Modeling and Design of the Vector Control for a Three-Phase Single-Stage Grid-Connected PV System with LVRT Capability according to the Spanish Grid Code

Abstract

This article deals with the vector control in dq axes of a three-phase grid-connected photovoltaic system with single-stage topology and low-voltage-ride-through capability. The photovoltaic generator is built using an array of several series-parallel Suntech PV modules and is modeled as a Lookup Table (two-dimensional; 2-D). The requirements adopted when grid voltage sags occur are based in both the IEC 61400-21 European normative and the allowed amount of reactive power to be delivered according to the Spanish grid code, which avoids the disconnection of the inverter under grid faults by a limitation in the magnitude of the three-phase output inverter currents. For this, the calculation of the positive- and negative-sequences of the grid voltages is made and a conventional three-phase Phase-Locked Loop is used for the inverter-grid synchronization, allowing the control of the active and reactive powers solely with the dq components of the inverter currents. A detailed enhanced flowchart of the control algorithm with low-voltage-ride-through capability is presented and several simulations and experiments using Matlab/SIMULINK and the Controller Hardware-in-the-Loop simulation technique, respectively, are run for several types of one- and three-phase voltage sags in order to validate its behavior.

A Novel MPPT Technique for Single Stage Grid-Connected PV Systems: T4S

“…It has been named T4S (a technique based on the proper setting of the sign of the slope of the photovoltaic voltage reference signal). It is designed with specific reference to a single-stage grid-connected PV system [13][14][15]. As shown in this paper, the tracking efficiency of the proposed T4S technique is more or less comparable to that of the P&O technique.…”

“…A typical single-stage grid-connected PV system is shown in Figure 1 [13][14][15]. The DC/AC converter is an active full bridge with a control circuitry exhibiting the presence of two control loops, an inner current control loop, and an outer voltage control loop [16,17].…”

Power Quality Assessment of Grid-Connected PV System in Compliance with the Recent Integration Requirements

“…and t 2 are differing from country to country [27,28]. Not only to withstand the fault but also to inject reactive current based on the voltage drop according to the curve shown in Figure 2b is also an advance LVRT requirement to mitigate voltage sag.…”

“…If the voltage at PCC is varying in area B and retrieved after sag event to Vx within t2, it is compulsory for the PVPP to stay in operation without the trip. It is also important to mention that the values of Vx, Vy, V0, t0, t1, and t2 are differing from country to country [27,28]. Not only to withstand the fault but also to inject reactive current based on the voltage drop according to the curve shown in Figure 2b is also an advance LVRT requirement to mitigate voltage sag.…”

New SOGI-FLL Grid Frequency Monitoring with a Finite State Machine Approach for Better Response in the Face of Voltage Sag and Swell Faults

“…Second, the same FSM algorithm is applied for voltage swells, due to the fact that they cause a perturbation in the frequency response that is symmetric and opposite to that of voltage sags. The response for a 1.8 pu voltage swell is like a mirror of the response to a 0.2 pu voltage sag [21][22][23][24][25][26][27]. Consequently, the same FSM is applied to voltage swells with a few additional considerations that make the algorithm more versatile.…”