Details
| Original language | English |
|---|---|
| Title of host publication | Cigré Symposium Aalborg - 2019 |
| Place of Publication | Aalborg |
| Publication status | Published - 1 Jun 2019 |
| Event | Aalborg Symposium 2019: GOING OFFSHORE - Challenges of the future power grid - Aalborg, Denmark Duration: 4 Jun 2019 → 7 Jun 2019 |
Abstract
Keywords
- grid resonance frequencies, harmonics, Monte Carlo simulation, overvoltages, probabilistic estimation, resonance mode analysis, transmission grid, underground cables
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Cigré Symposium Aalborg - 2019. Aalborg, 2019.
Research output: Chapter in book/report/conference proceeding › Conference contribution › Research › peer review
}
TY - GEN
T1 - Probabilistic Calculation of Harmonic Voltages in Transmission Grids with Varying Shares of Underground Cables
AU - Neufeld, Alexander
AU - Schäkel, Nils
AU - Hofmann, Lutz
AU - Lösing, Martin
PY - 2019/6/1
Y1 - 2019/6/1
N2 - The restructuring of the German power system with large on- and offshore wind farms in the North and the nuclear phase out, especially in Southern Germany, justifies the urgent need for new transmission grid connections. Due to public concerns, the erection of overhead lines is becoming increasingly difficult and time-consuming. Consequently, policy makers initiated the application of pilot projects for extra high voltage cable sections. Transmission lines consisting of both overhead line sections and cable sections are termed "hybrid lines". Due to the cable section's high capacitance in hybrid lines, the grid resonance frequencies are shifted off to lower values. This may cause high harmonic voltages if the resulting parallel resonance circuits are excited by typical harmonics (e.g. 3rd, 5th) in the grid. In order to investigate the shift of grid resonance frequencies due to an increased number of cable sections, firstly the modal resonance analysis is conducted. Based on the results, it is then analysed how the new grid resonance frequencies might affect the harmonic voltages during the grid's operation. A probabilistic calculation method is proposed to achieve this objective. The Monte Carlo method is applied to calculate the probability density functions of harmonic voltages as a forecast for grids with varying shares of underground cables. Measurements of the today's transmission grid harmonics are used as input for this calculation. The results show higher probabilities of harmonic voltages for grids with hybrid lines. They correspond with the modal resonant analysis of the grid, and together they present higher risks of impermissible harmonic voltages. This can become critical and must be taken into account in the further expansion of AC-hybrid circuits in the extra high voltage transmission grids.
AB - The restructuring of the German power system with large on- and offshore wind farms in the North and the nuclear phase out, especially in Southern Germany, justifies the urgent need for new transmission grid connections. Due to public concerns, the erection of overhead lines is becoming increasingly difficult and time-consuming. Consequently, policy makers initiated the application of pilot projects for extra high voltage cable sections. Transmission lines consisting of both overhead line sections and cable sections are termed "hybrid lines". Due to the cable section's high capacitance in hybrid lines, the grid resonance frequencies are shifted off to lower values. This may cause high harmonic voltages if the resulting parallel resonance circuits are excited by typical harmonics (e.g. 3rd, 5th) in the grid. In order to investigate the shift of grid resonance frequencies due to an increased number of cable sections, firstly the modal resonance analysis is conducted. Based on the results, it is then analysed how the new grid resonance frequencies might affect the harmonic voltages during the grid's operation. A probabilistic calculation method is proposed to achieve this objective. The Monte Carlo method is applied to calculate the probability density functions of harmonic voltages as a forecast for grids with varying shares of underground cables. Measurements of the today's transmission grid harmonics are used as input for this calculation. The results show higher probabilities of harmonic voltages for grids with hybrid lines. They correspond with the modal resonant analysis of the grid, and together they present higher risks of impermissible harmonic voltages. This can become critical and must be taken into account in the further expansion of AC-hybrid circuits in the extra high voltage transmission grids.
KW - grid resonance frequencies
KW - harmonics
KW - Monte Carlo simulation
KW - overvoltages
KW - probabilistic estimation
KW - resonance mode analysis
KW - transmission grid
KW - underground cables
M3 - Conference contribution
BT - Cigré Symposium Aalborg - 2019
CY - Aalborg
T2 - Aalborg Symposium 2019
Y2 - 4 June 2019 through 7 June 2019
ER -