ECE 6300 TRANSMISSION SYSTEMS CONTROL SPRING 2015 PROJECT #4
DUE: 04/11/2016 (ABSOLUTELY)
The objective of this project is to use Power Electronics active filter to control harmonics or total harmonic
distortion for power quality control in electric power systems.
Consider the LC filter shown in Fig. 1(b) used to reduce the ripple content of the output voltage for the
single-phase full-wave rectifier shown in Fig. 1(a). The load resistance R = 20 Ω, load inductance is L = 5
mH, and source frequency is 60 Hz. The single-phase source is a 120 V rms voltage.
1.
(a)
(b)
(c)
Design 1:
(i)
Determine the ripple factor of the output voltage of Fig. 1(a)
(ii)
Determine the ripple factor of input current iS of Fig. 1(a)
(iii)
Determine peak-to-peak ripple in the input current iS of Fig. (a).
(iv)
Determine total harmonic distortion in the input current iS of Fig. (a).
(v)
Simulate the circuit of Fig. 1(a) in SPICE to verify 1(a)(i)-(iv).
(vi)
Use SPICE to obtain the spectrum of iS.
Design 2:
(i)
Determine the values of Le and Ce required if the ripple factor of the output voltage is
10%.
(ii)
Determine the value for the peak-to-peak ripple in the input current iS using the Le and
Ce values from 1(a)(i).
(iii)
Determine the total harmonic distortion of iS.
Simulate the circuit of Fig. 1(a) in SPICE to verify that it meets all the specifications in 1(b).
(i)
Use SPICE to obtain the spectrum of iS.
i0
iS
vS
A
iL
D1
Le
R
0.15 mH v 1.5 mH
L
A’
Fig. 1(a)
XL = nLe
D3
v0 Vnh(n)
L
D4
XC =
1/(nCe)
R
Ce
V0n(n)
L
D2
Fig. 1(b)
Next, a single-phase active filter circuit is integrated into the single-phase diode rectifier of Fig. 1, as shown
Fig. 2. The single-phase source is a 120 V rms voltage, f0 = 60 Hz. The diode rectifier has the capacitor
determined in (1) connected in parallel with load. The single-phase active filter circuit of Fig. 2 has
a capacitive load of C = 500 F. The carrier frequency of the pure filter is 10 kHz and a modulation
index of M (see chapter 9 of “SPICE for Power Electronics and Electric Power” by Rashid for details on how
to set up Fig. 3). The filter uses the PWM control of Fig. 3. The filter is to be designed to reduce the total
harmonic distortion of iS to below 2%. The modulation index M is varied until the 2% distortion of iS is
achieved. [Hint: Use the given active filter capacitor as initial value. You may change the filter capacitor to
achieve the 2% distortion; you must use your design intuition in selecting the capacitor to avoid convergence
problems in SPICE.]
2.
3.
(a)
Use SPICE ONLY to obtain the following:
(i)
the modulation index M required to achieve less than 2% distortion in iS,
(ii)
the average of the output voltage v0,
(iii)
the average and rms current in the diodes of rectifier,
(iv)
the average and rms current in the transistors of active filter,
(v)
the average current and rms of current iZD1,
(vi)
the rms current in the source,
(vii) the power at the source,
(viii) the energy of filter capacitor,
(b)
Use SPICE to plot the following:
(i)
the input voltage vs at source,
(ii)
the input voltage vL at AA’ on the same plot of (i)
(iii)
the rectifier output voltage v0 and active filter output voltage vD on the same plot,
(iv)
the rectifier output current i0,
(v)
the rectifier capacitor current iC on the same plot of (iv),
(vi)
the load output current iL1 on the same plot of (iv),
(vii) the line current iS,
(viii) the active filter current iC1 on the same plot of (vii),
(ix)
the transistor Z2 voltage vZ2,
(x)
the transistor Z2 current iZ2,
(xi)
the diode D4 (rectifier) voltage vD4 on the same plot of (ix),
(xii) the diode D3 (rectifier) current iD3 on the same plot of (x),
(xiii) the current iF, and
(xiv) the current iZD1 on the same plot of (xiii).
(c)
Use PSPICE to obtain the spectrum of the following:
(i)
the input voltage vs at the source,
(ii)
the input voltage vL at AA’,
(iii)
the output voltage v0,
(iv)
the line current iS,
(v)
the line current iL,
(vi)
the rectifier output current i0,
(vii) the capacitor current iC,
(viii) the rectifier output current iL1,
(ix)
the current iF,
(x)
the current iZD1, and
(xi)
the current iC1.
Compare the spectra of 1(a)(vi), 1(c)(i), and 2(c)(iv).
(i)
What is the THD and the highest harmonic (not fundamental) of iS without any
filter?
(ii)
(iii)
What is the THD and the highest harmonic (not fundamental) of iS with only the
LC filter?
What is the THD and the highest harmonic (not fundamental) of iS with LC and
active filter?
Le
iS
iL
A
0.15 mH
vS
D1
D3
iL1
i0
iD3
iC
R
1.5 mH
vL
v0
Ce
L
A’
D4
vD4 D2
iF
iZD1
2.5 mH
D1
Z1
D3
vD3 Z3
iC1
C
D4
Z4
Fig. 2
fs = 10 kHz
Fig. 3
iZ2
Z2
D2
vZ2
vD