A grid in a rapid transition, with Power electronics (PE) as an enabler
The traditional electric power grid is dominated by passive components such as synchronous generators, circuit breakers and transformers. This worked well with primary energy sources like coal, gas and, nuclear power, which connect to the grid through these large synchronous generators and can be located close to population centers. Control is to a large extent made by the synchronous generators, which implies that matching load and generation and grid stability could be achieved without the use of advanced digital control systems.
However, the urgently needed decarbonization of the energy system calls for a rapid increase in the use of renewable energy sources like solar and wind power. These instead connect to the grid through many power electronic inverters. This implies both important possibilities and challenges for the development of the future power grid.
In addition, the best possible sites for renewables are frequently located far from load centres and often at sea, as in the case of offshore wind power. This means that new solutions for power transmission are also needed. Very often the only choice is to use high-voltage direct-current (HVDC) power transmission. HVDC also uses power electronics, to interface between the AC and DC power grids. In the end, we can expect to see a complete transition to a power electronics-dominated grid.
Notably, in addition to the climate crisis, the current energy crisis shows the importance and urgency to transform our electricity infrastructure to accommodate renewable energies. In line with the UN Sustainable Development Goals [1], and the EU Green deal [2], the European Commission targets 60 GW offshore wind by 2030 and 300 GW offshore wind by 2050 [3] compared to 14.6 GW offshore wind capacity installed in 2021. Furthermore, these already unprecedented offshore wind targets are rapidly stepped up, e.g. with additional targets of 76 GW (2030) and 260 GW (2050) only in the North Sea[4]. Most of this installed offshore wind generation will be connected to our electricity grid with power electronic (PE) converters that have to be interoperable with the power system and be embedded into a legal and regulatory framework.
Another major ongoing development is the electrification of the transport sector, which also entails more power electronics connected to the grid, since all types of electric vehicle chargers are based on converters.
Power electronics are yet to unleash their full potential
Power electronics offer near unlimited possibilities for control of a grid’s critical variables: voltage, active and reactive power, frequency, etc.
This freedom also implies challenges for the interoperability of equipment from different vendors connected to the same grid. For the correct operation of any modern multi-vendor power system asset, it will be of paramount importance that all components function correctly together and that adverse interactions[5],[6] that may jeopardize operation, or even cause damage to equipment, are avoided.
However, manufacturers of power electronic equipment are generally unable to exchange information about the control and protection systems of their products. In particular, the software that defines much of the external behaviour of the equipment is mostly proprietary and confidential. This has several reasons. First, a manufacturer does not want to divulge to its competitors any parts of the software that often has cost much effort to develop and test. Second, any information interchange among competitors may be perceived as restricting competition, and thus be violating anti-trust legislation.
Therefore, new methods and business models need to be developed so that interoperability among components of the future multivendor power system can be guaranteed. It will also require the training of experts with broad interdisciplinary knowledge, spanning different realms of technology, but also in financial, societal, and legal matters.
A strong focus for European research
This issue of interoperability is at the heart of European research on the matter and European researchers join forces on various initiatives, especially our Inter-oPEn network or the Inter-OPERA or HVDC-wise projects, all funded by the Horizon Europe program.
[1] UN Department of Economic and Social Affaire, The 17 Goals, 2015
[2] European Commission, European Green Deal, 2020
[3] EU strategy on offshore renewable energy, 2020
[4] North Sea Summit Dublin, 12 Sept. 2022
[5] Buchhagen et al., “Borwin1 – First Experiences with harmonic interactions in converter dominated grids,” 2015.
[6] Diaz et al., “Improvement of the oscillatory behaviour of the HVDC link between Spain and France,” 2020.