590 likes | 997 Views
HVAC Control Systems 101 Rich Aquino Jeff Cox. What We’ll Cover. Basics of Controls Integration Between Building Systems Trane controls and energy management system Energy Saving Control Strategies Summary. Terminology. controlled variable. airflow. sensor. controller. controlled
E N D
What We’ll Cover • Basics of Controls • Integration Between Building Systems • Trane controls and energy management system • Energy Saving Control Strategies • Summary
Terminology controlled variable airflow sensor controller controlled device controlled agent
Open Loop outdoor-air sensor airflow controller chilled water valve
Closed Loop discharge-air temperature sensor airflow controller valve chilled water
Control Reset discharge-air temperature sensor outdoor-air sensor airflow controller valve chilled water
Control “Points” • Binary input point (BI) • Examples: fan status (on/off), dirty filter • Binary output point (BO) • Examples: start/stop fan or pump, open/close damper • Analog input point (AI) • Examples: temperature, pressure, airflow • Analog output point (AO) • Examples: control valve or damper position • Analog Variable, Binary Variable
Types of Control Action • Two-position (on/off) • Floating • Proportional • Proportional–Integral (PI) • Proportional–Integral–Derivative (PID)
Two-Position (On/Off) 100% controller output 0% A on + 5°F controlled-variable deviation differential 0°F setpoint B - 5°F off time
Floating 100% controller output 0% switch differential A B open + 5°F stop controlled-variable deviation differential 0°F setpoint D stop - 5°F close C time
Proportional 100% controller output 0% + 5°F A offset throttling range controlled-variable deviation 0°F setpoint - 5°F time
Proportional–Integral (PI) PI 100% controller output proportional integral 0% + 5°F controlled-variable deviation 0°F setpoint - 5°F time
Proportional–Integral–Derivative (PID) PID 100% PI controller output derivative 0% + 5°F controlled-variable deviation 0°F setpoint - 5°F time
Comparison of Control Actions P offset PID controlled-variable deviation setpoint overshoot PI time
Control of an HVAC System Building Management System-Level Control Unit-Level Control
Unit-Level Control Unit-Level Control
System-Level Control System-Level Control Unit-Level Control
Chilled-Water VAV System VAV terminal units cooling tower VAV air handler exhaust fan pumps water-cooled chiller system-level controller boiler
Rooftop VAV System VAV terminal units packaged rooftop air conditioner system-level controller
Building Management Building Management System-Level Control Unit-Level Control
Any PC on LAN (with Internet Explorer) Access Control Panel Video Surveillance Integrated Facility Control System Integrated Facility Server Security Server Operator Workstation (Facility Commander) • View System Alarms • Check System Status • Time Control Schedules (Tracer Summit) (Tracer ES) • Create Schedules • Modify Graphics • Configure System • Access Control • Security Alarm Manager • Data Logging • Web Server District - Local Area Network (BACnet/IP) Lighting Tracer BCU JENEsys Building Controller Unit HVAC Legacy Controllers System Operator Workstation Tracer Unit Controllers • Photo ID Creation • CCTV Monitoring • Security Alarms • Security Status • Access Control
Communications Protocols • Proprietary • Used, produced, or marketed under exclusive legal right of an individual or organization • Open • Available to public domain and is shared among vendors • Standard • Open protocol that has been formalized by a governing body
Gateways PC workstation Proprietary Protocol LAN Gateways HVAC Lighting Proprietary Protocol LAN Fire Protection Security Gateways
System-Level Interoperability PC workstation Open, Standard protocol LAN HVAC Lighting Proprietary Protocol LAN Fire Protection Security Gateways
Unit-Level Interoperability PC workstation Proprietary Protocol LAN Gateways Lighting HVAC Open, Standard Protocol LAN Fire Protection Security
Binary input • Binary output • Binary value • Loop • Command • File • Calendar • Schedule • Program • Standard object types • Analog input • Analog output • Analog value • Multi-state input • Multi-state output • Device • Event enrollment • Notification class • Trend • Group • BACnet/IP, BACnet MSTP
LonTalk • Rooftop unit controller • Space-comfort controller • Temperature sensor • Thermostat • Unit-ventilator controller • Variable-speed motor drive • VAV controller • LonMark functional profiles • Boiler controller • Chilled ceiling controller • Chiller • CO2 sensor • Damper actuator • Discharge-air controller • Fan-coil controller • Heat pump • Lighting-panel controller • Occupancy sensor • Pressure sensor
Value to Customer System applications, pre-engineered Easy web-enabled access Improved user interface Key Features Web-based interface Scalability Smaller incremental steps to build up a system Open standard protocol support (and integration point) BACnetTM and LonTalkTM Delivery platform for engineered system applications Air systems and central plant control Building ControlTracer SC…Linking Trane systems to the Web
Value to Customer Improved operating productivity Web access Integration with other systems Key Features Easy-to-use customer interface for daily building operations Web-based, remote access Multiple building scheduling and control Historical data collection and analysis System Integration platform for non-Trane BACnetTM systems Enterprise ControlTracer ES…Managing Multiple Buildings
Tracer™ Architecture Firewall Tracer ES BACnet Ethernet LAN Tracer SC Building Control BuildingControl Internet/Intranet ProgrammableController AdaptiView & UC 800 ProgrammableController Field-applied Controller Air Handlers Chillers VAV
Any PC on LAN (with Internet Explorer) Access Control Panel Video Surveillance Integrated Facility Control System Integrated Facility Server Security Server Operator Workstation (Facility Commander) • View System Alarms • Check System Status • Time Control Schedules (Tracer Summit) (Tracer ES) • Create Schedules • Modify Graphics • Configure System • Access Control • Security Alarm Manager • Data Logging • Web Server District - Local Area Network (BACnet/IP) Lighting Tracer BCU JENEsys Building Controller Unit HVAC Legacy Controllers System Operator Workstation Tracer Unit Controllers • Photo ID Creation • CCTV Monitoring • Security Alarms • Security Status • Access Control
staticpressuresensor supplyfan P VAV boxes communicating BAS Energy Saving Strategies
P Fan-Pressure Optimization staticpressuresensor supplyfan VAV boxes communicating BAS
Fan-Pressure Optimization Benefits • Reduce supply fan energy use • Reduced pressure…. Less noise • Pressure sensor factory installed.
ASHRAE Standard 62.1-2004Dynamic Reset of OA • May reset OA intake flow (or zone OA flow) in response to: • Variations in zone population (DCV) • Variations in ventilation efficiency due to changes in airflow (ventilation reset)
AHU OCC OCC TOD CO2 CO2 TOD ventilation optimizationZone Level: DCV BAS lounge restroom mechroom storage office vestibule corridor elevators reception area office conference rm computer room
rooftop unitwith controls • Reset outdoor airflow (Traq™ damper) OCC CO2 TOD TOD communicating BAS DDC/VAV terminals • New OA setpoint…per ASHRAE 62 • Required ventilation (TOD, OCC, CO2) • Actual primary airflow (flow sensor) ventilation optimizationSystem Level: Ventilation Reset OA SA RA CO2 OCC
ventilation optimizationDCV and Ventilation Reset • Assures each zone is properly ventilated … without requiring a CO2 sensor in every zone • System-level ventilation reset equations are defined by ASHRAE 62
ventilation optimizationDCV and Ventilation Reset • Assures each zone is properly ventilated … without requiring a CO2 sensor in every zone • System-level ventilation reset equations are defined by ASHRAE 62
Optimization: Chiller - Tower Control • Traditional Tower Control Methods • Minimum tower LWT • Fixed design tower temperature • OAT wet bulb plus tower approach • Satisfy chiller pressure differential Reduce Operating Costs
Tower Optimization - Considerations • Fan energy varies by the cube of speed changes • Example: energy change = 0.5*0.5*0.5 ~12.5% • Chiller efficiency is dependent on tower temp, chiller load and chiller type Reduce Operating Costs
Trane’s Tower/Chiller Optimization Solution • Models interaction of tower and chiller • Factors ambient condition and chiller load • Factors chiller and tower - type and efficiency • Algorithm calculates optimal tower LWT • Real time control
Chiller - Tower Control what is optimal? • 85 F setpoint minimizes tower energy use • 55 F setpoint minimizes chiller energy use • Wb + 6 F optimizes nothing • Recommend real time optimization Reduce Operating Costs
Benefits • Reduced energy consumption • Reduced water consumption • Reduced chemical consumption • Reduced maintenance/person-hours resulting from automated control • Chiller plant will operate in a steady-state condition • Extended life cycle of equipment components • Short-term return on investment • Reduced maintenance costs