Automatic Load Control Research Articles

練習船「深江丸」のメカトロニクス

The training ship “Fukae Maru” is fitted many electoronic control systems. This paper especially introduces the electrohydraulic systems of her main engine among them. These are the speed control system, the automatic load control system and the active vibration isolating system.And also this paper introduces electrical troubles and improvement of software after entering service in Oct., 1987. They are numbered in 26 matters for about one year. The half of them are remarkably caused by mistake of handiwork and programing (or debugging) than the damage of hardware.It is important to increase the reliability of personal action for increasing that of marine electronics.

Analysis of tubular beam-columns and frames under reversed loading

The finite segment method, combined with the generalized stress-strain relationship, and the incremental stiffness approach and automatic load control techniques, is applied to trace the complete load-displacement and load-shortening relationship of some structural members and simple frames in offshore structural systems subjected to reversed loading. Extensive numerical results are obtained and compared with available experimental data as well as with the analytical results obtained previously by the influence coefficient method. Some simple frames are then solved using the computer model developed and also compared with the solutions using the simplified rigid plastic analysis. The structures considered in the present analysis are strut and portal types of beam-columns, simple moment frames with different structural systems, and simple single-diagonal braced frames.

Inelastic Post‐Buckling Behavior of Tubular Members

Post‐buckling, post‐peak, and cyclic behavior of beam‐columns and frames are studied using a computer model developed on the basis of the Finite Segment Method, using generalized cyclic stress‐strain relationships and an automatic load control technique. Numerical examples of structural members and simple frames are made using the computer model. The results are compared with available experimental data as well as the results of simple rigid‐plastic analyses to verify the proposed method.

CRTを利用したCPPコントロールバックアップシステム

This paper reports on a CPP Control Back-up System utilizing a CRT, which has been newly developed by NKK and installed on the NKK's new energy saving ships equipped with PC engines and controllable pitch propellers (CPP) .This system consists of a CPP control system featuring automatic load control, constant ship speed control and constant SHP control as well as a data display system utilizing a color graphic CRT which displays the characteristics of the main engine and the CPP, the operating point of the main engine and various actual operating data of the main propulsion system.This system makes it easy to perform fine aiming of such operation targets as energy savings, high operating rates, low maintenance costs, etc.

Crack-opening displacement as a method of measuring crack length in compact-tension specimens

A pseudo-compliance method is discussed as a means of measuring fatigue crack lengths in BS 5447, ASTM E399.72 compact-tension specimens. A calibration curve for these specimens is obtained together with a relationship between pseudo-compliance and K, the stress intensity factor. This method is suitable for automatic crack monitoring and load control.

Operational experience with fossil-fired generating plant under automatic load control

Automatic load following by fossil-fired generating units requires the control of the flow of air and fuel to the boiler, and of the steam flow to the turbine. Prototype load controllers designed to achieve this have been installed at coal and oil-fired power stations within the CEGB. The principle behind their design is that boiler-stored energy is made available only for system frequency regulation. This policy helps to maximise the regulation capability available to the grid system while minimising the cyclic damage inflicted on the plant. Test results and operating experience show that both coal and oil-fired units equipped with such load controllers respond successfully to both loading and frequency regulation demands. Evidence of improved coal-fired combustion efficiency has also been obtained.

サーボ割算器を用いた定応力クリープ試験機

The tensile load was automatically controlled so as to satisfy the loading condition for constant stress creep tests, W=W0l0⁄l, where W is the tensile force, l is the gauge length of specimen and suffix 0 stands for initial values. The elongation of specimen was measured by means of differential transformers. The output signal (equivalent to l) was fed into a servo-divider and a signal (equivalent to W) being proportional to reciprocal l was calculated. There were two holes at the bottom of a water vessel to increase or decrease the volume of water whose weight was applied to the specimen. Automatic control of the dead load was performed by free drainage and the supply of water controlled by a pneumatic valve in accordance with the calculated value of W. The tensile force acting on the specimen being directly measured by means of a load cell connected in series with the specimen and an automatic balancing indicator, could be controlled accurately against various disturbances. Maximum tensile force being 100 kg, a deviation of the force from the calculated value during constant stress creep tests could be kept within 1%. This creep tester can be applied for vacuum creep tests (>3×10−6 Torr) and also for tensile tests and stress relaxation tests at elevated temperatures (<900°C). A new precise temperature controller has been developed for stress relaxation tests.

Medium- and high-power automatically tuned linear amplifiers

The essential features of any communications transmitter are reliability, ready means of frequency changing and linearity. Recently developed high-gain power valves require 1 kW, or less, driving power, which can be obtained from untuned wideband stages instead of the usual tuned drives. With only one tuned stage, it is easy to obtain a high degree of linearity, and automatic tuning by a frequency-following system becomes particularly attractive, without being unduly complex or expensive. A continuous frequency-following system with automatic loading control offsets changes in feeder impedance, so that the final amplifier is always operating under optimum conditions. This is a great advantage compared with preset systems.The design of compact, self-contained equipments, requiring no special under-roof ducts for air or cables, simplifies installation, particularly in existing buildings where new equipments replace obsolescent types. For new buildings the cost can be kept to a minimum.The paper details the electrical design principles for 7½ and 30 kW automatically tuned linear amplifiers that contain wideband driving stages. The mechanical design is discussed and also the arrangement of suitable servo-tuning and rectifier circuits. Final specification figures and some typical test results are given.

Computers in Automatic Control Systems

Modern automatic feedback-control systems are making increasing use of electronic computers as active controllers. The trend from the use of simple electric circuits and elementary analog devices toward high-speed digital computers (or computers employing both digital and analog devices) is accelerated by 1) the rapidly growing complexity of modern control systems; 2) the increasing importance of self-adaptive control; and 3) the development of optimizing control. Recent applications of computer control include the automatic control of boiler operation in an electric generating station, the adaptive autopilots for piloted aircraft, and the automatic control of load dispatching in electric power distribution.

Combustion control-load control tie-in equipment

FREQUENTLY, when automatic load control has been applied to a turbine-generator, regulating performance of the unit has been limited by the ability of the boiler to keep up with the load changes. The purpose of this investigation is to evaluate the improvement in boiler response realized by sending load-regulating intelligence to the boiler as well as to the turbine. The results of a computer simulation study of the problem are verified by a comparison with actual field performance.

Automatic control and recording of load during relaxation tests on prestressing wires

Summary A simple unit has been incorporated in a universal testing machine to compensate automatically for the continuously reducing load during relaxation tests on prestressing wires. In conjunction with a recording camera, it dispenses with the presence of an observer over the long periods required for the tests. In operation it is found that alternate readings taken with automatic and manual control fall sensibly on a single curve.

A New Automatic Load Control for Turbine Generators

In an interconnected power system, load changes of sufficient magnitude to affect system frequency are normally shared by all the generators on the system in proportion to their ratings and the characteristics of their governors. This inherent sharing of load changes is highly desirable in the majority of cases. It may, however, present a problem in a few instances if some of the generators are remote geographically and electrically from that part of the system which includes a large fluctuating load. In such cases it would sometimes be preferable if the load changes could be confined in whole or in part to the local generators, thereby relieving the remainder of the system from having to respond to distant load fluctuations. This situation may become acute in the case of systems interconnected through long tie lines, where abrupt load changes in either system result in large transfers of synichronizing power through the interconnecting ties. This paper describes a new automatic load control arrangement which has the ability to respond to local load changes in anticipation of their effect on system frequency. At the same time, however, it does not deprive the conventional speed governor of its ability to control the prime mover input to help maintain constant system frequency. In this latter respect lies its essential and unique difference from other somewhat similar arrangements described previously. <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1,2,3</sup>

Telemetering circuits — Metallic and carrier

The art of telemetering has enjoyed a steady development for 30 years. The increased number of power system interconnections and the increased operating efficiency that is to be gained by use of automatic load control warrant careful study of the circuits that are used to transmit the required information. It is expected that as telemetering systems expand more multicircuit carrier channels will be used. Protective relay and communication circuits will be combined with telemetering circuits. Space radio probably will be added to provide trunk line service for communication, telemetering, supervisory, and protective relay control in locations that cannot be served economically by other means.

Telemetering circuits-metallic and carrier

The art of telemetering has enjoyed a steady development for 30 years. The increased number of power system interconnections and the increased operating efficiency that is to be gained by use of automatic load control warrant careful study of the circuits that are used to transmit the required information. It is expected that as telemetering systems expand more multicircuit carrier channels will be used. Protective relay and communication circuits will be combined with telemetering circuits. Space radio probably will be added to provide trunk line service for communication, telemetering, supervisory, and protective relay control in locations that cannot be served economically by other means.

Automatic Control of Large Synchronous Condensers

The considerations involved in the design of an automatic synchronous condenser control are discussed in this paper with an aim toward helping the designer and user of synchronous condenser equipment obtain modern and complete facilities in his design. A typical push-button-operated control for a large synchronous condenser is described and the diagrams involved are shown. The description includes a detailed resume of starting sequence, protective device operation, and automatic control of voltage and load. Emphasis is put on the adaptability of push-button control to full automatic operation or remote operation by direct or supervisory control.

Control of load, frequency, and time of interconnected systems

The general problem is stated and typical solutions indicated. Characteristics of governors and of frequency and load-control devices are briefly explained, and effects on generator and tie-line loads are summarized. Illustrating the principles enunciated, interconnected systems in southern Ontario and adjacent portions of Quebec totaling 1,650,000-kw generating capacity are described, also operating experience with automatic frequency control, and automatic load control of two ties, one of which is a 45,000-kw frequency-changer set interconnecting systems of relatively large capacity.

Control of Load, Frequency, and Time of Interconnected Systems

The general problem is stated and typical solutions indicated. Characteristics of governors and of frequency- and load-control devices are briefly explained, and effects on generator and tie-line loads are summarized. Illustrating the principles enunciated, interconnected systems in southern Ontario and adjacent portions of Quebec totaling 1,650,000-kw generating capacity are described, also operating experience with automatic frequency control, and automatic load control of two ties, one of which is a 45,000-kw frequency-changer set inter-connecting systems of relatively large capacity.

Supplementary Control of Prime-Mover Speed Governors

THE development of interconnected systems has required improvements in the manual and automatic control of load, frequency, and time. The speed governors of the prime movers have always provided the medium for supplementary control of frequency, load, and time. Experience with various types of control devices and the factors influencing their functioning have been discussed frequently in the technical literature. Recently the problem has been given renewed attention1–5 with an effort to correlate experience with theory and to provide a basis for determining the proper characteristics of governors2 and their supplementary control.

Remote Metering and Automatic Load Control

Power dispatching on an interconnected electric power system has been simplified and greatly improved by the adoption of a remote metering and automatic load control scheme recently developed. Remote metering at the power dispatching center provides continuous indication of the load on a distant 110-kv interconnection. The equipment also provides automatic control of the load on a hydroelectric generating plant located 160 miles from the metering point. The scheme, operating over company owned telephone lines, is based upon maintaining a constant beat frequency in the receiving apparatus, the transmission frequency being varied. Maintenance cost of the equipment is found to be negligible.

Remote metering and automatic load control

Power dispatching on an interconnected electric power system has been simplified and greatly improved by the adoption of a remote metering and automatic load control scheme recently developed. Remote metering at the power dispatching center provides continuous indication of the load on a distant 110-kv interconnection. The equipment also provides automatic control of the load on a hydroelectric generating plant located 160 miles from the metering point. The scheme, operating over company owned telephone lines, is based upon maintaining a constant beat frequency in the receiving apparatus, the transmission frequency being varied. Maintenance cost of the equipment is found to be negligible.