A Harmonic Impedance Measurement System for Reduction of Harmonics in the Electricity Grid
article
This paper describes the development of a Complex Harmonic Impedance Measurement system, called the CHIME-system. This system performs on-line impedance measurements in the electricity grid and will be designed for implementation in Digital Signal Processor (DSP) control systems of grid-connected electronic power converters, like photovoltaic inverters. This system could be used to estimate the potential of harmonic voltage distortion in low voltage distribution systems, due to large scale photovoltaic implementations. The CHIME-system estimates the complex small signal network impedance for a range of harmonic frequencies up to the 40th. To avoid disturbances in the grid, the injected stimulus for the measurement should be small enough to let the system comply with the standard for current emission of home appliances. This implicates that the system must be able to extract the complex network impedance from very small signals, often lower than noise levels. The CHIME-system can comply with these demanding specifications and works with the combination of a Lock-in system and Discrete Fourier Transformation (DFT) This paper discusses the principle of the CHIME-system and give results from computer simulations and laboratory measurements. These results show that the CHIME-system can work well by injecting a very low measurement current, lower than the allowed emission of a small home appliance. Beside that, the CHIMEsystem is capable of operating under a strong polluted grid voltage. Later this system will be implemented as an ancillary service, in a grid-connected power electronic converter
TNO Identifier
482369
Source
International Journal of Distributed Energy Resources, 5(October / December), pp. 315-331.
Pages
315-331