A Control Strategy for a Distributed Power Generation Microgrid Application With Voltage- and Current-Controlled Source Converter

Abstract

Abstract-This paper presents a pseudo-droop control structure integrated within a microgrid system through Distributed Power Generation modules capable to function in off-grid islanded, gensetconnected and grid-connected modes of operation. System efficiency has an important role in order to harvest the maximum available renewable energy from DC or AC sources whilst providing power backup capability. A control strategy is proposed in off grid islanded mode method based on the microgrid line frequency control as agent of communication for energy control between the DPG modules. A critical case is where the AC load demand could be lower than the available power from the photovoltaic solar array where the battery bank can be overcharged with unrecoverable damage consequences. The DPG voltage forming module controls the battery charge algorithm with a frequency generator function and the DPG current source module controls its output current through a frequency detection function. The physical installation between DPG modules is independent since no additional communication wiring is needed between power modules which represent another integration advantage within the microgrid type application.

Transient Analysis of Large Scale PV Systems with Floating DC Section

“…The natural variability of environmental conditions and nonlinear behavior of photovoltaic generators make the utilization of photovoltaic energy a challenging task [1][2][3][4]. The increasing penetration of renewable sources with power-electronic interface in the power systems is raising technical problems in various areas such as power quality control [5][6][7], voltage regulation [8], grid protection coordination [9,10], loss of mains detection [11,12], and generator operation following disturbances on the distribution grid [13][14][15].…”

“…The first architecture, appropriate for building integrated PV systems and small PV systems, incorporates a DC/AC converter or a DC/DC converter, equipped with MPPT algorithm and placed close to each PV module with the aim to reduce losses due to panel mismatching. The second architecture, appropriate for large PV plants, uses PV strings sub-fields with their own small size DC/DC converter (equipped with maximum power point tracking algorithms) placed close to the PV panels, and afterwards one or two large size common grid-connected inverters [13][14][15].…”

“…The power electronic converter must track the MPP of the PV cell [24][25][26] without modifying the mains voltage and frequency [13][14][15]. The conversion stage can be subdivided on the basis of the number of conversion stages (single or double) and on the basis of topology (e.g., centralized, string, modular, distributed).…”

Frequency-based control of islanded microgrid with renewable energy sources and energy storage

“…In [13,14], frequency is used as a communication agent for the energy control in an islanded microgrid, with no need of further communication. The goal focuses on the adjustment of the conventional droop method, considering the frequency variation and the SoC of the energy storage.…”

An Integrated Control Strategy Adopting Droop Control with Virtual Inductance in Microgrid

“…get widely used [1]. Thus we come to a definition of microgrid, namely, a network group consisting of DG units which are on the distribution network side and provide energy for local areas, energy storage devices, and loads [2,3]. Microgrid mainly operates in two modes: grid mode and island mode.…”