Set Point Automatic Adjustment Research Articles

Control coordination in inverter‐based microgrids using AoI‐based 5G schedulers

AbstractA coordinated set point automatic adjustment with correction enabled (C‐SPAACE) framework that uses 5G communication for real‐time control coordination between inverter‐based resources (IBR) in microgrids is proposed. Utilising slicing capability, 5G offers low‐latency communication to C‐SPAACE under normal conditions. However, given the multitude of power grid use cases, a certain 5G slice for C‐SPAACE may have access only to limited radio spectrum resources, which if not managed well, greatly undermines the communication needs of C‐SPAACE framework. Thus, optimally scheduling the available spectrum resources among IBRs in a sliced 5G network‐based C‐SPAACE framework becomes a critical problem. To address this issue, the authors utilise a novel age of information (AoI) metric and designs an AoI‐based 5G scheduler to provide low‐latency communication to C‐SPAACE. Following this, a co‐simulation environment is designed using PSCAD/EMTDC and Python to simulate a microgrid supported by 5G communication. Time‐domain simulation case studies are performed using the proposed co‐simulation environment to evaluate the performance of C‐SPAACE using 5G with both AoI‐based and other baseline (non‐AoI) schedulers.

Cooperative predictive set point modulation control of high‐speed trains

AbstractCooperative control of high‐speed trains can improve the safety and efficiency of high‐speed railway transportation. However, the velocity and distance overshoots in the cooperative control of multiple high‐speed trains is an undesirable behavior, which will lead to unsafe and inefficient train operation. To address this issue, a cooperative predictive set point modulation control approach for high‐speed trains is proposed. First, the cyber‐physical modeling of multiple high‐speed trains is presented. The longitudinal dynamic characteristics of high‐speed trains are established in the physical layer, and the cyber layer represents the communication topology of high‐speed trains based on graph theory. Second, a cooperative control rule is designed to achieve the velocity consensus and maintain safe distance between adjacent trains. Moreover, the set point automatic adjustment with correction enable (SPAACE) is leveraged to smoothly adjust the set‐point of high‐speed trains to suppress the overshoots of train velocities and inter‐train distance. Finally, the performance of the proposed method is verified in three different simulation scenarios: normal, acceleration and deceleration conditions. The simulation results show that the proposed method reduces the maximum relative displacement by 62% and the velocity error by 34%.

Adaptive set point modulation to mitigate transients in power systems

This paper presents an adaptive control strategy to improve the transient response of a stressed power system apparatus. This strategy, based on the set point automatic adjustment with correction-enabled (SPAACE), is an auxiliary control method to enhance the set point tracking of an apparatus. SPAACE modifies the set point of the controllable apparatus using a feedback signal from its output to mitigate transients that can be caused by events such as faults, load variations, and large reference set point changes. In this work, an adaptive version of SPAACE (ASPAACE), which uses an adaptive dead-zone band, adaptive scaling factor, and exponential prediction is introduced. Moreover, this study investigates the relationship between the natural frequency of the system and the prediction horizon of the ASPAACE controller. To demonstrate the performance of ASPAACE, different case studies are presented.

Smooth reference modulation based protection of fault current limiting DC/DC converters

Low voltage DC microgrids have been gaining great attention for the integration of renewable energy source and energy storage units, and electronic loads. DC microgrids are commonly controlled using the hierarchical control strategy (HCS) to provide flexible operation in both grid-connected and islanded modes. The HCS relies on proportional-integral (PI) controllers and employs the droop control strategy. To improve the fault ride-through of HCS based extra low voltage DC microgrids, this paper proposes a simple, accurate, and cost-effective current limiting strategy. The proposed control system based scheme modulates the current reference of the primary control level of HCS during an overcurrent condition using the smooth set point automatic adjustment with correction enabled technique. It properly protects the semiconductor switches of interface voltage-sourced DC-DC converters by accurate limiting their inductor currents. The main advantage of the proposed scheme is that it is implemented in the available PI controller based primary control level of the HCS. Also, it does not require the converter and load data. Several case studies performed in MATLAB/Simulink environment are presented to demonstrate the superior ability of this scheme for limiting fault current in different scenarios compared to conventional current limiters.

Facilitating the Transition to an Inverter Dominated Power System: Experimental Evaluation of a Non-Intrusive Add-On Predictive Controller

The transition to an inverter-dominated power system is expected with the large-scale integration of distributed energy resources (DER). To improve the dynamic response of DERs already installed within such a system, a non-intrusive add-on controller referred to as SPAACE (set point automatic adjustment with correction enabled), has been proposed in the literature. Extensive simulation-based analysis and supporting mathematical foundations have helped establish its theoretical prevalence. This paper establishes the practical real-world relevance of SPAACE via a rigorous performance evaluation utilizing a high fidelity hardware-in-the-loop systems test bed. A comprehensive methodological approach to the evaluation with several practical measures has been undertaken and the performance of SPAACE subject to representative scenarios assessed. With the evaluation undertaken, the fundamental hypothesis of SPAACE for real-world applications has been proven, i.e., improvements in dynamic performance can be achieved without access to the internal controller. Furthermore, based on the quantitative analysis, observations, and recommendations are reported. These provide guidance for future potential users of the approach in their efforts to accelerate the transition to an inverter-dominated power system.

Predictive Set Point Modulation to Mitigate Transients in Lightly Damped Balanced and Unbalanced Systems

Power system controllers are designed and tuned to achieve the desired dynamic performance under prespecified system conditions. However, changes in the system, e.g., load variation, generation changes, and faults, can cause departure of the system from previously assumed parameters. This in turn can change and reduce damping, which may enable large transients to violate the operational limits of a controlled apparatus. Set point automatic adjustment with correction enabled (SPAACE) is a strategy that modulates the set point of an apparatus to mitigate such transients. This paper 1) proposes a quadratic prediction algorithm for SPAACE to enhance its performance, 2) presents a supplemental strategy to improve set point tracking even when limits are not violated, 3) introduces an approach to implement SPAACE in unbalanced systems, and 4) analyzes the stability of SPAACE. Several case studies are presented to demonstrate the superior ability of this strategy for mitigating transients in different scenarios compared to conventional PI-based control strategies.

Online Set Point Adjustment for Trajectory Shaping in Microgrid Applications

This paper proposes and evaluates a strategy to mitigate the transients of an apparatus, e.g., an electronically-interfaced distributed energy resource (DER) unit. This strategy is based on response monitoring and can be implemented based on either set point automatic adjustment (SPAA) or set point automatic adjustment with correction-enabled (SPAACE). SPAA takes advantage of an approximate model of the system to calculate the intermediate set points. SPAACE monitors the trajectory of the variable of interest and bases its decisions on the trend of variations of that variable and accounts for the inaccuracies and unmodeled dynamics by switching the command input between alternative set points. Case studies are presented to demonstrate the application and effectiveness of the proposed strategy in limiting voltage or current excursions in balanced and unbalanced microgrid study systems, subsequent to a step change in set point, load switching, and black start.