POWER SYSTEM COMMUNICATION SENTHIL KUMAR.pdf
- 1. National Power Training Institute Power Systems Training Institute (Ministry of Power, GoI) Bengaluru, India R SENTHIL KUMAR Assistant Director POWER SYSTEM COMMUNICATION
- 2. PRESENTATION OUTLINE • POWER SYSTEM COMMUNICATIONS • SMART GRID COMMUNICATIONS • SMART GRID COMMUNICATION INFRASTRUCTURE • DEDICATED AND SHARED COMMUNICATION CHANNELS • WIRED COMMUNICATIONS • WIRELESS COMMUNICATIONS • STANDARD AND PROTOCOLS • IEC 61850 DATA STRUCTURE
- 3. COMMUNICATIONS A Communication system consists of a transmitter, a receiver and communication channels. Type of medias and network topologies in communications provide different opportunities to advance the speed, security, dependability, and sensitivity of Power system.
- 4. Comparison of Communications • Power Line Communication Advantage: Economic, suitable for station to station communication, Equipped installed in utility owned area. Disadvantage: Limited distance of coverage, Low bandwidth, inherently few channels available, exposed to public access
- 5. Comparison of Communications • Microwave Communication Advantage: Cost effective, reliable, suitable for establishing back bone communication infrastructure, high channel capacity, high data rates Disadvantage: Line of sight clearance required, high maintenance cost, specialized test equipment and need for skill technicians, signal fading and multipath propagation.
- 6. Comparison of Communications • Radio System Communication Advantage: Mobile application, suitable for communication with areas that are otherwise inaccessible. Disadvantage: Noise, adjacent channel interference, change in channel speed, overall speed, channel switching during data transfer, power limitation and lack of security.
- 7. Comparison of Communications • Satellite System Communication Advantage: Wide area coverage, Suitable to communicate with inaccessible areas, cost independent of distance, low error rates. Disadvantage: Total dependency to remote location, less control over transmission, continual leasing cost subject to tapping,
- 8. Comparison of Communications • Fiber Optics Communication Advantage: Cost effective, High Bandwidth, High data rates, immune to electromagnetic interference, Already implemented in telecommunication, video data, SCADA, Voice transfer etc., Disadvantage: Expensive test equipment, failure may difficult to pin-point, can be subject to breakage.
- 9. SMART GRID COMMUNICATIONS • Bi-directional flow of information (along with electricity) – for effective control of generation and consumption • Real-time information: Paves way for active consumer participation • Technologies used at each level of operation to be in sync with data rate, permissible latency, security and timing requirement of respective application • Communication protocols must account for specific needs of the power system applications
- 10. Smart Grid Communication Requirements • Security-Ensure secure information storage, transportation, privacy, avoid cyber attacks • Reliability, Robustness and Availability-Timely availability of time critical information, robustness to distortions and channel noise • Scalability-It should be flexible enough to add on new web services and protocols with increasing penetration of renewable and modernization • Quality of Service (QoS) -Reduce packet drops, minimize latency and delays
- 11. Smart Grid Communications: Key Considerations • Availability during power outage –more so during natural calamities –ensure observability of the network not on outage • The technology in use should in itself have low power requirement • Secured and resilient to attacks and intrusions • Scope for open standards and enable interoperability • Choice of technology based on density of nodes, last mile connectivity, cost of deployment • Choice of technology: Licensed versus Unlicensed
- 12. Information flows in Smart Grid Two way information flow between - • Sensors and electrical appliances to smart meters-HAN-Wireless : ZigBee, 6LowPAN, Z- Wave-Wired: Power line communication- (Mostly) Unlicensed technologies • Smart meters to utility’s data center-WAN, NAN-Internet, Cellular Technologies (2G,3G, 4G)-(Mostly) Licensed technologies
- 13. Smart Grid Communication Infrastructure • Customer: Home Area Network (HAN)Devices -Smart meters, thermostats, PCs, building automation, pumps Technology -ZigBee, WiFi, Open HAN, Home Plug • Distribution: Neighborhood Area Network (NAN)Devices - Smart meters, relays, distribution automation Technology - WiMAX, PLC, Cellular • Transmission and Operations: Wide Area Network (WAN)Devices -EMS, WAMS, lines, towers, sensors and actuators Technology -IEC 61850, DNP3, SANET, Satellite • Markets-Enterprise and external Participants -Retailers, Aggregators, Regulators, Customers Technology -Internet protocols
- 14. Dedicated and Shared Communication Channels • Dedicated-secured communication, exclusive link between source and destination, lesser latency, expensive Example: Differential protection of transmission lines - communication between differential relays (blocking signals) • Shared-Message sent by the source is received by all devices connected to the shared channel. An address field in the message specifies for whom it is intended. -higher latency but economic, higher utilization of available resource Example: Communication network inside a substation, star or ring connection of bay controllers and monitoring equipments (CT, PT)
- 15. Wired Communication Power Line Carrier Communication (PLCC)- -Sending data simultaneously with electricity over same medium -Minimal added installation -Line matching unit injects signals Into HV Transmission lines or LV and MV Distribution lines -Message captured by line traps-Originally used for low-rate SCADA, now being used in Home Automation
- 16. Wired Communication Power Line Carrier Communication (PLCC)- -High data rate and capacity: 200 Mbps within homes, but low bandwidth for NAN restricts usage -Challenge from discontinuity-transformers, circuit breakers, faults -Shared medium –data transmissions are broadcast in nature-security and privacy issues -Transmission medium is harsh and noisy –adds coloured noise, severe signal distortions. Channel modelling is a challenge.
- 17. Wired Communication Power Line Carrier Communication (PLCC)- -Ultra Narrow band (UNB):below 3KHz, low data rate, high connectivity over long distances -Low Data Rate (LDR) Narrow Band (NB): Between 3-500KHz, single carrier based, upto10kbps -High Data Rate (HDR) Narrow Band (NB): Upto1 Mbps, for NAN communication -Broadband PLC: Above 1.8MHz, short range, used in HAN
- 18. Wired communication • Twisted Pair-two twisted copper cables each with outer PVC or plastic insulator –up to 1.2 GBps -broadband services • Coaxial Cables-Outer coaxial conductor provides effective shielding from external interference -reduced losses from skin effect –up to 10 MBps • Optical Fibres - Core, cladding and buffer coating -internal reflection -less signal degradation than copper wires, no interference (EMI)-lesser weight than copper but high cost of installation -used for long distance transmission –no need for repeaters up to 100 Km-high capacities up to 1 Tbps-security high because of obscurity
- 19. Wired Solutions • DSL(Digital Subscriber Lines): High-speed digital data transmission technology that uses the wires of the voice telephone network, Frequency band 0 -2.208 MHz, inexpensive, scalable, poor data security, high latency, same applications as PLC • Ethernet: Frequencies -16 MHz, 100 MHz, 250 MHz, 500 MHz, 600 MHz, 1 GHz, 1.6-2.0 GHz.
- 20. Wireless Communication • Radio Communication-Alternative to expensive fibre optic and copper wire for long range, limited bandwidth1. Ultra High Frequency (300 MHz -3 GHz)2. Microwave (3 GHz -30 GHz) • Cellular Technology-service area divided into cells, each cell has a transceiver to control and communicate with users within a cell, operates on CDMA, communication between mobile objects -even when the object moves across different cells. Technologies -3G, GPRS, GSM. -In India 900, 1800, 2100 and 2300 MHz, short technology life cycle • Satellite Communication -Widely adopted for SCADA, microwave network with satellites acting as repeater, key challenge is delay
- 21. Short Range Wireless Solutions - 6LoWPAN • Low power RF in 800 MHz, 900 MHz and 2400 MHz bands • Applications: AMI (NAN), SCADA/EMS (NAN), SCADA/DMS(NAN), Building automation, Microgrids, Distributed generation, Electric Vehicles • Lightweight, versatile -can be used with any physical and data link layer • Scalable • Low power RF unreliable due to uncertain radio connectivity, battery drain, physical tampering
- 22. Short Range Wireless Solutions - ZigBee • Short range solution (10-100m), same application areas as 6LoWPAN • Low data rates: 20kbps, 250 kbps • Frequency bands ~ 868 MHz (20 kbps) for EU, 915 MHz (40 kbps) for US and AUS and 2.4 GHz (250 kbps) worldwide • High market penetration in home automation ~ Low cost of modules • Low reliability, poor interoperability with non-ZigBee devices • Low power consumption compared to other sub GHz protocols
- 23. Short Range Wireless Solutions - ZigBee • Ideal technology for smart lightning, energy monitoring, home automation, and automatic meter reading • Capable of being connected in a mesh of large number of devices ~ 1000 nodes and more • low processing capabilities, small memory size • Interference from other devices using the license free ISM frequency band (2.4GHz) like WiFi, Bluetooth and Microwave
- 24. Short Range Wireless Solutions -WiFi • Frequency 2.4 GHz, limited range, low power RF • Applications: Automatic meter reading (AMR), AMI -NAN, home automation • Higher power consumption than ZigBee (WiFi ~ 700 mW, ZigBee ~ 100 mW) • Based on IEEE 802.11 standard for WLAN, optimized for fast data rates -higher than other RF technologies • Cost effective
- 25. Other Low Power Short Range Wireless Technologies • Bluetooth-2.4 GHz, only connects two devices at any time, extremely short range, applied mostly for reading meter data • Infrared-2.4 GHz, extremely short range, line of sight communication, inexpensive, low power consumption, application-meter reading • Z Wave -865 MHz to 956 MHz, compared to ZigBee expensive and not scalable, poor penetration in IndiaApplications: SCADA/EMS, SCADA/DMS, microgrids, substation automation
- 26. Long Range Wireless Solutions • WiMAX: typically coverage of 20kms or more for 1.8 GHz link, based on IEEE 802.16 standard, Data rates up to 140 Mbps, low latency (10-50 ms) • Low Power Wide Area (LPWA): Frequency -TV spectrum, 900 MHz, 2.4 GHz, 5 GHz, Applications: SCADA/EMS, SCADA/DMS, Substation automation • Satellite Communication: Frequency -1 to 40 GHz, affected by weather, WAMS application • Long Wave Radio: Typically 100 -200 kHz, extremely high range, reliable, propagation affected by obstacles
- 27. Comparison of commonly used technologies
- 28. Comparison of commonly used technologies
- 29. Comparison of commonly used technologies
- 30. Communication Standards and Protocols • A communications protocol is a standard rule for data representation and data transfer over a communication channel. • If devices use different protocols they will not be able to share data with each other.This was a problem in earlier versions of SCADA networks where devices from different vendors used different manufacturer specific protocols (proprietary protocols). • Open standards for communications enables seamless interoperability between devices, this brings many advantages. Vendors can supply off-the-shelf SCADA solutions that can be easily modified and used.
- 31. Open Standards for Smart Grid
- 32. Standards for Information Exchange DNP3: -Distributed Networking Protocol -Communication between substation data acquisition and control equipments -Used by control centers, RTUs, IEDs -Reliable but not secure from attacks -Master DNP3 station sends request and Slave DNP3 stations respond to these request, slave can also transmit message without request -Recently adopted as IEEE standard 1815-2010
- 33. Standards for Information Exchange IEC 61850 -Framework for substation automation, addresses interoperability of IEDs -Uses an object model to describe the information available from different pieces of substation equipments -In addition to defining a protocol, specifies a data structure -For every physical device, logical devices within it are specified. Each logical device is then mapped to 86 different classes of logical nodes as defined in IEC 61850. For a IED with protection logic, the logical nodes could be -distance, over current, differential, etc.
- 34. IEC 61850 Data Structure