The main nonhydroelectric renewable source is wind power. Photovoltaic panels coupled with battery storage have considerable potential for distributed generation as prices drop.
• Energy storage to allow for increased use of renew ables and to improve resiliency of the entire grid. Improving the system load factor and utilizing renewable sources that are time and weather dependent require the use of energy storage. Prospects include batteries, pumped storage, compressed-air storage, and supercapacitors.
Findings on the Transmission Network-Short to Medium Term
Finding 6.1 Any increase in the reliability of the power grid makes the system more capable of withstanding terrorist attacks, more able to mitigate the impacts of such, and less interesting as a target of terrorists.
Finding 6.2 In many cases, increased performance of the electric power system may be achieved through stronger ERO reliability criteria and additional controls such as special protection systems. For example, the ERO and FERC could require NERC Category C performance for the common N-2 event of a short circuit on a line with line outage, and with simultaneous outage of a parallel line or line with common termination because of protective relay misop-eration. Meeting this requirement would improve system robustness and help protect against terrorist actions on lines on the same right-of-way. As an example of new operating procedures, the DHS red-alert condition could require more conservative system operation similar to storm-watch procedures.
Finding 6.3 The robustness and resilience of power systems can be signifcantly improved by prioritized modernization of power plant and transmission infrastructure and deployment of technological advancements. Many power plant and substation enhancements can be rapidly implemented at low cost compared to the construction of new transmission lines. Potential upgrades include modern circuit protection systems, communications, generator excitation equipment, and shunt capacitor banks to increase generator reactive power reserve.
Finding 6.4 The control center is the nerve center of the power system, and its resiliency is extremely important. The computer hardware and software in the EMS should be designed to withstand failures and to degrade gracefully when necessary. The control center as a whole must be protected from physical as well as cyber attacks, and a backup control center should be available. Adjacent control centers (e.g., PJM Interconnection and Midwest Independent Transmission System Operator [MISO]) should partially back each other up.
Finding 6.5 Much greater and more uniform use should be made of simulators during the training of electric power system operators.
Finding 6.6 Undesirable and unnecessary operations of protective relays during power system disturbances have contributed to many cascading power failures. These relays are intended to detect short circuits or other specifc conditions in a protection zone, but can operate inappropriately during other conditions such as overload and/or voltage sag. While commendable industry-wide improvements were implemented following the August 14, 2003, blackout, continual vigilance and careful design are required. Coordination among various control and protection devices is essential to system reliability.
Findings on Transmission Research and Other Long-term Needs
Finding 6.7 The electric power transmission system should move toward large-scale use of sensors that provide a complete physical and electrical picture of the power system in real time, and appropriate control measures that could be taken automatically and rapidly or suggested to system operators. Research needed to make such a system a reality is discussed in Chapter 9. With today’s digital control and communication capabilities, there are many opportunities for application of sophisticated local, distributed, and high-level control algorithms using various techniques such as adaptive or “intelligent” control coupled with wide-area measurements and adaptive islanding.
Finding 6.8 Improved intelligent, digital relays are needed that allow for self-evaluation and remote evaluation of settings and status to ensure reliable operation.
Finding 6.9 Improved control philosophies and strategies are needed for multiple contingency events occurring in close time proximity. The proper operations of relays in response to changing conditions, when taken as a whole, can create unrecoverable instability in the power system.
Finding 6.10 Consideration should be given to redesigning some critical substations using buswork in pipes insulated with SF6 with switchgear incorporated in the gas-insulated equipment. This approach allows more compact substation design, and the critical facility could then be relocated indoors or underground to provide more security against attacks.