Estimation method and estimation system of system harmonic impedance at electric system public connection point

A common connection point and power system technology, applied in the measurement of resistance/reactance/impedance, electrical digital data processing, calculation, etc., can solve problems such as complex calculations and inaccurate calculation results

Active Publication Date: 2019-07-23
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the existing methods for calculating harmonic impedance on the system side include "intervention" and "non-intervention", both of which have technical problems of inaccurate calculation results and complex calculations

Method used

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  • Estimation method and estimation system of system harmonic impedance at electric system public connection point
  • Estimation method and estimation system of system harmonic impedance at electric system public connection point
  • Estimation method and estimation system of system harmonic impedance at electric system public connection point

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Embodiment 1

[0026] figure 1 It is a flowchart of a method for estimating system harmonic impedance at a common connection point of a power system according to an embodiment of the present invention. Such as figure 1 As shown, the method includes the following steps:

[0027] Step S102, establishing a Thevenin equivalent circuit model of the system-side circuit at the common connection point of the power system; wherein, the Thevenin equivalent circuit model is used to characterize the connection relationship between the harmonic voltage source of the power system and the system-side harmonic impedance.

[0028] Optionally, figure 2 A Thevenin equivalent circuit model provided for the embodiment of the present invention, that is, the complex harmonic network on the system side of the Point of Common Coupling (PCC) is equivalent to a harmonic voltage source and harmonic impedance (Z u ) in series.

[0029] Step S104, collecting a plurality of harmonic voltage data and a plurality of ...

Embodiment 2

[0062] image 3 It is a schematic diagram of a system harmonic impedance estimation system at a common connection point of a power system provided according to an embodiment of the present invention, as shown in image 3 As shown, the system specifically includes: an equivalent circuit module 10 , a data acquisition module 20 , a data processing module 30 , a first calculation module 40 , a second calculation module 50 and a third calculation module 60 .

[0063] Specifically, the equivalent circuit module 10 is used to establish the Thevenin equivalent circuit model of the system side circuit at the common connection point of the power system; the Thevenin equivalent circuit model is used to characterize the harmonic voltage source of the system side circuit and the system side harmonics The connection relationship between impedances.

[0064] The data collection module 20 is used to collect a plurality of harmonic voltage data and a plurality of harmonic current data at the...

Embodiment 3

[0086] This embodiment is an application embodiment of calculating the estimated value of the system-side harmonic impedance by using the method provided in the first embodiment above.

[0087] The data of a 150kV busbar (PCC) of a 100MVA DC electric arc furnace is collected, and the sampling frequency is 6400Hz. Fast Fourier transform is performed on the sampled voltage and current data every minute to obtain the measured values ​​of each harmonic. Substituting the third harmonic voltage and current values ​​into the calculation program of this method, the calculation results are as follows: Figure 5a and Figure 5b As shown, the calculation results take the average value of the third harmonic impedance on the system side as 10.0374, and the phase angle as 68.0109.

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PUM

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Abstract

The invention provides an estimation method and an estimation system of system harmonic impedance at an electric system public connection point, wherein the method comprises the following steps: building a Thevenin equivalent circuit model of a system side circuit at the electric system public connection point; at the electric system public connection point, acquiring multiple harmonic voltage data and multiple harmonic current data; calculating a harmonic voltage fluctuation value and a harmonic current fluctuation value at the electric system public connection point; performing differentialoperation for two ends of a Thevenin equivalent circuit equation, and obtaining an electric relation equation about the harmonic voltage fluctuation value, the harmonic current fluctuation value and the system side harmonic impedance; according to 2 norm, establishing a system side harmonic voltage source fluctuation quantity function at the electric system public connection point, and based on aminimum value of the system side harmonic voltage source fluctuation quantity function, determining a system side harmonic impedance estimation value at the electric system public connection point. The method and the system provided by the invention can accurately and quickly obtain the system side harmonic impedance estimation value at the electric system public connection point.

Description

technical field [0001] The present invention relates to the technical field of power systems, in particular to a method and system for estimating system harmonic impedance at a common connection point of a power system. Background technique [0002] In recent years, people have put forward higher and higher requirements for the quality of electric energy. However, the connection of a large number of power electronic devices and nonlinear loads in the power grid has led to more serious harmonic problems, which not only interferes with the stable operation of the power system, but also brings huge economic losses to all parties. In order to monitor and control harmonic problems, relevant policies have been issued at home and abroad, and corresponding rewards and punishments are carried out according to the level of harmonic emission. It is very important to reasonably quantify the responsibility of harmonic pollution, and the key to evaluating the level of harmonic emission is...

Claims

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Application Information

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IPC IPC(8): G01R27/02G06F17/50
CPCG01R27/02G06F30/20
Inventor 徐方维舒勤王畅赵永扬
Owner SICHUAN UNIV
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