유□무선 데이터 통신을 이용한 무인 공급기지의 상황 감지 시스템 개발

노용우, 유휘룡, 박대진, 구성자

한국가스공사 연구개발원 공급연구팀

Development of Supervision and Data Acquisition System for Unattended Station Using Wire and/or Wireless Data Communication Fusion

Yong Woo Rho, Hui Ryong Yoo, Dae Jin Park and Sung Ja Koo

KOGAS  R&D Center, Ansan-city, KOREA

Introduction

This paper introduces a project to make unattended station by developing  supervision and data accquisition system in KOGAS. The supervision and data accquisition system is composed of host server, romte teminal uint(RTU) and wireless data process unit, which is installed at central control room, unattended station and  patrol car, respectively. Communication between host server and RTU may have two kinds of modes to reduce communication cost. One is the wire communication mode as a main line during normal condition, the other is wireless communication mode either as a backup line in normal condition or as a main line in abnormal situation where the wire communication line becomes interrupted. Communication between host server and patrol car is made by wireless  data communication network which transmits data by packet.

The RTU has sensing units enabling to detect gas leak, fire, earthquake, wire communication interruption, electric power failure, explosion and traspasser and CCD camera  to zoom in or out and to rotate to ±90[°] by remote control.

Wireless data process uint for patrol car has GPS(Global Position System) terminal unit to transmit position data of patrol car to host server, and wireless data communication terminal unit to receive informations about specified unattended stations. And it can maintain radio connect with GIS(Geometric Information System) through the internet.

It is expected that KOGAS can reduce $2,900,000 labor cost per year when this  system becomes available to make unattended station.

Stucture of host server

Task manager program with GUI(Graphic User Interface) receives digital and image data at intervals of five seconds from RTU in unattended station. If critical situation is suspected after analysis of the data, the program generate alarm signal and transmit it to patrol car to notify the situation to operators. Communication between host server and RTU may have two kinds of modes to reduce communication cost. One is the wire communication mode(56k[bps]) as a main line during normal condition, the other is wireless communication mode(9600[bps]) either as a backup line in normal condition or main line in abnormal situation where the wire communication line becomes interrupted. Communication between host server and patrol car is made by only wireless  data communication network which transmits data by packet. Host server is composed of task manager module, menu screen module, GUI module, communication drive module, image processing module and self diagnostic module as shown in Fig. 1.

Fig . 1 Block diagram of supervision and data acquisition system and host server

Structure of Remote Terminal Unit

The task of RTU is to acquisite data such as gas leak, fire, earthquake, wire communication interruption, electric power failure and explosion and to tramsmis data to host server using wire and/or wireless communication. As the RTU has a backup memory(192Mbyte) and battery pack, it can save situation data in backup memory at specified sampling interval and maintain communication with host server even after electric power failure at least for one hour.

Analog image signal of CCD camera is converted to digital signal in the image frame grab card(640 ×480, 256 color) and digital  image signal  is compressed to  JPEG file type. JPEG file containing image information is transmitted to host server.  Pan tilt of CCD camera can rotate to ±90[°] for up-and-down and left-and- right directions by remote control. References of rotation angle is given by operator in certral control room and pan tilt drive module control it's rotation angle according to the angle references.

Upon sensing interruption of wire communication line, the communication drive module switchs to wireless commnication network. Acording to the demand of commnication drive module in RTU, communication drive module in host server changes communicaton line from the wire to wireless communication network. Fig. 2 shows block diagram of RTU.

Fig. 2 Block diagram of RTU

Wireless data process unit for patrol car

Wireless data process unit for patrol car has GPS(Global Position System) terminal unit to transmit position data of patrol car to host server, and wireless data communication terminal unit to receive informations from specified unattended station. And it can maintain radio connect with GIS(Geometric Information System) through the internet.

Conclusion

KOGAS has plan to install host server, RTU and wireless data process unit untill December, 1997, followed by the test operation about 6 months. Depending on reliability of  the system, it will be implemented to 71 unattended stations untill 1999. It is expected that KOGAS can reduce $2,900,000 labor cost per year when this  system becomes available to make unattended station.

Reference

1. Yong Woo Rho, Dae Jin Park and Sung Ja Koo "Devolopment of Black Box System for Reporting the Emergency", KOGAS R&D Center, 1996