segunda-feira, 11 de julho de 2016
Emission and Interaction from Domestic Installations in the Low Voltage Electricity Network, up to 150 kHz - Sarah Rönnberg -Luleå University of Technology Department of Engineering Sciences and Mathematics Division of Energy Science
Emission and Interaction from Domestic Installations in the Low Voltage Electricity Network, up to 150 kHz - Sarah Rönnberg -Luleå University of Technology Department of Engineering Sciences and Mathematics Division of Energy Science.
This thesis work has focused on conducted emission (up to 150 kHz) from common lowvoltage appliances. The emphasis has been on equipment that contributes to a sustainable energy system: photovoltaic (PV) installations and energy-saving lamps (LED lamps). The frequency components present in the grid in addition to the fundamental 50 Hz component can be divided into harmonics (up to 2 kHz in a 50 Hz system) and supraharmonics (2 kHz to 150 kHz). These frequency components are partly the effect of normal operation of equipment due to power-electronic converters and the switching technique used. Power line communication, PLC, is an important source of frequency components in the range 9 to 95 kHz. Even though from an equipment viewpoint there is no difference between a signal used for communication and a signal that is a residue from a switching circuit, PLC is a useful signal for operation of the grid and for communication with electricity meters. The amplitude of the communication signal is in in almost all cases higher than the emission from any other equipment connected to the grid. Understanding the different types of interaction between PLC and end-user equipment has been a major part of this work. Five types of interaction have been identified; some negative for PLC, some negative for end-user equipment. An important conclusion from this part of the work is that loss of communication with PLC, as is often reported with remote reading of electricity meters, is not due to emission by end-user equipment but due to the EMC filter of the end-user equipment providing a low-impedance path. The understandings acquired from the work with PLC have been applied to other types of emission as well. Supraharmonics from individual devices, above about 10 kHz, flow mainly to neighboring devices, not into the grid. This behavior was found by laboratory experiments and confirmed by other studies as well. A circuit-theory model has been developed that explains this behavior. The EMC filters are shown to be the main cause of this behavior. Other configurations of those filters may result in a larger flow of emission towards the grid. One type of appliance that has been introduced recently is the LED lamp. LED.