The power grids of industrial plants have changed dramatically over the past two decades. In the past, the primary concern was still reactive power compensation to ensure that the voltage would remain stable and transmission losses would be reduced. But since the 2000s, an increasing number of frequency-controlled drives are being used in machines. These machines are very energy-efficient, but the power electronics have negative impacts on the grid. The more these types of drives are used, the more harmonics occur.
Putting an End to Harmonics in Industries
Harmonics can bring entire industrial operations to a halt. With the modular system "Total Harmonic Solution", Reinhausen Power Quality provides a useful tool to combat these unwanted grid disturbances.
Putting an End to Harmonics in Industries
Harmonics can bring entire industrial operations to a halt. With the modular system "Total Harmonic Solution", Reinhausen Power Quality provides a useful tool to combat these unwanted grid disturbances.
Harmonics are waves with a frequency many times higher than the fundamental frequency. For the electrical voltage, this frequency has a sinusoidal curve. But only in ideal cases. This is because interference factors, such as the frequency-controlled drive, override and distort this ideal sinusoidal curve with other sinusoidal waves. This causes harmonics, which in turn have negative impacts on the electrical equipment – and it becomes a vicious cycle. Holger Kretzschmar from Reinhausen Power Quality explains. "Initially, the fifth harmonic was the one that caused the most problems. This was eliminated with passive filters. But as the number of frequency-controlled drives increased, more harmonics appeared, from the seventh, through the eleventh, and up to the 51st harmonic. Active filters are needed to get these under control." Simply put, passive filters act like a resistor that dissipates the harmonic, while active filters eliminate it by emitting waves in the opposite direction.
Example 1: Automotive industry
Example 1: Automotive industry
Without power electronics, it would be impossible to manufacture mass-produced, highly automated vehicles. But these production lines, operated by robots, feed various frequencies of harmonics into the power distribution system. This leads to heating, and thus causes the electrical equipment to age prematurely. In the worst case, this can potentially lead to the failure of electronic controls, and therefore production, not to mention overloads in transformers and cables. In addition, the power consumption increases due to the harmonics. Active filters help to safeguard production, extend the service life of machines, and reduce power consumption in production.
Supraharmonics is the new threat
A relatively new source of interference involves what are known as supraharmonics, with oscillations in higher frequency ranges from two to nine kilohertz. The origins of these are called active front ends (AFEs), meaning frequency inverters, which will be applied much more often in the future. In the past, supraharmonics never bothered anyone. A die-cutting machine is robust enough to endure them, but modern loads, such as LED lights, are increasingly becoming more sensitive. Small types of power electronics break down quickly at higher oscillations. "This is why we wanted to develop a filter solution that would eliminate problems with harmonics and supraharmonics once and for all. In real life, such filter systems are often complex and oversized, which turns people many away. Therefore, our solution should be simple and tough," says Kretzschmar.
Example 2: Water management
Example 2: Water management
The goal of the water management industry is to achieve a high level of energy efficiency. For example, more and more wastewater treatment plants are integrating power generation systems with frequency converters (for example, solar) to run electric pumps, which in turn are increasingly being equipped with frequency converters themselves. Interference from harmonics is practically inevitable.
„This is why we wanted to develop a filter solution that would eliminate all interfering harmonics once and for all.“
By developing the Total Harmonic Solution, the experts at Powerquality have created a modular system solution featuring passive and active filters as well as SHU filters for the supraharmonics. Operators can decide which modules they actually need, so they can assemble a both standardized and customized filter solution and retrofit it at any time. The special feature of the solution is the device software. It measures the harmonics, and the algorithm continuously evaluates the interference levels and counteracts them automatically so that the defined limit values are not exceeded. Experience from the field has also been incorporated into the programming. The system regulates itself automatically and filters exactly whatever is needed. If an operation changes its production line and the power grid changes as a result, that is also no problem. The new parameterization runs on its own, without any service technician having to physically go to it.
