Design and Control of a Buck–Boost Charger-Discharger for DC-Bus Regulation in Microgrids

Abstract

Abstract:In DC and hybrid microgrids (MG), the DC-bus regulation using Energy Storage Devices (ESD) is important for the stable operation of both the generators and loads. There are multiple commercial voltage levels for both ESD and DC-bus; therefore, the ESD voltage may be higher, equal or lower than the DC-bus voltage depending on the application. Moreover, most of the ESD converter controllers are linear-based, hence they ensure stability in a limited operation range. This paper proposes a system to regulate the DC-bus voltage of an MG accounting for any voltage relation between the ESD and the DC-bus voltage. The proposed system is formed by an ESD connected to a DC-bus through a bidirectional Buck-Boost converter, which is regulated by a Sliding-Mode Controller (SMC) to ensure the system stability in the entire operation range. The SMC drives the Buck-Boost charger-discharger to regulate the DC-bus voltage, at the desired reference value, by charging or discharging the ESD. This paper also provides detailed procedures to design the parameters of both the SMC and the charger-dischager. Finally, simulation and experimental results validate the proposed solution and illustrate its performance.

Stability Criteria for Input Filter Design in Converters with CPL: Applications in Sliding Mode Controlled Power Systems

“…Stable operation region S for first-order filter. It should be remarked that, unlike condition (5) obtained via eigenvalue linear analysis, the condition given by (12) defines the stable region of the first-order filter, fully determining the admissible range for the capacitor voltage v. It establishes that if the voltage v satisfies:…”

“…where similarly to (12), g 0 is the equivalent output conductance viewed from the filter and g s is the internal conductance of the source. Second Lyapunov condition in terms of conductances.…”

“…For the case under study, the condition arrived in (12) provides a relation between the output conductance g 0 and the source conductance g s for the stability of the ZD system described in (1). This relation can be compared for different values of the output power P f in a conductance diagram, where a stable operation region can be established.…”

“…In this context, Sliding Mode (SM) control have been increasingly accepted for controlling power conditioning systems [5][6][7][8][9]. These control techniques proved to be particularly suitable for electronic converters, granting excellent features of robustness and finite-time convergence, which make them highly appropriate for microgrid applications [10][11][12][13][14].…”

Energy Management in PV Based Microgrids Designed for the Universidad Nacional de Colombia

“…For example, the DC/DC converter associated with the PVS is regulated using algorithms and/or control strategies aimed at tracking the maximum power point (MPP); hence, such algorithms are known as MPP tracking (MPPT) solutions. The ESS integration with the DC-bus is performed using bidirectional converters and control strategies [23,24] to regulate the DC-bus voltage and to guarantee the global power balance in the standalone MG when excess or shortage power exists. However, additional conditions can also be considered; for example, a limitation to the power generated by the PVS [25][26][27], which is applied when the ESS reaches the maximum state of charge (SOC) during low power demand, or a load disconnection when the ESS reaches the minimum SOC during high power demand [25,28].…”