Study On Harmonic Detection And Suppression In Power System Based On Instantaneous Power Theory

With the development of power electronic technology, more and more non-linear loadsin the grid, current waveform distortion is increasingly serious, if not checked governancewill seriously affect the safe and stable operation of power system. Therefore, the powersystem harmonic current real-time detection and necessary suppression measures are taken, isto guarantee safe and stable operation of power system is one of the great tasks.In order to systematically study the harmonic current detection and suppressionmethods based on the instantaneous power theory, Paper first analyzes the concepts,representations, measures, harms of the power system harmonic and the main harmonicsources in power grid. Based on it, this paper introduces the definition and relevantconclusions of instantaneous power theory, then the instantaneous power theory is applied toharmonic current detection method, and gets the p-q detection method and the ip-iqdetectionmethod. This paper adopts the method of theoretical derivation and simulation experiment tostudy applications of the p-q detection method in three-phase three-wire circuits with voltagedistortion or not and applications of the ip-iqdetection method in three-phase three-wirecircuits with voltage distortion, three phase four wire circuits, and single-phase circuits. Thep-q detection method can accurately detects the harmonic current in power grid only when thegrid voltage without distortion, the detecting results are error when the grid voltage withdistortion; And the ip-iqdetection method can obtains satisfactory detecting results in a varietyof circuits under different running condition, so the ip-iqdetection method has widerapplication space than the p-q detection method. In addition, the low pass filter is theimportant factor influencing the effect of harmonic current detection which in the harmoniccurrent detection circuit based on p-q detection method or ip-iqdetection method. This paperanalyzes the detecting effectiveness of the harmonic current detection circuit which base onip-iqdetection method with different low pass filter, and provides help to select low pass filter.Using the active power filter based on instantaneous power theory to detect and suppressharmonic current is one of the most effective methods of management of power systemharmonic current. The paper analyzes the basic operation principle of active power filter andthe way of access to the power grid, based on it, the main circuit structure of shunt activepower filter were studied in detail. Finally, the paper puts forward a design scheme of shuntactive power filter based on instantaneous power theory in three-phase three-wire system, andfocuses on the hardware design and control strategy, for the practical application of activepower filter based on instantaneous power theory laid a certain foundation. In terms ofhardware design, this paper focuses on the current, voltage detection circuit, the zero crossingdetection circuit, the circuit of sampling period signal, AD conversion circuit and main circuit and so on. In the aspect of control strategy, this paper focuses on the specific workingprocesses of compensation current hysteresis control and the DC side voltage control.