Interference of HVDC transmission systems with long wave radio services

The transition of the German energy system leads to an additional request for further transmis-sion capacitance of electrical energy from the North to the South of the country. Due to the long distances have to be gaped are HVDC transmission systems in some cases superior to conventional AC-transmission systems. Caused by the used self-commutated multilevel converter higher frequency harmonics will be injected into the transmission lines. This research project deals in general with the question if parts of the spectrum (frequencies from 9 kHz to 30 MHz) are capable to influence long wave radio services negatively or even disturb this services.

Approach

Due to the geometric dimensions of the assessed components are simulations the method of choice to deal with the following question. Can long wave radio services be disturbed by operation of HVDC transmission systems and which preconditions have to be fulfilled? The following aspects have to be investigated:

• Which frequencies will be excited with which amplitude by converter operation and by which measures can it be influenced by the converter control

• Which attenuation of the spectrum can be expected by grid components like transformers and inductors

• How are higher frequencies are transmitted by overhead lines

• To which extent are electromagnetic waves propagating to the surroundings (not ideal conducting ground, Ground waves)

• Which amplitude of the frequencies is acceptable to prevent disturbances of radio services

Modelling of particular parts is separate as far as possible. The system behavior will be extracted by co-simulation of the system parts. Under investigation are the DC-side as well as the AC-side. (See Figure 1).