## 5 Conclusions  
The results of the studies on the effect of unbalanced and non-linear loads on the load flows of a low-power synchronous generator allow us to draw the following conclusions:  
1. When the generator serves an unbalanced load, there is a noticeable negative sequence current, which may exceed the maximum allowable value with respect to overheating. The generator begins to emit higher harmonics into the network, which leads to extra heating. The average excitation current of a generator serving an unbalanced load was practically unchanged, but there was a 100 Hz current in the field winding whose amplitude increased linearly with increasing load unbalance. Therefore, the excitation current and the generator load should be limited. The power limitation of a generator serving unbalanced loads can be determined by the difference in phase currents, which must not exceed 12% of the nominal current. 2. The following effects occurred when the harmonic distortion of the load current increased: * The generator stator and rotor currents increased significantly; for example, at \(k_{Ula}=15.6\%\), the RMS value of stator current increased by 32% as compared with the load flow when there was no rectifier load; at \(k_{Ula}=3.5\%\), the mean value of the excitation current increased by 2.5% as compared with the load flow when there was no rectifier load; and at \(k_{Ula}=15.6\%\) (rectifier load was 25% of the generator rated power), the mean value of the excitation current increased by 20%. This fact was due to the improper operation of the ARE under such conditions, which required the application of harmonic filters and excitation current limitation in the ARE. * The amplitude of the forced oscillations of the excitation current of the generator at a frequency multiple of 300 Hz increased; for example, at \(k_{Ula}=15.6\%\), the amplitude of forced oscillations was 5% of the effective signal. This led to additional losses and extra heating. * There were additional mechanical vibrations of the rotor with a frequency of 300 Hz; as the deviation from the sine waveform increased, the amplitude of these vibrations increased as well, which can lead to excessive runout during operation, rapid wear of the generator, and loss of stability. 3. Applicable to the case where there was a joint effect of unbalance and harmonic distortion, the following conclusions can be stated: * There was a noticeable negative sequence current, which may exceed the maximum allowable value with respect to overheating; the generator began to emit higher harmonics into the network, which led to additional losses and a decrease in the power factor. * The amplitude of the forced oscillations of the excitation current of the generator with frequency multiples of 100 and 300 Hz increased, which also led to additional losses and extra heating. * Additional mechanical vibrations of the generator rotor occurred, which can lead to excessive runout during operation, accelerated wear of the generator, and loss of stability. Conceptualization, Y.B. and A.K. ; methodology, Y.B., A.K. and K.S. ; software, Y.B. ; validation, Y.B., A.K. and K.S. ; formal analysis, A.K. and K.S. ; investigation, Y.B., A.K. and K.S. ; resources, K.S. ; data curation, Y.B. ; writing--original draft preparation, Y.B., A.K. and K.S. ; writing--review and editing, Y.B. and K.S. ; visualization, K.S. ; supervision, K.S. ; project administration, A.K. and K.S. ; funding acquisition, K.S. All authors have read and agreed to the published version of the manuscript. **Funding:** The research was carried out within the framework of state task \"Conducting applied scientific research\" on the topic \"Development of methods, algorithms and software for modeling the modes of traction power supply systems for DC railways and electromagnetic fields at traction substations for AC railways\". **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** Data sharing not applicable.