Influence of self-synchronization mode of autonomous power supply system generator on overvoltages in the excitation windings

Abstract

Modern technologies of agro-industrial production impose high demands on electrification systems. This is especially true for the reliability of power supply. This issue is relevant both for large agro-industrial facilities and small farms. The most logical way to increase the reliability of power supply is to use several parallel connected, different power sources. Examples of such a solution are the recently widespread hybrid power supply systems where the power sources are a combination of a conventional power supply system and various types of renewable energy sources. These systems may contain synchronous generators for which parallel operation is provided. To turn on the generators for parallel operation, the following three synchronization methods are used: accurate synchronization; self-synchroni-zation; coarse synchronization. Activation for parallel operation by the method of accurate synchronization is performed at the moment of close coincidence of amplitudes, frequencies and phases of voltages of the connected generator to the network. With a strict coincidence of these values, synchronization proceeds ideally in the sense that there are absolutely no current shocks at the moment the generator is turned on. But in autonomous and hybrid power supply systems where the voltage and frequency of the network are not strictly constant, it may be difficult, and sometimes impossible, to fulfill the conditions for accurate synchronization. Moreover, this process takes a lot of time which is unacceptable for a number of agro-technological processes. An alternative to the process of accurate synchronization may be to turn on the synchronous generator for parallel operation using the self-synchronization method. The process takes quite a little time, but at the same time it is important to know and adhere to the boundaries of permissible deviations from the conditions of accurate synchronization under which there are no overvoltages in the excitation circuit.