When all the required parameters don’t exactly match those of the network, a generator will not be able to provide power to an electrical power system. Especially when there’s a need for two or more alternators to operate hand in hand to deliver power to the load – it is all the more important for generator synchronisation to be done properly.
Besides, without proper synchronisation – the healthy power system will be negatively affected, resulting in mechanical and electrical transients which may degrade the generator, prime mover, transformers, and other such power system parts.
Below, we will discuss the following consequences that will occur in your generator due to improper synchronisation.
Incorrect phase matching
Just matching the frequencies of the two different power sources isn’t enough to prevent damage – phase angles have to be matched as well for optimal generator performance. Without a proper matching of the phase angles – a significant difference will be seen in the stator flux angle and rotor angle.
The difference will lead to a high transient torque as it synchronises with the grid power supply as a result of a pull force from the huge power system. As such, it will lead to further deterioration of the generator windings and rotor mass as compared to a difference in frequency.
Adding on, when the equipment is synchronised with incorrect phase angle match with the electrical power system – it will result in a high resultant transient voltage that may cause damage to equipment’s insulation. This may mean that your trusted engineer may have to go down to your workplace to diagnose for any other issues by doing generator overhauling. At the same time, the generator will also assist in doing proper generator synchronisation to ensure your equipment returns to its original condition.
Incorrect voltage magnitude matching
When it comes to matching parameters amid synchronisation, magnitude is one of them. The magnitude fluctuates accordingly by altering the generator’s excitation – in which low magnitude signifies low excitation while high magnitude signifies high excitation.
When the incoming voltage magnitude is significantly higher as compared to the running voltage, it will result in high reactive flow from the electrical generator – leading to high mechanical forces on stator winding and damage to the generator shaft. Meanwhile, if there’s a lower reading of voltage magnitude – it means that there’s a weak excitation field.
But with high currents, the generator’s windings are prone to suffering severe damage. Moreover, slip protection operation may possibly occur during such conditions and disrupt the power generation. All in all, incorrect voltage magnitude does have a considerable negative effect on the generator.
That said, depending on your brand of generator – you may need to seek maintenance from a professional who has the necessary expertise in dealing with specific generator brands – for example, a Siemens or Cummins generator repair. This will ensure they know exactly how to conduct the synchronisation process or check for any damaged parts.
Poor frequency matching
When a generator has to be linked with a group of generators that are operating at the same frequency, it is known that the group of generator’s rotating force will be huge in comparison to the one generator alone.
After the generator is linked with the electrical power system – the frequency or speed of the generator is controlled by the group of generators. For instance, the electrical power system will push the new generator into its synchronised rotating condition.
Hence, once the circuit breaker is closed and the frequency of increased voltage or rotor speed diverges from the electrical power system frequency, for example, improper matching – the high rotation force from the power system will pull the generator into it. As a result of the pulling, sudden deceleration or acceleration may potentially occur to the rotor and hence, the prime mover rotating torque. This may cause damage to the rotor and shaft body due to the momentary variation in rotating torque of the prime mover which raises the rotating mass forces on the generator’s shaft.
Moreover, the high torque can potentially lead to an increased current passing through the generator transformer winding and generator itself, which can result in severe damage to the winding.
Hence, it is highly important for generator synchronisation to be done properly with parameters of another alternator, generator, or bus bar to allow for the system to operate smoothly as per normal.
Otherwise, if improper generator synchronisation does occur – then, you may have to consider generator rewinding if you notice a drop in equipment performance or spot any faulty parts.
