Power system protection in a smartgrid perspective

The project investigated relaying strategies in an increasingly more complex power system with distributed generation. The approach is to communicate real-time information (synchronized measurements) from the grid to in combination with continuous analyses. The project studied both transmission and distribution networks where many local sources require a larger system perspective in addition to the traditional local. The project also recommended relay protection requirements with integration of smaller power stations with involvement from SINTEF and update of the much reference technical report TR A6343 "Technical guidelines for connecting <10 MW production units to the distribution system" (in Norwegian). The project was a cooperation between the NTNU departments Electrical Power Engineering and Telecommunications, and Michigan Technological University (MTU) in USA. As this was the first project within relay protection the competence and network building activities were very important. The project contributed to the Norwegian Smart Grid Centre. The industry partners were Statnett, ABB, Eidsiva, Hafslund, Lyse, Statkraft and Skagerak. The project educated four PhD students within relay protection and communication. 15 master students were educated within the project. The project established and organized the Nordic Workshop in in Protection and Control in 2016 and 2017 with 40-50 participants from Nordic universities (KTH, Chalmers Aalborg, Vaasa, NTNU, Reykjavik in addition to Delft and Michigan Tech) as well as industry and Norwegian utilities (ntnu.edu/prosmart/nw2017). The main purpose was to create a meeting place for Nordic research groups, industrial companies and energy agencies with the exchange of information to promote future cooperation. Mai 14, 2018, the third Workshop was organized at KTH in Stockholm with around 40 participants. In 2019 it was hosted in Vaasa, Finland. A PhD student at NTNU, Konstantin Pandakov, defended his thesis "Improvement in protection of medium voltage resonant grounded networks with distributed sources" on December 14, 2018. The work consists of one part that studies usage of distance protection with compensation of in-feed from distributed sources, and one part that explores and proposes improved methods for fault location in resonance grounded systems. The approach has been transient and real-time simulations and testing; micro-processor board implementation and comparison with state-of-the-art relays. Another PhD student at NTNU, Charles Adrah, is aiming at completing a thesis on communication issues and solutions for relay protection the early 2020. A third PhD student, Maciej Grebla, was employed on 10. mai 2017 and works with islanding detection and protection in microgrids of relevance to and partly funded by FME CINELDI. The PhD student at MTU, Jaya Yellajosula, defended his thesis "IEC 61850 based GOOSE and SV services for wide-area protection and automation". This work consisted of solutions for communication between sub-stations, new algorithms for phasor estimation, and application into out-of-step, islanding and line differential protection. A second (bonus) PhD student (Zagros Shahooei) affiliated with the project at MTU defended his thesis "Time-Domain Voltage Stability Assessment and Wide Area Control" on 4 May 2017. The work consisting of time-domain analysis of stability for increased accuracy. The PhD students have cooperated extensively and there have been student exchanges both at MTU and NTNU. The project developed a laboratory for relay protection with fully digital solutions in testing and simulation. The many different components were synthesized in the final stage of the project. Solutions to subscribe and publish IEC61850 GOOSE/SV on process bus and prototyping of algorithms are implemented on microprocessor cards. A new university course on master's level, TET4215, was developed via the project and run for the second time in the spring semester of 2019.

Prosjektet har gitt et betydelig løft i kompetanse om relevern tilkoblet prosessbuss. Det er utviklet metoder for å studere og manipulere kommunikasjonen (IEC 61850 SV/GOOSE) på prosessbuss. Det er utviklere flere nye algoritmer og indikatorer som kan ha betydning for sikker drift av og feildeteksjon i kraftnett og dermed økt pålitelighet. Det er etablert et nytt laboratorium med sanntidssimulator, releer, reletester, mikroprosessorkort, merging unit, stasjonsklokke og analyseprogramvare tilkoblet prosessbuss. Dette vil ha nytteverdi utover prosjektet på sikt både i nye prosjekt og i utdanning og kunnskapsformidling. Det er utviklet et nytt fag ved NTNU som gir den nye generasjon studenter vesentlig bedre kunnskap om pålitelig drift av kraftnett. Det er utdannet 15 masterstudenter direkte tilknyttet prosjektet.

Protective relays are used to maintain a reliable operation of power systems. State of the art technology is numerical relays that sample data and perform calculations and logical operations. Protection is generally localized to a specific component (transmission line, cable, transformer, generator, compensator etc., and circuit breaker) and there is limited communication between relays. Settings are fixed and are done manually and typically based on steady-state analysis and hardware testing based on simulations. Fault location and isolation in distribution systems is highly manual with substantial technological room for automation. The newest generation of relays is able to communicate real time data and take advantage of information from other parts of the power system. As the power system becomes more complex the dynamic and transient behavior becomes of greater importance when setting and testing the protective relays. The project will explore protection strategies in an increasingly complex power system with dynamic, distributed energy resources. This is done by allowing communication of synchrophasor data from sources into a central combined with advanced analysis of the system. The project addresses both the distribution level and the transmission level where aggregation of a large number of sources requires better wide-area protection and control. The project will also recommend future practice for protection when integrating a large number of renewables. The project is organized at NTNU and aims to educated 4 PhD students within the field of power systems protection. This proposal addresses the Norwegian Research Council call on energy systems and principles, methods and tools for integrated control of smart grids. It supports the Energi21 strategy on flexible power system and automation and the SRA2035 document where communication technologies and protection systems are listed as prioritized.