transmission line interconnection

bigjoe · Feb 6, 2010

hi there,

I have this question regarding interconnecting transmission line. In order for us to synchronize or connect in parallel two different system, they have to satisfy the condition same phase, same voltage and same frequency, although in reality they are not perfectly equal but approximately the same.
Question: what is the maximum voltage difference between the incoming source and of the other system so that they can be successfully link together? are there standard values or formula regarding that matter? for example the nominal voltage is 69kV, the grid has only 68.2kV and the incoming source is 69kV with that voltage difference, can they be successfully synchronize?

thanks in advance

IanP · Feb 6, 2010

**broken link removed**

1.1.1 Voltage Magnitude Synchronizing Variable

If the voltage magnitudes are not closely matched, a sudden rise in Mvar flow will appear across the circuit breaker as it is closed. For example, if a 345 kV circuit breaker were closed with a 20 kV difference in voltage across the open circuit breaker, a large Mvar flow would suddenly occur upon closing. The allowable voltage magnitude differences across the open circuit breaker are system specific. However, for general guidance, a difference of a few percent is unlikely to cause any serious problem.

So, it looks like 68.2kV source and 69kV source fit into the above general guidance and therefore can be synchronized ..

Rgds,
IanP

bigjoe · Feb 8, 2010

thanks ian..

advance angle = 360 x Δf x Tbc

Δf = slip and Tbc = circuit breaker closing time

this is theoretically the formula used when synchronizing a generator to the other system.
can this formula be used when connecting transmission line in parallel or closing a loop? by the way what is meant by "static ties"?

thanks

transmission line interconnection

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