Survey of Smart Grid concepts and
demonstrations
Smart substation
Ari Nikander
1.10.2010
Content
1. Drivers and requirements
2. New setup with a central station computer
3. Functionality in future smart substations
4. Aspects of electricity network company
5. Device applications
6. Summary
Drivers for Smart substation
• Distributed generation / distributed energy resources (DER)
• Electric vehicles
• Extensive cabling of MV networks
 New needs for condition monitoring
 Active methods for compensation of residual earth fault current
• Utilizing of islanded operation
• Legislation
 Responsibilities for network companies
 E.g. reporting and fault statistics
• Rapid development of protection systems
 Need for adapting new requirements - no willingness to continuous and
costly upgrades of the whole protection system
Drivers for Smart substation
• Ageing network and substations
 Renewal asset needs
 Significant amount of Finnish substation installations start to be outdated
and must be refurbished.
• Conflicting requirements:
 Low life cycle costs
 Fast new technology utilization
• The control of the network moves further away from the actual
physical network
 Company fusions
• Introduction and increasing acceptance of the IEC 61850 standard
New setup with a central Station Computer (ABB)
•
Corresponding approaches
have also been investigated
by other vendors
 Often more centralized
functionality
 Centralized><decentralized
–
–
–
Reliability
Costs
Commercial off-the-shelf
(COTS)
Functionality in future smart substations
•
Division based on the importance of the functions
 First functionality group
–
Functions must operate within a given short operate time.
–
High security requirements - functions need to be backed up
–
Mandatory functions such as primary protection and control functions
 Second functionality group
–
Optional functions, such as monitoring and analysis
–
Not vital for safe operation of the network
–
Necessary for continuous delivery process, “preventative functions”
Functionality in future smart substations
•
Division based on the location of the functions
 Unit level functions
–
Functions need measured data from the unit e.g. feeder bay.
–
The algorithm can be considered “simple” but it can be either a very
important protection function (e.g. overcurrent protection) or a value
added functionality (e.g. circuit breaker condition monitoring)
–
Extensively investigated and widely used in unit level protection and
control IEDs
–
More closely connected to the electricity distribution process
–
Longer life cycles than station level functions
Functionality in future smart substations
•
Division based on the location of the functions
 Station level functions
–
Need or make use of data from several sources.
–
Algorithms can be more complex making the computational requirements
more demanding.
–
Updated more frequently due to new inventions or new requirements e.g.
through legislation.
–
Can include both critical protection functions (e.g. high impedance earth
fault protection, bus bar protection, etc.) and value added functionality
(e.g. fault location algorithm)
–
Currently often implemented on the unit level where they sometimes
cause unnecessary upgrades of the IEDs and increase the need for
communication between IEDs.
Functionality division criteria
•
Communication requirements
•
Response time
•
Utilization frequency
 How often these functions are used in real-time operation of the
distribution network?
 Statistics gathered from different disturbances
•
Function maturity
 How often an upgrade of the function can be expected?
Functionality division criteria
•
From the communication requirement point of view the following
functions are more suited for the station level:
 Protection functionality based on multiple source measurements
•
–
Advanced directional earth fault protection
–
Advanced directional overcurrent protection
–
Bus bar protection based on blockings
Control operations based on blocking

Interlocking
Response times for different functions
Functions
Fast response time
Protection: Overcurrent, earth fault,
overvoltage, differential
Control: Circuit breaker operation
Self supervision: Breaker failure, trip
circuit supervision
Slow response time
Protection: Overload, phase discontinuity
Control: Disconnector operation,
autoreclosure
Monitoring: Circuit breaker condition, PQ,
disturbance recorder
Supervision: IED self-supervision, CT/VT
circuit supervision
Aspects of electricity distribution network company
- main drivers
•
Renewal asset need
•
The EU climate and energy package: EU 20/20/20 targets
•
Making electricity clean
•
Smart grid plans of the network company
•
Cost efficiency in management, operation and purchasing
•
Increased customer demands
New substation concept of network company
emphasizes
• Standardized software based platform
 Standard operating system
 Well defined interface
• Commercial off-the-shelf (COTS) hardware components
 Standard computers
 Standard communication products
• Totally integrated software based functions
• Software programs from different vendors with different
functions
 The best vendor for each product can be chosen
• IEC 61850 as design base
Devices - earth fault protection and active
compensation of residual current
• RCC ground fault neutralizer
 Centralized E/F protection
 Residual current compensation
 Measuring of phase-to-earth
admittances
 PD based diagnostic
• First version introduced in 1993
• Total response time less than 3
cycles
• Extensive cabling
 Safety
 Restriking faults
Summary
• Different considerations for centralizing rate of the functions
• Vendors and network companies




Need for adapting new requirements
Costs
Reliability aspects
Rapid development of protection systems
- No willingness to continuous and costly upgrades of the whole
protection system
 Commercial off-the-shelf (COTS)
• Some commercial device applications which represents
centralized functionality exist.