Advanced Metering. Distribution Grid Operation

Transcription

1 Advanced Metering Infrastructure and Data Mining for Smart Distribution Grid Operation [ September 2010 ] DR. SIOE T. MAK PhD. EE. IEEE LIFE FELLOW Sioetmak@aol.com 1

2 The Electric Energy Delivery Infrastructure Electric energy is a transitional form of energy. It can be transported in bulk across large distances through narrow corridors at the speed of light. The corridors are the transmission and distribution lines. It can be easily split into bulk or minute quantities. Conversion into other forms of useful energy is a wellknown technology. ( electric motors, heating elements, light bulbs, etc.) Alternating currents (50 Hz or 60 Hz) permit voltages to be converted to high or low voltages using transformers. High voltages are used for long distance transmission to reduce losses in the lines. 2

3 Unique properties of the energy delivery infrastructure Three phase 4-wires or 3-wires and transitions through step-down transformers can be Y-Y, Y Y-D DandDY D-Y, grounded or ungrounded at the Y side. Under steady state conditions, the 3-phase voltages V an, V bn and V cn can be defined as 3-phase phasors. For any of the phasors defined at the distribution substation bus, there is a remote corresponding phasor, slightly yphase shifted from the phasor at the bus with a magnitude dependent on the intervening step-down transformer ratio and the voltage drop in the circuit due to circuit loading. 3

4 Automatic Meter Reading ( AMR ) is possible Advances in micro-electronics, communication and computer technologies Deregulation of utilities, unbundling of utilities structure Electricity loses its social status and is now a commodity Rlibl Reliable communication i is available ilbl and can reach every point of the utility distribution network. Remotely monitored data can be brought back in timely fashion Huge numbers of data transfer per unit time can be handled by the communication network Large data storage and handling is available 4

5 What is beyond simple meter reading applications? Advanced Billing systems, Pre-payment, Time of Use Novel rate design Services to other utilities ( gas and water utilities ). Demand Response, Remote Service Connect and Disconnect. Integrated t dvoltvar VOLT-VAR Control, Load Balancing, Assets Management Outage management functions Alarm functions. Etc. 5

6 FUNDAMENTAL ISSUE Can a system that is designed for automatic meter reading be economically expanded or upgraded to implement future added-value capabilities without requiring a major overhaul, large increase in capital expenditures and future added utilization costs. 6

7 DIFFERENT PARTIES REQUIREMENTS Customer Service wants timely retrieval of metering data, handling of customer complaints, service connect and disconnect, pre-pay metering, etc. Energy management age e needs load survey data and perform demand response type functions. Maintenance and repair group requires outage management and distribution control applications. 7

8 SYNCHRONIZED INTERVAL METERING DATA Coincident peak demand Time of Use rates, Demand Response strategy, etc. Customer load utilization profile, improve load control algorithms Distribution transformer loading, feeder load balancing Coupled with voltage monitoring, improved feeder VAR and Voltage control Retail wheeling billing, pre-pay metering 8

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10 System Architecture and Infrastructure The Communication Net Server Computer handles data flow control and commands to various computers and remote devices Maintain and updates remote devices ID and path parameters Decodes and codes messages/commands for transmission to remote devices Send retrieved data from remote devices to appropriate computers 10

11 THE MEANING OF DATA THROUGHPUT 11

12 Baud rate : OPERATION AND RELIABILITY One physical path and one communication channel. Limited data throughput More parallel non-interfering physical paths, one communication channel per physical path. Larger data throughput More parallel non-interfering physical paths, more communication channels per physical path. Maximum data throughput Two-way way communication performance. 1. Noise filtering, error control 2. Physical path problems ( spill-over, cross-talk, obstructions, standing waves, node problems) 12

13 COST OF RELIABILITY & ADDED UTILIZATION COST Cost of non-performing: 1. Equipment reliability (MTBF), communication reliability 2. Added utilization cost: a. Sensitivity to network expansion, expensive support 13

14 THE ISSUE OF OBSOLESENCE Electric Utilities are used to equipment with 10 to 20 years of useful life. Digital electronic devices manufactured a few years ago may not be available anymore. New devices have more capabilities. During contract negotiations, downwards compatibility is a requirement in addition to more advanced capabilities offered by the new devices. 14

15 ORGANIZATION, ADDRESSING AND COMMUNICATION CONTROL Design functional group addresses requiring one group command to reduce the number of communication transactions ti for scheduled d operations. Identify location and communication path of each transponder at the network. (By substation bus, feeder number, phase, etc.). Each transponder is accessible by serial number using the communication system Outages at communication nodes and group of transponders and the relocation of the transponders at the utility network have to be monitored and identified to avoid wasteful communication. Alternate routing in emergency, recovery to original communication paths are necessary 15

16 REAL TIME AND SYNCHRONIZATION Transponders need an internal time clock which can be synchronized. (Boulder NBS standard clock or GPS clock) After a large outage, transponders need to be synchronized Interval data time stamping. Time information is needed to assess coincident demand, real time voltage distribution on a feeder, etc. 16

17 DATA SECURITY, SYSTEM RECOVERY AND LOSS OF DATA Error control and reasonability check Data access control and cyber security Power-ride-through ride and non-volatile memory at nodes and remote devices Back-up memory for transponders path maps and addresses and synchronized to incorporate the most recent state of the distribution network and the communication network. 17

18 Advanced Metering and Added Value Functions A. Customer Services and Demand Side Management B. Improvement of Service Reliability and Oti Optimization i of fenergy Delivery Dli C. Supporting Functions 18

19 1. Synchronized Time Stamped Interval Metering (Cat.A ) Time interval depends on application Energy (.5 hour to 1 hour ), Demand (15 minutes ) Data is integrated over the interval 2. Interval Voltage Monitoring( Cat. A ) Instantaneous value Needs good definition if voltage is distorted 3. Locating Faulty Part of the Network ( Cat. B ) Prevent waste of time to communicate to deenergized units 4. Cost of Not Knowing ( Cat. C ) Can section be avoided if outage mapping is in place Locating nodes on de-energizedenergized network 19

20 Customer Services and Demand Side Management Advanced Metering : 1. Electric Energy retail wheeling - Prepay metering - Service Disconnect - Gas and Water Metering 2. Demand Response - Time of Use and Load Control - Averting Rolling Blackouts and Reducing Impact of Cold Load Pickup 3. Detection of Theft 4. Alarm 5. Etc. 20

21 Advanced Metering Applications Retail Wheeling Meter reading services, interval data and time stamping Data warehousing Competition amongst retailers Different rates, start of contract and duration Services fees Billing services 21

22 Pre-pay Metering Customer energy use profile and customer education Rate, Start and Duration of Contract Payment deposit, where and how Activation Customer alert to deposit more money What happens if it is on a holiday Grace period Total disconnect 22

23 Remotely Operated Service Disconnect Thermal and contact t ratings of switch Short circuit handling capability Remote checking of switch status Manual operation Device address linked to metering transponder address On site operational testing and switch activation Customer alert before opening switch Arm the switch and customer activates the switch 23

24 Gas and Water Metering Coupled to the electric metering transponders through short hop RF link or hard wired link RF transmitters at the gas and water meters need batteries For hard wired gas meters, safety barriers are required Water meters inside metallic manholes can pose problems for RF Gas and water meters can be coupled to one data concentrator at the electric metering transponder Interval gas and water consumption metering has not taken off yet 24

25 Demand Response To defer or avoid the need to build a peaking unit Can be considered as dispatching negative generation Load Control Load survey data are needed Load cycling switching schedule for specific appliances have to be designed to shift system peak demand The scram function is used to drop load in emergency Two-way communication system for load control reduces the cost of reliability 25

26 Time-of-Use Different rate structure during system peak demand is applied to qualified customers. Small customers with near constant load are excluded. Expectation of customers to curtail load and customer alert Charging higher energy prices during peak periods Definition of shoulder,,peak and valley Interval time synchronized meter reading can be used to verify the effectiveness of the Time-of-Use strategy 26

27 Hybrid Cars and Electric Vehicles 1. Generate additional peak demand 2. New Demand Response Strategy 3. Price competition with the oil industry 4. Requires sub-metering 5. Harmonics issues 27

28 Home and Commercial Automation Network 1. Gaining popularity 2. Sub-network uses its own local l communication for monitoring and controlling its load 3. Requires set-point from the electrical utility 28

29 Energy Trading/Exchange With Privately Owned Generation 1. Control and Protection Issues 2. Exchange Pricing Issues even at Utilities Parity Energy Cost of Generation 3. Guarantee Energy Availability by the Electric Utility 29

30 General System Alarm 1. Demand Response Scram to participants 2. General System Alarm to Curtail Demand to Avoid Loss of System Stability 3. Different Use of Alarm by the Civil Defense. 30

31 Service Reliability and Optimization i of Energy Delivery 1. Feeder load balancing 2. Integrated Voltage and VAR control 3. Electric Utility Network Outage Management 4. Averting Rolling Black-outs and Cold-Load Pickup 5. Monitoring Distribution Transformer Overloads 6. Monitoring Unauthorized Use of Electric Energy 31

32 Feeder Load Balancing Load imbalance causes unbalanced 3-phase voltages. Increase in circuit losses, 3-phase motors overheating, stray currents, etc. Hourly meter reading can be used to determine coincident demand on each phase of a feeder Comparing the coincident demand of each phase on the same feeder can be used to determine which loads can be shifted to a different phase 32

33 LOAD CONTROL TO IMPROVE LOAD FACTOR [ NETWORK LOSSES REDUCTION ] 33

34 Dynamic Network Modeling 1. Time synchronized data can be used to generate equivalent circuits which reflect the dynamics of the network voltages, current and load as a function of time. 2. Example : A single phase lateral is tapped from a 3-phase feeder. For the time interval ΔT obtain KW AVG, V AVG and KVA AVG. Calculate the equivalent circuit Z AVG = R LOAD + jx LOAD Combine all line impedances and load impedances plus the distribution transformer impedance The single phase lateral is replaced by an equivalent impedance and its voltage and equivalent lateral lcurrent are also known. 34

35 Balancing Operations 1. Obtained profiles of coincident loads on each phase of a feeder. 2. Determine which loads cause recurrent unbalance conditions 3. Is there a permanent load transfer possible which minimizes the feeder unbalance? 4. Can Demand Response applications be used to improve the feeder load factor? 5. For each case obtain voltage profile along the feeder 6. Also determine line segment currents and their power factors. 7. All these operations will help the design of algorithms for load balancing and integrated VOLT-VAR control. 35

36 VOLTAGE UNBALANCE 36

37 GROUND STRAY CURRENTS DUE TO SYSTEM UNBALANCE 37

38 Integrated VOLT-VAR VAR control Practical problems Voltage level profile along the feeder difficult to determine as function of time and load Switching of capacitor banks based on calculated models and simplified assumptions New possibilities Hourly synchronized meter reading and voltage monitoring Helps to design more accurate switching algorithm for capacitor banks Check effectiveness of the switching algorithm 38

39 Electric Utility Network Outage Management Electric utilities already implement selective coordination of protective devices to isolate faults Polling of transponders can be used to determine which protective device has operated. Units that are de-energized will not respond to a polling command. Non-responding transponders have to be related to physical locations at the network. 39

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41 1. Communication technologies which are not power line based have to monitor intermediate nodes that are affected by an outage. 2. Rerouting paths to reach transponders initially i i affected by the outage and reenergized 3. Outage detection and mapping reduce wasted communication time trying to reach the deenergized transponders. 41

42 Averting Rolling Blackouts and Reducing the Impact of Cold Load Pickup Brown outs are rolling blackouts to reduce system demand dwhen the spinning i reserve is very low. Prolonged disconnect of power to part of a network can cause cold load pickup problems. Load control (some form of scram function) can be used to reduce the need of applying rolling blackouts. Loads can be restored in a staggered fashion to reduce the effects of cold load pickup. 42

43 Distribution Transformer Overload 1. Obti Obtain coincident id tload of fthe distribution ditib ti transformer 2. Develop coincident load profile of the transformer 3. Identify the period of time when overload occurs. 43

44 DETECTION OF ENERGY THEFT 1.Reconciling total coincident demand with coincident demand of all customers served by the same distribution transformer in real time 2. Compare outage counter with adjacent transponders outage counter. 44

45 Alarm Civil Defense Traffic routing Peak load alert to customers to curtail load Alert to pre-paying customers to deposit more money Alert customers that the service disconnect is going to be activated Peak load alert to smart homes 45

46 Power Quality Monitoring Distorted voltages and currents affect meter reading accuracy ( DC component in the load current ) Standard distorted wave-shapes for meter calibration not yet developed by the industry Increase system losses, damage to digital electronics Polling power quality monitoring devices at the network to perform patrol to spot harmonic polluters Effects of distributed generation on the distribution network. 46

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50 Supporting Functions Communication Network Monitoring and Control Extension of SCADA capability into the distribution network AM/FM systems Data Management and Data Warehousing Communication path-maps and transponder address data base Multiparty Users Etc. 50

51 Communication Network Monitoring and Control Effects of power outages on the communication nodes Determination of de-energized transponders Eliminate communications to de-energized transponders Rerouting algorithms to reach transponders that are alive Reestablish normal operating conditions when everything goes back to normal 51

52 Area Map and Facilities Management systems Electric network is very dynamic Man made switching due faults or for maintenance Use AMR capability to update circuit to the latest conditions using the Outage Mapping function 52

53 DATA WAREHOUSING For data to be useful : Synchronized interval meter readings, voltage data, etc. have to be time stamped and can be related to substation bus, feeder, phase, etc. Sufficient i historical i data have to be kept for reference and for application and control strategy algorithm development. Data mining should be fast, easy and yet secured. 53

54 DIFFERENT TYPES OF COMMUNICATION SYSTEMS FOR UTILITY APPLICATIONS Power line based technologies Radio frequency communication technologies Hybrid systems, hard wired and RF networks Other hard wired networks, telephone, dedicated fiber optic networks Broadband d systems, satellite based systems 54

55 TWO WAY POWER LINE OMMUNICATION 55

56 POWER NETWORK CHARACTERISTICS Designed to deliver power at 50 Hz or 60 Hz Multiple step-down transformers, different power ratings, winding ratios, winding configurations Overhead and underground conductors Capacitor banks and voltage regulators Line lengths between 2 miles and 60 miles Natural transient oscillatory frequencies between 200 Hz and 600 Hz 56

57 Low Frequency Carrier Uses the power frequency carrier Signal frequency ranges between 200 Hz and 500 Hz and superimposed on the 60 Hz or 50 Hz carrier Capacitor banks, underground d cables do not cause signal attenuation Separation between phases is excellent (phasor specific) Communication paths can be associated with phase wires Simplify search and path parameter for remote devices 57

58 Baud rate is low but communication performance is excellent Increase in data throughput by implementing simultaneous communication channels per physical path Additional increase in data throughput by using different physical paths (concurrent feeders) connected to the same distribution substation bus simultaneously 58

59 Medium Frequency Carrier Operates at the medium voltage distribution network Operating frequency between 5 KHz and 15 KHz, several order of magnitudes of the power frequency Operates at the medium voltage distribution network For most distribution lines, these lines are considered long for that range of frequencies Frequency Quarter wave-length 60 Hz miles 1000 Hz 46.6 miles 5000 Hz 9.3 miles Hz 3.1 miles 59

60 Standing wave problems, need repeaters at the nodal points on the line Power factor capacitors require medium frequency signal blockers Underground cables may pose problems Spill-over between phase wires makes phase and address identification difficult Distribution network expansion or reconfiguration require complex modifications of the communication infrastructure 60

61 Medium Frequency Power Line Carrier at Service Voltage Network Operating frequencies 90 khz or higher Data concentrator at the distribution transformer and linked to the Net Server computer Sub-node at the metering device initiates communication at any time Peer to peer communication, collision detect and avoidance are implemented In many foreign countries the low voltage network is massive Few step-down distribution transformers per substation. 61

62 Few data concentrators and telephone links to the Net Server required per medium voltage network. In the USA, smaller distribution transformers are used at medium voltage network. Many data concentrators and links to the Net Server required and is not economical. Spill-over between distribution transformers can occur Underground cables impair the communication Mutual interference slows communication 62

63 HYBRID TELEPHONE SHORT HOP RADIO SYSTEM 63

64 HYBRID TELEPHONE SHORT HOP RADIO SYSTEMS Random access by large number of customer calls Large random delays for utility operation. Top ppriority to paying customers Hybrid telephone RF systems Telephone to data concentrator RF link to gas, water and electric meters. Telephone shared with other users RF network difficult to install Requires field testing 64

65 SHORT HOP RF COMMUNICATION PLUS HIGH POWER TWO-WAY RF TRUNKING SYSTEM 65

66 Short Hop RF one-way Communication plus High Power Two-way RF Trunking System Short hop one-way radio from transponders to data concentrator Communication from transponder to concentrator is unsolicited Time stamping at data concentrator Collisions are allowed Individual outages are detectable Two-way way RF trunking network from data concentrator to Net Server Re-routers and power required during outage. 66

67 LOW POWER MULTI-NODE TWO-WAY RADIO 67

68 Low Power Multi-Node Two-Way Radio Frequency Communication Very high frequency Spread spectrum technology Line of sight Acknowledges to sender upon receipt of message Only few retries of communication allowed to avoid bottle-neck conditions Alternate routing algorithm Bad node causes data loss Difficult to track communication problem or bad nodes 68

69 Broadband Systems using Power Line and other Types of Communication Systems Goal is to use broadband technology for non-utility applications Frequencies used are in the Mega-hertz range - Baud rate of 20 Mega-bits being considered for power line carrier at the medium voltage level. -Up to 200 Mega-bits / sec. at the low voltage network to accommodate HDTV Customers are willing to pay for services AMR may one day piggy back on this system No good full scale system available for reference FCC may eventually regulate the Broadband PLC due to the RF frequency range, which might cause interference to existing devices ( portable telephone, domestic RF linking devices, computer processors, etc. ) 69

70 WiFi WiFi, the most popular wireless standard for networking computer systems, has the following basic characteristics: Multi-user configuration IEEE b data rate is 11Mbps IEEE802.11g data rate is 54Mbps Frequency band is the 2.4Ghz band Range of feet Equipment and WiFi systems/access points are usually privately owned 70

71 Bluetooth is used in cell-phones Personal Digital Assistants (PDAs), and other mobile wireless devices, primarily for communicating with computers, Intelligent Electronic Devices (IEDs), headsets, hands-free systems, and other gadgets. Point-to-point links Very short range of only 33feet t( (approx 10m) Frequency band is the 2.4Ghz band. Relatively low data rate of 1.5Mbps Equipment and Bluetooth systems are privately owned 71

72 Zigbee Based on IEEE Defines low-rate, very low duty cycle, wireless personal area networks. Meshed networks as opposed to point-to-pointto Builds upon standard. Defines application profiles shared among different manufacturers. Provide system-to-system interoperability. Effort is still a work in progress. Of great interest est to industries ies (such as the power industry) that have extensive sensor networks. 1. Multi-user configuration 2. Range between devices is feet 3. Low data rate of <250 kbps 4. High availability due to meshed network configuration 5E 5. Equipment and dzib Zigbee systems are usually privately tl owned 72

73 WiMax (IEEE ) Wireless technologies with primary focus of enabling a wireless alternative for cable, DSL, and T1 communication channels for consumer last-mile access to the Internet. High-speed data, Voice over IP (VoIP). Video on Demand (VoD) Backhaul for IEEE LANs. WiMax addresses the "first- mile/last-mile" connection for longer distances and faster rates. 1. Multi-user configuration 2. Range of 5 to 30 miles (5 more likely) 3. Data rates of (45-75 Mbps 73

74 Cell-phone Cell-phone data standards, GPRS. Part of GSM effort to create a common European mobile telephone standard for a pan-european mobile cellular radio system (and now worldwide). The resulting mobile telephone standard allows cell-phone users to roam across many cell-phone systems and between most countries world-wide. New generations of cell-phone technologies, termed 2.5G, 3G, and 4G are deployed in certain countries or are still under development Multi-user configuration. 1. GPRS commonly used for data, with kbps typical. 2. EDGE (enhancement to GPRS) provides kbps 3.The range is wherever cell-phone coverage is available! 4. Cell-phone systems are owned by telecommunication providers 74

75 Conclusions AMI and Smart Meters open the door for implementing Smart Distribution Grid Operation. System architecture and infrastructure design determine adaptability to various advanced applications Data base management systems capable of handling large numbers of data, prevent tloss of fdata and accessible to multiple parties. Immunity to Cyber attacks Multiple types of data can be collected simultaneously in controlled intervals in synchronism for generating g information used for distribution control Novel methodologies for optimization have yet to be designed and implemented 75