08/02/2016

SAFETY FIRST: HANDLING PEAKS IN VOLTAGE


All over the globe experts from the MR Power Quality division are keeping grids stable. Especially in circumstances where customers have requirements which cannot be satisfied by standard solutions. This was the case, for example, in Lüchow, Lower Saxony, where additions to the machine fleet of a large automotive supplier was threatening to throw the grid of a regional electricity provider off balance.

The order books at Hay Speed Umformtechnik GmbH are nice and full. The successful automotive supplier in Wendland uses high-speed forging presses and automated ring-rolling systems to produce components for axles, gearboxes, and engines for almost all well-known car and truck manufacturers. When the company brought two more large inductive systems on line to cope with rising demand, the factory's existing reactive power compensation reached its limit – the aged medium-voltage system had to be replaced. Given the complexity of the requirements involved, a standard solution wasn't available to Hay Speed. Power Quality needed no better reason to give the project top priority.

The enormous Hatebur and Hasenclever hot-forging presses used at Hay Speed Umformtechnik GmbH in Lüchow exert a force in excess of 20,000 N on the red-hot bar stock in order to split it and shape one truck or car component after another in a matter of seconds. Eight ring-rolling mils roll many forged parts to even larger diameters. Each of these systems is switched on and off again several times a day, requiring huge amounts of reactive power when powering up and during operation. When Hay Speed last expanded its fleet of machines, it encountered a problem.

The shift to renewables in the district of Dannenberg, most of which is rural, is gathering pace: Hundreds of photovoltaic systems are feeding environmentally-friendly electricity into the grid of the region's largest electricity provider. When everything is running smoothly, the provider can ensure the grid quality needed for the many connected localities. But expanded production capacity at Hay Speed jeopardized this. Of late, each time the company's systems were started up they caused peaks in voltage in the superordinate grid which couldn't be compensated for. Several times, this had forced the electricity provider to switch off all photovoltaic systems. The owners of these systems and the electricity provider itself rightly demanded that Hay Speed resolve the problem and do it quickly.

A project team from MR designed two reactive power compensation systems for Hay Speed to quickly and reliably compensate for the voltage peaks produced by the switching operations of the large inductive loads. The individually constructed MR hybrid solutions each comprise a pure medium-voltage section for the base load and a low-voltage system of thyristor-controlled stages to compensate for dynamic voltage fluctuations; in each case a step-up transformer raises the voltage from 690 V to 20,000 V.

The systems are installed outside the HAY Speed factory in protective concrete stations. Since they were commissioned, the voltage fluctuation problems have been a thing of the past. Another benefit is paying dividends too. Reactive power doesn't cost the company anything any more because it takes up no more than a third of the free allocation provided by the grid operator.

POWER QUALITY BY MR Wherever rapid changes in load dynamically affect the voltage at the connection point or wherever very sensitive voltage regulation is needed, dynamic compensation systems from MR provide an effective remedy.