ddcsequencingand# redundancy# - ashrae · • serieswaterside(economizer •...
TRANSCRIPT
DDC Sequencing and Redundancy
Presenter
• Importance of sequencing • Essen%al piece to designing and delivering a successful project • Defines how disparate components interact to make up a ‘system’
• The fundamentals to sequencing • Mechanical designers intent • How it should operate • How to control to meet both
• Simplicity is key • Clear, concise and complete
• Overview of process • Analyze mechanical design • Outline SOO • Fill in details • Op%mize system
Sequencing
• Systema@c approach to developing SOO’s. • Map out en%re system, compartmentalize components if possible,
analyze system on a component level • Define instrumenta%on on a component level • Develop I/O list for components including hardwired points and data
connec%ons • Define Instrumenta%on on the system level • Develop I/O list for system • Iden%fy set points, alarms, schedules and trends
Sequencing
• Series water-‐side economizer
• Primary-‐secondary chilled water pumping
• Variable speed condenser water pumping
• Dual piping loops
Example System – Chilled Water Plant
• Systema%c approach to developing SOO’s. • Map out en@re system, compartmentalize components if possible,
analyze system on a component level • Define instrumenta%on on a component level • Develop I/O list for components including hardwired points and data
connec%ons • Define Instrumenta%on on the system level • Develop I/O list for system • Iden%fy set points, alarms, schedules and trends
Sequencing
• Define system by it’s disparate components
• N+1 component redundancy
• One-‐to-‐one rela%onships
Map Out En@re System
Compartmentalized Components
• Compartmentalize system as best as possible.
• Create “Line-‐ups” of equipment
Chiller Plant System – Component Level
• Break down system to the individual component level
• Systema%c approach to developing SOO’s. • Map out en%re system, compartmentalize components if possible,
analyze system on a component level • Define instrumenta@on on a component level • Develop I/O list for components including hardwired points and data
connec%ons • Define Instrumenta%on on the system level • Develop I/O list for system • Iden%fy set points, alarms, schedules and trends
Sequencing
Component Level – Defining Instrumenta@on
• As laid out by the mechanical designer
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable
Component Level – Defining Instrumenta@on
• Unit Mounted Controller
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable
Component Level – Defining Instrumenta@on
• Unit Mounted Controller
• Shut-‐off/Isola%on Valves
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable
Component Level – Defining Instrumenta@on
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable • Capacity Control
• Unit Mounted Controller
• Shut-‐off/Isola%on Valves
Component Level – Defining Instrumenta@on
• Unit Mounted Controller
• Shut-‐off/Isola%on Valves
• Temperature Sensor
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable • Capacity Control
• Unit Mounted Controller
• Shut-‐off/Isola%on Valves
• Temperature Sensor
Component Level – Defining Instrumenta@on
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable • Capacity Control • Opera%ng Restraints
• Unit Mounted Controller
• Shut-‐off/Isola%on Valves
• Temperature Sensor
• Head Pressure Control
Component Level – Defining Instrumenta@on
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable • Capacity Control • Opera%ng Restraints
• Unit Mounted Controller
• Shut-‐off/Isola%on Valves
• Temperature Sensor
• Head Pressure Control
Component Level – Defining Instrumenta@on
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable • Capacity Control • Opera%ng Restraints • Op%miza%on
• Unit Mounted Controller
• Shut-‐off/Isola%on Valves
• Temperature Sensor
• Head Pressure Control
• Addi%onal Sensors
Component Level – Defining Instrumenta@on
• What instrumenta%on is required to meet intent and opera%on? • Enable/Disable • Capacity Control • Opera%ng Restraints • Op%miza%on
• Systema%c approach to developing SOO’s. • Map out en%re system, compartmentalize components if possible,
analyze system on a component level • Define instrumenta%on on a component level • Develop I/O list for components including hardwired points and data
connec@ons • Define Instrumenta%on on the system level • Develop I/O list for system • Iden%fy set points, alarms, schedules and trends
Sequencing
Develop I/O List for Components
Develop I/O List for Components
Repeat instrumenta@on and I/O for other components
• Cooling Tower
• Condenser Water Pump
• Primary Chilled Water Pump
• Secondary Chilled Water Pump
• Systema%c approach to developing SOO’s. • Map out en%re system, compartmentalize components if possible,
analyze system on a component level • Define instrumenta%on on a component level • Develop I/O list for components including hardwired points and data
connec%ons • Define Instrumenta@on on the system level • Develop I/O list for system • Iden%fy set points, alarms, schedules and trends
Sequencing
• How do the disparate components interact with the system?
System Level – Defining Instrumenta@on
• System Valves
System Level – Defining Instrumenta@on
• System Valves
• Flow Meters
System Level – Defining Instrumenta@on
• System Valves
• Flow Meters
• System Temp Sensors
System Level – Defining Instrumenta@on
• System Valves
• Flow Meters
• System Temp Sensors
• Differen%al Pressure Sensors
System Level – Defining Instrumenta@on
• Systema%c approach to developing SOO’s. • Map out en%re system, compartmentalize components if possible,
analyze system on a component level • Define instrumenta%on on a component level • Develop I/O list for components including hardwired points and data
connec%ons • Define instrumenta%on on the system level • Develop I/O list for system • Iden%fy set points, alarms, schedules and trends
Sequencing
Develop I/O List for System
• Systema%c approach to developing SOO’s. • Map out en%re system, compartmentalize components if possible,
analyze system on a component level • Define instrumenta%on on a component level • Develop I/O list for components including hardwired points and data
connec%ons • Define instrumenta%on on the system level • Develop I/O list for system • Iden@fy set points, alarms, schedules and trends
Sequencing
• Avoid exact set points, baselines are recommended • Typically done by Cx agent along with the balancing contractor
• Define schedules
• Alarms can be addressed as virtual points in points list as well as safe%es that typically take the form of hardware
• Define trends
Iden@fy Set Points, schedules, alarms, trends
• Understand the importance of sequencing
• Become in%mate with the fundamentals of the design
• Define your systema%c approach to developing sequences
• Keep it simple!
Sequencing
Ques@ons?
• Where and why redundancy in DDC is required
• Redundant systems within a facility
• DDC System Redundancies
• Redundant Instrumenta%on • Redundancy in system architecture • Physical separa%on of installed control components • Dual power supplies with separate feeds to each control panel • Network Redundancy • Separate supervisory networks • Redundant Servers
• PLC Systems
Redundancy in DDC
• Where:
• Mission Cri%cal Facili%es (MCF)
• What it means to be a ‘Mission Cri%cal’ • Facili%es that require 100% up%me 24 hours a day 7 days a week for
normal business opera%on
• Redundancy provides maximum reliability but also generates maximum cost and complexity
• Examples: Data Centers, Hospitals, Laboratories
Redundancy in DDC
• Why:
• Enables con%nuous opera%on during cri%cal system failures
• Meets owner’s requirements for minimized down%me • Designing for redundancy in all building systems, including the DDC
system may be required
• Site-‐wide control coordina%on • Example coordina%on types: Temperature Control , Power restart,
Load Shedding, Humidity Control, Pressuriza%on
Redundancy in DDC
Redundant Systems
• N+1 component redundancy
• Dual piping loops
Redundant Systems
• DDC system redundancy isn’t addressed by Up%me
• Redundant mechanical equipment s%ll needs DDC to func%on properly
• Fault Tolerant Control Systems – any single controller or communica%on network
• Redundancy in DDC is necessary to ensure any malfunc%on or loss of power within the control system will not affect cri%cal equipment opera%on
Redundant Systems
• Redundant Instrumenta@on
• Redundancy in system architecture
• Physical separa%on of installed control components
• Dual power supplies with separate feeds to each control panel
• Network Redundancy
• Separate supervisory networks
• Redundant Servers
DDC System Redundancies
• System Valves
• Flow Meters
• System Temp Sensors
• Differen%al Pressure Sensors
Redundant Instrumenta@on
• Redundant Instrumenta%on
• Redundancy in system architecture
• Physical separa%on of installed control components
• Dual power supplies with separate feeds to each control panel
• Network Redundancy
• Separate supervisory networks
• Redundant Servers
DDC System Redundancies
Redundancy in System Architecture
• DDC system architecture depends on the make-‐up of the mechanical and electrical systems
• DDC system architecture designs to achieve redundancy:
• Primary-‐Redundant Managers (True Primary/Redundant) • Distributed Control (Line-‐Up Configura%on) • Hybrid (Line-‐Up Configura%on with PR Managers)
• How to find the right design for your applica%on
• Compartmentalize the systems as best as possible
Redundancy in System Architecture
• Primary-‐Redundant Managers (True Primary/Redundant)
Redundancy in System Architecture
• Distributed Control (Line-‐Up Configura%on)
Redundancy in System Architecture
• Hybrid (Line-‐Up Configura%on with PR Managers)
• Redundant Instrumenta%on
• Redundancy in system architecture
• Physical separa@on of installed control components
• Dual power supplies with separate feeds to each control panel
• Network Redundancy
• Separate supervisory networks
• Redundant Servers
DDC System Redundancies
Physical Separa@on of Components
• DDC Controllers
• Variable Frequency Drives
• Redundant Sensors
• Control Valves
• Wiring
• Redundant Instrumenta%on
• Redundancy in system architecture
• Physical separa%on of installed control components
• Power redundancy
• Network Redundancy
• Separate supervisory networks
• Redundant Servers
DDC System Redundancies
Power Redundancy
• Control panels need to be powered at all %mes to properly func%on
• Examples: • UPS power from two sources with a local ATS • UPS power from electrical system with back-‐up generator and local UPS
• Redundant Instrumenta%on
• Redundancy in system architecture
• Physical separa%on of installed control components
• Dual power supplies with separate feeds to each control panel
• Network Redundancy
• Separate supervisory networks
• Redundant Servers
DDC System Redundancies
Network Redundancy
• Concept of ‘self-‐healing’ communica%on busses
• Redundant topologies (network’s virtual shape or structure)
• Ethernet Topologies • Bus Topology • Classic Star Topology • Tree Topology (combina%on of bus and star) • Ring Topology
• Redundancy through ring topology is becoming the most popular for the BMS market
• Wireless Mesh
Network Redundancy
• Bus Topology • Uses a common backbone to connect all devices. Failure of one node or
link affects the rest of network • Works best with a limited number of devices due to the broadcast traffic
it generates
Network Redundancy
• Star Topology • Most common network setup • If the central hub fails, all devices connected to that hub would be
disconnected • Performance of the network is dependent on the capacity of central hub
(router or switch)
Network Redundancy
• Tree Topology • Integrates mul%ple star topologies together onto a bus. • This hybrid approach supports future expandability of the network much
beier than a bus
Network Redundancy
• Ring Topology – N+1 • U%lizing industrial switches • Redundant rings is becoming the most popular for the BMS market • Ethernet rings will cause broadcast storms and can ul%mately cause the
network to stop working • How to fix this? -‐ Spanning Tree Protocol
Network Redundancy
• Spanning Tree Protocol (STP)
• Although two cable paths exist, messages can only travel in one direc%on
• STP solves problems in a ring topology including broadcast storms
• STP does for an Ethernet network what a router does for an IP network
• Typically provides network recovery %mes of 30-‐60 seconds
• Rapid Spanning Tree Protocol (RSTP)
• Provides faster spanning tree convergence aler a topology change
Network Redundancy
• Wireless Mesh Topology • Can take any of several possible paths from source to des%na%on. • Devices are connected with many redundant interconnec%ons between
network nodes • In a true mesh topology every node has a connec%on to every other node
in the network.
Network Redundancy
• The most common problems in any fieldbus or high speed digital communica%ons system are:
• Cabling and wiring faults: • Reflec%ons, interference, cable rou%ng and grounding faults etc.
• Poor design and installa%on: • Lack of awareness of avoidable issues at design stage, poor rou%ng,
layout, untrained installers, inaccurate or insufficient system documenta%on
• Device and wiring failures: • Rare but can lead to communica%ons faults or peripheral faults
• Redundant Instrumenta%on
• Redundancy in system architecture
• Physical separa%on of installed control components
• Dual power supplies with separate feeds to each control panel
• Network Redundancy
• Separate supervisory networks
• Redundant Servers
DDC System Redundancies
Separate Supervisory Networks
• SNMP monitoring on equipment back to a separate owner network and server
• Other secondary monitoring methods such as web based services
• Redundant Instrumenta%on
• Redundancy in system architecture
• Physical separa%on of installed control components
• Dual power supplies with separate feeds to each control panel
• Network Redundancy
• Separate supervisory networks
• Redundant Servers
DDC System Redundancies
Redundant Servers
• Servers are also at risk for being a single point of failure
• Server redundancy minimizes down%me caused by:
• Planned Maintenance • Hardware Failure
• Redundancy Methods
• Two separate servers –passive synchroniza%on rou%ne • Two separate servers – with an ac%ve synchroniza%on rou%ne • Clustering and/or VM’s (Virtual Machines)
Redundant Servers
• Two separate servers – would have some manual back up and a passive synchroniza%on rou%ne
• Two separate servers – with an ac%ve synchroniza%on rou%ne
• Two computers using separate network between them that buffers and replicates the data going into one machine
• Poten%ally lose the buffer as data is being passed between the two.
Redundant Servers
• Clustering and/or VM’s (Virtual Machines)
• Two different things but from controls perspec%ve doesn’t maier
• Server Clustering – combining two or more servers that are interconnected to appear as one
• Load balanced clustering/fail over clustering
• Need clustering solware that monitors the ac%ve nodes in a server cluster and transi%ons a failed server’s workload to the secondary node
• Virtual Machines – maintain an exact mirror copy on a second physical server
PLC Systems
• PLC systems are more robust, have higher performance, faster networks and more flexible programming capability
• PLC’s have the capability to have Hot Standby Processors (no PID tuning required): the scans of the primary and standby controllers are synchronized
• Redundant Power Supplies – separate power supplies can be provided for PLC controllers.
• Redundant Networks
• Difference in costs between PLC and DDC control -‐ up to 5:1 cost
• Where and why redundancy in DDC is required
• Redundant systems within a facility
• DDC System Redundancies
• Redundant Instrumenta%on • Redundancy in system architecture • Physical separa%on of installed control components • Dual power supplies with separate feeds to each control panel • Network Redundancy • Separate supervisory networks • Redundant Servers
• PLC Systems
Redundancy in DDC
Ques@ons?