ABSTRACT
This paper presents a transformerless static synchronous compensator
(STATCOM) system based on multilevel H-bridge converter with star
configuration. This proposed control methods devote themselves not only to the
current loop control but also to the dc capacitor voltage control. With regards
to the current loop control, a nonlinear controller based on the
passivity-based control (PBC) theory is used in this cascaded structure STATCOM
for the first time. As to the dc capacitor voltage control, overall voltage
control is realized by adopting a proportional resonant controller. Clustered
balancing control is obtained by using an active disturbances rejection
controller. Individual balancing control is achieved by shifting the modulation
wave vertically which can be easily implemented in a field-programmable gate
array. Two actual H-bridge cascaded STATCOMs rated at 10 kV 2 MVA are constructed
and a series of verification tests are executed. The experimental results prove
that H-bridge cascaded STATCOM with the proposed control methods has excellent
dynamic performance and strong robustness. The dc capacitor voltage can be
maintained at the given value effectively.
KEYWORDS:
Active disturbances rejection controller (ADRC), H-bridge cascaded,
passivity-based control (PBC), proportional resonant (PR) controller, shifting
modulation wave, static synchronous compensator (STATCOM).
SOFTWARE:
MATLAB/SIMULINK
CONTROL
BLOCK DIAGRAM:
Fig. 1.
Control block diagram for the 10 kV 2 MVA H-bridge cascaded STATCOM.
Fig. 2.
Block diagram of PBC.
EXPERIMENTAL
RESULTS:
Fig. 3.
Experimental results verify the effect of PBC in steady-state process. (a) Ch1:
reactive current; Ch2: compensating current; Ch3: residual current of grid. (b)
Ch1: reactive current; Ch2: compensating current; Ch3: residual current of
grid.
Fig. 4.
Experimental results show the dynamic performance of STATCOM in the dynamic
process. Ch1: reactive current; Ch2: compensating current; Ch3: residual
current of grid.
Fig. 5.
Experimental results in the startup process and stopping process. (a) Ch1:
reactive current; Ch2: compensating current; Ch3: residual current of grid. (b)
Ch1: reactive current; Ch2: compensating current; Ch3: residual current of
grid.
CONCLUSION
This paper
has analyzed the fundamentals of STATCOM based on multilevel H-bridge converter
with star configuration. And then, the actual H-bridge cascaded STATCOM rated
at 10 kV 2 MVA is constructed and the novel control methods are also proposed
in detail. The proposed method has the following characteristics.
1) A PBC
theory-based nonlinear controller is first used in STATCOM with this cascaded
structure for the current loop control, and the viability is verified by the
experimental results.
2) The PR
controller is designed for overall voltage control and the experimental result
proves that it has better performance in terms of response time and damping
profile compared with the PI controller.
3) The ADRC
is first used in H-bridge cascaded STATCOM for clustered balancing control and
the experimental results verify that it can realize excellent dynamic compensation
for the outside disturbance.
4) The
individual balancing control method which is realized by shifting the
modulation wave vertically can be easily implemented in the FPGA.
The
experimental results have confirmed that the proposed methods are feasible and
effective. In addition, the findings of this study can be extended to the
control of any multilevel voltage source converter, especially those with
H-bridge cascaded structure.
REFERENCES
[1] B.
Gultekin and M. Ermis, “Cascaded multilevel converter-based transmission STATCOM:
System design methodology and development of a 12 kV ±12 MVAr
power stage,” IEEE Trans. Power Electron., vol. 28, no. 11, pp.
4930–4950, Nov. 2013.
[2] B.
Gultekin, C. O. Gerc¸ek, T. Atalik, M. Deniz, N. Bic¸er, M. Ermis, K. Kose, C.
Ermis, E. Koc¸, I. C¸ adirci, A. Ac¸ik, Y. Akkaya, H. Toygar, and S. Bideci,
“Design and implementation of a 154-kV±50-Mvar
transmission STATCOM based on 21-level cascaded multilevel converter,” IEEE
Trans. Ind. Appl., vol. 48, no. 3, pp. 1030–1045, May/Jun. 2012.
[3] S.
Kouro, M. Malinowski, K. Gopakumar, L. G. Franquelo, J. Pou, J. Rodriguez,
B.Wu,M. A. Perez, and J. I. Leon, “Recent advances and industrial applications
of multilevel converters,” IEEE Trans. Ind. Electron., vol. 57, no. 8,
pp. 2553–2580, Aug. 2010.
[4] F. Z.
Peng, J.-S. Lai, J. W. McKeever, and J. VanCoevering, “A multilevel voltage-source
inverter with separateDCsources for static var generation,” IEEE Trans. Ind.
Appl., vol. 32, no. 5, pp. 1130–1138, Sep./Oct. 1996.
[5] Y. S.
Lai and F. S. Shyu, “Topology for hybrid multilevel inverter,” Proc. Inst.
Elect. Eng.—Elect. Power Appl., vol. 149, no. 6, pp. 449–458, Nov. 2002.
