Protective Measures for Starting Diesel Generator Sets

Do you know what protective measures are used to start diesel generator sets? Which protective measures to choose depends on the capacity of the generator. Today we will tell you about the protective measures for generators. First of all, the longitudinal differential protection is the short-circuit protection for the stator winding and its lead wire, and the transverse differential protection is the short-circuit protection for the one-phase turn of the stator winding. This kind of protection is installed only when one phase stator winding has two or more parallel branches to form two or three neutral point terminals. Single-phase grounding protection is a single-phase grounding protection for generator stator windings.

The excitation circuit grounding protection is the ground fault protection of the excitation circuit. The low excitation and loss-of-excitation protection is to prevent large generators from under-excitation or loss of excitation, absorbing a large amount of reactive power from the system and adversely affecting the system, 100MW and above Power generators of all capacities are equipped with this kind of protection. Overload protection is the protection that acts on the signal when the generator runs over the rated load for a long time. Small and medium-sized generators are only equipped with setting sub-overload protection.

Large generators should be equipped with sub-overload and field winding overload protection respectively. The stator winding over-current protection is when a short circuit occurs outside the generator longitudinal differential protection range, and the protection of the short-circuit element or the circuit breaker refuses to operate, this kind of protection acts as The backup of external short circuit also doubles as the backup protection of longitudinal differential protection. Stator winding over-voltage protection is used to prevent over-voltage in the stator winding after all loads are suddenly thrown off. Over-voltage protection is installed in hydro-generators and large-scale turbo-generators. Small and medium-sized turbo-generators are usually not installed in over-voltage. protect.

Negative sequence current protection means that when an asymmetric short circuit or asymmetric three-phase load occurs in the power system, it will overheat the end of the rotor, the inner surface of the guard ring and other parts with high current density, causing local burns to the rotor. Therefore, a negative sequence should be installed. Current protection. Out-of-step protection is the out-of-step protection that reflects the oscillation process of large generators and the system. Reverse power protection is when the main steam valve of the steam turbine is closed by mistake, or the boiler protection action closes the main steam valve and the generator outlet circuit breaker does not trip. The system absorbs active power and causes a steam turbine accident. Therefore, a large diesel generator set should be equipped with a reverse power protection composed of a reverse power relay to protect the steam turbine.

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