You don’t synchronize grid to Turbine / DG but vice versa. To successfully synchronize the DG ( incoming generator ) to the grid one needs these 4 things: 1.Equal instantaneous voltages / Voltage Magnitude at the incoming generator and the bus ( Grid ). 2. Same phase sequence for the three phases of incoming generator and the grid three phases. 3. Equal frequency of the incoming generator and the bus. 4. Phase angle between generator and the grid must be zero. Use synchronizer device to synchronize these two and connect your generator with the bus or grid.

No, you can parallel two generator without load.

The parallel operation of the transformer is different from the parallel operations of alternators. In short two transformers are said to bein in parallel if their primary winding is connected to the common supply and both secondary windings connected to the load. Just like the parallel operation of generators, it is done to share the load in excess of the ratings of the transformer. Note: if this was your article request, please follow the appropriate request form to request an article on the topic.

In the case of automatic synchronization failure, you need to either do it manually or check/ replace the faulty synchronization kit in portable generators. For larger generators, there is always a system in place to do it manually so here you first synchronize the generators and later rectify the faults in automatic sync kit.