Abstract:This paper presents the development and performance capability of a comprehensive Low voltage ride through (LVRT) control scheme that makes use of both the DC chopper and the current limiting based on the required reactive power during fault time. The study is conducted on an 8.5 MW single stage PV power plant (PVPP) connected to the Rwandan grid. In the event of fault disturbance, this control scheme helps to overcome the problems of excessive DC-link voltage by fast activation of the DC chopper operation. At… Show more
“…According to the LVRT requirement, the GCPV system tolerates voltage sags to a specific ratio of the rated voltage for a certain period, as shown in Fig. 22 [ 49 ]. Fig.…”
“…According to the LVRT requirement, the GCPV system tolerates voltage sags to a specific ratio of the rated voltage for a certain period, as shown in Fig. 22 [ 49 ]. Fig.…”
“…Figures 9b and 18b show the active power injected into the grid under fault conditions. The simulation results presented in Ntare, R et.al, [33] show the effectiveness of the DC-break circuit and current limiter strategies to enhance the LVRT capability, mitigate voltage sag by addressing excessive DC link voltage, and ride through the grid fault safely. However, this control scheme does not analyze the inverter reactive power support to the grid under fault conditions.…”
The high penetration level of solar photovoltaic (SPV) generation systems imposes a major challenge to the secure operation of power systems. SPV generation systems are connected to the power grid via power converters. During a fault on the grid side; overvoltage can occur at the direct current link (DCL) due to the power imbalance between the SPV and the grid sides. Subsequently; the SPV inverter is disconnected; which reduces the grid reliability. DC-link voltage control is an important task during low voltage ride-through (LVRT) for SPV generation systems. By properly controlling the power converters; we can enhance the LVRT capability of a grid-connected SPV system according to the grid code (GC) requirements. This study proposes a novel DCL voltage control scheme for a DC–DC converter to enhance the LVRT capability of the two-stage grid-connected SPV system. The control scheme includes a “control without maximum power point tracking (MPPT)” controller; which is activated when the DCL voltage exceeds its nominal value; otherwise, the MPPT control is activated. Compared to the existing LVRT schemes the proposed method is economical as it is achieved by connecting the proposed controller to the existing MPPT controller without additional hardware or changes in the software. In this approach, although the SPV system will not operate at the maximum power point and the inverter will not face any over current challenge it can still provide reactive power support in response to a grid fault. A comprehensive simulation was carried out to verify the effectiveness of the proposed control scheme for enhancing the LVRT capability and stability margin of an interconnected SPV generation system under symmetrical and asymmetrical grid faults.
“…Although this method is verified for fault conditions, it does not perform as expected in terms of regulating the DC link voltage. Ronald et al [7] discussed FRT control strategy based on fault detection scheme which provides reactive current injection by limiting active current. But the drawback is that it always injects more reactive power with active power curtailment even during less severe faults.…”
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