DSP Based Harmonic Detection Method In Power Distribution Network

With the continuous increase of non-linear load in electrical power system, harmonic current pollutes electrical power system increasingly, influences power quality and reliability, so the harmonic current detection and compensation in electrical power system play a strikingly important role. The appearance of active power filter provides equipment support for the compensation of harmonic current and reactive current, and the real-time and exaction performance of harmonic current detection in active power filter design is of great importance. Therefore, the paper does research on harmonic current detection as follows:First, Analyses and comparisons are made among the impacts on systems influenced by harmonic current, reactive current and different detection methods so that all kinds of detection method characteristics are received;meanwhile the detection method in the thesis is concluded based on the merits of instantaneous power theory, namely harmonic detection based on instantaneous reactive power theory.Second, the characteristics of harmonic current in power distribution network are gained by doing further research on familiar non-linear load harmonic current in electrical power system, and the reception of the trait provides the theory basis for harmonic current detection as well as predigestion of checking system. Analyzing instantaneous power theory of tri-phase circuit, the thesis educes the checking circuit design methods according to that theory and probe into the means as well as theories involving digital signal processing as to advance correlative design notion, especially the pertinence improvement of table look-up scheme and Integral algorithm filter which raise checking precise and calculating speed.Finally, On the basis of the current hardware equipment such as FPAG and DSP, the paper designs all the models in detection system by using verilog_HDL hardware narration and simulates the detection system in MATLAB and MODLESIM. On the basis of checking system the thesis completes the creation of APF simulation system utilizing MATLAB and SIMULINK as well as simulating that APF system so that the simulation results are gained. It can be seen from the results that APF can restrain system harmonic, so that the real-time and valid performance are reflected.