Abstract
In this paper, a novel method for real-time prediction of voltage sag duration is proposed. It is based on the recently introduced new characteristic of voltage sag, named harmonic footprint, and is formulated using a logistic regression model. The concept is mathematically formulated and statistically analyzed using an extensive set of real grid measurement data which are recorded in distribution grids. Furthermore, the proposed method is applied as a part of an advanced grid-tie converter control. It is included in previously developed methods for fast sag detection and magnitude of voltage sag prediction. The algorithm is applied to the control of grid-tie converters used in distributed generators and tested with real/grid measurement data in the IEEE 13-bus test grid by simulations and in the IEEE 33-bus test grid using a hardware-in-the-loop (HIL) microgrid laboratory testbed. It is shown that this method can prevent unnecessary tripping of distributed generators (DG) and improve low-voltage ride-through (LVRT) support. In addition, the model has the potential to be applied to a wide range of devices or algorithms for the protection, monitoring, and control systems of distribution grids.
Highlights
Modern distribution networks are characterized by increased penetration of distributed energy resources (DERs), that is, distributed generators (DGs) based mainly on renewable energy sources (RESs)
THE RTTP ALGORITHM The real-time prediction of probability (RTPP) method is a real-time method; it is suitable for implementation in the control system of power electronic converters connected to the grid
It can be seen that as a result of the RTPP application, the inverter control system can achieve a time gain for moving the operating point according to the low-voltage ridethrough (LVRT) requirements and starts supporting the grid
Summary
Modern distribution networks are characterized by increased penetration of distributed energy resources (DERs), that is, distributed generators (DGs) based mainly on renewable energy sources (RESs). They are stipulating that a DER should stay connected during a voltage sag for a predefined short time and support the grid by providing a certain amount of reactive power (Q) and active power (P) depending on the voltage sag depth and duration [22, 23] This task requires momentary adaptation of the DER control system and the setting of a new operation point [24,25,26,27]. The establishing of the mathematical model and verification using a set of voltage sags data obtained by real-grid measurements are presented Such a solution is implemented for DER control circuit improvement and tested in a modified IEEE 13-bus test grid. The rest of the paper is composed of conclusions, acknowledgments, and references
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