With the accelerating movement toward distributed generation and the rapid shift in energy consumption patterns, today’s power utilities are facing growing requirements for improved management, capacity planning, control, security and administration of their infrastructure and services.
UTILITY NETWORK BUSINESS DRIVERS
These requirements are driving a need for greater automation and control throughout the power infrastructure, from generation through the customer site. In addition, utilities are interested in providing end-customers with new applications, such as advanced metering infrastructure (AMI), online usage reports and outage status. In addition to meeting these requirements, utilities are under pressure to reduce costs and automate operations, as well as protect their infrastructures from service disruption in compliance with homeland security requirements.
To succeed, utilities must seamlessly support these demands with an embedded infrastructure of traditional devices and technologies. This will allow them to provide a smooth evolution to next-generation capabilities, manage life cycle issues for aging equipment and devices, maintain service continuity, minimize capital investment, and ensure scalability and future-proofing for new applications, such as smart metering.
By adopting an evolutionary approach to an intelligent communications network (SmartGridNet), utilities can maximize their ability to leverage the existing asset base and minimize capital and operations expenses.
THE NEED FOR AN INTELLIGENT UTILITY NETWORK
As a first step toward implementing a SmartGridNet, utilities must implement intelligent electronic devices (IEDs) throughout the infrastructure – from generation and transmission through distribution directly to customer premises – if they are to effectively monitor and manage facilities, load and usage. A sophisticated operational communications network then interconnects such devices through control centers, providing support for supervisory control and data acquisition (SCADA), teleprotection, remote meter reading, and operational voice and video. This network also enables new applications such as field personnel management and dispatch, safety and localization. In addition, the utility’s corporate communications network increases employee productivity and improves customer service by providing multimedia; voice, video, and data communications; worker mobility; and contact center capabilities.
These two network types – operational and corporate – and the applications they support may leverage common network facilities; however, they have very different requirements for availability, service assurance, bandwidth, security and performance.
Network technology is critical to the evolution of the next-generation utility. The SmartGridNet must support the following key requirements:
- Virtualization. Enables operation of multiple virtual networks over common infrastructure and facilities while maintaining mutual isolation and distinct levels of service.
- Quality of service (QoS). Allows priority treatment of critical traffic on a “per-network, per-service, per-user basis.”
- High availability. Ensures constant availability of critical communications, transparent restoration and “always on” service – even when the public switched telephony network (PSTN) or local power supply suffers outages.
- Multipoint-to-multipoint communications. Provides integrated control and data collection across multiple sensors and regulators via synchronized, redundant control centers for disaster recovery.
- Two-way communications. Supports increasingly sophisticated interactions between control centers and end-customers or field forces to enable new capabilities, such as customer sellback, return or credit allocation for locally stored power; improved field service dispatch; information sharing; and reporting.
- Mobile services. Improves employee efficiency, both within company facilities and in the field.
- Security. Protects the infrastructure from malicious and inadvertent compromise from both internal and external sources, ensures service reliability and continuity, and complies with critical security regulations such as North American Electric Reliability Corp. (NERC).
- Legacy service integration. Accommodates the continued presence of legacy remote terminal units (RTUs), meters, sensors and regulators, supporting circuit, X.25, frame relay (FR), and asynchronous transfer mode (ATM) interfaces and communications.
- Future-proofing. Capability and scalability to meet not just today’s applications, but tomorrow’s, as driven by regulatory requirements (such as smart metering) and new revenue opportunities, such as utility delivery of business and residential telecommunications (U-Telco) services.
A number of network technologies – both wire-line and wireless – work together to achieve these requirements in a SmartGridNet. Utilities must leverage a range of network integration disciplines to engineer a smooth transformation of their existing infrastructure to a SmartGridNet.
The remainder of this paper describes an evolutionary scenario, in which:
- Next-generation synchronous optical network (SONET)-based multiservice provisioning platforms (MSPPs), with native QoS-enabled Ethernet capabilities are seamlessly introduced at the transport layer to switch traffic from both embedded sensors and next-generation IEDs.
- Cost-effective wave division multiplexing (WDM) is used to increase communications network capacity for new traffic while leveraging embedded fiber assets.
- Multiprotocol label switching (MPLS)/ IP routing infrastructure is introduced as an overlay on the transport layer only for traffic requiring higher-layer services that cannot be addressed more efficiently by the transport layer MSPPs.
- Circuit emulation over IP virtual private networks (VPNs) is supported as a means for carrying sensor traffic over shared or leased network facilities.
- A variety of communications applications are delivered over this integrated infrastructure to enhance operational efficiency, reliability, employee productivity and customer satisfaction.
- A toolbox of access technologies is appropriately applied, per specific area characteristics and requirements, to extend power service monitoring and management all the way to the end-customer’s premises.
- A smart home network offers new capabilities to the end-customer, such as Advanced Metering Infrastructure (AMI), appliance control and flexible billing models.
- Managed and assured availability, security, performance and regulatory compliance of the communications network.
THE SMARTGRIDNET ARCHITECTURE
Figure 1 provides an architectural framework that we may use to illustrate and map the relevant communications technologies and protocols.
The backbone network in Figure 1 interconnects corporate sites and data centers, control centers, generation facilities, transmission and distribution substations, and other core facilities. It can isolate the distinct operational and corporate communications networks and subnetworks while enforcing the critical network requirements outlined in the section above.
The underlying transport network for this intelligent backbone is made up of both fiber and wireless (for example, microwave) technologies. The backbone also employs ring and mesh architectures to provide high availability and rapid restoration.
INTELLIGENT CORE TRANSPORT
As alluring as pure packet networks may be, synchronous SONET remains a key technology for operational backbones. Only SONET can support the range of new and legacy traffic types while meeting the stringent absolute delay, differential delay and 50-millisecond restoration requirements of real-time traffic.
SONET transport for legacy traffic may be provided in MSPPs, which interoperate with embedded SONET elements to implement ring and mesh protection over fiber facilities and time division multiplexing (TDM)-based microwave. Full-featured Ethernet switch modules in these MSPPs enable next-generation traffic via Ethernet over SONET (EOS) and/or packet over SONET (POS). Appropriate, cost-effective wave division multiplexing (WDM) solutions – for example, coarse, passive and dense WDM – may also be applied to guarantee sufficient capacity while leveraging existing fiber assets.
From a switching and routing perspective, a significant amount of traffic in the backbone may be managed at the transport layer – for example, via QoS-enabled Ethernet switching capabilities embedded in the SONET-based MSPPs. This is a key capability for supporting expedited delivery of critical traffic types, enabling utilities to migrate to more generic object-oriented substation event (GOOSE)-based inter-substation communications for SCADA and teleprotection in the future in accordance with standards such as IEC 61850.
Where higher-layer services – for example, IP VPN, multicast, ATM and FR – are required, however, utilities can introduce a multi-service switching/routing infrastructure incrementally on top of the transport infrastructure. The switching infrastructure is based on multi-protocol label switching (MPLS), implementing Layer 2 transport encapsulation and/or IP VPNs, per the relevant Internet engineering task force (IETF) requests for comments (RFCs).
This type of unified infrastructure reduces operations costs by sharing switching and restoration capabilities across multiple services. Current IP/MPLS switching technology is consistent with the network requirements summarized above for service traffic requiring higher-layer services, and may be combined with additional advanced services such as Layer 3 VPNs and unified threat management (UTM) devices/firewalls for further protection and isolation of traffic.
CORE COMMUNICATIONS APPLICATIONS
Operational services such as tele-protection and SCADA represent key categories of applications driving the requirements for a robust, secure, cost-effective network as described. Beyond these, there are a number of communications applications enabling improved operational efficiency for the utility, as well as mechanisms to enhance employee productivity and customer service. These include, but are not limited to:
- Active network controls. Improves capacity and utilization of the electricity network.
- Voice over IP (VoIP). Leverages common network infrastructure to reduce the cost of operational and corporate voice communications – for example, eliminating costly channel banks for individual lines required at remote substations.
- Closed circuit TV (CCTV)/Video Over IP. Improves surveillance of remote assets and secure automated facilities.
- Multimedia collaboration. Combines voice, video and data traffic in a rich application suite to enhance communication and worker productivity, giving employees direct access to centralized expertise and online resources (for example, standards and diagrams).
- IED interconnection. Better measures and manages the electricity networks.
- Mobility. Leverages in-plant and field worker mobility – via cellular, land mobile radio (LMR) and WiFi – to improve efficiency of key work processes.
- Contact center. Employs next-generation communications and best-in-class customer service business processes to improve customer satisfaction.
DISTRIBUTION AND ACCESS NETWORKS
The intelligent utility distribution and access networks are subtending networks from the backbone, accommodating traffic between backbone switches/applications and devices in the distribution infrastructure all the way to the customer premises. IEDs on customer premises include automated meters and device regulators to detect and manage customer power usage.
These new devices are primarily packet-based. They may, therefore, be best supported by packet-based access network technologies. However, for select rings, TDM may also be chosen, as warranted. The packet-based access network technology chosen depends on the specifics of the sites to be connected and the economics associated with that area (for example, right of way, customer densities and embedded infrastructure).
Regardless of the access and last-mile network designs, traffic ultimately arrives at the network via an IP/MPLS edge switch/router with connectivity to the backbone IP/MPLS infrastructure. This switching/routing infrastructure ensures connectivity among the intelligent edge devices, core capabilities and control applications.
THE SMART HOME NETWORK
A futuristic home can support many remotely controlled and managed appliances centered on lifestyle improvements of security, entertainment, health and comfort (see Figure 2). In such a home, applications like smart meters and appliance control could be provided by application service providers (ASPs) (such as smart meter operators or utilities), using a home service manager and appropriate service gateways. This architecture differentiates between the access provider – that is, the utility/U-Telco or other public carrier – and the multiple ASPs who may provide applications to a home via the access provider.
By employing smart meters and developing the ability to retrieve electricity usage data at regular intervals – potentially several readings per hour – retailers could make billing a significant competitive differentiator. detailed usage information has already enabled value-added billing in the telecommunications world, and AMI can do likewise for billing electricity services. In time, electricity users will come to expect the same degree of flexible charging with their electricity bill that they already experience with their telephone bills, including, for example, prepaid and post-paid options, tariff in function of time, automated billing for house rental (vacation), family or group tariffs, budget tariffs and messaging.
MANAGING THE COMMUNICATIONS NETWORK
For utilities to leverage the communications network described above to meet business key requirements, they must intelligently manage that network’s facilities and services. This includes:
- Configuration management. Provisioning services to ensure that underlying switching/routing and transport requirements are met.
- Fault and performance management. Monitoring, correlating and isolating fault and performance data so that proactive, preventative and reactive corrective actions can be initiated.
- Maintenance management. Planning of maintenance activities, including material management and logistics, and geographic information management.
- Restoration management. Creating trouble tickets, dispatching and managing the workforce, and carrying out associated tracking and reporting.
- Security management. Assuring the security of the infrastructure, managing access to authorized users, responding to security events, and identifying and remediating vulnerabilities per key security requirements such as NERC.
Utilities can integrate these capabilities into their existing network management infrastructures, or they can fully or partially outsource them to managed network service providers.
Figure 3 shows how key technologies are mapped to the architectural framework described previously. Being able to evolve into an intelligent utilities network in a cost-effective manner requires trusted support throughout planning, design, deployment, operations and maintenance.
Utilities can evolve their existing infrastructures to meet key SmartGridnet requirements by effectively leveraging a range of technologies and approaches. Through careful planning, designing, engineering and application of this technology, such firms may achieve the business objectives of SmartGridnet while protecting their current investments in infrastructure. Ultimately, by taking an evolutionary approach to SmartGridnet, utilities can maximize their ability to leverage the existing asset base as well as minimize capital and operations expenses.