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A Novel Bifurcation Diagram Drawing Method Applicable to Sliding Mode Variable Structure Control Inverters

A sliding mode variable structure and inverter technology, which is applied in the direction of instruments, special data processing applications, AC network circuits, etc., can solve the problems of not responding to system dynamic behavior and bifurcation phenomena, and drawing bifurcation diagrams, etc.

Inactive Publication Date: 2019-05-03
SOUTHWEST PETROLEUM UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Existing methods and fast-changing stability criteria can only be used to judge the stability of the SMC nonlinear control inverter system, but they cannot reflect the system dynamic behavior and bifurcation phenomenon, and cannot rely on it to draw accurate and stable bifurcation diagram of

Method used

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  • A Novel Bifurcation Diagram Drawing Method Applicable to Sliding Mode Variable Structure Control Inverters
  • A Novel Bifurcation Diagram Drawing Method Applicable to Sliding Mode Variable Structure Control Inverters
  • A Novel Bifurcation Diagram Drawing Method Applicable to Sliding Mode Variable Structure Control Inverters

Examples

Experimental program
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Effect test

Embodiment 1

[0086] Using the traditional inverter bifurcation diagram drawing method: first select a certain parameter as the bifurcation parameter, and in the case of a certain bifurcation parameter, select an initial value of the inductance current i of the state quantity of the inverter and substitute it into the discrete iterative equation to start the iteration ; Remove the transition process, and continuously sample the value of the state quantity at the same fixed sampling position for multiple sine cycles to obtain a set of steady state values. The bifurcation diagram of the inverter can be obtained by plotting the bifurcation parameter as the horizontal axis and the set of steady-state values ​​under the bifurcation parameter as the vertical axis.

[0087] Select the circuit parameters as follows: E=400V, R 1 =R 2 = R = 2Ω, L 1 = L 2 =L=6.85mH,f 1 = 50Hz, i ref = I ref ×sin(100πt)A,I ref =5A,f s = 5kHz,k p = 0.2. N points are sampled per sine cycle, where N=f s / f 1 =...

Embodiment 2

[0091] SMC is used to control the experimental prototype of NGI-H6 system, and the parameters of the prototype are: E=400V, u grid frequency f ac = 50Hz, R 1 =R 2 = R = 10Ω, L 1 = L 2 =L=6.85mH, CNC chip: DSP2812, switching frequency f s=5kHz, the power grid is simulated by Chroma AC source. Taking different ε as an example, the experimental waveform of i is obtained.

[0092] The principle of inverter state mutation point generation is: error signal e=i ref -i, when the system error signal e appears in the nth switching cycle e(n)=i ref (n)-i(n)control (n)=-ε+k p ×e(n)control (n)carrier (n), so the duty cycle d n will suddenly become 0, and the inductor current will drop sharply, resulting in e(n+1)=i in (n+1) switching cycles ref (n+1)-i(n+1)>0, u control (n)=-ε+k p ×e(n)>0,u carrier (n+1) and u control (n+1) must have two intersections, the duty of the n+1th switching cycle d n+1 >0; therefore, in the positive half-period decline period of the inductor curren...

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Abstract

The invention provides a novel bifurcation diagram drawing method suitable for a sliding mode variable structure control inverter. The method comprises the steps of 1, establishing a sliding mode variable structure control discrete iteration mapping model; 2, analyzing conventional bifurcation diagram drawing methods and determining the reasons for the inaccurate determination of stability domains and bifurcation behaviors thereof to find a solution; 3, researching the mechanism of the phenomenon of sudden change of states; 4, according to the mechanism of sudden change of states, deriving a method of variable-sampling point inverter bifurcation diagrams drawing and drawing a corresponding diagram. The invention provides the variable-sample point bifurcation diagram drawing method; it is proved that bifurcation diagrams drawn with the method can determine systematic stability work regions accurately and can be used for analyzing bifurcation behaviors of systems; finally the accuracy of theoretical analysis is verified through circuit experiments and research results provide reference for the research of nonlinear behaviors of sliding mode variable structure control inverters and drawing of bifurcation diagrams thereof.

Description

technical field [0001] The invention relates to the technical field of power system stability control, in particular to a novel bifurcation diagram drawing method suitable for sliding mode variable structure control inverters. Background technique [0002] As an important part of solar power generation, the function of grid-connected inverter (GI) is to convert direct current into alternating current and transfer it to the large power grid. Since GI is directly connected to the large power grid, the instability of large-scale distributed photovoltaic GI may cause fluctuations in the large power grid, and even cause the system to suddenly collapse in a critical state. GI is a strongly nonlinear time-varying system, and there are nonlinear phenomena such as period-doubling bifurcation, fast-varying and slow-varying instability, and Holf bifurcation. In the future, new energy will partially replace or completely replace traditional energy for power generation, so it is essenti...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F17/50H02J3/38H02J3/00
CPCG06F30/367G06F30/398H02J3/383H02J3/00H02J2203/20Y02E10/56
Inventor 代云中蒋林吴显松吴俊任海军赵鹏程樊新建
Owner SOUTHWEST PETROLEUM UNIV
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