Power Quality Investigation and Analysis

Power Quality Investigation and Analysis
Issues such as overheating of cables and transformers, nuisance tripping of protection devices, transformer noise and premature equipment failure are all symptoms of underlying power quality problems. These quality issues stem from a variety of sources, harmonics being the most common but flicker due to large loads and transient voltage deviations due to local network issues are also possible.

In order to identify the root causes the investigation first needs to select the appropriate monitoring arrangement. Typical power quality analysers record the averaged values over a defined time period, resulting in losses in the detail surrounding the incident(s) when they are captured. Better analysers 'adaptively' capture data based on the incoming raw signals in order to capture more detailed information from both before (with pre-trigger) and after the event. Hence, for example, you would be able to identify if a particular load had been switched on the system which may have coincided with a voltage deviation.

Having the sampled data is one important aspect. The second aspect needs to be in the interpretation and analysis of the data. Whilst educated assessments can predict the size of a suitable filter circuit or capacitor installation based both on experience and approximation of the data collected, the best approach is to create a software-based model of the system and simulate the running system to see if the same incidents can be re-created. Typical examples would be harmonic injection, switching instants and motor starting assessments.

The model enables both the assessment of likely root causes to be completed and also to assess the effectiveness of a solution to be determined. Hence if a harmonic filter is suggested, the filter can be integrated into the system and 'fine-tuned' if required for optimal performance or even compared against other options.

As we are independant from any of the suppliers or manufacturers of reactive compensation equipment we are best placed to advise you on any suggestions that come out of the analysis and can provide data regarding the modelled system performance with different proposals, even going as far as to simulate manufacturer's suggested specifications within the model to identify the most cost-effective solutions.

In short, the combination of selecting the correct type of data analysis equipment with the benefits of producing system models allows all the difficult and detailed work to be completed before any work commences building the actual equipment. This way the equipment can be proven effective prior to cmmitting to purchase.





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Director: Stuart Shaw


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Last Modified 8th October 2018