Subsynchronous resonance is not encountered very often, but if it occurs it is a very serious problem and can cause severe damage in a power station. Given the severe consequences, power plants that risk subsynchronous resonance are equipped with suitable protection. In the Nordic system, two nuclear power plants risk problems caused by subsynchronous resonance - Forsmark 3 and possibly Olkiluoto 3.
Should the subsynchronous resonance frequencies of the network coincide with any of the mechanical frequencies of the turbine-generator shaft torsional interaction may appear which is referred to as Sub Synchronous Resonance (SSR). Similar phenomena can occur also between a control system of for instance a HVDC converter and the turbine generators, this is often referred to as Sub Synchronous Torsional Interaction (SSTI).
The purpose of the seminar was to gather people from the nuclear industry, nuclear authorities, transmission network operators, researchers from universities, equipment manufacturers, consultants etc. to discuss and to spread knowledge and experience about different kinds of resonance phenomena. At the seminar, different aspects of subsynchronous oscillations such as methods of analysis calculations, mitigation methods, demonstrations of measuring principles and new filtering techniques for monitoring of and protection against SSR were given.
