Active control strategy based on vector-
proportion integration control ler for proton
exchange membrane fuel cell grid-connected
system
ISSN 1752-1416
Received on 21st July 2014
Revised on 29th May 2015
Accepted on 3rd June 2015
doi: 10.1049/iet-rpg.2014.0245
www.ietdl.org
Qi Li
✉
, Weirong Chen, Zhixiang Liu, Guohua Zhou, Lei Ma
School of Electrical Engineering, Southwest Jiaotong University, Chengdu 610031, Sichuan Province, People’s Republic of China
✉ E-mail: liqi0800@163.com
Abstract: Considering the influence of slow response characteristic of a high-power proton exchange membrane fuel cell
(PEMFC) on a grid-connected system adequately, a 150 kW PEMFC grid-connected system, including a PEMFC power unit
based on a Ballard Stack Modules-FCvelocity™ HD6 is developed in this study. Moreover, then an active control strategy
with vector-proportion integration controller is proposed to regulate the cascade system actively and improve the
performance of c ompensating low-order harmonics. The comparisons with conventional active/reactive power (PQ)
control are carried out to verify the val idity of the pro posed method under different conditional tests. The results
demonstrate that the proposed strategy can not only track the grid power demand quickly, but also prevent the
unsteady phenomena which are aroused by PQ control method from the relatively slow response of high-power
PEMFC power unit. Furthermore, the total harmonic distortion of grid-connected current is measured by means of the
crit erion of IEEE Std1547-20 03 an d th e result of fast Fourier transform analys is testifies that the proposed strategy can
decrease the total harmonic c ontent of c urrents better. Therefore, this proposed method will be an optional effective
technique for the design of advanced high-power PEMFC grid-connected control system.
1 Introduction
Due to the energy crisis, environmental issues, and rapid growth of
the load, the penetration of small size (1–200 kW) distributed
generation (DG) systems, especially the fuel cell DGs, are
increasing rapidly for future energy productions, distribution
networks, and smart grids [1–4]. Due to its low pollution, low
operating temperature, and high efficiency, a proton exchange
membrane fuel cell (PEMFC) is considered as one of the most
promising technologies for a wide range of applications, such as
distributed power generation, automobile, and portable power
source [5–7]. In order to encourage the development of hydrogen
economy and reduce dependence on fossil fuels, large research
efforts have been underway to develop PEMFC grid-connected
systems in recent years.
At present, some researchers have reported the theory of
small-power or medium-power PEMFC grid-connected system,
and several topological structures and control strategies have been
used to achieve DG of grid-connected PEMFC. Thounthong et al.
[8] provided an innovative control strategy for a voltage-regulated
DC hybrid power source employing PEMFC as the main energy
source for a DG system. The strategy has been based on a
standard DC-link voltage regulation. Marquezini et al. [9]
presented an improved calculation algorithm to simulate the
dynamic and static states of the PEMFC operation and have
discussed the interaction between the PEMFC stack and the
converter under distinct load conditions. Sergi et al. [10] studied
on a 5 kW pre-commercial PEMFC system at direct current
constant load and in grid-connected configuration. Hawke et al.
[11] achieved a family of new multiport power-sharing converter
topologies for utility-scale fuel cell power generation. Chen et al.
[12] developed a medium-power (50 kW) PEMFC grid-connected
system based on a traditional active/reactive power (PQ) control
strategy with the resonant current controller to overcome low-order
harmonics. Yang et al. [13] proposed a medium-power (75 kW)
fuel cell grid-connected model for the distribution network based
on the traditional PQ control strategy. Thammasiriroj et al. [14]
provided a non-linear single-loop feedback control scheme based
on the differential flatness concept for a multiphase interleaved
converter for the fuel cell power source used in DC grid
applications. Zhang et al. [15] investigated a novel pulse-width
modulation (PWM) scheme for two-phase interleaved boost
converter with voltage multiplier for fuel cell power system by
combining alternating phase shift control and traditional
interleaving PWM control. Nevertheless, these proposed control
methods had not sufficiently considered the influence of the
high-power PEMFC operating characteristics. For instance, the
large delay caused by air supply subsystem will reduce the lifetime
of the PEMFC system for long operating condition and the
‘overmodulation’ phenomenon will be aroused by the PQ control
strategy due to the demand power is unable to be provided rapidly
by the high-power PEMFC system as load changes [16–18].
In addition, the reduction of the current total harmonic distortion
(THD) is a key issue for the PEMFC grid-connected system [
10, 19].
The IEEE Std1547-2003 standard allows a limit of 5% for the
current THD. In the general PEMFC grid-connected system, a
proportional–integral (PI) regulator with grid voltage feed-forward
is commonly used as the inner-loop current controller, but this
solution exhibits two well-known drawbacks: inability of the PI
regulator to track a sinusoidal reference without steady-state error
and poor disturbance rejection capability [20]. Thus, there is a
large number of low-order harmonics in the PEMFC
grid-connected system. This issue will produce a series of negative
impact of power supply reliability and power quality [21].
In this paper, a high-power (150 kW) PEMFC grid-connected
system including a Ballard Stack Modules-FCvelocity™ HD6, a
boost DC/DC converter, and a grid-connected DC/AC inverter is
developed according to the operating characteristics of a PEMFC
power unit. Moreover, then an active control strategy based on a
vector-proportional integral (V-PI) controller is proposed to
regulate the cascade system actively and improve the performance
of compensating low-order harmonics. Finally, the grid-connected
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Research Article
IET Renew. Power Gener., 2015, Vol. 9, Iss. 8, pp. 991–999
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