Electric power system reliability

See also. Electric Power, Generation of Electric Power, System Reliability and Electric Power Transmission and Distribution Systems. 

See also Capacitors and Ultracapacitors Electric Motor Systems Electric Power, Generation of Electric Power, System Protection, Control, and Monitoring ol Electric Power, System Reliability and Electric Power Substations Environmental Problems and Energy Use Insulation T ransformers. 

In electric power systems, it is essential to have permanent control of the power in electricity production, transportation, and consumption. Because of speed and reliability requirements, electric power systems were the first large systems to use a variety of automatic control devices for the protection of different parts of the system. 

The reliability of a modern electric power system depends on continuous real-time control of power and energy production, transmission line flows, system frequency, and voltage. This complex task will get more involved in the new environment with increased market participation on both the supply and the demand sides. 

The North American electric power transmission system has been described as the largest, most complex machine ever built by humanity. It is a massive network of generating stations, transmission lines, substations, distribution lines, motors, and other electrical loads all interdependently linked for the conversion, transportation, and control of electrical energy. Approximately 60 percent of all energy utilized in the United States passes through the interconnected electric power system. The major goal of the system is to most efficiently and reliably deliver electric power from generating stations to residential, commercial, and industrial consumers. 

Ever since the major power failure in 1965 that blacked out the northeastern United States, an important site consideration has been the reliability of electrical power systems. For instance, a 5-hour power failure cost a New Jersey firm two days downtime. In another case the Sun Oil Company s 170,000-barrel-per-day refinery at Marcus Hook, Pa., suffered a 250,000 loss due to a 3 1/2-hour power failure. It was four days before full production could be restored. The problem is that there is no section of the country that has not had a major power failure. 

Electrical power systems that serve pharmaceutical equipment must be safe, reliable, functional, predictable, flexible, clean, and sometimes validated. The electrical power systems have voltages ranging from 120 to 69,000 V. Pharmaceutical plants in the United States and Canada can purchase 3 phase, 60 Hz electric power from utility companies that is more reliable than the power they could generate in house. Whereas in other countries, electric power is purchased at 3 phase, 50 Hz, and may not be as reliable as power that is generated in the plant. 

A maintenance program should document all tests, inspections, and faults cleared by a main and feeder circuit breaker. Lack of such a program will reduce the reliability of the electrical equipment.Molded case circuit breakers require no internal maintenance. They should be inspected for broken casing and loose connections after they operate to clear a fault and should be replaced after they have operated to clear two faults. Feeder circuit breakers, especially older circuit breakers, should be exercised (repeatedly opened and closed) whenever possible.f" Part of the initial commissioning of an electrical power system must include testing of the ground fault protection. ... 

Glavitsch, Hans, "Computer Control of Electric-Power Systems", Scientific American, Vol. 231, No. 5, November 1974, Page 34 Kalhammer, Fritz R. "Energy Storage Systems", Scientific American, Vol. 241, No. 6, December 1979, Page 56 Abelson, Philip H., "Reliability of Electric Service", Science, Vol. 245, No. 4919, August 18, 1989, Page 689... 

Changes to the architecture of the vehicle electric power system are expected to proceed in an evolutionary rather than a revolutionary manner. It is the intention of the automotive industry and its suppliers that the 42-V PowerNet [9,11] will be available for technical situations which require very high power demands. Due to cost considerations as well as to uncertainties with respect to the availability and reliability of newly designed components [35], modifications will be introduced stepwise only when really needed. This process is expected to last many years. Therefore, the long-term solutions to the problems of increased vehicle electric power demand, the implications for battery design and manufacturing, and the possible intermediate steps have all to be considered carefully by the battery industry. 

R. Billinton, W. Li Reliability Assessment of Electrical Power Systems Using Monte Carlo Methods, Springer 1994... 

A critical infrastructure (e.g. an electric power system) is abstractly modeled as a network G of nodes interconnected by links. Let G (N, A) represents a network. N corresponds to the set of nodes and A represents the set of links. Each link (ij) could have an attribute defined by k ,, for example, e distance between i and j, or the link reliability. 

Billinton, R. and Li, W. (1994) Reliability Assessment of Electric Power Systems Using Monte Carlo Methods Plenum Press, New York. 

Endrenyi, J. 1978. Reliability modeling in Electric Power Systems. Wiley, New York. 

The induction motor has been used rehably for production hoists for over 20 years. When it is fed by modern medium voltage PWM drives it provides an ideal solution for hoisting applications. Combined, they provide improved system reliability as well as providing many benefits for the design of the electrical power systems. 

The station services power supplies are classified according to their required levels of reliability. The reliability requirement of these power supplies is divided into four classes that range from uninterruptible power to power that can be interrupted with limited and acceptable consequences. The electric power system station services comprise the supply systems described below. 

The electrical power system of a country or utility consists of two principal components, the electricity generating system and the high-voltage transmission system or the electric grid. Both systems must be kept "in-step", since the quality of the electric power provided to the users requires both available generation and reliable dispatching of the electrical output. 

Most automated SiFs are designed as de-energize to trip. As a result, the PFDavg calculation for these SIFs generally does not take into consideration any utility systems. Operator action inherently requires support systems to compiete the safety function. Display/alarms require power to actuate the light and/or horn for operator response. Therefore, the reliability of the electrical power system directly affects the PFDavg of the credited operator action. 

The provision of an emergency electrical power system with adequate reliability to ensure the availabiUty of emergency electrical power when it is required for systems important to safety shall be considered. 

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