Analysis And Calculation Of The Power Based On Load Identification

The traditional power theory is defined based on linear circuit. But for nonlinear circuit,it is irrational, because the traditional power theory, which is generated from average value,cannot explain the concept of power flow, and there are many unresolved problems in reactivecompensation and electric measurement.This article includes the following works:(1) Firstly, several popular power theories are analyzed, including advantages anddisadvantages among them, especially the different of reactive power theory. Throughcalculating power of circuits with rectifier load using different power theories, problems ofexisting power theories appear.(2) the Poynting vector can explain the electromagnetic energy transfer mechanism.TheAnalysis shows that the conductor can not transmit electromagnetic energy, electromagneticenergy can only be transmitted along the conductor near the surface of the space, and the wireitself can serve to guide the directional transmission of electromagnetic energy.(3)The plural form of the Poynting theorem was introduced,and derive the averagepower defined by the complex Poynting theorem in the case of sinusoidal.Poynting vector isused to extract Instantaneous Power without any special assumptions of conductor’s shape andcircuits. Form the analysis, instantaneous power is decomposed only into the instantaneousactive power and instantaneous reactive power.(4)A new Load identification method is proposed.The load is equivalent to the resistanceand capacitance in parallel. This method can identify the load of linear circuit and switchingcircuit. The instantaneous power related with the realistic energy flow is defined.When itis applied to a nonlinear circuit, the limitations of the method is found.(5) This paper presents a new method to measure the power components，the powerquantities such as apparent power, reactive power can provide the right physical meaning.New power calculations based on the new method are proposed, compared to the powerquantities obtained by some widely accepted power theories.