Foreword:
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Overview
This solution is designed for a Building Automation System (BAS). Based on the characteristics of this project, we will use the BAS system to control and manage the building's public lighting, air conditioning, heating and ventilation, water supply and drainage systems around the clock. The system collects, records, and saves important information and data related to the system, achieving integrated management, improving operational efficiency, ensuring the needs of the office environment, saving energy and manpower, and maximizing the safety and lifespan of equipment.
1. Design Basis
Provide some standards and specifications
and related materials and technical documents provided in the tender documents;
2. Requirements Analysis
The primary task of a building automation system (BAS) is to monitor and manage the electromechanical equipment within a building. To effectively manage this equipment, it's essential to understand its operational status, its role within the system, and its characteristics. A BAS is built upon the electromechanical systems, utilizing automation technology, computer software technology, and computer network communication technology to aggregate information generated by different electromechanical systems within the building. This enables data and information exchange between various devices and comprehensive processing of different types of information to achieve integrated management of all monitored electromechanical equipment.
The specific details of the Building Automation System (BAS) monitoring required for this modern urban complex are described below:
Air conditioning and power equipment (connected to BAS via DDC)
Supply/exhaust fan system
Fresh air system
Exhaust and smoke extraction
Water supply and drainage system (via DDC and BAS connection)
water collection well
Drain pump
Public lighting (connected to BAS via DDC)
Public lighting
3. BAS system monitoring content
According to project requirements, the building automation system monitors the following electromechanical equipment: public lighting, air conditioning system, heating and ventilation system, and water supply and drainage system. Based on the different system configurations of various functional buildings within the building, the scope and monitoring content of the building equipment monitoring system are as follows:
3.1 Fresh Air Unit Control
Monitoring content control methods
The start/stop control air conditioner can be automatically controlled by the BAS system or manually controlled on-site; it has a timed start/stop function, allowing equipment to start and stop according to a predetermined schedule; it has interlocking functions: before the supply fan starts, the air valves are fully open; after the supply fan starts, the temperature and flow control loops are enabled; after the supply fan stops, the air valves and water valves are closed; it supports fire alarm linkage, receiving fire alarm forced signals to control the supply fan and air valves. This is implemented based on the information provided by the fire alarm system.
Temperature monitoring tracks the supply and return air temperatures and determines whether they exceed preset high or low limits, outputting an alarm if any limit is exceeded. We use a cascade control loop to control the return air temperature. The inner loop controls the supply air temperature via PID control. The supply air temperature setpoint can be reset manually by the operator or automatically by the BMS. This is the outer loop control (setpoint reset loop). When the return air temperature exceeds its upper limit and remains above it for a preset dead time, the supply air temperature setpoint will automatically decrease by one offset. When the return air temperature falls below its lower limit and remains below it for a preset dead time, the supply air temperature setpoint will automatically increase by one offset.
The damper actuator is controlled by analog signals, and the opening degree of the damper actuator can be controlled at any level through BAS.
Differential pressure status monitoring involves installing differential pressure switches before and after the filter to monitor the filter's clogging status and output alarm signals.
The alarm and fault handling system monitors the fault alarm status of the blower, the differential pressure status of the blower, and the differential pressure alarm status of the filter. Once an alarm status is detected, the air conditioner will stop and the shutdown procedure will be followed.
The software control mode provides a delayed start function for the start and stop of the blower to protect the equipment from potential damage during over-start conditions; it also provides a timetable control function, allowing the air conditioning unit to be started and stopped in day/night mode, holiday mode, and customized time mode.
According to the requirements of the tender documents, the control contents of the air conditioning unit in this project are as follows:
Air valve control
Differential pressure status monitoring
3.2 Air supply and exhaust system
3.2.1 Fan switch control
The fan's on/off control is primarily achieved through a pre-set schedule in the Building Automation (BA) system. In special circumstances, such as overtime work, the fan may need to start outside the pre-set schedule; in such cases, the user can operate the fan on the BAS (Banner Access System) workstation. The BA system allows users to configure interlock monitoring between the fan status and control. After this function is configured, the BA system automatically monitors whether the fan status matches the control requirements. If they do not match, it indicates a fault in the equipment at that control point, and the BA system will display an alarm on the workstation to alert the operator. Furthermore, the BA system records relevant information for future inspection. Additionally, the BA system allows users to set the cumulative operating time of the measuring equipment, enabling maintenance personnel to perform maintenance work after the equipment has run for a certain period.
3.2.2 Fan Operating Status
The BA system measures the actual status of the fan through the main contactor of the fan, so that operators can understand the operating status of the fan in real time.
3.2.3 Cumulative running time
The BA system utilizes software statistics and timing functions to accumulate and record the operating time of the wind turbine in real time.
3.2.4 Fan Alarm Monitoring
The DDC controller detects tripping alarms from the fan's thermal relay. When an alarm occurs, the fan stops and the alarm is displayed on the operator station to alert operators to arrange for maintenance. The BA system also records all relevant information for future reference.
3.3 Water Supply and Drainage System
The water supply and drainage system of a certain building mainly consists of sewage pumps, sump pits, and air conditioning water supply pumps.
3.3.1 System Design Content
Monitoring equipment design content, hardware configuration, and software settings.
High and low water level monitoring in the sump. High and low water level monitoring (DI). Setting equipment linkage parameters.
Drainage pump, air conditioning water supply pump start/stop, operating status, fault alarm, manual/automatic status. Start/stop (DO), operating status, fault alarm, manual/automatic status (DI). Cumulative operating time.
3.3.2 Key Points of System Design
(1) DDC parameter acquisition and monitoring
An alarm is triggered when the high liquid level in the sump exceeds the limit.
It monitors the operating and fault status of submersible drainage pumps and can rotate the equipment according to the cumulative operating time, thereby improving the service life of the equipment.
It can monitor the operating status and fault status of the air conditioning water supply pump and enable the equipment to operate in rotation according to the cumulative operating time, thereby improving the service life of the equipment;
(2) Software control function
Monitor the high and low liquid level alarm status of the water collection well and generate dynamic trend charts;
Cumulative equipment operating time;
Monitor and record the liquid level alarm status of water tanks and pools, and generate dynamic trend charts;
Central management station software functions;
The 3D image displays a system diagram of each unit and water pump;
Print out relevant alarm signals;
3.4 Lighting System
Monitoring content control methods
The switch controls the DDC output DO contact to control the auxiliary relay, enabling remote start and stop.
Timed/special effects control starts and stops the lighting circuit at a predetermined time, and the logic control is implemented through software.
Running time statistics software accumulates lighting time.
3.5 Energy-saving measures
This design optimizes the start-stop control of the air conditioning system without compromising comfort. This is achieved by calculating the optimal setpoint for chilled water temperature and the actual cooling load, thereby shortening equipment operating time and achieving energy savings. Specific energy-saving measures are as follows:
1) Chilled water temperature setting
The system's energy-saving program automatically adjusts the outlet temperature of the chilled water according to changes in outdoor temperature in different seasons and daily, thus dynamically controlling the system.
2) Temperature setting in air-conditioned spaces
For office buildings, appropriately raising the set temperature in public areas such as lobbies and corridors can reduce energy consumption. For example, if the office area temperature is set at around 25℃, and the lobby, which is the transition area between indoors and outdoors, is also set at around 25℃, the temperature difference with the outdoors will be too large, and people will feel uncomfortable as soon as they enter. It can be set at 28℃~30℃, which is (4~5)℃ lower than the outdoors. The corridor can be set at 27℃~28℃. This gradual transition to the office area not only makes people feel comfortable, but also effectively reduces unnecessary energy consumption.
3) Overcome equipment capacity redundancy
Traditional air conditioning designs, due to numerous variables such as seasonal changes and the heat generated by people and equipment, struggle to accurately calculate the load demand of the air conditioning system. This often results in a certain amount of equipment capacity redundancy in the design, and relying on simple manual start-stop systems inevitably leads to energy waste. By utilizing the energy-saving control algorithms and group control mode of a Building Automation (BA) system, the operating time and number of units deployed are dynamically adjusted based on the actual cooling load required by the terminals. This ensures a balance between cooling supply and demand, allowing the cooling source equipment to operate at its highest efficiency, avoiding over-engineering and effectively overcoming energy waste caused by equipment capacity redundancy.
4) Fresh air control
Adjusting fresh air volume according to seasonal changes is another energy-saving measure. Taking XXX region as an example, under design conditions (summer room temperature 26℃, relative humidity 60%; winter room temperature 22℃, relative humidity 55%), processing one kilogram of outdoor fresh air requires 6.5 kW of cooling and 12.7 kW of heating. Therefore, reducing the fresh air volume while ensuring indoor air hygiene has a significant energy-saving effect. The following are some methods for controlling fresh air volume:
o When the outdoor temperature is lowest at midnight in summer, turn on the fresh air fan to fill the room with cool outdoor air, and then close the air damper to reduce the pre-cooling time of the air conditioning system before going to work the next day.
Based on the changing patterns of indoor occupants, a statistical method is used to establish a start-stop control model for the fresh air system, in order to reduce the start-up time and cooling load loss of the fresh air system. For example, when there are fewer people indoors during lunchtime, the number of fresh air systems that can be turned on can be reduced.
During transitional seasons, try to use outdoor fresh air as much as possible to reduce cooling load loss.
5) Improve the accuracy of indoor temperature and humidity control
Changes in temperature and humidity inside a building are closely related to building energy conservation. According to US national statistics, lowering the temperature setpoint by 10°C in summer will increase energy consumption by 9%. Therefore, controlling the temperature and humidity inside a building within the setpoint accuracy range is another effective measure for building air conditioning energy conservation.
4. System Design
This project utilizes the XXXBAS system XX series to implement the corresponding building automation functions. This system is currently the world's most advanced, high-efficiency, and integrated BMS system. It can integrate the building control system, power monitoring, fire alarm system, and security automation system onto a single system platform, adapting to the building's architectural characteristics and advanced control and management requirements. This includes the use of state-of-the-art LonWorks technology digital controllers and open interfaces with other vendor systems and OA systems.
The system design meets the requirements of the project, adopts the most advanced technologies and systems, and follows the requirements of the tender documents. Based on the principle of the highest price-performance ratio, it employs optimized equipment configuration, operation schemes, and management methods to provide the building with efficient system management, a good operating environment for the building's electromechanical equipment, and a comfortable working and living environment.
The Building Automation System (BAS) of a certain building has approximately 2000 physical points. In designing this monitoring solution, our company also followed the above principles, rationally arranging the controllers and their control modules, and reserving sufficient system expansion capacity to ensure the controllers maintain redundant expandability.
4.1 Design Concept
This project involves setting up a BAS (Building Automation System) management software suite and connecting it to 31 network controllers, directly integrating it into the building's local area network (LAN). The network controllers transmit data from the LonWorks bus via an IP network, connecting 236 LonWorks expansion modules. Furthermore, the controllers are multi-protocol integration platforms supporting various protocols including Modbus and LonWorks. The system can be flexibly integrated in multiple ways, either directly interconnecting with field controllers or accessing the system via Ethernet.
Using this BAS system, all aspects of building equipment management can be easily completed, providing users with a comfortable and safe environment. While meeting various user requirements, it can also maximize energy savings, thereby better realizing the building's potential.
4.2 Communication Network
This BAS system is a distributed intelligent system with a three-layer network structure: a network management layer, an automatic control layer, and a field control layer. The management layer consists of IP controllers using the TCP/IP communication protocol. The automatic control layer comprises digital controllers (DDCs), communicating with them using the LonTalk standard communication protocol. In the event of a Xenta701 network controller failure, each field digital controller's DDC can continue operating independently. The field control layer consists of various sensors and actuators connected to the DDCs for signal acquisition and real-time control.
a. Ethernet (TCP/IP): National standards recommend using Ethernet with a bus topology as the backbone of a local area network to achieve network resource sharing.
b. Fieldbus: A regional network consisting of twisted-pair cables connecting each substation to the central control room, forming a substation bus. Data is transmitted digitally, and the communication protocol adopts the standard LonTalk bus format.
The design/structure of the BAS system must meet the following technical specifications:
The communication rate between DDCs is 78.6 Kbps.
The communication rate between the IP device and each DDC is 78.6Kbps.
Communication between IP devices is at 10 Mbps.
Communication between the IP device and the workstation is at 10Mbps on the same level. The workstation is only used as an interface for operators, and network communication can continue to function normally even if the workstation fails.
4.3 Control Center
The central control center is directly connected to the building's internal LAN and serves as the system's master—the center for remote monitoring, control, data processing, and central management. Furthermore, the central control station monitors data and alarm information from each substation in real time, issues various control commands to each substation, processes data, prints reports, and allows users to control equipment operation or confirm alarm information via text and graphics on the screen.
The hardware includes original commercial PCs, online uninterruptible power supplies (with software that automatically shuts down/starts), printers, network controllers, etc.; the software includes various operating software based on a certain system.
4.4 Network Controller (DDC)
The Data Center (DDC) directly monitors and controls equipment within a building, including chiller systems, air conditioning systems, heating and ventilation systems, water supply and drainage systems, public area lighting, landscape lighting, power distribution systems, and elevator systems. Considering the building's characteristics, our DDC selection and configuration followed the principle of allocating the number of DDCs based on the number and distribution of controlled equipment in different areas. We also flexibly configured the DDCs according to the specific features of the system, ensuring sufficient margin for the number of controlled points while facilitating installation and wiring. The Xenta series network controllers offer comprehensive functions and high reliability. The controllers can also be programmed and modified locally, simplifying debugging and maintenance. When external power is lost, the DDC permanently stores data; when power is restored, the DDC automatically resumes normal operation without manual intervention. If data stored in the DDC is abnormally lost, the user can rewrite the data through the network operator station. The DDC can be mounted on a DIN rail for on-site installation or installed in a control box, simplifying the process and reducing on-site cabling.
4.5 Field Terminal Equipment
The XXXBAS system provides a complete and compatible range of field terminal devices, including various sensors, valves, actuators, etc.
4.6 Introduction to a Certain System
The 5 series is the latest building management system launched by XXX Building Systems based on the original 4 series. Its product series includes modular field controllers, powerful IP controllers, and various hardware gateways.
In terms of functionality: This system was developed using advanced LonWorks bus technology and successfully solved various practical problems commonly encountered in distributed real-time control systems. For example, the software provides users with pre-defined and tested object blocks, which users can easily generate using modules; the graphical object library can be expanded.
As a solution: obsolescence of automation and information systems is not due to wear and tear; systems become obsolete when they cannot adapt to or integrate with new applications or emerging technologies. One system offers an open architecture that, while maintaining essential real-time control functionality, allows users to build next-generation interoperable control systems to meet the open requirements of the increasingly widespread use of the Internet. Therefore, it can be said that this system provides a supportive working environment and a customizable system architecture, enabling easy integration between different protocols and systems, reducing overlap and duplication of work, and preventing system obsolescence.
For end users: Users of a system have full control over their equipment and can purchase products that meet their requirements from suppliers they are satisfied with. Users can also dynamically reconfigure their control systems via the internet to adapt to changing needs.
Meanwhile, this series is an open system that provides multiple interfaces for system integration to meet user requirements. Its unprecedentedly powerful ability to integrate third-party device management systems ensures that third-party system functions can be fully implemented through BAS while maintaining independence.
4.7 Basic Network Structure and System Composition
4.7.1 Basic Network Structure
A five-story building automation system comprises a central computer, a Xenta network controller, and field digital controllers, forming a distributed architecture. The management level consists of a central monitoring computer equipped with a series of software and Xenta network controllers; the intelligent control level is composed of various control substations (DDCs) connected together, including multiple series of Xenta controllers. Controllers are interconnected via a LonWorks FTT-10 bus, and the controllers are connected to the central computer via a standard twisted-pair cable through a TCP/IP interface; the Xenta network server and controllers are interconnected with the central computer via Ethernet. The intelligent control level directly connects to field control elements (valve actuators, relay contacts) and sensing elements (temperature, pressure differential, flow, etc. sensors). This network structure of the system realizes the "distributed control, centralized management" control mode currently popular in building automation systems. This control mode not only facilitates system expansion but also ensures that each substation operates independently, greatly reducing the probability and scope of system failures. It features high reliability, flexibility, and advanced technology.
The system management bus uses a 10M high-speed Ethernet to ensure the high-speed operation of the entire system.
In addition to network management functions for standard and legacy devices, it also provides:
A complete graphical user interface.
Synchronize, save, and back up the controller's database;
Password protection;
Data collection and provision of enterprise-level information exchange;
Synchronization function between global time and central timetable;
Alarm handling and transmission;
Extensive support for all standard energy management functions;
Supports online communication with running workstations via IP address network;
Supports offline communication by directly reading the workstation's database;
The disk-based library supports network and local browsing and includes resources such as nodes and images for building workstation databases.
It has a text-based help system, which includes a complete set of online or offline system files.
4.7.2 Components of the Network Layer
Management Network
The XXXTAC™ system runs on the Microsoft Windows 2000/NT/XP platform. Its built-in peer-to-peer LAN can connect up to 16 workstations into a single control network system. Up to six workstations can communicate directly with the control unit, and the total network capacity can reach 240,000 physical points. All workstations on the LAN are peers and can establish communication with each other as needed. If one workstation shuts down, the others continue operating. Each workstation on the network can connect to up to three printers.
The Lonworks network employs a bus-based network topology to construct its local area network (LAN), supports the TCP/IP protocol, and provides an Internet-based remote management solution. Operators can also monitor the system using a web browser (IE), entering the IP address or domain name to browse and control units within the Lonworks network via the Internet or corporate intranet. System alarms can be transmitted to one or more recipients via email through the Internet or corporate intranet.
Remote monitoring of the equipment does not require central station software; the system can use a small web server to achieve intuitive and dynamic monitoring of the controlled equipment. Authorized network users can modify system parameters and setpoints; check and confirm alarms. Depending on their authorization level, users can also browse specific files in the system, such as technical documents, reports, etc. All updated values are displayed dynamically in real time. If a user modifies a setting, all network user data is updated in real time.
It can easily achieve data communication, system integration, and connection with other related systems and independently set intelligent systems in the building, as well as with equipment and systems from other manufacturers.
This network allows all monitoring information from the BAS to be fed back to the central station display screen in a timely manner, and the central station system can also transmit programs, instructions and other relevant equipment through this network.
Provide third-party interface software for OPC or DDE.
The data transmission rate shall not be less than 10Mbps.
Control layer network
When using the TP/FT-10 network, each TAC segment can contain 60 network nodes or 30 controllers, with a communication rate of 78Kbps and a bus length of up to 2700 meters. Two TAC segments can be connected using an extender to expand system capacity, allowing up to 60 controllers per bus. Each workstation can have four LonTalk adapters to support four buses and 240 controllers.
When using the TP/XF-1250 backbone network, each bus can be connected to the LonWorks backbone with a communication rate of 1.25Mbps via a router. The number of routers can reach 63, and the entire network can support up to 400 controllers. The backbone is connected to workstations via LonTalk adapters and supports a large number of advanced network features, such as virtual subnets, workgroups, domains, and advanced addressing methods.
It adopts internationally leading Lonworks control network technology, and all freely programmable controllers have the LonMark certification mark.
The controller has four CPUs: three 8-bit neural network chips for Ionworks communication and one 32-bit CPU for the application program. Both the A/D and D/A conversion resolutions are 12 bits.
The communication network between distributed control substations adopts a bus topology or a free topology to realize data communication between substations, between substations and the central station, and between them and dedicated control and interface equipment.
The central station can use this network to transmit information to any designated data communication.
All branch stations communicate with each other on an equal footing, i.e., in a point-to-point manner.
The monitoring layer network can establish its subnets according to actual needs.
The data transmission rate is no less than 78Kbps, and can be increased to 1.25Mbps as needed. The bus communication distance is no less than 2700 meters.
Menta – A unified graphical programming tool for all DDC controllers
In a certain system of XXX, all DDC controllers except for the Xenta100 series can be programmed and configured for inputs and outputs via Menta. The entire system adopts a distributed intelligent control approach, and its rational design ensures stable and reliable operation, so that a failure in any node will not affect the normal operation of other parts of the system. In large-scale systems, Menta programming can be performed simultaneously in the central control room and in the field, greatly improving programming and debugging efficiency.
Download the program directly to the host computer (Workstation) for easy debugging.
The controller database management has the function of uploading and downloading applications.
L Based on project development applications, simplify various database management tasks
l Provides convenient usage instructions
Menta software is a graphical controller configuration tool used to create, modify, download, and upload control programs for Xenta 280/300/401/700 series controllers. Menta can run on a laptop or desktop computer. It allows for file management through methods such as accessing application software, modifying application parameters, printing application files, downloading databases, and selecting nodes. Menta software connects to a Xenta series controller via a LonWorks communication card or Ethernet.
4.7.3 Main Features of the System
From hospitals to high-rise buildings, from schools to skyscrapers, buildings of all shapes and sizes can now achieve a higher level of operational efficiency. This has been made possible by using XXX's truly open, interoperable, and powerful intelligent building automation system.
Now, from a simple workstation, you can collect all the information you need, making your facilities more stable, comfortable, and secure, and more importantly, more cost-effective. XXX's system significantly reduces your investment risk by using an open network architecture.
Our product series has won numerous patent awards, with our HVAC control system and related equipment being among the most innovative and cutting-edge products in the industry. Excellent engineering and FDA certification ensure that our products meet the highest international standards, allowing our customers to enjoy stable and reliable performance, unparalleled value, and unique quality.
Easy to access
- The internet provides a comfortable operating environment, and users are generally familiar with the internet and know how to use it.
Users can access their system from anywhere.
Lower cost
- Advantages over traditional client/server applications
-The advantages become more apparent as the number of customers increases.
-A true integrated platform
- Construction is compatible with different hardware devices
- Capable of integrating LON and BACnet
Modbus, DDE, and SNMP drivers enhance integration capabilities.
- Establishing a target library facilitates the reuse of solutions and reduces solution processing time.
Data integration function
- Compatible with multiple protocols and various devices
Enables integration between control system data and enterprise applications.
- Application development can be adapted to any practical requirements.
- Enterprise-level information sharing adopts unified industry standards.
