Power-line-communication-based data transmission concept for an LVDC electricity distribution network – Analysis and implementation

摘要

Communications play a key role in modern smart grids. New functionalities that makethe grids ‘smart’ require the communication network to function properly. Datatransmission between intelligent electric devices (IEDs) in the rectifier and thecustomer-end inverters (CEIs) used for power conversion is also required in the smartgrid concept of the low-voltage direct current (LVDC) distribution network. Smart gridapplications, such as smart metering, demand side management (DSM), and gridprotection applied with communications are all installed in the LVDC system. Thus,besides remote connection to the databases of the grid operators, a local communicationnetwork in the LVDC network is needed. One solution applied to implement thecommunication medium in power distribution grids is power line communication(PLC). There are power cables in the distribution grids, and hence, they may be appliedas a communication channel for the distribution-level data.This doctoral thesis proposes an IP-based high-frequency (HF) band PLC datatransmission concept for the LVDC network. A general method to implement theEthernet-based PLC concept between the public distribution rectifier and the customerendinverters in the LVDC grid is introduced. Low-voltage cables are studied as thecommunication channel in the frequency band of 100 kHz–30 MHz. Thecommunication channel characteristics and the noise in the channel are described. Allindividual components in the channel are presented in detail, and a channel model,comprising models for each channel component is developed and verified bymeasurements. The channel noise is also studied by measurements. Theoretical signalto-noise ratio (SNR) and channel capacity analyses and practical data transmission testsare carried out to evaluate the applicability of the PLC concept against the requirementsset by the smart grid applications in the LVDC system. The main results concerning theapplicability of the PLC concept and its limitations are presented, and suggestion forfuture research proposed.