Power grid impedance adaptive method for active power filter
A power filter and grid impedance technology, applied in active power filtering, adaptive control, instruments, etc., can solve the problems of active power filter frequent protection, affecting the stable operation of the power system, and not working normally, and achieve calculation Small amount, easy to realize, and the effect of improving compensation accuracy
Active Publication Date: 2017-07-04
BEIJING INST OF COMP TECH & APPL +1
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[0004] In practical applications, due to the uncertainty of various parasitic parameters and loads, the harmonics emitted by the active power filter may resonate with the system impedance or load, affecting the stable operation of the power system, burning other loads, or causing active power The filter itself is frequently protected and cannot work normally
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[0020] In order to make the purpose, content, and advantages of the present invention clearer, the specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.
[0021] figure 2 Shown is the flow chart of the grid impedance adaptive method of the active power filter of the present invention, as figure 2 As shown, the inventor found through research that the existing impedance adaptive algorithm generally needs to measure and calculate the impedance of the system at each frequency point or frequency band, and suppress resonance by adjusting control parameters and increasing damping. Accurately calculate the system impedance Z by measuring the voltage and current at the harmonic injection point ih =U g_ih / I g_ih , the algorithm is complex and computationally intensive.
[0022] The basic principle of the grid impedance self-adaptive method of the active power filter of the...
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The invention discloses a power grid impedance adaptive method for an active power filter. The power grid impedance adaptive method comprises the steps of performing current collection; calculating an instantaneous current value error, comprising a formula which is as shown in the specification; calculating an effective current value error, a formula which is as shown in the specification, wherein i<*><n>(k) is a set current instantaneous value of the k sampling point of the active power filter; i<n>(k) is an actual current sampling current of the k sampling point of the active power filter; I<*><nrms> is a set n-degree harmonic effective value of the active power filter; I<nrms> is an actually output current effective value of the active power filter; N is the number of sampling points of a power frequency period; performing weighing normalization processing on the effective current value error and the instantaneous current value error to obtain an equation which is as shown in the specification; making comparison between the normalized weighed error en and an error threshold value Er, if the absolute value of en is greater than Er, not performing compensation in the actual operation of the active power filter, and controlling a parameter Pn to be equal to 0; and if the absolute value of en is less than or equal to Er, performing correction on the control coefficient Pn of the active power filter: comprising a formula which is as shown in the specification.
Description
technical field [0001] The invention relates to the technical field of active filtering, in particular to an adaptive method for grid impedance of an active power filter. Background technique [0002] With the complexity and diversity of current grid loads, problems caused by power quality such as harmonics and reactive power are becoming more and more serious. Both the power grid and electrical equipment have relevant standards to limit the harmonic content. [0003] figure 1 The working principle diagram of the active power filter is shown, refer to figure 1 , the active power filter (abbreviated as APF) is a power electronic device that can dynamically suppress harmonics and compensate reactive power. It is equivalent to a controllable current source connected in parallel to the power grid. The load harmonic currents are equal in magnitude and opposite in direction to the grid, so as to realize the compensation of system harmonics. The load current iL of the active po...
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IPC IPC(8): H02J3/01G05B13/02
CPCG05B13/021H02J3/001H02J3/01Y02E40/20
Inventor 郑丹
Owner BEIJING INST OF COMP TECH & APPL