“Smartgrid”, also called “Grid 2.0”, generally refers to a class of technology peopleare using to bring utility electricity delivery systems into the 21st century,using computer-based remote control and automation. These systems are made possible by two-waycommunication technology and computer processing that has been used for decadesin other industries. They are beginning to be used on electricity networks,from the power plants and wind farms all the way to the consumers ofelectricity in homes and businesses. They offer many benefits to utilities andconsumers -- mostly seen in big improvements in energy efficiency on theelectricity grid and in the energy users' homes and offices.
Situation of the Grid Communication System
The traditional grid communication system has greatly hindered the development ofelectric power distribution automation systems, because many techniques (suchas GPRS/CDMA, 230MHzwireless broadcasting stations, power private optical fibers, PSTN and PLC) inthe traditional grid communication system expose obvious disadvantages infunctions. For instance, the single point failure is likely to occur in thetransmission link, which impairs the capacity of service protection. Thecommunication medium and service interfaces are hard to manage and maintain, asthey are so complicated. With the narrow transmission bandwidth, the key datetransmission cannot be guaranteed and the integrated service is difficult toexpand. Besides, the internal information security in the electric power sectormay be under threat, as GPRS/CDMA is supported by the operator networkplatform.
By contrast,Electric Power Distribution Automation not only improves all the deficienciesin traditional grid communication system, but is more efficient. Therefore,upgrading the grid communication system is on the top of the top priority inconstructing a modern Smart Grid.
ElectricPower Distribution Automation is consisted of several systems such asSupervisory Control and Data Acquisition (SCADA),Substation Automation (SA) and Distribution Automation (DA).
NetworkingSolution
Instead oftraditional GPRS/CDMA or 230MHz networking solution, the EPONnetworking solution has become the best choice of electric power communicationplatform. As a pioneer in this field, STEC introduces its own EPON solutions.These solutions involve three parts: Power management substation (such as,110KV substation), transmission channel and data collection and user-endaccess.
Here presentsfour BDOM EPON solutions of Electric Power Distribution Automation Systems indetail: Solution to Electric Power Distribution Automation Systems (1),Solution to Electric Power Distribution Automation Systems (2), Solution to theUser Information Collection System, and Solution to Digital Transformer Station.
Solution to Electric Power Distribution Automation Systems (1)
Similar totraditional EPON networking, the EPON system in this solution is also consistedof three parts: OLT, ONU and ODN. The OLTs and ONUs adopted in this solutionare laid out respectively between the 110KV substations and the 10KV switchingstations. Each OLT of the substation are connected to several ONUs throughfibers and passive optical splitters. Each ONU with dual PON interfaces isconnected to two OLTs through fibers. Thus, a topology characterized by Hand-in-handProtection Shift is established.
Each S8500/P3310 OLT and each substation IP/ATMswitch is connected by a single gigabit Ethernet link or multiple gigabitEthernet links. S8500 OLTs and P3310 rack-mounted OLTs can satisfy the need ofsubstations of different scales.
The user network interfaces of ONUs connect to RTUs, TTUs, Networkingmonitoring ends and PCs. STEC ONUs support multiple interfaces such as FE, GE,RS232/485, among which RS232/485 interfaces can be flexibly set.
Solution to Electric Power Distribution Automation Systems (2)
The OLTs and ONUs adopted in this solution are laid out respectivelybetween the 10KV switching stations and the user side. The substations and the10KV switching stations (Ring Main Units) are connected through two fibers. The10KV switching stations constitute a ring network by two fibers, which realizeself-healing with EAPS technology. Each OLT of the switching station isconnected to ONUs in the user side by fibers and passive optical splitters.Each ONU with dual PON interfaces is connected to two OLTs in the 10KVswitching stations through fibers. Thus, a topology characterized by Hand-in-handProtection Shift is established.
The user network interfaces of ONUs connect to RTUs, TTUs, Networkingmonitoring ends and PCs. STEC ONUs support multiple interfaces such as FE, GE,RS232/485, among which RS232/485 interfaces can be flexibly set.
Solution to the User Information Collection System
The OLTs andONUs adopted in this solution are laid out respectively between the 110KVsubstations and the 10KV switching stations. Each OLT of the substation areconnected to several ONUs through fibers and passive optical splitters. EachONU with dual PON interfaces is connected to two OLTs through fibers. Thus, atopology characterized by Hand-in-hand Protection Shift is established.
Each S8500/P3310 OLT and each substation IP/ATM switch is connected by a single gigabitEthernet link or multiple gigabit Ethernet links. S8500 OLTs and P3310rack-mounted OLTs can satisfy the need of substations of different scales.
The user network interfaces of ONUs connect to RTUs, TTUs, Networkingmonitoring ends and PCs. STEC ONUs support multiple interfaces such as FE, GE,RS232/485, among which RS232/485 interfaces can be flexibly set.
The data acquisition system in powerdistribution automation is mainly in charge of:
l Dataacquisition (the acquired data include the electric energy data, the AC analogvalue, the work state data, the electric energy over-threshold statistics data,the event record data, etc.);
l Datamanagement (including data reasonability checkup and data calculating/analyzing/storing);
l Controlfunctions (including control of the rated power, rated electric energy, ratedfee ratio, remoteness, electric fee hand-in aid);
l Comprehensiveapplications (automatic meter's data acquisition control, prepaid fee control,orderly power consumption control, power usage statistics analysis, abnormalpower usage analysis, electric energy quality statistics, line-loss andvalue-added services);
l Operationand maintenance management (system’s time checkup, permission and passwordcontrol, terminal control, file control, communication and routing control,working status control, maintenance and trouble record, report form control);
l Systeminterface (connecting the marketing system, the schedule system and othersystems).
SolutionCharacteristics
Powerful andflexible network construction mode: Its topology adopts the hand-in-hand safetyrotation mechanism, secure and reliable. The link between station and electricpower distribution terminal has the “1+1” protection function and a protectiveshift of less than 50ms, so the electric power distribution network can runreliably. Moreover, other topologies, such as tree, hand-in-hand link and ring, canbe applied according to different actual network structures.
The hand-in-handprotection switching mechanism mainly adopts the above-mentioned model: OLTOand OLTI can either be two independent OLT devices or two PON boards of themodularized OLT devices. The active PON interface and the passive PON interfaceare in working state, the service information is synchronously backed up, andduring the protection switching process the passive PON interface remains theservice features of ONU. Both OLT and ONU have the link-state detectingmechanism, so protection switching can be realized through the auto or forcedmode and automatic recovery can be conducted after the protection switchingfault is removed.
PON transmission network: The optical fiber is used as the transmissionmedia and there is no source in the whole transmission, so it runs stably andreliably. The bidirectional high-bandwidth services can be realized on a singlefiber with a downlink/uplink rate of 1.25Gbps.
QoS guarantees for multi-services: The QoS mechanism, based on ITU-TY.1291, is supported, including priority labeling, queue schedule, flowshaping, congestion limit and cache management. Different users and serviceshave different delays, jitters, guaranteed bandwidths and maximum bandwidths,and the DBA mechanism is supported so that the uplink bandwidth of each ONU canbe distributed and limited.
Advanced system architecture:The whole series of products is based on the modularized design, supportsmultiple access modes and various bandwidths, guarantees smooth networkexpansion and upgrade; its modularized structure of the power supply canprovide various power supply modes according to clients' requirements, such asDC12V/DC24/DC-48/AC220V power supply.
VariousEthernet functions: Multiple technologies are supported, such as VLANisolation, port protection, MAC binding, IP binding, port limit, queue and flowcontrol, so the combination of multiple services can be developed withouttechnical bottleneck and upgraded smoothly.
Unified andversatile network management system: The network management system is serviceoriented and it provides the unified network transmission and networkingprotocol, address management, domain management, security management, useraccess management and so on. It has rich OAM functions such as configuration,alarm, performance monitoring, trouble isolation and security management. Atthe same time, it supports the CLI/GUI management, which is easy to use.
Industrial-leveldesign suitable to the electric power industry: ONU has two PON uplinks andprovides interfaces for services like GEPON, FE and RS232/485.It is suitable todifferent harsh environments for they can run in the temperature from -40℃ to 85℃, prevent thunderbolt and powerful electromagnetic interference andcomply with the requirements of IEC61850 electromagnetic compatibility.
Solution to Digital TransformerStation
1) Overview
The digital automatic transformer systemis a 35kV to 500kV comprehensive system involving protection, control,monitoring, measurement and other automatic functions, which can be dividedinto three layers: the isolation layer, the communication layer and thetransformer layer.
As to the communication layer, itsadopting the standard communication regulations makes sure of itsinterconnection with devices of different manufacturers, while it’s adoptingdual industrial Ethernets as its communication mode guarantees its highreliability.
2) Network Requirements
The digital automatic transformer system, since it adopts the dual industrial Ethernets as its communication mode, can provide two independent communication networks for all installations. Both networks can be used for communication so that communication is more reliable. Of cause, you can also apply one network for communication and the other one for recording fault wave. Communication devices have to meet harsh industrial environment such as high temperature, strong electromagnetic interference and heavy humidity, and at the same time they have to comply with requirements of IEC61850-3.
3) Product Application
TOM1000, TCC4100 and TNM4000 of MRD can bewidely applied to the digital automatic transformer systems of 110Kv, 220kV and500kV.
Collecting Information aboutElectricity
1) Overview
The intelligent grid, consisting of thesuper-high-tension power system and all levels of power system and integratingtechnologies of advanced communication, information and control, characterizesinformation, automation and interaction. The typical hardware logic structuresof the SCADA power distribution system mainly include the computer nodes,communication devices and other assistant devices.
In order to enhance the efficiency andreliability of power distribution, service and information interaction, gridsof all places are under construction with focus on power’s generation,transmission, transformation, distribution, utilization and schedule, amongwhich automatic power distribution and power-consuming information collectionare first undertaken and the industrial Ethernet technology is used to back upthe information-based, automatic and interactive intelligent grid.
2) Network Requirements
Automaticpower distribution has the following communication requirements:
l Highreliability and auto healing at the occurrence of faults
l Flexibleinternetworking and strong expansibility
l Bidirectionalcommunication
l Realtime and high security
l Adoptingindustrial chips and special interface protection measures (e.g. thunderprevention, electromagnetic interference prevention, static release, andredundant power source)
l Theattributes of automatic power distribution are shown below:
l Lotsof nodes
l Scatteredcommunication nodes
l Smallvolume of communication data on each node
l Shortcommunication distance (within several kilometers)
l Harsh environment (mostly outdoors and having strong electromagnetic interference)
3) Product Application
TOM1000 and TCC4100 of MRD can be widely applied at the section of automatic power distribution of the intelligent grid where the real power system and the information platform, strong and reliable and smooth, are framed, the whole production procedure is served, all information about real-time production and operation is collected, analyzed, diagnosed and optimized, complete and delicate diagrams of the power distribution state are provided for grid running and managerial personnel and corrective assistant strategies, solutions and precautions are given, all above guaranteeing more correct, prompt and delicate operation and management of power distribution. The investment of optical-fiber cable or optical network takes a big proportion in the construction of the fiber industrial Ethernet, so the adjustment and upgrade of the optical fiber cable and the optical network is a thing involving many aspects, long construction term, complexity and long-term and stable operation after being established successfully. The follow-up technical and bandwidth upgrade is better carried out at the device layer. The following figure shows the network topology of electricity-consuming information collection in a city:
