Overview
- Power electronic technologies can introduce various types of distortions in electrical power systems due to their high switching frequency.
- A large part of PV power generation comes from large-scale and high-power inverters, which are normally connected to the grid through a distribution transformer.
- This core research studies the harmonic distortions in the frequency range of 2-150 kHz in distribution networks. Detailed study of voltage and current harmonics is performed based on field measurements with different load characteristics and solar inverter integration.
- To analyse the harmonic performance of PV inverters in 2-150 kHz, in short-term and long-term, field measurement data from several large-scale inverters have been captured for an extended time.
- The existing standards and concerns for future standardisation are discussed.
- Analyses of high frequency voltage and current harmonics in LV and MV distribution networks along with immunity analysis are performed.
- Simulation modelling of a grid-connected inverter is performed to show the existence of high frequency harmonics above 2 kHz in inverter controlling, and impact of inverter controller gains to these harmonics.
Outcomes
- High level of harmonics has been observed at some locations. The level of emissions could increase when PCC is far from the transformer in a distribution system with high PV penetration.
- The filter capacitors in loads could absorb current emissions and reduce their value at PCC.
- PV inverters generate high harmonics during short-term, which could potentially cause power quality and failure issues of grid equipment such as transformers, cables, and capacitor banks.
- Large level of distortion was observed when the inverters operate in partial-power level.
- The performed modelling and simulation results of the grid connected inverters verify the sensitivity of grid connected inverters with respect to grid and load disturbances.
Further Readings:
J. Yaghoobi, F. Zare, T. Rehman, and H. Rathnavake, “Analysis of high frequency harmonics in distribution networks: 9 – 150 kHz.,” in 2019 IEEE International Conference on Industrial Technology (ICIT), 2019, 00. 1229-1234,
J. Yaghoobi.A. Abdullah. D. Kumar. F. Zare. and H. Soltani. “Power Quality Issues of Distorted and Weak Distribution Networks in Mining Industry: A Review.” IEEE Access. vol. 7. DD. 162500-162518. 2019 J. Vagnooni. F 7are and D. Solatialkaran
“Harmonic missions in 0-9 kH7 Frequency Range and Transient Effects in Grid-Connected Inverters Utilised in Solar Farms.” in 19th International Conference on Harmonics and Quality of Power (ICHOp) and nn 1-6