Atsumi Watanabe

A Combustion Diagnosis Method for Pulverized Coal Boilers using Flame-Image Recognition Technology

A flame image recognition system (FIRES) has been developed, which calculates the estimated value of NOX emission from pulverized coal combustion by two dimensional measurements and digital image processing of flame forms. This system can be effectively applied to low NOX and high efficiency combustion is industrial and utility boilers. ITV cameras observe the flame image in the vicinity of burners through optical-fiber probes attached to each burner stage, and a minicomputer digitizes and processes the image data. The NOX-reducing index (INOX), indicating the amount of NOX reduction can be calculated from the form and the location of high radiant intensity zones. Using INOX and stoichiometric ratio of combustion, NOX concentration in ehaust gases can be acculately estimated. This paper discusses the system concepts, NOX estimation algorithm and experimental results.

Development of New Distance Relays to Cope with Natural Frequency Transients in UHV/EHV Transmission Systems

This paper describes distance relay characteristics to natural frequency transients caused by a fault. Discussions include response considerations and characteristics of conventional relays and newly developed distance relays with distorted inputs.

Development of custom LSIs for protective relays and their evolution to new static relays

A relay LSI and a filter LSI are developed for static distance relays. The relay LSI is based on the phase-comparison scheme and applicable to a reactance relay, a mho relay, an offset mho relay, and an ohm relay. Key technologies used to meet the relay requirements are CMOS switched-capacitor technologies. Circuit compositions and characteristic test results are described. A prototype relay unit demonstrated superiority to a conventional unit in terms of its compactness. High reliability (because of the small number of parts), high accuracy, and very low power dissipation. >

Cooperative Control Scheme for an HVDC System Connected to an Isolated BWR Nuclear Power Plant

This paper describes a cooperative control system to achieve stable operation of an isolated BWR nuclear plant linked to an HVDC system.

Neutral Line Protection System for HVDC Transmission

This paper described the principle of fault detection and its simulator study, principal circuitry, field test results and field performance records on the neutral line protection system for an HVDC transmission system. In the protection system, 125 Hz AC current injected to the neutral line is utilized as a pilot current to detect the neutral line faults. The pilot current injection is made through the neutral line surge capacitor without detracting its capability. Combined with a metallic return protecting breaker, this protection system has demonstrated a satisfactory performance on the grounding fault clearance without interrupting the power transmission.

Cable Section Fault Detection for HVDC Line Protection

For DC line protection of the Hokkaido-Honshu HVDC Link, a submarine cable fault detection system was developed. In this system, a DC line fault is declared when DC currents at both cable heads change mutually in the reverse direction. Combining this detection system with a current difference detection system which operates for any fault occurring on the high voltage DC transmission line, the high voltage DC line protection system is composed. Through the simulator tests and five-year field experience, the detection system has been verified to be satisfactory.

Development and Field Tests on a Distribution Line Carrier Communication System

A communication system through distribution lines was developed for distribution automation. This system consists of a two level hierarchy system : a zero-phase-sequence carrier communication system through ungrounded 6kV distribution lines and an earth return communication system through grounded 100V/200V lines. In each system, transmission signals are generated by switching a passive element of small capacity between a line and the ground, and the signals are circulated through the line and the ground. By using this method, the influence of load impedance change and noises generated in loads is avoided sufficiently. Field tests were carried out at Ijiri Substation of the Kyushu Electric Power Co., Inc. for one year starting in September 1983. High reliability of the system was verified in terms of endurance in a severe environment and data transmission performance.