IEEE C37.118.1a-2014 IEEE Standard for Synchrophasor Measurements for Power Systems Amendment 1: Modification of Selected Performance Requirements.
This IEEE document is made available for use subject to important notices and legal disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading “Important Notice” or “Important Notices and Disclaimers Concerning IEEE Documents.” They can also be obtained on request from IEEE or viewed at http://standards.ieee.org/IPR/disclaimers.html. NOTE—The editing instructions contained in this amendment define how to merge the material contained therein into the existing base standard and its amendments to form the comprehensive standard. The editing instructions are shown in bold italic. Four editing instructions are used: change, delete, insert, and replace. Change is used to make corrections in existing text or tables. The editing instruction specifies the location of the change and describes what is being changed by using strikethrough (to remove old material) and underscore (to add new material). Delete removes existing material. Insert adds new material without disturbing the existing material. Insertions may require renumbering. If so, renumbering instructions are given in the editing instruction. Replace is used to make changes in figures or equations by removing the existing figure or equation and replacing it with a new one. Editing instructions, change markings, and this NOTE will not be carried over into future editions because the changes will be incorporated into the base standard.
4. Synchrophasor measurement 4.3 Measurement time synchronization Change first paragraph in 4.3 as shown below: The PMU shall be capable of receiving time from a reliable and accurate source, such as the Global Positioning System (GPS), that can provide time traceable to UTC with sufficient accuracy to keep the total vector error (TVE), the frequency error (FE), and the rate of change of frequency (ROCOF) error (RFE) within the required limits. All measurements shall be synchronized to UTC time with accuracy sufficient to meet the requirements of this standard. Note that a time error of 1 µs corresponds to a synchrophasor phase error of 0.022 degrees for a 60 Hz system and 0.018 degrees for a 50 Hz system. A phase error of 0.57 degrees (0.01 radian) will by itself cause 1% TVE as defined in Equation 12. This corresponds to a time error of ±26 µs for a 60 Hz system and ±31 µs for a 50 Hz system. A time source FE of 0.083 MHz in a 60 Hz system or 0.1 MHz in a 50 Hz system will cause the maximum allowed steady-state FE of 0.005 Hz. Similarly, a time source with a varying frequency will cause a corresponding error in ROCOF (the relationship is not as direct as those above). A time source that reliably provides time, frequency, and frequency stability at least 10 times better than these values corresponding to 1% TVE is highly recommended. The time source shall also provide an indication of traceability to UTC and leap second changes.
IEEE C37.118.1a pdf download.