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POWER ENGINEERS SUPPORTING TRUTH
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Comments
and Questions of “Power Engineers
Seeking Truth” Our comments, in many ways, mirror and support many of the comments made by other speakers at the two prior forums. However, we have some that we want to add to the list and others that we’d like to reinforce. Most blackout investigations are conducted to learn lessons that can be used to prevent the public from suffering the consequences of a subsequent blackout. These prior investigations have been wide ranging and not confined to the conditions immediately before the incident. We recommend that this Report be expanded as follows. 1. In its Dec. 4, 2000 public forum, requests are made for recommendations for actions by utilities, transmission owners, operators or generators, reliability organizations or other entities. Table 6.1 in the report shows the complexities added by the restructuring of the electric power industry mandated by the Federal and state governments. The Report also contains many references to a wide range of deficiencies in the coordination of the operation of the bulk power system by FE, MISO and surrounding RTOs including but not limited to communications, metering, training of operators, observance of procedures, control room facilities etc. Since the organizational structure of the industry’s participants in place at the time of the blackout was a result of initiatives and approvals by FERC, did the large increase in the number of participants complicate communications and increase the difficulty of deciding on and executing corrective actions that might have prevented the blackout? 2. The Report contains a number of references relating to the role of NERC. The Report should examine the role of NERC and the Reliability Councils in operator training and qualification and control center and RTO certification. 3. In the Report, the role of low transmission voltage is not fully investigated as a contributor to the blackout. Low voltages can have a number of significant impacts on system performance: Ø They increase the current flow through transmission facilities for a given level of power flow. Since current, and not megawatts, determines a transmission line’s capability, this increase could be critical if transmission line measurements are made of megawatts and not of amperes. Ø They reduce the stability margin of the system. The well known equation describing steady state stability reflects the role of voltage Ø They change the apparent impedance of transmission lines possibly resulting in loss of transmission lines due to relay action The table on Page 23,”Causes of the Blackout”, does not list low voltage as a cause although the section on Page 18 entitled “Voltages” refers to depressed voltages on the system and attempts by operators at FE and in other areas to maintain voltage. On Page 63 the Report states that “low voltage never became the primary cause of line and generator tripping”. However, on the same page, reference is made to the loss of generation because of “excitation system failures during extremely low voltage conditions on portions of the power system”. The Report also does not examine the results operator efforts to maintain voltages including responses to their requests for additional voltage support from generators and the efficiency of actions to change transformer tap settings. Further, the Report does not address whether the operational studies made prior to the blackout considered the impact of the unavailability of some of the generators on the capability of the system to maintain adequate voltages at the power transfer levels being anticipated. The Report should more thoroughly examine the role of low voltage as a contributor to the blackout. It should also address the voltage and frequency transients that existed earlier in the day on August 14 to see if there were any indications of subsynchronous resonance problems that may have contributed to some of the outages?. 4. Were the results of the computer simulations used to reach conclusions in the report checked against actual system line loading and voltage data at various time and location points as the sequence of events developed?. Were there instances where actual system data and the computer step by step data did not check? What was done in these situations? January 26, 2004
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