Vibration Measurement

Keeping harmonics under control

Keeping harmonics under control

Keeping harmonics under control

Keeping harmonics under control

For MVV's Rheinufer Neckarau (Berun) district heating backup plant, which is currently under construction, Bilfinger GreyLogix is supplying the electrical and control technology for feeding the recovered heat into the energy company's district heating network. Low Harmonic Single Drive cabinet units ACS880-37 from ABB help to ensure that the power grid is not burdened with grid harmonics.

MVV Energie AG is currently building a district heating backup system in the Neckarau district of Mannheim as part of the Berun project. This will serve to secure and cover peak loads for the district heating supply of customers of the Mannheim-based company, which is gradually converting its district heating generation to climate-neutral energies.

The main purpose of the project is to secure the district heating supply against the backdrop of the medium-term closure of the existing power plant units of Grosskraftwerk Mannheim AG (GKM) as part of the politically motivated coal phase-out. The plant will consist of a hot water boiler plant with an installed useful heat output of 286 MWth, a gas pressure control and metering station and a district heat pump plant with a hydraulic output of approx. 9,000 tph. The hot water boiler plant is mainly composed of two boiler units as well as the district heat pump plant, which consists of two pump groups with three pumps each.

For the project, Bilfinger GreyLogix GmbH - now Bilfinger Life Science Automation GmbH - is supplying the electrical and control technology for the efficient feeding of heat from MVV's district heating backup plant into the energy company's district heating network. To meet MVV's harmonic requirements, the system integrator ordered three ACS880-37 Low Harmonic Single Drive frequency converter cabinet units (1,100 kW each) from ABB Motion Germany to control the plant's feed and drain pumps. Three single drive frequency converter cabinet units (630 kW each) complete the order. The frequency converters will be delivered to Bilfinger GreyLogix in September 2022.

Very low harmonic content

Grid harmonics pollute the power grid and cause unpredictable behavior of connected equipment. Among the devices that can pollute the power grid with harmonics are frequency converters, along with many other electronic systems. Devices with a very low Total Harmonic Distortion (THD), such as the ACS880-37 cabinet devices in the Low Harmonic version, can improve the power quality and meet the increased demands for higher quality of the mains voltage.

In a conventional frequency converter with a 6-pulse diode bridge as rectifier, the line-side current is not sinusoidal and has a significant harmonic content, especially of the 5th and 7th harmonics. This is also reflected in the THD value of the total harmonic distortion, which can reach 30 to 50%. A significantly better harmonic behavior is shown by ABB's Low Harmonic Drives. With a THD value of 3 %, they ensure high power quality.

On the way to green heat

MVV currently supplies district heating to around two thirds of Mannheim's households as well as the municipalities of Heidelberg, Schwetzingen and Speyer. Until now, most of it came from GKM's hard-coal-based cogeneration plants. The connection of Friesenheimer Insel in Mannheim to MVV's district heating grid has created the prerequisite for district heating to also be supplied to the Mannheim district heating grid from the thermal waste treatment plant (TAB).

During the summer periods, district heating is to be supplied exclusively by TAB. Alongside the electricity turnaround and green products and solutions, the district heating turnaround is a component of the Mannheim Model, with which MVV aims to become climate-neutral and subsequently climate-positive by 2040.

Against the backdrop of the upcoming coal-fired power plant closures in the GKM, Berun primarily serves as a flexible, highly reliable reserve in the event of a selective failure of heat generation plants and to cover peak loads on particularly cold winter days. The plant is fired with natural gas. Later use of biomethane and green gases is possible.

Neugart Rack Gear September Oktober 2022