Safeguarding renewable energy with power quality

A well-known company was bidding to supply the control systems for the upgrade of a major biomass power plant, and it needed a way of mitigating harmonic noise as part of the tender. If these issues weren’t addressed, the harmonic noise could cause component failure and severe damage to the local power supply. Therefore, the company approached power quality specialist CP Automation for a solution.

The UK-based plant was planning a major upgrade and issued a tender, which was won by a well-known control systems supplier. As part of the upgrade, the control systems supplier needed to minimise harmonic noise on site and ensure a reliable back-up power supply.

The supplier knew that power quality was an important factor, but it lacked the expertise in this area. At this point, it approached CP Automation, which has decades of experience in the power quality industry.

The problem with power

Harmonic noise is a pressing challenge in many industrial facilities that contain non-linear loads. Power plants typically include variable speed drives (VSDs) to control motor speed and transformers — a common source of harmonic distortion. Though critical for keeping industrial machinery running, VSDs can introduce harmonics due to the rapid switch of power electronic components like Insulated-Gate Bipolar Transistors (IGBTs).

If the total harmonic current distortion (THDI) of the VSDs increases significantly and passes back to the transformer, this can cause problems. All the different loads sum at the transformer with current distortion and if they exceed normal levels, they can breach the harmonic loss factor (FHL) curve, and the transformer will start distorting the waveform it sends out to surrounding electrical equipment.

As well as derating the available power from the transformer, the distorted voltage waveform that follows will degrade the hardware receiving that signal in the power network. This can damage the components inside and shorten the devices’ life expectancy by several years.

Clean, continuous power

Every project has its unknowns but, in this case, CP Automation had a solution designed to specification. It supplied six Comsys ADF P300 active harmonic filters, which help clean up the total harmonic distortion (THDI) of the current caused by VSDs.

“The filters actively inject a counter signal to cancel out the harmonic noise returning to the transformer, acting like noise-cancelling headphones,” explained John Mitchell, global sales and marketing director at CP Automation. “We supplied six of these filters across the site.”

Meanwhile, CP Automation helped ensure a back-up system was in place so that essential services would continue in the event of a mains outage. It did this by supplying two uninterruptible power supply (UPS) units, which can provide almost instantaneous power for critical services, like fuel handling and conveyer systems and boiler control units. Crucially, it also specified Ixon IoT routers to improve site connectivity and enable remote monitoring. Therefore, if an outage or a power quality event was detected, CP Automation’s team could dial in and provide remote support.

Effective, round-the-clock monitoring

With the Comsys filters and UPS systems now in place, the control systems supplier could complete the upgrade, and the plant would be protected from unexpected power issues. Not only would this boost uptime, but it would also help reduce long-term costs by prolonging the lifespan of the electrical equipment on site — protecting them from the effects of waveform distortion.

“Like other power plants and industrial facilities, the installation of harmonic filtration has opened the door for subsequent monitoring capabilities,” added Mitchell. “Analysing options include portable clamps such as multimeters and fixed power quality meters, such as Powerside’s PQube 3 and Janitza’s range of panel mounting and din rail analysers.”

By strategically placing these power quality meters across plants, engineers can track long-term trends and carry out root-cause analysis. Meanwhile, conducting a power quality survey can help them gain a snapshot of what the plant looks like and identify any ongoing issues.

To find out more about tailored solutions for your power quality needs, visit CP Automation’s website https://www.cpaltd.net/.

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