Integration of Metering, GIS and SCADA DataBenefits the Utility and indirectly Consumers
Obtaining Information from Metering, Distribution and Transmission Network Data Bases• Requires a knowledge of what the data represents• How the data is obtained• From where the data is sourced• What values should be Expected• Sources of distortion to the information obtained from data
The Value of Information derived from data can be time Dependant• A large number of beneficial outcomes can be obtained with data which is hours / days or Months Old• Major benefits can be obtained by having data available and processed near real time
Applications with historical Data• Customer Billing• Planning for Line and Transformer Loading• Voltage Line Drop Compensation Fine Tuning• Monitoring Service Cable condition (Safety)• Customer Phase allocation• Identifying locations for real time monitoring• Strategic Asset Placement• Identifying sites to investigate for non-technical losses• Maximum Safe Load analysis of Protection
Applications with Near Real Time Data• Targeted Demand Response• Closed Loop Line Voltage Regulation• Customer Outage / Restoration Notification• Micro Grid Stability• Field Battery Discharge Test• Phase Identification• Meter Tampering• Registered & Unregistered solar site identification• Excessive protection operations
Applications with Near Real Time Data (cont.)• SCADA triggers to auto extract fault recordings from relays – Via engineering access (not SCADA)• Flicker analysis
Advanced Metering Infrastructure (AMI)• Interval Metering• Under Voltage Alarm (unsolicited priority)• Over Voltage Alarm (unsolicited priority)• Tampering alarms• Voltage
Customer Voltage Map (AMI Alarms) • Telemetered Metering provides indication of Under Voltage , Normal Voltage and Over Voltage in Real Time • Red Dots are Over Voltages • Green Dots are Normal Voltage • Can be used as feedback for IVVC – exclude customers with solar as control points • What to do about customers who are over voltage due to solar?
Load Balancing• Ideally equal real time loading on each phase• Establish LV phasing connectivity for each transformer• Summate AMI load data for each meter to create virtual transformer load profile per phase• Identify solar distribution across phase and affect on voltage drop• Identify load to be moved to a different phase• Establish correct phasing for HV line devices, ACRs etc.• Identify lateral phases that can be moved to a different phase• Identify single phase transformers that can be moved to different phases
Load Balancing Important for Voltage Regulation • The more uniform the load distribution across phases, the easier voltage regulation is to achieve
Phase Identification • All phases can be referenced real time to a master phase identifier • Use to correct phase reporting for remote SCADA connected devices • Helps to balance load distribution • Useful when commissioning new devices • Also use SCADA / AMI data matching for faults and voltage drop
Customer Phase allocation• Use supply outages and voltage drops to allocate individual single phase customers to a particular phase.• Phase out LV of an individual transformer• Phase out HV line devices• Phasing should be absolute so that customers on B phase on one transformer can be compared to a customer on B phase on another transformer for comparison of line loading
Transformer Load Planning• Large load increases often experienced on Distribution Transformers during Heat Waves• Virtual Load Profile can be constructed by combining the load profiles of those customers connected to the Transformer• Virtual Load Profile run day after Heat Wave• Used to identify those Transformers that Require Real time Monitoring and Demand Response Capability• SP – AusNet had approximately 300 Transformer Failures in 4 Days during a Heat wave 3 years ago
Identifying sites to investigate for non-technical losses• Phase measurement of a distribution transformer• Phase assignment of customers• Summations of customers on each phase• Allowance for line loss• Compare to actual measurement at the Transformer• Flag areas for closer examination• Also use line drop models based on Voltage at transformer and each house• Houses with measure values less the calculated value are possibly consuming unmetered load
Meter Tampering• Cover removal switches which are connected to alarms in AMI• Cross reference to works orders to see if legitimate• Flag tamper alarms where no works orders for site• Unauthorised disconnection of supply – Removal of supply fuse to “work” on home
Maximum Safe Load analysis of Protection• Checking load data from SCADA against Protection Settings for field device• Alarm when limits are encroached on• For Over Current• For Distance relay starter – Plot position of mho for protection review
Line Loss Reduction•For distribution companies no economic drivers at themoment for line lose reduction.•Under a Carbon Tax ?•Regulatory Change ?
Field Battery Discharge Test• Small sealed lead acid batteries in the filed are a maintenance issue for utilities• Typical life 2 to 7 years• Affected by Heat, charging conditions, Level of discharge• Resistive load test periodically done on some• Outage enables discharge testing to be done – Know time until coms lost after supply loss – Know expected hold up time for battery – Flag batteries that didn’t keep communications going long enough / flat
Excessive protection operations• Mostly an issue with ACR fast trips & trees• ACR trips reclose on fast operation• Tree contact isn’t lone enough for time delayed operation so protection resets (40 seconds)• Another fast trip occurs soon after• etc.• Can also be unravelling conductor strand• Alarm if more than X operations in a time period Y (e.g. 6 in 3 hours) – Dispatch crew to fix issue – Indicate to temporarily suppress fast trip operation
SCADA triggers to auto extract fault recordings from Relays• Via engineering access (not SCADA)• Package and distribute for analysis – Reduce to hours or min. way presently takes days if field staff dispatched – Stored data often over written before it can be retrieved – During a fault, not enough staff to do manually – Data for difficult faults can aid analysis real time. – Important for in depth post fault analysis• Applicable for Transmission & Distribution
Improve Environment for LV EmbeddedGeneration• LV Inverters should shut down when Voltage they need to generate at is greater then 253 Volts• Voltage to the zero current flow point held by dominant generator (grid).• Embedded generator needs to have voltage high enough to allow for voltage drop from Inverter to the zero current flow point• Keep zero current flow point Voltage down to enable maximum Voltage build on Inverters.
Why Closed Loop Voltage Regulation?• Embedded feeder Generation – Domestic Solar – Small Generators (Base load 300kVA to 8 MVA) – Intermittent Generators (Wind, peak micro Generation)• Voltage Compliance• Demand Reduction during Peak Loading time – Set before Load Shedding – Differ Capacity Upgrades on individual Feeders
Closed Loop Voltage Regulation• Real Time Voltage (LV) Monitored in the Field• Used to control the Tap Position of Zone Substation LTC• Also used to control Tap Position of Line Regulators• Control Switching of field capacitor banks• Objective to reduce the Voltage spread at individual supply Points• Makes driving the Voltage at supply points lower possible
Outage Management• Important to Know Both Loss and Restoration of Supply – Many examples of when an individual Customers Supply Fuse Operates at the same time as Major Line Protection Device • Call Out Crew fixes Main issue and assumes that everybody is back on • Secondary Call Out Hours Later to Restore Supply to Individual Customers – Credit in Network Performance for Partial Restorations• Integration of SCADA Data and Metering Information in Real Time• Important that it is Loss of Supply NOT Loss of Communications• Used to Audit SAIDI, SAIFI & MAIFI
Real Time Data accessible locally• Historical Metering Data used to select real time Monitoring Locations• SCADA signals communicating locally to control generation, Storage & Switching• SCADA requests to Metering system for Demand Response so as to NOT overload Micro Grid Capability – Load Shed Water Heating – Demand Restriction of Customers? – Contracted Manageable Loads
Issues That Need to Be Considered When Designing Smart Data Applications
Missing Data• Not all data sources are present for the historical point of time you are mining for• Equipment can go offline• Disruption to data with equipment failure and change over
Flat Lining• Transducers can lockup• Maintaining a variable such as ambient air temperature at a constant value is an indication of flat lining• Affects variables such as – Temperature – Currents – Voltages – Complex analogue variables
Order of Magnitude• Simple Order of Magnitude storage of values can cause issues. Especially if they come form different transducer types. i.e. CB feeder relay and down line switch.
Range Control• Range control can often clip analog variables causing them to flat line at a magnitude higher or lower then expected.• Example of a variable for SWER line Voltage. Record indicated a constant 8 kV. Line voltage should have been nominally 12.7kV. Two issues; – Value less then expected. – Value flat lined, would expect some small fluctuation. Note when line was off this value also went to Zero. – Initially Suspected incorrect variable mapped
Signed Data• Signing of data can cause issues when looking at data from different sources about the same physical quantity. – Mostly when analysis is done of binary variables
Events Generated during Test & Commissioning• Operation number for field devices can look higher than actual field performance• Distorts network reliability analysis unless filtered out.• Many IEDs cannot exclude testing from their wear and life indicators• Desirable to have flags to indicate data being generated by test and commissioning
Variations Due to Network Switching• The operation of the network can affect what loads are connected to a particular part of the electricity network at any point in time• Apparent Load increase could be due to extra line segments being switched onto the end of the line. – Issue when looking for maximum line loads
Phase Rotation• Line construction can affect the mechanical position of electrical phases• Field transducers often assume phases allocated to a mechanical position. i.e. B phase is in the centre. A phase is on the left and c phase on the right. – Affected by which side of the pole a transducer is located on – Phase rotations associated with power lines Teeing off around corners• Makes line segment loading calculations problematic
Field Time and SCADA time• Because of communications delays often desirable to process events based on field time rather the time stamp associated with data being received.• Some systems don’t report field time correctly• Important to note time source when reconstructing events record
Time Synchronisation and Drift• When considering the sequence of data from different transducers consideration should be made for the degree to which field time can be compared – Are all the times synchronised to the same time ? – Is their an offset in some IEDs ? – To what accuracy ? – What is the clock drift of the IED ? – What is the accuracy to the synchronisation method ?
Daylight Savings• Sometime daylight savings adjustments is made to records – Is it a correction on the display only? – What is the base time of the raw data? – Are the transducers affected by daylight savings? i.e. new smart meter clocks. – Does the real world change with daylight saving, however the data locked to UTC for example.
Accuracy and linearity of Field Transducers• Often variations are seen because the field devices are not linear over the complete range being monitored. – Notably current Transducers recording fault levels – Did the transducer have sufficient time to accurately record field value e.g. high magnitude fault currents – What is the accuracy to the field transducers?