Meter Clock Drift / Time Synchronization

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Corey Boone
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1 Meter Clock Drift / Time Synchronization RMSC/MSP User Group Meeting Zahir Gohgari, Supervisor, Meter Data Management June 12, 2018

2 Introduction / Background IESO market rules require all meter clocks to be synchronized to eastern standard time (EST) in the province of Ontario. IESO systems verify the meter clock by comparing meter time to system time during the daily interrogation. This requirement comes from the following Market Rules: Market Rules Chapter 9 (Appendices): 1.5 Validation, Estimation and Editing: Main/Alternate Metering Installation 1.5.1The following validation procedures shall be conducted, in accordance with the VEE standard, by the IESO s automated validation process test for synchronization of the clock in each of: a. the main meter; and b. the alternate meter, against the standard of accuracy described in section of Chapter 6; 2

3 Introduction / Background (cont) Market Rules Chapter 6: 11.2 Meter Time Each metering installation and the metering database shall be referenced to eastern standard time in the Province of Ontario The IESO shall synchronize each meter clock to within ±5 seconds of eastern standard time in the Province of Ontario, or to such greater standard of accuracy as can be reasonably achieved by the IESO, at the time of commissioning of a metering installation and thereafter whenever it reads a meter. 3

4 Introduction / Background (cont) Market Manual 5.2 : Settlements Metering Data Processing All meters will be validated for time tolerance. Three possible conditions may occur: 1. The meter time is within ±5 seconds of system time, a time reset is not performed. 2. The meter time is greater than ±5 seconds of system time but less than ±60 seconds of system time, an automatic time reset is performed by the IESO only. 3. Meter time is greater than 59 seconds of system time; a meter trouble reportis issued(the MSP can synchronize only if authorized though an MTR) 4

5 Introduction / Background (cont) Strong emphasis on the importance of meter clock synchronization. We wanted to study the extent of meter clock drift and the occurrences of daily time resets performed. Implemented hourly status calls on a select number of meters to gather meter clock drift data. 5

6 Process and Preliminary Observations Implemented hourly status calling utilizing our Meter Data Acquisition System -MDAS (MV-90). Gathered hourly MDAS system time and Meter recorder time to determine time drift. Gathered data from various conforming meters at various connection points/locations. 6

7 Process and Preliminary Observations - cont Consistent time drift amongst all meters (subject to daily time sync) full extent of clock drift not observed 7

8 Process and Preliminary Observations - cont Removing daily time synchronization 8

9 Process and Preliminary Observations - cont Main and Alternate meter comparison 9

10 Process and Preliminary Observations - cont Observing full drift 10

11 Process and Preliminary Observations - cont Potential time drift reporting error due to poor/slow connection to meter 11

12 Process and Preliminary Observations - cont Potential time drift reporting error due to poor/slow connection to meter Potential for MDAS system to report excessive time drift due to poor communications/connection with the meter. MDAS system first establishes system time and then reads actual time of meter. When the connection/communication with the meter is good, the MDAS system brings back the actual time of the meter in a timely manner. When the connection/communication with the meter is poor, the MDAS system takes longer to communicate with the meter (i.e. read retry in the event of read error or time-out). In this case, the actual time brought back is delayed from the determined system time. Looking into potential enhancements to minimize this error. 12

13 Process and Preliminary Observations - cont Meter clock configuration Line frequency to Internal crystal clock 13

14 Process and Preliminary Observations - cont Clock drift correlation to system frequency? 14

15 Process and Preliminary Observations - cont Further review required to establish relationship with frequency 15

16 Conclusions / Considerations / Summary Preliminary observations have highlighted the extent of meter clock drift. IESO will continue to review meter clock drift and formalize observations / results Meter time synchronization will continue to be an important concept with the release of new Measurement Canada specifications related to the standardization of legal unit of measure(important to Totalization and Demand values) Results may be useful for meter manufacturers. Consider potential changes to IESO s time synchronization rules/manuals. 16

17 Questions 17

Total Market Demand Wed Jan 02 Thu Jan 03 Fri Jan 04 Sat Jan 05 Sun Jan 06 Mon Jan 07 Tue Jan 08

Total Market Demand Wed Jan 02 Thu Jan 03 Fri Jan 04 Sat Jan 05 Sun Jan 06 Mon Jan 07 Tue Jan 08 MW This report provides a summary of key market data from the IESO-administered markets. It is intended to provide a quick reference for all market stakeholders. It is composed of two sections: Section