Communications for Smart Grids Hem Thukral Research Officer ISGF Introduction • Smart grid is a superposition of 2 networks – The electrical network • Generation • Transmission • Distribution – The communications network • • • • Core/backbone Backhaul/Wide Area Network (WAN) Last mile/access/Neighbourhood Area Network (NAN)/ Field Area Network(FAN) Home Area Network (HAN) • Communication is the backbone of a smart grid – 2-way communication is essential for the operation of a smart grid – Monitoring and controlling the power flow in the grid Topologies in Communications • The topologies that are commonly used are – – – – – Star Mesh Ring Bus Serial/line • Selection of a topology depends on the application – – – – – Wi-Fi: Star topology Connecting smart meters to a data concentrator unit: mesh topology Backbone networks using optical fiber: ring topology Ethernet: Bus topology Between an electronic meter and modem: serial topology Use of Communications in a Smart Grid – – – – – – – – – – – – AMR AMI SCADA/DMS SCADA/EMS Wide Area Monitoring System (WAMS) Substation Automation Electric Vehicles Distributed generation Energy storage Microgrids Demand response Redundant links for critical applications such as Distribution Automation and Substation Automation Automated Meter Reading (AMR) Typical architecture of AMR (Note: Communications is only ONE-WAY) AMR is used extensively in R-APDRP for HT consumers, distribution transformers and feeders. Both GSM and CDMA were used. It is reported that reliability is in the range of 50-60%. Advanced Metering Infrastructure (AMI) Typical Architecture of AMI COMMUNICATION IS 2-WAY Advantages of communications in AMI • Consumers could – View their energy consumption accurately on a regular basis – informed consumer – Manage loads via remote turn ON/OFF and managing total demand – SMART PHONE/IHD to turn off! – Save money from ToU tariffs by shifting non-priority loads – Face reduced outages (SMART METER WILL CONVEY TO UTILITY) • Utilities could achieve financial gains by – Reading the meter remotely: REDUCED TRUCK ROLLS – Managing the load curve by introducing demand response, ToU/ToD tariff, etc. • No need to purchase expensive power at the last hour. – Enabling faster restoration of electricity service after fault/events • Outage detection easier using Smart Meter – Detecting energy theft/pilferage on near real-time basis – Billing and collection will be automatic Supervisory Control And Data Acquisition (SCADA) for DMS and EMS Communications for SCADA(contd.) • Monitoring – Status • Switch status, protection relay status, fault of FTU, flow detection, momentary voltage drop etc. – Measurement • Voltage, current, active power, reactive power, power factor etc. • Control – Switch gear (open/close) – Relay (in use/not in use) Typical Architecture of SCADA Wide Area Monitoring System(WAMS) Typical architecture of WAMS 21 Sep 2012 WG <no> : <WG Title> Communications for WAMS –Voltage stability assessment –Oscillation detection –Post-fault analysis –State estimation –System state prediction Other applications • • • • • • • Substation Automation Distributed Generation Electric Vehicles Energy Storage Microgrids Demand Response Home Automation/Building Automation Characteristics of communications for smart grids • • • • • • • • High bandwidth • AMI/AMR - low • SCADA - high Low latency • AMI/AMR – low • SCADA - high High availability of network High reliability High level of security • Meter – privacy of data • SCADA – trip feeders using ONE click of mouse High level of scalability Long range: choice of frequency! Low power consumption • Long technology life-cycle • Compliant with regulations • 865-867 MHz and 2.4 GHz ONLY; • Interoperable • Low Total Cost of Ownership (TCO) – Cost of infrastructure acquisition (towers, PLC lines) – Cost of communications media acquisition (license fee) – Operating cost Potential Smart Grid Solutions Wired options • PLC (Narrowband and broadband) • Ethernet(co-axial cable, twisted pair, optical fiber, radio) • RS-232 • RS-485 Wireless options • Low Power RF (eg. 6LOWPAN, ZIGBEE, proprietary) – Operate mostly in SLEEP mode • Cellular (GPRS, EDGE, 3G, HSPA, LTE, WiMAX) • Wi-Fi (data security ???) • V-SAT • Infra-Red • Bluetooth • Private point-to-point microwave links • Private point-to-multipoint microwave links Wireless Spectrum – Global Scenario For India, 2 MHz might be too less • Millions of IEDs in a smart grids • Billions of smart devices in a smart city Spectrum for PLC – Global scenario Region Europe Frequency band for PLC CENELEC A: 3-95 KHz for power utilities CENELEC B: 95-125 KHz for any application CENELEC C: 125-140 KHz for in-home networking with mandatory CSMA/CA protocol USA CENELEC D: 140-148.5 KHz Alarm and Security systems 10-490 KHz, and 2-30 MHz Japan China 10-450 KHz 3-500 KHz Selection Criteria – some parameters Criteria Preferred Technologies High Bandwidth Optical fiber, BPL, WiMAX, 3G, HSPA, LTE, VSAT Low Latency DSL, optical fiber, Wi-Fi High Reliability Optical fiber, HSPA, LTE, V-SAT, DSL, Wi-Fi, RS-232, RS-485 High Security Optical fiber, BPL, private RF Pt-to-MPt, WiMAX, V-SAT Low Cost Narrowband PLC, 6LoWPAN, ZigBee, Wi-Fi, Bluetooth, Infrared, GPRS, EDGE, RS-232, RS-485 The selection of a technology will depend on the application • For mission critical applications (such as Distribution Automation and Substation Automation), security, latency and reliability will be the key. Cost will not be considered as a parameter during selection. • For non-critical applications (such as AMI), cost will be decisive. Case Study (International) Southern California Edison • • • • AMI – HAN: ZigBee AMI – NAN: Proprietary RF mesh at 902 MHz AMI – WAN: 3G SCADA Wide area connectivity: Optical fiber (mostly) + V-SAT (for remote locations) Local Area connectivity: Proprietary solution using 902 MHz RF mesh network Case Study (National) MSEDCL – AMR for R-APDRP: GPRS using modems for 58,000 meters (feeder + DT +HT consumers) – Meter reading using HHU • ZigBee with modified SEP for 6.31 lac meters in dense urban areas • InfraRed for 30 lac meters in rural areas – Distribution Automation and Substation Automation • Between field devices and RTU: RS-232 • Between RTU and control centre: leased line(optical fiber) The Way Forward • Un-licensed communication bands in India are: – 865-867 MHz for low-power RFID devices (un-licenced in 2005) – 2.4 GHz band • Short range • Interference: Wi-Fi, microwave ovens etc. • Use of lower frequency bands (<865 MHz) could be considered • Additional spectrum might be needed to cater to millions of connected devices as part of the IoT • National Optical Fiber Network (NOFN) – Connecting all 33 kV substations USING OPTICAL FIBER for e-governance, e-learning etc. – Smart Grid applications could use this network The Way Forward (contd.) • To ensure interoperability, standards-based communication technologies will be promoted – IP-based technologies will gain traction in the market • Use of proprietary solutions would reduce as these do not lead to interoperability • Standardization in India - BIS – For formulation of standards in the field of Electronics and IT • Electronics and IT Department (LITD) – Sectional Committee LITD-10 (Power System Control and Associated Communications) has Panels dedicated to smart grids • AMI, Interoperability, CIM, Cyber Security, Digital Architecture Conclusion • Different geographic regions have different requirements and constraints – PLC might not be feasible in some areas where the wiring infrastructure is not clean – Low power RF mesh networks might not be feasible in densely populated areas • No ‘one’ communication technology will dominate the smart grid – It will be a mix-and-match of different technologies • Choice of technology will depend on the application Conclusion (contd.) • Performance (bandwidth, latency, reliability, security, availability etc.) needs to be balanced with cost • The Total Cost of Ownership (TCO) to be considered – Cost of infrastructure acquisition – Cost of communications media acquisition – Operating cost • The results of the 14 pilot projects will give us an indication on what technology to use for large scale roll outs Thank you..