Utility Power Supply Research Articles

Reliability Impact of Solar Electric Generation upon Electric Utility Systems

The introduction of solar electric systems into an electric utility grid brings new considerations in the assessment of the utility's power supply reliability. This paper summarizes a methodology for estimating the reliability impact of solar electric technologies upon electric utilities for value assessment and planning purposes. Utility expansion and operating impacts are considered. Sample results from photovoltaic analysis show that solar electric plants can increase the reliable load-carrying capability of a utility system. However, the load-carrying capability of the incremental power tends to decrease, particularly at significant capacity penetration levels. Other factors influencing reliability impact are identified.

Long‐span installation machine for optical cables

AbstractLong‐span installation of optical cables is realizable by virtue of their light weight, small outer diameter, lower transmission line loss due to reduction of the number of splices, effective installation operations, etc. The authors have developed a novel long‐span installation machine for optical cables and a practical method of installation using this machine. The machine is found to be applicable in practice based on its fundamental composition of a pair of upper and lower caterpillars and a drive motor. The machine is distinguished by the following performance characteristics and functions: (i) it can pull cables of different OD and a pulling rope with a constant speed; (ii) the maximum pulling load is 300 kgf; (iii) the small, light‐weight equipment can be installed in any kind of manhole; (iv) the equipment can be operated by a utility power supply or portable generator; (v) there are control provisions for pulling force limitation and cable slack detection to facilitate automatic cable installation. Another advantage is the “distributed pull system,” wherein the pulling force needed for cable installation is distributively loaded over the cable length. In combination with these features, 14 optical cable sections were actually installed in a duct section of 18 km length. The average section length was 1,300 m and the maximum was as long as 2,500 m. As a result, the practical applicability of the above equipment was proved, showing that they satisfy the design criteria and functions and that there is no significant increase in cable losses after the installation operations.

The Application of Statistical Reliability Data in the Selection of a Utility Power Supply Scheme for an Industrial Plant

A detailed analysis was made to determine the most economical electrical utility supply configuration to serve a new polyester manufacturing facility. The basis used for the analysis centered around: a) IEEE survey reliability data and IEEE statistical reliability techniques, b) historical outage cost data from the three existing manufacturing facilities, and c) an estimated power restoration curve developed by the facilities maintenance department. Explicit definitions were developed to define what power outages meant for the various types of loads to be served. The minimum total yearly cost, made up of yearly facilities' cost plus yearly outage cost was used to identify the most economical configuration.

Economic Load Dispatch and Load Frequency Control Realized by a Process Computer System

The paper describes the use of a process computer system for instantaneous optimization of power station scheduling and for load frequency control at the Vereinigte Elektrizitätswerke Westfalen (VEW), one of the major power supply utilities in the Federal Republic of Germany. Only thermal power stations - most of which operate in the variable pressure mode - are used for the control action. The widely varying control characteristics of the power stations necessitated special steps in the design of the control system. A single computer system for similar functions has been successfully in operation since 1970. The new concept was developed on the basis of the experience gained with the former system and integrated into the computer system which is set up in the new load dispatch centre for operational managment of the 380, 220 and 110 kV systems.