ZTE Electric Utility Communications Transmission Network Solution

Electric utility communications networks, as the network support and assurance systems, are responsible both for the communication of command and dispatch production instructions, and for handling administrative and automation information data. Due to the critical importance of electric power to any economy, electric utility communications networks are usually private networks and, similar to the electrical grids, are nation-wide networks which are comprised of backbone networks and local metro networks identical to any operator's national transmission network.

1.Analysis on electric utility communications transmission network

1.1  Services delivered over electric utility system

Automation: Supervisory Control And Data Acquisition (SCADA) automatic scheduling, power metering system, integrated automation of transformer stations, production scheduling Management Information System (MIS), and technical support system.

Protection: Fault recording system, power grid security stability control system, lightning detection system and relay protection system.

Voice: Scheduling telephone service, administration telephone service and teleconference. Scheduling telephone is used for voice communications between various scheduling centers and transformer stations, power plants and ensuring secure and stable operation of electric utility communications network; administration telephone system is used for internal production and management of electric utility system; teleconference system enables multi-party call.

Management and information: The MISs for power usage, finance, power supply projects, power production and security, human resources and operations, Office of Administration (OA) and geographical information systems (GIS).

Video services: Videoconferencing, automatic monitoring for transformer stations.

1.2　Analysis on service transmission in electric utility communications network

The above power system communications services are provided by different service networks and will be transported as narrowband voice, narrowband low-speed data, broadband data, video and multimedia services.

Voice and low-speed data services: These services are delivered by the 64K pulse code modulation (PCM) system which provide such services interface like POTS、2W/4W、E&M、V.35、V.24、V.11、ISDN, and require transmission equipment to provide an E1 interface.

Broadband data and multimedia services: Most of these are newly emerged utility communication services offered by an IP network. The IP network is comprised of routers and Ethernet switches and needs transmission interfaces such as FE/GE, POS, STM-N.

Video services: They are mainly delivered by the videoconference system. The E1 or FE interface is required for the transmission network.

Different service networks can be carried over the same or different transmission networks. The PCM network is carried over the traditional SDH network; the IP-based network can be deployed through fiber direct connection, or carried over the traditional SDH or the multi-service transport platform (MSTP) network. But, fiber direct connection can not provide carrier-class OAM and protection switching; on the other hand, SDH is lack of support for multi-service. So, the MSTP, after years of applications, supports for a wide range of services, OAM and protection switching, and has become the preferred transmission method of electric power companies as it bears both the PCM and IP networks, avoids overlapping investment and lowers overall costs. Combined with long-haul WDM and intelligent ASON, it is evident that the utility communication transport network can adapt to future needs with a layered, multi-service, and reliable architecture.

2.  ZTE’s electric utility communications solution

2.1  Total network solution

After years of research and product development, ZTE has successfully launched the Unitrans series of optical network products. These products are now in service with over 250 operators in more than 90 countries.

Full series of WDM/OTN, MSTP, ASON products, ranging from standardized, integrated to compact, are available. Customers can select different products based on different capacities and requirements, and serve electric utility communications network’s requirement for multi-layered network construction and centralized planning and management by use of unified NM solution. Electric power companies can select flexibly according to the capacity, interface and upgrade requirements in their own network construction.

Electric utility communications network is classified as national backbone, inter-provincial backbone, inner-provincial backbone and metro access aggregation layer in correspondence with the scheduling architecture of national electric power system.

The access network mainly implements multi-service access and adaptation in all stations, including power plants, electric power distribution stations, transformer stations, transformer substations and electric power bureaus. ZXMP S200/S325/S330, ZTE’s MSTP equipments, features high level of integration, high reliability, simple installation, multiple power supply working modes, strong adaptability to environment and high cost effectiveness. They can be used to build 155M/622M rural power network, enabling access of voice, data and Internet in all stations, whilst delivering multimedia services. ZTE PCM equipments can be used for access of narrowband voice services and narrowband low-speed data services, making it easy for access of voice, data and Ethernet signals. The highly integrated PCM equipments can be deploy in bulks in nodes with low traffic.

As for aggregation of services from transformer stations (substations) to county/city electric power bureaus, ZTE’s multi-service transmission equipments ZXMP S385/S380/S390/S325, with rates of 622M/2.5G/10G, can be used to implement hybrid transmission of IP/ATM/TDM services. Service switching and aggregation are well performed, owing to Ethernet L2 switching function. ZTE EoS technology supports L2 switching and QinQ, as well as EPL/EPLAN/EVPL/EVPLAN networking modes. ZTE RPR-embedded technology provides following benefits: value-added bandwidth, pushing bandwidth utilization up 2-5-fold than EoS; perfect service awareness, enabling delivery of differentiated services for real-time services and non-real-time services; rapid service provisioning; simple network planning and configuration; flexible provisioning of RPR ring bandwidth, realizing elastic bandwidth utilization for services; carrier-class 50ms protection switching, enhancing network reliability. ZTE’s further enhanced RPR technology supports RPR trans-ring networking. With ATM service statistic multiplexing function, ZTE MSTP products implement ATM service processing. MSTP equipments adopt standard GFP (Generalized Framing Procedure) encapsulation, enabling better interoperability.

As for inner-provincial backbone, ZTE supplies its ZXMP S385 or ZXONE 5800, the large-capacity, highly reliable and scalable 10G multi-service transmission equipments to build the inter-provincial backbone network from various cities to the provincial center. With large-capacity higher-order cross-connect capability and multiple 10G or 2.5G optical directions, they can be used to form multiplexing section protection, serving the requirements of core layer nodes for large-capacity and multi-service scheduling and grooming and high reliability. They support high-speed service scheduling and add/drop of vast 2M services, fully satisfying the complex requirements in network scheduling.

National backbone and inter-provincial backbone transmission networks mainly implement service scheduling and management between large regions and regional electric power companies, requiring their ability for large-capacity service carriage, long-haul transmission and high reliability. ZTE Unitrans series’ long-haul DWDM equipments, large-capacity MSTP/ASON equipments based on mainstream DWDM+MSTP/ASON technologies, are recommended. DWDM equipments support up to 3.2T transmission capability and repeaterless transmission over 5000km, resulting in greatly reduced transmission cost per bit. MSTP/ASON equipments can build 10G/40G MESH network or ring network, utilize the perfect protection mechanism of MESH and ring networks to provide the strong ability for multi-service scheduling and processing, and ensure large-granule service grooming, ideally fitting the requirements of electric utility communications network for highly reliable, scalable and large-capacity transmission at backbone layer.

Fig. 1 ZTE total power communication transmission network solution

2.2 Solution feature-3R

ZTE solution’s resilient, reconfigurable and reliable (3R) features fully accommodate the requirements in electric utility communications network.

• Resilient

Power utility communication transmission networks provide multiple services consisting of TDM services and the packet services. The packet services account for most of the new services and require different QoS levels. ZTE’s MSTP based resilient transport network can satisfy these requirements.

It adds Ethernet over SONET (EoS), resilient packet ring (RPR) and multi-protocol label switching (MPLS) technologies based on SDH to deliver both TDM and IP services and provide different QoS levels for IP services thus accommodating future services development. 

• Reconfigurable

The transmission network should be able to offer reconfigurability to enable future service diversification. ZTE’s WDM and MSTP equipment take into account such requirements and capacity reconfiguration can be easily achieved by adding wavelengths and increasing the rate on single wavelengths. This means that the maximum capacities of, for example, the ZXWM M900 and ZXMP M800 are 160×10Gb/s and 800Gb/s respectively.

According to network requirements, the ZXMP M900 and ZXMP M800 can be configured as an optical terminal multiplexer (OTM), optical add-drop multiplexer (OADM), reconfigurable OADM or optical line amplifier (OLA), and can support point-to-point, chain, ring, ring and chain, and crossbar topologies. By adopting a multi-ADM (MADM) design, ZTE’s Unitrans series MSTP equipment can be flexibly configured as ADM, MADM, TM or REG network unit types to meet the requirements of multiple network topology modes, and support smooth upgrading from STM-1 to STM-64. At the initial network construction stage, the network features relatively small scale with a few sites, simple topology and small bandwidth. As the network develops, the number of sites will become greater, the topology more complex, and the bandwidth more ample. Reconfigurable equipment makes it possible to implement effective network planning, ensure the sustainable development of the network, and offer phased investments to reduce the initial and overall construction costs.

• Reliable

Electric power grids have far reaching effects on the quality of life in all sectors of society and are crucial to a nation’s development, thus they require high security and availability. ZTE can provide highly reliable network solutions. ZTE’s optical transmission systems provide equipment-level protection with hardware redundant backups. For example, the ZXMP S385 adopts 1+1 hot backup for the cross-connect clock board and NCP, and 1:N protection for electrical tributary interface boards. In terms of network-level protection, ZTE optical transmission equipment can implement all network protection modes adopted by ITU-T. It is worth noting that the ZXMP M800 is the only WDM equipment in the industry capable of offering six protection modes consisting of 2-fibre bidirectional path shared protection, 1+1 path protection, 2-fibre bidirectional multiplex section shared protection ring, sub-network connection protection, 1:N OTU protection, 1+1 multiplex section protection.

2.3　 Centralized NM

New generation serial product portfolio T3 network management equipments are responsible for centralized management of all transmission equipments in the network; they realize multi-service and multi-equipment integrated management, provide robust end-to-end management capability, enable rapid multi-service provisioning, and offer diversified data for network planning and decision system.

3.  Case study

ZTE has installed a national backbone optical network for Zambia’s power utility with the turnkey contract mode. ZTE introduced Optical Fibre Composite Overhead Ground Wire (OPGW) technology and installed OPGW cables on Zesco’s power lines, utilizing existing resources such as the nation-wide electrical power towers. The 1200-km optical transmission line covers Zambia’s richest regions including the capital, Lusaka, Copper-belt Province, Central Province, Northern Province and Southern Province. The network is based on ZXMP S385 MSTP equipment that features unique logic sub-network protection function, smooth upgrade to the 10G system and provision of E1 and FE services, thus building an integrated multi-service transport platform for Zesco.

Fig. 2　 ZESCO’s national optical transmission backbone network

4.  Summary

With years of proven track record in delivering telecoms solutions and in-depth understanding of electric utility communications network, ZTE offers Unitrans series optical networking products to delvier the secure and perfect end-to-end solution to electric utility communications network. Full series of DWDM, ASON and MSTP equipments are available, helping customers in electric power industry build the integrated service optical network.