Protective Elements
At the instant of synchronization, the angular difference of the two systems should be nearly zero because,
otherwise, unwanted load inrushes occur. Theoretically, the angular difference can be regulated to zero by giving
short pulses to the speed governors. When paralleling generators with the grid, in practice, synchronization is
requested as quick as possible and so usually a slight frequency difference is accepted. In such cases, the angular
difference is not constant but changes with the slip frequency
ΔF
.
By taking the breaker closing time into consideration, a lead of the closing release impulse can be calculated in a
way that breaker closing takes place at exactly the time when both systems are in angular conformity.
Basically the following applies:
Where large rotating masses are concerned, the frequency difference (slip frequency) of the two systems should
possibly be nearly zero, because of the very high load inrushes at the instant of breaker closing. For smaller rotating
masses, the frequency difference of the systems can be higher.
This sync-check cannot be used for two voltages that are shifted by a fixed angle (e.g
because they are measured on the two sides of a block transformer of a generator).
882
MCDLV4
DOK-HB-MCDLV4-2E
Line VL1
Bus VL2
Line VL3
Line VL2
Bus VL1
Bus VL3
Angle Diff
Bus f = Line f
Summary of Contents for HighPROtec MCDLV4
Page 3: ...Order Code Order Code 3 MCDLV4 DOK HB MCDLV4 2E...
Page 47: ...Installation and Connection 47 MCDLV4 DOK HB MCDLV4 2E...
Page 164: ...Input Output and LED Settings 164 MCDLV4 DOK HB MCDLV4 2E...
Page 433: ...Parameters 433 MCDLV4 DOK HB MCDLV4 2E...
Page 457: ...Device Parameters 457 MCDLV4 DOK HB MCDLV4 2E...
Page 473: ...Blockings 473 MCDLV4 DOK HB MCDLV4 2E...
Page 988: ...Protective Elements 988 MCDLV4 DOK HB MCDLV4 2E P P Q P Q P Q Q Q P S S...
Page 989: ...Protective Elements 989 MCDLV4 DOK HB MCDLV4 2E Pr Q P Q P Qr...
Page 1023: ...Protective Elements 1023 MCDLV4 DOK HB MCDLV4 2E...
