directly from the SmartMeterTexas.com portal, or indirectly from their retail electric provider in the deregulated Texas electric market. Another 9,000 Houstonians get a near-real-time view of their electricity use via in-home display (IHD) energy monitors. Two-way digital communications have also enabled over five million remote electric service connections and disconnection to date, saving consumers about $24 million in eliminated fees while reducing the company’s vehicle fuel consumption by about 500,000 gallons and avoiding over 4,500 metric tons of carbon emissions.
Smart meters also notify CenterPoint Energy automatically when power goes out, and the installation of 394 intelligent grid switching devices (IGSDs) and automation of 21 substations through 2012 has already resulted in a 21 percent improvement in outage response when the intelligent grid was able to localize and reroute power around an outage so that 70 percent of affected customers were returned to power in minutes instead of a half hour or more. Nearly 600 IGSDs will be installed in Houston by the end of 2013, along with automation equipment at 31 substations. An advanced distribution management system (ADMS) now under development will be deployed in 2014 to help usher in an era of automated fault location identification and remote switching to continue improving power reliability and restoration.
Network requirements and design
CenterPoint’s Telecom Planning and Engineering Design team worked with Enaxis Consulting to deploy an advanced IP transport network to support the company’s growing communications requirements. The network’s foundation is multiprotocol label switching (MPLS) using CenterPoint’s existing fiber optic cable and new RF network. Enaxis architected the network with layer-3 virtual private network technology (MPLS L3VPN) to increase reliability while maintaining virtual security boundaries among multiple internal users. Said Telecom Design Manager Theo Woodard, “This high-speed network serves as the foundation of our intelligent grid and allows us the flexibility to provide IP communications anywhere IG requires.”
CenterPoint worked with IBM, Itron, GE and Quanta Services to design and build the field area communications network for their advanced metering system (AMS) and intelligent grid. IBM’s network methodology was the basis for the network architecture; Itron provided meter, cell relay and system hardware, software and services; GE supplied microwave access (WiMAX) radios, communications systems software and services; and Quanta installed meter and communications equipment. The network was designed to meet exacting requirements:
- Comprehensive coverage of the company’s 5,000 square-mile service area
- Provision of two-way communications to cell relays and IGSDs
- Sufficient throughput capacity to transmit 96 daily reads for 2.2 million meters and execute 4,000 service orders per day in under 30 minutes each on average
- High reliability under storm conditions
- Adherence to strict cyber security standards
- Scalability to handle “big data” as more smart meters and IGSDs are installed
- Redundancy to ensure failover in the event of component failures
The meters form a mesh network to pass data by wireless radio from meter to meter to cell relay. A 400:1 meter-to-cell relay ratio maximizes efficiency while allowing meters to migrate to an adjacent cell relay if their primary cell relay fails. The primary communication path from cell relays is via the company’s WiMAX radio network through radio towers built at company substations. A failure of any segment of the WiMAX backhaul causes the cell relays to fail over to AT&T’s cellular global systems for mobile (GSM) communications network as a secondary path. More than 1,600 RFLAN range extenders connect hard-to-reach meters to the network.
Operations expertise is built along with design and deployment
Building a telecommunications network to support a smart grid may be one thing, and operating the network may be another—but not in CenterPoint’s eyes. A key success factor was bringing the radio field technicians now responsible for servicing cell relays into the cell relay system design and deployment project team. The cell relay and radio enclosure are mounted to an aluminum conduit in the warehouse before attachment on a distribution pole to save time in the field. The unit is then mounted on the pole in a “communications space” at a secure height yet below the wires and transformers where linemen work. “We designed the equipment to fit on the pole,” said Telecom Manager Donna Demmon, “So that linemen working on the electric lines have clear access, but the communication space allows us to have a different workforce work on the cell relays, radios and antennae.” Ensuring street access to cell relay sites and the ability of radio technicians to disconnect cell relays without requiring a lineman to de-energize the power line also allows the radio techs to focus on communications and linemen to focus on power. Involving operations personnel in design and deployment helped them develop a knowledge base and assume ownership and management of the system.
Engineering and Telecom Operations were also jointly involved in pushing configuration changes to products during deployment. Communications hardware, software, and firmware evolve more rapidly than poles and wires, so the crews have already been through a number of upgrades and enhancements, including replacement of cell relay backup batteries. Maintaining a close relationship with equipment suppliers is essential. CenterPoint Energy and its technology partners have built knowledge together on the vanguard of the smart grid. “It goes with being on the leading edge of technology,” says Radio Communications Manager, James Bradshaw. “We learned a lot, and the vendors learned a lot. Their products are better today because of what we’ve learned from using them.”
Although the smart meter deployment is complete, annual customer growth in Houston remains a solid two percent, so the network and the processes to maintain it continue to evolve. The radio team is developing periodic preventive maintenance cycles to address issues before a failure. As the network evolves, the team analyzes cell relay data to determine where new cell relays are needed to levelize the number of meters communicating with each cell relay.
Telecommunications control center provides end-to-end network management
CenterPoint Energy’s telecom team has managed the company’s LAN/WAN, SCADA, and fiber optic network for years, but with the advent of AMS and IG and the associated premium on network reliability and resilience, the team has implemented a telecom control center (TCC) consisting of 18 console stations and a 63-monitor video display wall to provide end-to-end network monitoring and management.
As the network grows with the addition of cell relays and radio tower TOPs, the TCC follows a standard acceptance process for the new sites and equipment they will manage and maintain. Field techs perform acceptance tests on radios, batteries, and other equipment; ensure monitoring/management system connections have been established; and then enter the equipment into IBM’s Tivoli Event Management System. Again, close cooperation between the implementation and telecom operations teams is crucial.
With the TCC’s input, CenterPoint’s Smart Grid Data Analytics team developed Google Earth-based applications to graphically depict the status of TOPs, cell relays and remote IG radios to provide visibility into the network and increase operational effectiveness through early alerts of potential communications issues. Large color-coded screens give a quick indication whether the primary WiMAX and secondary GSM paths are up, the status of IGSDs, and down to individual radios and routers. If TCC technicians see an issue or get an alert, they can drill down to the individual equipment level, diagnose and troubleshoot the issue and request dispatch of a field crew if necessary.
CenterPoint’s telecommunications network design is based on a core ring of fiber and microwave. The majority of radio TOP sites have multiple routes to transfer data back to the core ring and the company’s data center, with few isolated spurs. Thus, network reliability and resilience are buttressed by two forms of redundancy: the primary WiMAX and secondary GSM paths as well as multiple routes along the backhaul network. The redundancy of the ring allows the team to prioritize work rather than be forced to react immediately to issues at single points of failure.
The TCC’s management tools provide the real-time reporting necessary for proactive network management. “We’re not just historians,” said Telecom Operations Manager Diana Mayo, “We work in the now.” There is a lot for her team to monitor from the broad network view down to substation control houses, and TOP site communication buildings housing master radios (they can even tell when an Ethernet cord is unplugged, the room temperature has been adjusted, or a door or gate has been left open), along with the LAN/WAN, SCADA and fiber environment. A balance has to be maintained to integrate new technology into the existing network.
The importance of the human network
Technology and processes, of course, depend on people. The successful operation of CenterPoint Energy’s smart grid communications network has been built on personnel with initiative, dependability, a love of learning, and an eagerness to collaborate with vendors and each other in building and transferring knowledge of new technology and systems. Their work is transforming the industry and bringing electricity into the digital age.
