Quasi-synchronous and auto-synchronous parallel methods for generating units

Many companies need toGenerator setParallel operation is performed to meet power requirements. Jiangsu Haixing Power gave its own understanding, starting fromGenerator setDifferences in juxtaposed methods parse issues of concern to businesses.
Generally, generator paralleling methods are divided into two categories: quasi-synchronous method and auto-synchronous method. Let’s analyze their advantages and disadvantages:
A. Advantages of parallelism with the quasi-contemporaneous method:
(1) There is no inrush current from the generator when closing;
(2) It has no impact on the power system;
B. Disadvantages of parallelism with the quasi-contemporaneous method:
(1) If non-synchronous paralleling occurs for some reason, the inrush current will be very large, even twice as large as the three-phase short-circuit current at the machine end;
(2) When manual quasi-synchronous paralleling is used, it is not easy for operators to grasp the lead time of parallel operation.

A. Advantages of paralleling since the same period:
(1) The operation method is relatively simple, and the automation of the closing process is also simple.
(2) In case of accident, close quickly.
B. Disadvantages of parallelism since the same period:
(1) There is an inrush current and it has an impact on the system;
(2) The voltage of the system decreases at the moment of closing.

It should be noted that quasi-contemporaneous parallelism needs to meet the following conditions:
(1) The voltages are equal. (2) The voltage phases are consistent. (3) The frequencies are equal. (4) The phase sequence is the same.
What are the consequences if these conditions are not met?
1. Unequal voltages: The consequence is that after paralleling, there will be reactive circulation between the generator set and the system.
2. Voltage phase inconsistency: The consequence is that a large impact current may be generated, causing the generator to burn out, or the end to be damaged by huge electric power.
3. Different frequencies: The consequence is that the vibration voltage and vibration current will be generated. The active component of this vibration current will generate a torque on the generator shaft, which will cause the generator set to produce mechanical vibration. When the frequency difference is large, the generator sets cannot be synchronized even after being merged.

In addition, when the synchronous generator is parallel to the system when it does not meet the quasi-synchronous parallel conditions, we call it non-synchronous parallel. What are the dangers of non-contemporaneous juxtaposition?
Non-synchronous paralleling is a serious accident in a power plant. It is very destructive to related equipment such as generator sets and their series connected transformers, switches, etc. In severe cases, the generator windings will be burned and the ends will be severely deformed. Even at that time Failure to damage the equipment immediately may also cause serious hidden dangers. As far as the entire power system is concerned, if a large unit is paralleled out of sync, the impact will be great. It may cause power oscillation between the generator and the system, seriously affecting the power system. Disrupting the normal operation of the entire system or even causing a crash.