Real time test benchmark design for photovoltaic grid-connected control systems

Abstract

This paper presents a dual digital signal processor (DSP) hardware architecture for a grid-connected photovoltaic interface test benchmark, based on a cascade DC/DC converter and DC/AC inverter, with coordinated control algorithms. The control hardware has been designed to test distributed generation (DG) interfaces to be integrated in a hierarchical structure of computational agents, to apply distributed control techniques to the power system management. The proposed dual DSP architecture enables the programming of the control software for the DC/DC converter and the DC/AC inverter in the same processor, to keep the other one for additional operations that are required when there is a high degree of interaction between the DG 2 unit and the rest of the electrical grid components. The hardware architecture has been tested in several real situations such as power factor correction and anti-islanding protection.

Review of Synchronization Algorithms used in Grid-Connected Renewable Agents

“…The design of the dq PLL gain is a critical point within the process; from the point of view of dynamic systems high gains will imply higher dynamics than low gains, but stability will be compromised [8]. A dq PLL structure consists in two parts: on the one hand, the Park and Clarke transformations [9,10] and on the other hand, the control [11], which is formed by a PI regulator. Under the influence of some harmonic distortions and frequency variations of the 3-phase utility grid voltages, the dq PLL may have an acceptable operation, but its major disadvantage is its high sensibility to voltage unbalances [3,5], as well as the offset of the voltage sensors used due to accuracy errors, which produces second order harmonic distortions [12], worsening its behaviour response.…”

Synchronization Algorithms for Grid-connected Photovoltaic Systems under Grid Disturbances

“…The natural reference frame (v a , v b , v c ) is converted into the stationary αβ-reference frame (v α and v β ), then to the rotating dq-reference frame (v d and v q ) as presented, respectively, in (1) and (2) [13]. To estimate the phase angle, the quadrature component v q is passed through the PI controller [14] and tuned to make it zero, then, v d gives the amplitude of the positive sequence components of the input voltages. The phase angle is obtained after integrating the estimated frequency ω, this angle is used as a feedback for the Park's transformation.…”

Real-time Implementation of Space Vector Modulation using Arduino as a Low-cost Microcontroller for Three-phase Grid-connected Inverter

“…The synchronization algorithm must detect the phase angle of the three-phase utility grid voltages with good precision and dynamic response in order to guarantee the synchronization of the controlled threephase inverter currents and guarantee the correct behavior of the inverter control method. Different synchronization structures are given by several studies [5], [24]. Consequently, due to its advantages, the Phase-Locked Loop (PLL) can be considered as the optimal one.…”