Survey of Smart Grid concepts and demonstrations Smart

Survey of Smart Grid concepts and demonstrations Smart substation Ari Nikander 1. 10. 2

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 Ø New needs for condition monitoring Ø Active methods for compensation of residual earth fault current • Utilizing of islanded operation • Legislation Ø Responsibilities for network companies Ø E. g. reporting and fault statistics • Rapid development of protection systems Ø 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network and substations Ø Renewal asset needs Ø Significant amount of Finnish substation installations start to be outdated and must be refurbished. • Conflicting requirements: Ø Low life cycle costs Ø Fast new technology utilization • The control of the network moves further away from the actual physical network Ø 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 Ø Often more centralized functionality Ø Centralized><decentralized – – – Reliability Costs Commercial off-the-shelf (COTS)

Functionality in future smart substations • Division based on the importance of the functions Ø 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 Ø 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 Ø 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 Ø 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 Ø How often these functions are used in real-time operation of the distribution network? Ø Statistics gathered from different disturbances • Function maturity Ø 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: Ø 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 Ø Interlocking

Response times for different 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 Ø Standard operating system Ø Well defined interface • Commercial off-the-shelf (COTS) hardware components Ø Standard computers Ø Standard communication products • Totally integrated software based functions • Software programs from different vendors with different functions Ø 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 Ø Centralized E/F protection Ø Residual current compensation Ø Measuring of phase-to-earth admittances Ø PD based diagnostic • First version introduced in 1993 • Total response time less than 3 cycles • Extensive cabling Ø Safety Ø Restriking faults

Summary • Different considerations for centralizing rate of the functions • Vendors and network companies Ø Ø 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 Ø Commercial off-the-shelf (COTS) • Some commercial device applications which represents centralized functionality exist.