Parameter for seven type of voltage sag.
1. Introduction
A recent survey attributes that 92% of all disturbances in power system is caused by voltage sags. Three-phase voltage sag can be classified in seven types as shown in Fig.1 (Bollen MHJ, 2000). The electrical sensitive load often trips of shunts down when voltage sag occur. It's very important to know how these sensitive equipment works when the voltage sag occur. This is the reason to develop the voltage sag generator that can created varied type of voltage sag waveform. The purpose of voltage sag generator is use to test the immunity of equipment against the voltage sag.
The magnitude and angle of three phase voltage sag can calculate form equation 1 to equation 7(Bollen MHJ, 2000).
Type A
Type B
Type C
Type D
Type E
Type F
Type G
2. Voltage sag generator
Previous works (Takahashi et al., 2008; Rylander
An autotransformer is used as the 1-phase voltage sag generator as demonstrated (Rylander
3. Graphic user interface (GUI) waveform generator
The graphic user interface (GUI) “SagWave” (Oranpiroj et al., 2010, Oranpiroj
The window for showing the 3-phase voltage.
The window for showing vector of A, B and C phase.
Magnitude of Voltage (A, B and C phase), user had used value box or slider bar.
Phase angle jump of voltage sag on A, B or C phase.
Sag type for selected the voltage sag type (single-phase, two-phase and three-phase).
Display normal or repeat mode of voltage sag.
Point on wave in degree.
Sag duration time for period time of voltage sag.
Number of repeat of voltage sag.
The button “Plot” for generated the voltage sag waveform.
The button “Send” for send the data from SagWave to the dsPIC microcontroller.
The button “Refresh” for clear the value and graphic display.
The layout of GUI "SagWave" designed as shown in Fig.2. The SagWave development on MATLAB's Graphical User interface Development Environment (GUIDE)(Patrick Marchand & O. Thomas Holland., 2003).
3.1. The window for showing the 3-phase voltage
This is an "Axes" object in component palette () on the left-side of window. The "Axes" can move and resize by drag it with the mouse. This "Axes" to shown the 3-phase voltage of voltage sag, then we assigned name to "Time_Plot" in Property inspector by double click on "Axes1" as shown in Fig. 3.
3.2. The window for showing vector of A, B and C phase
This "Axes2" to shown the vector of A, B and C of voltage sag, then we assigned name to "Com_pass" in Property inspector by double click on "Axes2" as shown in Fig. 4.
3.3. Magnitude of Voltage (A, B and C phase), user had used value box or slider bar
This group used the Edit Text and Slider object. The Edit Text and Slider object set the default value as 100%. In the property inspector of three Edit Text changed the String to "100", Max to "1.0" and Min to "0.0", as shown in Fig. 5. The String in Edit Text property to changed to the number value in m-file. In the property inspector of three Slider changed the Value to "[100.0]", Max to "100.0" and Min to "0.0", as shown in Fig. 6.
3.4. Phase angle jump of voltage sag on A, B or C phase
This group used the Edit Text () and Slider () object, that the same as Magnitude group. In the property inspector of three Edit Text changed the String to "0", Max to "1.0" and Min to "0.0", as shown in Fig. 7. The String in Edit Text property to changed to the number value in m-file. In the property inspector of three Slider changed the Value to "[0,0]", Max to "90.0" and Min to "-90.0", as shown in Fig. 8.
3.5. Sag type for selected the voltage sag type (single-phase, two-phase and three-phase)
This group are "Radio Button" objects in component palette () on the left-side of window. The Radio Button of this group used to select the voltage sag type, Single-phase, Two-phase and Three-phase type. The property inspector was shown in Fig. 9.
3.6. Display normal or repeat mode of voltage sag
These groups are "Radio Button" objects same as the voltage type group. The Radio Button of this group used to select the graph to shown normal and repeat mode of voltage sag. The property inspector was shown in Fig. 10.
3.7. Point on wave in degree
This object is the Edit Text for input degree of voltage on wave. The property inspector was shown in Fig.11.
3.8. Sag duration time for period time of voltage sag
This object is the Edit Text for input time duration of voltage sag. The property inspector was shown in Fig.11.
3.9. Number of repeat of voltage sag
This object is the Edit Text for input the repeated number of voltage sag. The property inspector was shown in Fig.11.
3.10. The button “Plot” for generated the voltage sag waveform
This object is "Button" objects in component palette () on the left-side of window. The "Plot" button is the main object of the GUI "SagWave", this button used to calculate and showed the graph of voltage sag. The property inspector was shown in Fig.12.
3.11. The button “Send” for send the data from SagWave to the dsPIC microcontroller
The "Send" button used to send the wave form data of voltage sag to dsPIC microcontroller. The property inspector was shown in Fig.12.
3.12. The button “Refresh” for clear the value and graphic display
The "Refresh" button used to clear the graphic, all of the value in program to provide the new value. The property inspector was shown in Fig.12.
Finally users are ready to let GUIDE create the Fig-file and M-file. They are two options to create; one, simply select menu File Save As.., or users can run GUI by select menu Tools Run or click on tool bar. GUIDE will save user's GUI to file with the name as gave by user with extension *.fig and *.m of the same name.
4. SagWave programming
The concept of SagWave programming shown in Fig. 13. Form the 3th topic, GUIDE will create an M-File with callback function prototypes. The callback function was response to an event by MATLAB code. There must be a callback to implement the function of each graphical component on the GUI. Now we must be programming the callback to implement the function of each component on the SagWave.
4.1. Magnitude of Voltage Sag
These groups to input the magnitude of the voltage sag. There are two ways to input the magnitude;
Edit Text (Phase A, Phase B, Phase C Magnitude)
The Edit Text is an element that user to enter a text string(0 to 100). The program of this element is shown in Fig.14, in this program shown how to converse string to numeric.
Slider (Phase A, Phase B, Phase C Magnitude)
The Slider is the element that user to select values from continuous range between a specified minimum and maximum value by moving a bar with mouse. The program of this element is shown in Fig.15.
4.2. Phase angle of Voltage Sag
These groups to input the phase angel of voltage sag. There are two ways to input the magnitude;
Edit Text (Phase A, Phase B, Phase C Phase angle)
The Edit Text is an element that user to enter a text string (-90 to +90). The program of this element is shown in Fig.16, in this program shown how to converse string to numeric.
Slider (Phase A, Phase B, Phase C Phase angle)
The program of this element is shown in Fig.17.
4.3. Voltage Sag Type
These groups to select the voltage sag type, the program of this element shown in Fig. 18.
4.4. Show
These groups to select the program to show single or repeat of voltage sag, program of this element shown in Fig. 19.
4.5. Point on Wave, Sag Duration and Repeat
These groups to enter the value of Point on Wave, Sag duration and Repeat of voltage sag, the program of this element shown in Fig. 20.
4.6. Send Button
The Send Button is the button for user to send the data from SagWave to dsPIC microcontroller. The Duty.dat was generated by SagWave. The user clicked the "Send" button to send the Data.dat to dsPIC microcontroller by a RS-232 port. The program of this element shown in Fig. 21.
4.7. Refresh Button
The Refresh Button is the button for user to clear the parameter and graph in SagWave for the next simulation. The program of this element shown in Fig. 22.
5. Simulation result
From equation 1 to equation 7 in Topic 1, if we need 60%(V = 0.6) voltage sag there can be calculate and result in Table. 1. The operation of this program with the user designing the voltage sag wave form SagWave software. Then the user clicks the “Send” button to send the parameters to dsPIC microcontroller. The actual voltage sag is created by a 3-phase 4-leg 4-wire inverter based on an
For example, the designed waveforms have parameters as found in “Bollen, (2000)”. The parameters in Table 1. are used to generate seven types of voltage sag. Users can verify waveforms through graphic display windows as shown in Fig. 24.
Voltage Sag Type | Phase Voltage | |||||||||
A | B | C | ||||||||
Magnitude | Phase | Magnitude | Phase | Lag | Lead | Magnitude | Phase | Lag | Lead | |
A | - | - | - | - | ||||||
B | - | - | - | - | ||||||
C | - | - | ||||||||
D | - | - | ||||||||
E | - | - | - | - | ||||||
F | - | - | ||||||||
G | - | - |
SagWave software can create point on wave single-phase(phase A) voltage sag, the parameters are shown in Table 2. The display of waveforms was is in Fig. 25. The parameters of single-phase(phase A) repeated voltage sag is shown in Table 3, and the simulation waveform in Fig.26.
Case | Manitude(%) | Duration(ms) | Point on Wave (degree) |
Case | Manitude(%) | Duration(ms) | Number of repeated |
6. Experimental of 3-phase 4-wire voltage sag generator
From section 3 the SagWave software generates the parameter file and sends it to the dsPIC microcontroller. The dsPIC uses this file to control the 3-phase 4-leg 4-wire inverter in order to create the actual waveform. Experimental results for voltage sag types A, B and E are shown in Fig. 27-29, respectively.
The experimental results in Fig. 27 are according with simulation results in Fig.24 (Type A). Fig.27 shows the 3-phase voltage and 3-phase current of voltage sag Type A. During voltage sag, the voltage on phase A (
The experimental results in Fig. 28 are according with simulation results in Fig.24(Type B). Fig.28 shows the 3-phase voltage and 3-phase current of voltage sag Type B. During voltage sag, the voltage on phase A (
The experimental results in Fig. 29 are according with simulation results in Fig.24 (Type E). Fig. 29 shows the 3-phase voltage and 3-phase current of voltage sag Type E. During voltage sag, the voltage on phase B (
The experimental results of point on wave are shown in Fig. 30. The sag generator can generate waveform at any point of wave of sine wave as desired.
The experimental results of repeated voltage sags are shown in Fig. 31. The sag generator can generate repeated voltage sag waveform as many as desired.
7. Conclusions
This chapter has proposed the use of GUI SagWave software to provide a visual interactive capability generating data for the dsPIC controller. SagWave software can show the waveform and the phasor of the three-phase voltage. The simulation and experimental results have shown a simple control algorithm for generating the sag signal for testing. The experimental results have shown the main advantages of this prototype: point on wave, sag duration, magnitude of voltage sag and varied type of voltage sag. A future study will design software for the dsPIC microcontroller to generate all seven types of voltage sag and to test the dynamic and nonlinear loads.
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