Solar DG synchronisation
Solar On grid inverters don't work when the grid supply goes off.
Due to Anti Islanding feature in the inverter it will isolate itself from Grid as a protection feature to protect a wireman working on the line. He must have switched off the grid supply but he will not be expecting any power from solar plants to get pumped into the system while he is working. Ok that was more about anti islanding lets quickly get into the Solar DG synchronisation.
Owner of a plant who has invested so much money for his solar plant will not want his power plant to be idle while he is really in need of power. Now how do we solve his problem. Its simple! switch on his DG set fool the inverter and make it work.
But what if all the loads are satisfied? what will happen to the excess power from solar. the inverter will simply push it into the DG set thinking it as the Electricity Grid. and the Poor DG will burn its alternator. we are stuck again. how to solve this?
This is why we employ a smart guy to our solar plant and he is called the "SOLAR DG SYNCHRONISING MODULE". we will simply call him as "DG Synch". DG synch is generally used in big ships where the DG keeps running for the propeller and whenever needed power has to be sent to other equipments of the ship. The loads are managed in a smarter way by using DG synch. this is one way of doing it. And a few companies are now invading into the solar market using this. But let me tell you a simple way to do it.
A DG always needs to be run on its minimal load, u cannot drive your car on a first gear for 100Km. it will basically bring down the life of the car and increase the maintenance cost, This is the same with a DG. you cannot run DG without its minimal load. your DG Guy will be able to give you the value. Normally it is 30% of the DG rating.
Knowing this lets get into a little maths. Consider a DG with 100KVA rating. then it should be loaded to min of 30KW. now if the customer has load for about 60kw and has a solar plant for 30kw. then this plant will not need a DG synch. At any given point of time the solar generation will not exceed the load and feed its excess energy to DG.