Analysis of 3-level inverter scheme with DC-link voltage balancing using LS-PWM &amp;amp; SVM techniques

IET Renewable Power Generation

Konstantinou

et al. 2017

Low-voltage ride-thorough capability is among the challenges in the operation of medium-and large-scale gridconnected photovoltaic power plants (PVPPs). In addition, reactive power injection during voltage sags is required by power system operators in order to enhance the voltage of the point of common coupling. The performance of medium-and largescale grid-connected PVPPs during these events is studied. An algorithm for the calculation of current references, in the dqframe, during voltage sags is introduced, which considers the inverter current limitation, grid code requirements and the amount of extracted power from photovoltaic strings. The proposed algorithm uses the full current capacity of the inverter in injecting active or reactive powers to the grid during voltage sags, which leads in a better grid voltage enhancement. The performance of proposed control strategies is investigated on a 150-kVA PVPP connected to the 12.47-kV medium-voltage test-case system simulation model during different fault conditions. An experimental setup of the 3.3-kVA grid-connected three-level neutral-pointclamped inverter with a dc/dc converter illustrates and validates the performance of the controller in injecting required active/ reactive power and supporting the network voltage.

Section: Proposed Control Strategy For Pvpp During Voltage Sagsmentioning

confidence: 99%

Low‐voltage ride‐thorough capability of photovoltaic grid‐connected neutral‐point‐clamped inverters with active/reactive power injection

IET Renewable Power Generation

Konstantinou

et al. 2017

“…The implementation of the ASVM in the control for the system provides good DC-link capacitor voltages balancing since there are several pairs of vector to generate the same output voltage level for the NPC inverter [16]. However, each vector pair has an opposite effect in charging or discharging of the DC-capacitors (C 1 and C 2 ).…”

Section: Proposed Voc-pr Controller Under Grid Faultsmentioning

confidence: 99%

NPC photovoltaic grid-connected inverter with ride-through capability under grid faults

2015 IEEE 11th International Conference on Power Electronics and Drive Systems

Lim

et al. 2015

Self Cite

Fault ride through (FRT) capability is one of the challenges faced in the medium to high voltage grid-tied large-scale photovoltaic (PV) power plants. This paper proposes a novel control strategy to enhance the FRT capability of a two-stage multi-string PV plant which consists of DC/DC converters and NPC inverter. The proposed control is implemented to the DC/DC converter to maintain the DC-link voltage under any grid fault conditions by adjusting the extracted PV power to the inverter output power. This is achieved by changing the PV string reference voltage from its maximum power point voltage to a new voltage point with less power. On top of that, a novel voltage-oriented control (VOC) control structure using proportional-resonant (PR) controller is proposed for the NPC inverter. Additionally, the DC-link capacitor voltages are remained balanced at all times due to the adaptive space vector modulation (ASVM) scheme. The evaluation results have verified the feasibility and the FRT capability of a 14kW PV plant using the proposed control scheme under different grid fault conditions. Index Terms-Photovoltaic systems, adaptive space vector modulation, voltage oriented control, proportional resonant control, Fault Ride-Through capability, NPC inverter.I.

“…The inverter current is controlled using the proportional resonant (PR) controller which results faster dynamic response, achieves smaller steady state error and requires lesser computational complexity. Lastly, the switching signals are generated through the adaptive space vector modulation (ASVM) which balances the DC-link capacitor voltages [7].…”

Section: B Proposed Pvpp Controller Under Unbalanced Grid Faultsmentioning

confidence: 99%

A review of active/reactive power control strategies for PV power plants under unbalanced grid faults

2015 IEEE Innovative Smart Grid Technologies - Asia (ISGT ASIA)

Lim

et al. 2015

Self Cite