Measurement-Based Monitoring and Control in Power Systems with High Renewable Penetrations

Power systems are experiencing rapid changes in their generation mixes because of the increasing integration of inverter-based resources (IBRs) and the retirement of traditional generations. This opens opportunities for a cleaner energy outlook but also poses challenges to the safe operation of the power networks. Enhanced monitoring and control based on the increasingly available measurements are essential in assisting stable operation and effective planning for these evolving systems. First, awareness of the evolving dynamic characteristics is quintessential for secure operation and corrective planning. A quantified monitoring study that keeps track of the inertial response and primary frequency response is conducted on the Eastern Interconnection (EI) for the past decade with field data. Whereas the inertia declined by at least 10%, the primary frequency response experienced an unexpected increase. The findings unveiled in the trending analysis also led to an improved event MW size estimation method, as well as discussions about regional dynamics. Experiencing a faster and deeper renewable integration, the Continental Europe Synchronous Area (CESA) system has been threatened by more frequent occurrences of inter-area oscillations during light-load high-renewable periods. A measurement-based oscillation damping control scheme is proposed for CESA with reduced reliance on system models. The design, implementation, and hardware-in-the-loop (HIL) testing of the controller are discussed in detail. Despite the challenges, the increasing presence of IBRs also brings opportunities for fast and efficient controls. Together with synchronized measurement, IBRs have the potential to flexibly complement traditional frequency and voltage control schemes for improved frequency and voltage recovery. The design, implementation, and HIL testing of the measurement-based frequency and voltage control for the New York State Grid are presented. In addition to the transmission level development, IBRs deployed in distribution networks can also be valuable assets in emergency islanding situations if controlled properly. A power management module is proposed to take advantage of measurements and automatically control the electric boundaries of islanded microgrids for maximized power utilization and improved frequency regulation. The module is designed to be adaptive to arbitrary non-meshed topologies with multiple source locations for increased flexibility, expedited deployment, and reduced cost

System configuration, fault detection, location, isolation and restoration: a review on LVDC Microgrid protections

Low voltage direct current (LVDC) distribution has gained the significant interest of research due to the advancements in power conversion technologies. However, the use of converters has given rise to several technical issues regarding their protections and controls of such devices under faulty conditions. Post-fault behaviour of converter-fed LVDC system involves both active converter control and passive circuit transient of similar time scale, which makes the protection for LVDC distribution significantly different and more challenging than low voltage AC. These protection and operational issues have handicapped the practical applications of DC distribution. This paper presents state-of-the-art protection schemes developed for DC Microgrids. With a close look at practical limitations such as the dependency on modelling accuracy, requirement on communications and so forth, a comprehensive evaluation is carried out on those system approaches in terms of system configurations， fault detection, location, isolation and restoration

Combined Unbalanced Distribution System State and Line Impedance Matrix Estimation

To address the challenges that the decarbonization of the energy sector is bringing about, advanced distribution network management and operation strategies are being developed. Many of these strategies require accurate network models to work effectively. However, distribution network data are known to contain errors, and attention has been given to techniques that allow to derive improved network information. This paper presents a novel method to derive line impedance values from smart meter measurement time series, with realistic assumptions in terms of meter accuracy, resolution and penetration. The method is based on unbalanced state estimation and is cast as a non-convex quadratically constrained optimization problem. Both line lengths and impedance matrix models can be estimated based on an exact nonlinear formulation of the steady-state three-phase network physics. The method is evaluated on the IEEE European Low Voltage feeder (906 buses) and shows promising results

Batch Measurement Extremum Seeking Control of Distributed Energy Resources to Account for Communication Delays and Information Loss

Distributed Energy Resources (DER) have great potential to enhance the operation of electric power distribution systems. Previously, we explored the use of 2 Dimensional Extremum Seeking (2D-ES) control algorithms to enable model-free optimal control of DER to provide grid services to both the distribution and transmissions systems. Motivated by preliminary deployments of DER managed by 2D-ES algorithms in hardware-in-the-loop tests and in operational distribution grids, in this work, we extend the control scheme to accommodate communication delays and information loss. We propose a modification to the 2D-ES scheme to allow for the processing of batches of possibly noncontiguous objective function measurements at unknown and possibly uneven intervals. We provide a proof of the convergence of the batch 2D-ES (2D-BES) scheme when optimizing a generic convex objective function, as well as simulation results that demonstrate the suitability of the approach for substation active and reactive power target tracking

Design and Test of a Gate Driver with Variable Drive and Self-Test Capability Implemented in a Silicon Carbide CMOS Process

Discrete silicon carbide (SiC) power devices have long demonstrated abilities that outpace those of standard silicon (Si) parts. The improved physical characteristics allow for faster switching, lower on-resistance, and temperature performance. The capabilities unleashed by these devices allow for higher efficiency switch-mode converters as well as the advance of power electronics into new high-temperature regimes previously unimaginable with silicon devices. While SiC power devices have reached a relative level of maturity, recent work has pushed the temperature boundaries of control electronics further with silicon carbide integrated circuits. The primary requirement to ensure rapid switching of power MOSFETs was a gate drive buffer capable of taking a control signal and driving the MOSFET gate with high current required. In this work, the first integrated SiC CMOS gate driver was developed in a 1.2 μm SiC CMOS process to drive a SiC power MOSFET. The driver was designed for close integration inside a power module and exposure to high temperatures. The drive strength of the gate driver was controllable to allow for managing power MOSFET switching speed and potential drain voltage overshoot. Output transistor layouts were optimized using custom Python software in conjunction with existing design tool resources. A wafer-level test system was developed to identify yield issues in the gate driver output transistors. This method allowed for qualitative and quantitative evaluation of transistor leakage while the system was under probe. Wafer-level testing and results are presented. The gate driver was tested under high temperature operation up to 530 degrees celsius. An integrated module was built and tested to illustrate the capability of the gate driver to control a power MOSFET under load. The adjustable drive strength feature was successfully demonstrated

Digital current control of electric arc furnace by parallel modular three-phase IGBT inverters

Electric Arc Furnaces (EAF) have been traditionally fed by means of a medium to low voltage transformer (between grid and electrodes), where the main control action consists of modifying the electrodes vertical position. This simple and robust arrangement suffers from grid \u201cpollution\u201d and poor current control. Current control of EAF by means of three phase modular inverters is reported here for the first time. Several control issues are analyzed and addressed, ranging from pure control (e.g. addressing load imbalance and limits due to low switching frequency) to system management. Two different current regulation methods are proposed and compared, namely a scalar approach and a vector method using \u201cquasi zero phase lag\u201d sampling and gains adaptation. The second technique achieves very good control, leading to lower oversizing of the converter stage and process optimization. Simulations have been performed including digital controller architecture, converters and arc electrical behavior. Preliminary experimental measurements are reported based on an actual plant