Improved direct current compensation (DCC) system for Austrian network operator Austrian Power Grid (APG)
Direct current in transformers leads to increased noise levels and high no-load losses. In order to counteract these problems, Siemens has developed a system for direct current compensation. An improved system has now been installed at Austrian network operator Austrian Power Grid (APG).
Reducing losses and noise emissions
Power grid operators are required to constantly maintain and improve the efficiency of their grids and power equipment. At the same time, growing public awareness and urbanization requires minimization of noise pollution in the surrounding environment. As a result, power grid operators are specifying lower and lower values for noise pressure and electrical losses in their power transformers.“Decentralized energy systems in combination with ongoing urbanization will bring electrical substations into the close vicinity of residential areas. Resulting direct currents, for example from renewables and semi-conductors, will have a negative impact on electrical losses for grid operators and noise pollution for the residents. Our direct current compensation is the sole system that eliminates the resulting loss increase and noise pollution almost entirely.”Stefan Klaassen, CEO Large Power Transformers, Siemens Gas and Power
The effects of DC on transformer noise
Step 1: DC detection
Giving a first real-time indication of DC effects
The easy-to-use app (available soon) transforms any smartphone into a DC detection device and can be used by any person at the site. The app records the noise level for all kind of transformers, independent of manufacturer. It processes the audio data and visualizes any DC noise effects directly on the smartphone offline in real-time. A detailed report including recommendations can be requested directly from the Siemens experts by submitting the data online.
Benefit DC detection
- Quick and easy first indication of DC effects (snapshot)
- Proper indication of required next step
Step 2: DC ready
Preparing transformers to be ready for DC measurement and compensation
The DC-ready design enables the subsequent DC measurement and DC compensation. The active parts of these transformers are already equipped with all required components, like compensation windings, internal measurement sensors, and connections. These components will be used for DC measurement (step 3) or DC compensation (step 4).
Benefit DC ready
- Future-proven design with state-of-the-art compensation hardware embedded
- No additional built-in hardware needed if DC needs to be compensated in the future
Step 3: DC measurement
Solid determination and proof of DC level in the asset
The measurement device is connected to the DC-ready system. It determines the actual DC level. The measurement device connects to the DC-ready components installed inside the transformer and analyses the DC effects continuously over several weeks.
Benefit DC measurement
- Transparency about the dimensions of DC effects in the grid over some weeks
- Determine appropriate compensation power
Step 4: DC compensation
Eliminated DC in the asset and reduction of no-load loss and noise impacts
The compensation device is connected to the DC-ready system. It constantly analyses the DC effect on the transformer and generates the necessary direct current needed for compensation. The compensation windings installed in the DC-ready design are generating a magnetic field in the core to counteract the field produced by DC current. The required DC current is determined by sensors at the active part and controlled by a control unit. The DC effects on transformer noise and loss level can be nearly completely eliminated.
Benefit DC compensation
- Set back noise and loss levels to nominal values
- Compliance to local regulations regarding noise pollution
- Reduction of costs for no-load losses
- Save additional noise enclosure
Siemens has over eight years of experience with DC compensation.
DC compensation systems from Siemens are currently in operation in Europe, North America, and Asia.
DC compensation from Siemens enables noise reduction of up to 13 dB.*
*For a human being, an increase of 10 dB is perceived as doubling the noise.
