TY - JOUR
T1 - Enhanced Current-Limiting Droop Controller for Grid-Connected Inverters to Guarantee Stability and Maximize Power Injection Under Grid Faults
AU - Paspatis, Alexandros G.
AU - Konstantopoulos, George C.
AU - Guerrero, Josep M.
PY - 2021/3
Y1 - 2021/3
N2 - Droop-controlled inverters are widely used to integrate distributed energy resources (DERs) to the smart grid and provide ancillary services (frequency and voltage support). However, during grid variations or faults, the droop control scheme should inherit a current-limiting property to protect both the inverter and the DER unit. In this brief, a novel structure of the recently developed current-limiting droop (CLD) controller is proposed to accomplish two main tasks: 1) guarantee current limitation with maximum power injection during grid faults and 2) rigorously guarantee asymptotic stability of any equilibrium point in a given bounded operating range of the closed-loop system for a grid-connected inverter. Since the maximum power of the DER unit can be utilized under grid faults with the proposed enhanced CLD and then inspired by the latest fault-ride-through requirements, it is further extended to provide voltage support to a faulty grid via the maximum injection of reactive power. This is achieved by simply adjusting the reactive power reference opposed to the existing control schemes that require adjustment of both the real and the reactive powers. Hence, a unified current-limiting control scheme for grid-connected inverters under both normal and faulty grids with a simplified voltage support mechanism is developed and experimentally verified in this brief.
AB - Droop-controlled inverters are widely used to integrate distributed energy resources (DERs) to the smart grid and provide ancillary services (frequency and voltage support). However, during grid variations or faults, the droop control scheme should inherit a current-limiting property to protect both the inverter and the DER unit. In this brief, a novel structure of the recently developed current-limiting droop (CLD) controller is proposed to accomplish two main tasks: 1) guarantee current limitation with maximum power injection during grid faults and 2) rigorously guarantee asymptotic stability of any equilibrium point in a given bounded operating range of the closed-loop system for a grid-connected inverter. Since the maximum power of the DER unit can be utilized under grid faults with the proposed enhanced CLD and then inspired by the latest fault-ride-through requirements, it is further extended to provide voltage support to a faulty grid via the maximum injection of reactive power. This is achieved by simply adjusting the reactive power reference opposed to the existing control schemes that require adjustment of both the real and the reactive powers. Hence, a unified current-limiting control scheme for grid-connected inverters under both normal and faulty grids with a simplified voltage support mechanism is developed and experimentally verified in this brief.
KW - Current-limiting property
KW - Droop control
KW - Inverter
KW - Nonlinear control
KW - Stability analysis
KW - Voltage sags
KW - Voltage support.
UR - http://www.scopus.com/inward/record.url?scp=85077254750&partnerID=8YFLogxK
U2 - 10.1109/TCST.2019.2955920
DO - 10.1109/TCST.2019.2955920
M3 - Journal article
AN - SCOPUS:85077254750
SN - 1063-6536
VL - 29
SP - 841
EP - 849
JO - IEEE Transactions on Control Systems Technology
JF - IEEE Transactions on Control Systems Technology
IS - 2
M1 - 8943267
ER -