Neutral-earth harmonic resonance

In summary, it is common practice to check and measure the neutral-earth harmonics during the design stage of a system analysis, especially in systems where variable speed drives are connected to three transformers in parallel. This is because the neutral path of the power system can be a source of interference for communication systems due to the flow of third harmonic current. To mitigate this issue, it is recommended to use a delta connection for the converter transformers, which can be predicted in a VSD system. For more information, refer to Transformer riddle No.5 from http://electrical-riddles.com/.
  • #1
luc4van
4
0
When carrying out a system analysis During design stage (Variable speed drives connected to 3 transformers in parallel) is it a normal practise to check/measure neutral - Earth harmonics, can this be predicted?
 
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  • #2
The neutral path of power system is a suitable path for flowing of 3th harmonic current which can interfere to communication systems. One of known way for elimination this harmful effect is the trapping of 3th and other its multiplier harmonic in delta connection of converter transformers which can be predicted in mentioned VSD system.
For similar discussion you can refer to Transformer riddle No.5 from http://electrical-riddles.com
 
  • #3


I can say that neutral-earth harmonic resonance is a phenomenon that occurs when the neutral and earth connections in an electrical system have a resonant frequency that causes excessive current flow and potential damage to the system. It is important to consider this phenomenon during system analysis, especially in the design stage.

In the case of variable speed drives connected to three transformers in parallel, it is a normal practice to check and measure neutral-earth harmonics. This is because the presence of variable speed drives can introduce harmonics into the system, which can then interact with the neutral and earth connections. This can result in resonance and potential damage to the system.

To predict the occurrence of neutral-earth harmonics, it is necessary to have a thorough understanding of the system and its components, including the variable speed drives and transformers. There are various mathematical models and simulation tools available that can help predict the behavior of the system and identify potential harmonic issues.

In conclusion, it is crucial to consider neutral-earth harmonic resonance during system analysis and design, and it is a normal practice to check and measure these harmonics in systems with variable speed drives connected to transformers in parallel. With the right tools and knowledge, it is possible to predict the occurrence of neutral-earth harmonics and take necessary measures to prevent any damage to the system.
 

1. What is neutral-earth harmonic resonance?

Neutral-earth harmonic resonance is a phenomenon that occurs when there is a perfect balance between the voltage and current in an electrical system. This results in a resonance frequency that can cause unwanted vibrations and energy losses.

2. How does neutral-earth harmonic resonance affect power systems?

Neutral-earth harmonic resonance can lead to increased heating and losses in power systems, as well as damage to equipment. It can also cause flickering lights, voltage fluctuations, and harmonic distortion.

3. What causes neutral-earth harmonic resonance?

Neutral-earth harmonic resonance is caused by a combination of factors, including the presence of nonlinear loads (such as computers and electronic devices), system impedance, and the presence of a neutral-ground connection.

4. How can neutral-earth harmonic resonance be mitigated?

There are several ways to mitigate neutral-earth harmonic resonance, including adding filters or reactors to reduce the harmonic current, adjusting system grounding, and minimizing the use of nonlinear loads.

5. What are the potential dangers of neutral-earth harmonic resonance?

In addition to causing damage to equipment and power systems, neutral-earth harmonic resonance can also pose a safety hazard to workers and the public. It can result in electric shocks, fires, and other dangerous situations.

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