# Electrophysical Method for Identifying the Causes of Excessive Hydro Generator Vibration
## Appendix B Results of Steady-State Mode Recording  
The research performed included recordings of steady-state processes and transients in the 10 kV GSWG busbars of the HPP-I and higher harmonics emitted by the load of the aluminum smelter in the supply network. The recordings were carried out by using certified Parma recorders and the metering complex purpose-designed for long-term continuous recording of processes across several channels. Continuous recording was performed in several stages in compliance with the standard requirements.  
The results of recording were obtained as archived numerical data that can be presented as daily and hourly graphs, histograms with different time scales, or in tabular form and in protocols. Detailed experiment protocols describing all electrical parameters are the property of the customer of these works, being protected by a nondisclosure agreement (NDA), so the positioning of the protocols with a specific enterprise is impossible. However, observations of the physical processes occurring in the high-voltage networks under study are the subject of great interest for the scientific community to study and optimize the operation of hydro generators, regardless of location in the world. The most interesting results are presented in this article.  
From the results of recordings of steady-state processes, parameters of electrical energy flows and power quality indices, the following characteristics of the operating conditions of the HPP-I hydro generators that have direct low-impedance connection to facilities of the smelter have been deduced.  
1. Voltage deviations on both busbars are 1.3-6.7%. The maximum deviations exceed 6-7%, being systematic (mathematical expectation is greater than 4%), indicating the presence of surge current impact and the lack of load control effect.
2. The voltage imbalance ratio is less than 2%, indicating the load is evenly distributed among the phases.
3. The recording data (with output in 1 min) identifies current variations of up to 500 A with an intensity of up to seven variations per hour. According to the detailed recording data, the variation in current loads has a surge nature. The rate of current variation reaches 750 A/s on the front edge, with this being about 500 A/s on the back edge. The surge impacts have an irregular but systematic nature, repeating multiple times within 1 min.
4. The current impact on the hydro generators has ULF components with frequency of 1.2-1.5 Hz and about 0.1 Hz permanently superimposed.
5. The voltage harmonic distortion exceeds the permissible values specified by the standard. Exceeding the maximum permissible value in feeder 6 of the 10 kV GSWG of the HPP-I are the 11 th, 13 th, 23 rd and 25 th harmonics, this being of systematic nature. This indicates high emission of higher harmonics into the supply network in practice. The reduction in harmonics is mainly enabled by a shunt effect of the hydro generator's low impedance.  
The recordings of transients emitted in the 10 kV GSWG busbars of the HPP-I and the corresponding current loads showed an aperiodic component with amplitude up to 1.3-1.6 kA and current pulses of 0.5 kA to 3.9 kA, with duration less than 0.1 ms being superimposed. The rate of the aperiodic component variation on the front edge is up to 20 kA/s, while the aperiodic component duration on the back edge does not exceed 0.3 s. The equivalent frequency of the current impact is about 2 Hz.