World Technology

Unscheduled Flow Mitigation Plan Approved The U.S. Federal Energy Regulatory Commission unconditionally approved the Western Systems Coordinating Council's (WSCC) Unscheduled Flow Mitigation Plan on Nov. 29, 1995. The plan, which has been in effect - subject to refund - since April 1, 1995, provides the terms, conditions and procedures under which WSCC members coordinate operations to reduce unsched-uled flow (loop flow) on members' electric systems. WSCC members anticipate the plan will produce immediate operating benefits because of increased scheduling capability.

WSCC one of the nine electric reliability councils, encompassing a geographic area equivalent to more than half the United States - is an international organization responsible for promoting electric system reliability and providing a forum for coordinating the operating and planning activities for its 86 member systems. The members provide power to 59 million people in 14 western U.S. states, two Canadian provinces and portions of one Mexican state.

As part of the plan, utilities will reimburse power companies to use phase shifters to keep unwanted electrons from flowing to undesired areas, which is a problem in a system as interconnected as the Western grid.

Manufacturer Passes Test ABB Kabel und Draht GmbH, Mannheim, has taken a step forward in the development of plastic- insulated cable systems for 400 kV. For the first time ever, a 400-kV XLPE cable system with solid insulation made of cross-linked polyethylene (XLPE) has passed an endurance test featuring the requirements set by CIGRE. Now that the cable system has received official certification, a complete concept for 400-kV XLPE cable installations is available. The major application category for this kind of system is power supply grids in densely populated networks of urban communities, where construction of high-voltage overhead transmission lines is not a viable option.

R&D Center Launched Georgia Institute of Technology, Atlanta, Georgia, U.S., has launched a new research and development center to engage in research, development, test and education programs to serve the electric utility industry, its customers and the manufacturers serving them. The National Electric Energy Testing, Research and Application Center (NEETRAC) merges the human and technological resources of Georgia Power Research Center with Georgia Tech's research and instructional programs in electric power. NEETRAC's creation is particularly timely in the emerging electric utility industry environment under the auspices of deregulation and intensified competition between utilities. As competition often leads large, vertically integrated utilities to shed their internal research and development capabilities, the need arises for centers such as NEETRAC where electric utilities, manufacturers and end-users can engage in long-term research programs and short-term application projects, according to NEETRAC.

Providing Effective Zone Protection Digital technology has now made it possible to build control logic into relays. Groupe Schneider provides a range of Sepam protection and control units along with application diagrams for subtransmission and distribution substations. Designers can produce specific logic diagrams by customizing standard applications for individual needs.

Logic discrimination allows the utility to protect specific zones (such as busbars or lines) in a substation or distribution network through the exchange of logic data between protection devices. To provide zone protection, logic discrimination is used to Detect a fault (from the detection scheme available in the relay). Trip the related circuit breaker according to data received from the processing unit (as well as logic data received from other protective devices)

According to Groupe Schneider, logic discrimination has additional advantages over differential protection devices: Better earth fault sensitivity. The sensitivity can be adapted to suit the specific earthing system. Simple wiring. Logic data is much simpler to process than analog signals. Simple setting. Logic discrimination is used in both definite time and inverse time protection devices. Use of standard sensors. To be used for a wide variety of applications. Passive safety. In the event of a logic data transmission failure, each protective element will perform independently. Cost reduction. Logic discrimination makes it possible to distribute the zone protection function between substation protection devices.

Transmission Tower Design Is Simplified The design of transmission line towers has entered the computer age, according to IMI Software Ltd., Hyderabad, India. The company has designed an alternative to current methods of transmission tower design. TOWERS creates a transmission tower design that provides the best cost and weight of steel solution through the generation and analysis of alternatives. Modular input design, powerful tools and a comprehensive library of more than 1000 tower patterns, tested and in international use today, allow for automatic creation of tower geometry.

Structural engineers can try different tower profiles, easily changing the basic dimensions, optimized across types of steel and angle shapes, in full compliance with all codes of practice. Analyzing the panel, class and steel bills of materials automatically generated for each option gives the designer the best cost solution to weight of steel.

TOWERS integrated software has been used to design a 500-kV single circuit river crossing tower across the Nile River and 150 other towers in 45 major international projects around the world.

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