Open Journal of Applied Sciences, 2013, 3, 30-34
doi:10.4236/ojapps.2013.32B006 Published Online June 2013 (http://www.scirp.org/journal/ojapps)
Fault Ride-Through Capability Enhancement of PV
System with Voltage Support Control Strategy*
Dehui Zeng, Gang Wang, Guoqing Pan, Haifeng Li
School of Electric Power, South China University of Technology, Guangzhou, China
Email: 705484965@qq.com, gq.pan@163.com
Received 2013
ABSTRACT
With continuously increasing of photovoltaic (PV) plant’s penetration, it has become a critical issue to improve the fault
ride-through capability of PV plant. This paper refers to the German grid code, and the PV system is controlled to keep
grid connected, as well as inject reactive current to grid when fault occurs. The mathematical model of PV system is
established and the fault characteristic is studied with respect to the control strategy. By analyzing the effect of reactive
power supplied by the PV system to the point of common coupling (PCC) voltage, this paper proposes an adaptive
voltage support control strategy to enhance the fault ride-through capability of PV system. The control strategy fully
utilizes the PV system’s capability of voltage support and takes the safety of equipment into account as well. At last, the
proposed control strategy is verified by simulation.
Keywords: PV System; Fault Ride-Through; Voltage Support; Control Strategy
1. Introduction
Under the pressures of environment pollution and energy
shortages, power generation from renewable energy
sources has been increasing significantly. Photovoltaic
(PV) power generation can be used conveniently and
gives no pollution, and has become one of the most
widely used distributed generation technologies in recent
years[1].
With the increasing of PV penetration, the grid codes
from German[2,3], Japan[4] and China[5] have required
the PV system to have the low voltage ride-through ca-
pability, which defines as the PV inverters’ capability of
remaining grid-connected in the event of grid failures.
What’s more, in the German grid code, the PV inverter is
required to supply reactive power when voltage drops, so
as to support the voltage. This requirement can make full
use of the auxiliary functions of PV plant, which would
take benefit to the participation of the PV plant[6]. On
the other hand, the reactive power supplied by the PV
plant can support the voltage effectively with high pene-
tration of PV plant[7]. Therefore, when voltage drops,
making full use of the voltage support capability of the
PV plant will lead the trend of grid code in the future.
But at the moment, there is no theoretical research on the
effect of the reactive power from PV plant to voltage
support, which would limit the enhancement of fault
ride-through capability of PV system.
This paper refers to the German grid code, and the PV
inverter is controlled to supply reactive power when
voltage drops. The fault characteristic of the PV system
is studied with respect to the control strategy. Based on
this, the effect of the reactive power from PV inverter to
the point of common coupling (PCC) voltage is analyzed
and an adaptive voltage support control strategy is pro-
posed to enhance the fault ride-through capability of PV
system. At last, the proposed control strategy is verified
by simulation.
2. PV Inverter Mathematical Model and
Fault Characteristic
PV array produces dc current by photovoltaic effect. The
maximum power point tracking (MPPT) control strategy
is generally used to control the dc voltage to stay at the
maximum power point as the volt-ampere characteristic
shows serious nonlinearity[8]. With the synchronous
reference frame control, the output power of the PV in-
verter can be written as:
This work is supported by the National Basic Research Program o
China (973 Program) (2009CB219704), the Crucial Field and Key
Breakthrough Project in “Guangdong-Hongkong” (No. 2009A0913
00011), Guangdong Special Fund Project of Industry, University and
Research Institute Collaboration (2011A090200127,2011A090200074),
Guangdong Nature Science Foundation(S2012010008355).
outP CCd
outP CCq
PUI
QU
I
(1)
where is magnitude of PCC voltage, and
PCC
Ud
, q
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