Design of the Control Subsystem

Nicolae Badea and Marian Barbu

One of the basic functions of the automation and control system of the building is a timely control of the procedures and processes that provide an efficient energy operation.

The control programs make sure that the lighting and heating are not automat­ically shut down at the end of the day, that the building temperature is reduced during the night and that the mCCHP installation does not function more than it is necessary. The operations of switch on time provided by the automation and control system are implemented through the BACnet standard, using the BACnet objects “Schedule” and “Calendar”. This function allows a flexible management of the building. From ordinary programs to unusual exceptions, these functions make the monitoring more flexible. By using the BACnet standard functions, the time pro­grams BACnet can be operated from the entire system from the touch panel unit type, as well as from the management station. For the exchange of information between its own components, three standard protocols are used, namely BACnet, LONWORKS, and Konnex (KNX) S-mode (EIB). The BACnet communication protocol is used for the exchange of information between the distributed automation equipment and among the touch panel operating units, using LonTalk or point – to-point (PTP, modem or null modem) as transport medium. Inside the room automation, the communication is done through the LONWORKS and KNX S-mode (EIB) standard.

The clearly structured, modular software, oriented on objects of the management station is based on the latest standard Windows technology. The functional purpose and the ease in using the software reduces the operating costs and those of getting familiar with it, while the operational level is maintained. The main applications transmitted through web are described as follows:

• Plant Viewer the realistic graphics, which allows the rapid monitoring and operating of the system.

• Time Scheduler the centralized time programming of the building’s service functions.

• Alarm Viewer detailed panoramic view of the alarms for rapid localization and elimination of errors.

• Alarm Router flexible routing of alarms to printers, faxes, mobile phones, or emails.

• Trend Viewer Comfortable analysis of trend data for the optimization of oper­ations and the increase of EFF.

• Report Viewer questions for the meeting of the clients’ necessities and showing them in reports. The reports provide information on the analysis on the func­tioning of the installation as well as on the evaluation and documentation.

• Object Viewer an efficient tool for the navigation through the hierarchic struc­ture of all the data points of the system. These points can be read or manipu­lated, depending on the user’s access rights.

• Log Viewer The alarms, errors, and user’s activities are registered in chrono­logical order and may be displayed for a subsequent evaluation, depending on the necessity.

• Database Audit Viewer The registration of the unauthorized modifications in the data base which guarantees the highest integrity possible of the data.

• System Configurator It is used for the general configuration of the management station and of the associated applications.

• Graphics Builder The efficient creation of the installation graphics.

• BACnet, OPC, KNX S-Mode (EIB), LONWORKS drivers For the direct inte­gration of various interfaces in the management station.

• The online tool that operates on the existent system.

The user’s access in the system is simplified through the specific start-up sequences of the preselected programs and of the installation.

The Plant Viewer application shows the areas of the building of the installation associated in graphic form. The user works interactively with these images for the monitoring and control of the data points in the building. The values may be modified and the alarms noticed. The measured values, the set points, the func­tioning modes, and the alarms are displayed on the screen in real time and con­tinuously actualized. The display form is determined during the visualization. The modifications either are indicated by a symbol, for example an animation or change in forms and colors, or by the movement, the change in color or in the text of the affected value.

The Time Scheduler application is used for the centralized programming of all controlled functions depending on the time, of the building’s installations, including the control system for individual rooms.

The Alarm Viewer application shows the alarms depending on their type and provides helpful information depending on the action needed by the system.

Together with the extensive filter and the search functions, Alarm Viewer facilitates rapid and clear access to the necessary information.

The Trend Viewer application is used for the reviewing of the process’s actual data in real time (online) and of the subsequent data (off-line) for a certain period. Trend Viewer is user friendly, being used to optimize the operation of the instal­lation and to reduce the consumed energy. A few of the Trend Viewer’s facilities are presented below:

• The registration of the process value and of the measured values for a period of time and the minimal and maximum values registered in the graphics according to a period time;

• The monitoring of the present conditions of the installation;

• The optimization of the installation and its adjustment;

• Response times for the data base support.

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