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Parallel.pptx

Parallel operation of generators connects one live generator to another or to the grid to share the load. It allows for continuity of supply, maintenance, efficiency, and expandability. Generators must be synchronized by matching their voltage, phase angle, frequency, and phase sequence before connecting. Synchronization ensures the voltages add instead of cancel out to prevent damage. Common synchronization methods include using dark lamps to match phase sequence, bright lamps to identify frequency differences, or a synchroscope to visually match voltage and phase angle.

Engineering◦
What is Parallel Operation of Generator? • Parallel Operation of Generator Means to connect one generator to another live generator or grid (infinite bus bar) for sharing load. • The live generator is called running generator and others is called incoming generator. • Parallel operation of generator need synchronization.
Generator 1 - Running Generator Generator 2 - Incoming Generator
Why Parallel operation of Generator? • Continuity of Supply and Maintenance (Redundancy and serviceability) • Efficiency • Expansion Plans (Expandability) • Size of Alternators • Maximize Power System Reliability:
AC Generator
Voltage Induced in a Single Phase Generator
Voltage induced In a Three Phase Generator
Condition of Synchronizing • Voltage of all generators must be equal. • Voltage phase angle of all generators must be equal. • Phase sequence/ ratation of all generators must be equal. • Frequency (no load frequency) of the incoming must be slightly greater than the frequency (no load frequency) of the generator already connected to the system.
Voltage of all generators must be equal.
Synchronizing of Single Phase AC Generator + VE - VE + VE - VE Va Vb Vd = Va-Vb Synchronizing Current I= Vd/R
Va Vb
Va Vb Va-b
Voltage phase angle of all generators must be equal.
Va Vb
Va Vb Va-Vb
Phase sequence/ rotation of all generators must be equal.
Phase Sequence • Phase sequence – R, Y, B • Phase sequence – A, B, C
Va Vb
Vb Va Va-Vb
Frequency (no load frequency) of the incoming must be slightly greater than the frequency (no load frequency) of the generator already connected to the system.
--------- Incoming Generator --------------- Running Generator
--------- Incoming Generator --------------- Running Generator
Method of Synchronization • Three Dark Lamps Method • Two Bright, One Dark Method • Synchroscope Method
Three Dark Lamps Method If lamps go ON and OFF concurrently, indicating that the phase sequence of alternator-2 matches with bus bar. On the other hand, if they ON and OFF one after another, it resembles the incorrect phase sequence.
Two Bright, One Dark Method Slow /fast identification is possible
• The sequence of becoming bright and dark L1- L2 – L3 indicates that the incoming generator frequency is higher than the bus bar frequency. Hence, the alternator speed has to be reduced by prime mover control till the flickering rate is brought down to a small. • On the other hand, the sequence flickering L1- L3 – L2 indicates that incoming alternator frequency is less than that of bus bar.
Synchroscope Method
Synchroscope