Dynamic performance comparison involving grid‐connected PV systems operating with active power‐line conditioning and subjected to sudden solar irradiation changes

Abstract

This study presents a comparative performance analysis involving single-and double-stage photovoltaic (PV) systems, which are connected to a three-phase four-wire electrical system by means of a four-leg inverter topology. The doublestage PV system is composed of a step-up DC/DC converter and a four-leg grid-connected inverter, while in the single-stage PV system the PV array is directly connected to the inverter DC bus. In addition to the active power injection into the grid, both PV systems have two attractive features, described as follows: (i) power quality improvement due to their capability to perform active power-line conditioning, such as load harmonic current suppression, reactive power compensation, and load unbalance compensation; (ii) dynamic improvement in the occurrence of abrupt solar irradiation variations, which is achieved through the implementation of a feed-forward control loop (FFCL) acting directly in the inverter DC-bus voltage control loop, resulting in speeding up of the dynamics of both the DC-bus voltage and the injected grid-inverter currents. The referred comparative analysis addresses the static and dynamic performances considering the PV systems operating under the action of the FFCL, as well as performing active power-line conditioning. Simulation and experimental results are presented to evaluate and validate the proposed study.

Performance enhancement of photovoltaic system under grid voltage distortion utilising total least‐square control scheme

“…For that reason, feed‐forward compensation (FFC) is required to get the desired energy balance between the output power of DC–DC converter and injected power to the grid during transient conditions. The desired PV array weight component is estimated using FFC as [7] where D is the duty ratio of the front side converter and MPPT algorithm controls this converter by generating the reference voltage ( V ref ) according to MPP. Thus, the optimal value of D is estimated as …”

“…A broad variety of control algorithms for GIPV systems have been reported in the literature. Several researchers have incorporated the instantaneous p–q theory [5], power balance theory [6] and synchronous reference frame (SRF) theory [7] for controlling the GIPV system, which were initially used for active power filters. Inherently, p–q theory introduces undesirable harmonic components into the system; which were not present in the original load current and will not give accurate compensation under distorted unbalanced supply conditions.…”

Photovoltaic system operation as DSTATCOM for power quality improvement employing active current control

“…In this sense, possible disturbances due to deviation in the DC-bus terminal voltage and voltage undershoot/overshoot is actively diminished. Besides, the settling time duration of DC-bus terminal voltage in the event of severe transients is also reduced [16]. The following procedure estimates the peak amplitude (i Fpeak ) of fundamental current that would be transferred to the electric grid.…”

“…Furthermore, a proportional-resonant (PR) [16] and vector proportional-integral (VPI) [17] current controllers have been presented to tune the fundamental frequency under input grid voltage disturbances and in turn achieving minimum steady-state error in current control loop (CCL) of the PV inverter. Besides, in [18], fractional-order (FO)-based voltage control scheme is proposed to ensure satisfactory operation under unbalanced and distorted load currents.…”

Impact of Load Ramping on Power Transformer Dissolved Gas Analysis

“…Since the Kyoto agreement was ratified by most of the nations, there has been a global common goal for reducing greenhouse gas emissions through adopting more renewable energy sources such as photovoltaic (PV) and wind power generation [1]- [3]. Due to the intermittent characteristics of these sources such as solar irradiations and wind speed fluctuations and impact of diffused solar irradiations resulting from passing clouds, power transformers are expected to exhibit…”