Transformer innovation in a changing energy landscape – Part II
5. Pursuing efficiency, reliability and resilience
Reliability and resilience are two different concepts but closely related. Power grids need to be prepared to secure a continuous sourcing energy, and at the same time, be ready to react in case of incidents or events.
The integration of renewables also possesses challenges to the efficiency and reliability of the transmission grids and distribution networks.
Digitalization is a powerful tool to strengthen the power and distribution systems, but other traditional alternatives are also used with good results.
For example, in transmission grids, the reactive power needs to be managed or compensated in order to run the power system efficiently. That can be done with a variety of technical solutions with different features, advantages and applicability, specifically, those where transformers and reactors are used, i.e., synchronous compensators, shunt reactors, static VAR compensators (SVCs), flexible alternating current transmission system (FACTs) and static compensators (STATCOMs). Phase-shifting transformers are another alternative used successfully to control the power flow in high voltage transmission systems.
As the complexity of the systems is increasing, the use of shunt reactors is more common since they are a cost-effective and reliable solution
An example in distribution networks is line voltage regulators that are helping in the shift to a more decentralized power generation where distribution grids not only experience voltage drops due to loads, but also large variations of voltage caused by local generation.
As the complexity of the systems is increasing, the use of shunt reactors is more common since they are a cost-effective and reliable solution. The active power flow and the balance of reactive power in the grid must be controlled to maintain voltage stability, with the voltage level being maintained within a range in different operating conditions.
Shunt reactors improve voltage stability and power quality and support the integration of renewable energy.
Although some may think that the shunt reactors are a simpler version of a transformer, they have their own set of challenges – some of those are related to vibrations and noise coming from the magnetic field existing inside, impacting maintenance, reliability and long-term life expectancy. As a reference, the magnetic field in the gaps is in the range of 1.3-1.5 Tesla and depending of the size of the reactor, the resulting forces in these gaps can be up to 50 t, forces that appear 100 times per second over the reactor’s lifetime in a 50 Hz systems, 120 times in the 60 Hz systems .