Excitation Control Research Articles

Optimization of Design Method and Experiment of A Repetition Pulse Charging HIA-CCPS

Due to the advantage of high-power density, high energy storage density and fast repetition pulse charging ability, homopolar inductor alternator (HIA) has been successfully applied in the capacitor charging power supply (CCPS) system, leading to a new capacitor charging power supply (HIA-CCPS) in recent years. To obtain a compact HIA-CCPS with high performances of light weight, small size, high repetition pulse output ability and so on, it is still of great necessity to develop quantitative analysis from alternators to the pulse load such as capacitors. Unfortunately, many researchers only focus on the alternator design or use a single charging process with constant speed instead of the repetition charging dynamic process with a large speed change for simplifying analysis. As a result, parameters' influence between alternators and others in the system is not clear, it is not easy to find out a system-wide optimal scheme. In this text, a comprehensive design method for HIA-CCPS with repetition pulse charging is proposed. Firstly, a simplified model is presented to analyze the influence of different parameters. The repetition pulse charging characteristics of HIA is investigated. After that, a novel design method of repetition pulse charging is given, and an excitation control strategy during the charging is put forward to ensure the charging time remains almost constant between each charging time. Finally, a platform of HIA-CCPS is developed and experiments are carried out. The experiment results indicate that the proposed method is very helpful for a repetition charging HIA-CCPS to develop the optimization design.

Enhancing Rotor Angle Stability of Synchronous Generators Using Neuro-Fuzzy Excitation Control Model

This paper proposes a neuro-fuzzy excitation control model to enhance the rotor angle stability of synchronous generators. The proposed model combines the advantages of both neural networks and fuzzy logic control to improve the performance of the excitation system. The proposed model is designed to regulate the excitation system to generate the required reactive power and maintain the synchronous operation of the generator. The proposed model is tested on a single-machine infinite-bus power system, and the results are compared with a conventional proportional-integral (PI) controller. The simulation results demonstrate that the neuro-fuzzy excitation control model provides better performance than the PI controller in terms of transient stability, damping oscillations, and response to disturbances. The proposed model also shows robustness against changes in system parameters and different operating conditions. The results of this study suggest that the neuro-fuzzy excitation control model can be a suitable alternative to conventional PI controllers in enhancing the rotor angle stability of synchronous generators.

Design of controls for ISS and Integral ISS Stabilization of Multistable State Periodic Systems

This paper is devoted to the construction of continuous and periodic controllers for ISS or iISS stabilization of a class of multistable state periodic systems. For this purpose, the concepts of practical ISS-, ISS- and iISS-control Leonov functions are introduced. Then, it is proven that the existence of these functions is a sufficient condition to ensure that the system under study is ISS- or iISS stabilizable, and explicit feedback control laws can be obtained by means of a mild adaptation of Sontag's universal formula. The proposed method is illustrated by the design of an excitation controller for a synchronous generator ensuring ISS of the closed-loop system.

Efficiency of a Six-Phase Induction Generator Employing a Static Excitation Controller to Generate AC Power for Wind Energy

The most widely applied six phase induction generator (SPIG) leads to insufficient frequency regulation ability of power system. A six phase induction generator (SPIG) Combined with appropriate capacitors and a motor, it produces an induction generator that is self-excited. The advantage of this generator, which has recently caught the interest of various experts, particularly in the field of wind energy, combines the advantages of multiphase devices. This study aims to offer a technique for regulating the voltage of a wind-powered SPIG. The methodology suggests two different compensation setups for (V-f) control, involving two switching capacitors. Different setups’ performance constraints, controls, and features will be closely scrutinized and contrasted. The performance limits of the suggested system will be contrasted. to those of variable speed and variable capacity systems after being modelled and simulated. The results show that using the optimal capacitances for each configuration improves voltage and frequency regulation significantly. The preferable option, however, is short-shunt compensation since it regulates the output voltage and frequency with the fewest capacitances and the least amount of necessary duty fluctuation.

Izbor parametara i analiza dinamičkih karakteristika limitera minimalne pobude primenom računarskog modela

This paper presents a method for selecting parameters and analyzing the dynamic characteristics of a under-excitation excitation limiter using a computer model. The parameters are determined using the pole cancellation method for the worst-case operating regime from the perspective of the under-excitation limiter to ensure stability in all operating regimes. The analysis of the dynamic characteristics presented in the paper first obtained the time responses and frequency characteristics of the excitation control system when the limiter is active. Based on these, the values of dynamic performance indicies that indicate the quality of regulation are determined. The paper also provides a brief description of the implementation of the limiter and the computer models used in the analysis.

Ellipsoidal Design of Robust Stabilization of Power Systems Exposed to a Cycle of Lightning Surges Modeled by Continuous-Time Markov Jumps

Power system stability is greatly affected by two types of stochastic or random disturbances: (1) topological and (2) parametric. The topological stochastic disturbances due to line faults caused by a series of lightning strikes (associated with circuit breaker, C.B., opening, and auto-reclosing) are modeled in this paper as continuous-time Markov jumps. Additionally, the stochastic parameter changes e.g., the line reactance, are influenced by the phase separation, which in turn depends on the stochastic wind speed. This is modeled as a stochastic disturbance. In this manuscript, the impact of the above stochastic disturbance on power system small-disturbance stability is studied based on stochastic differential equations (SDEs). The mean-square stabilization of such a system is conducted through a novel excitation control. The invariant ellipsoid and linear matrix inequality (LMI) optimization are used to construct the control system. The numerical simulations are presented on a multi-machine test system.

A Behavioral Study of Different Controllers and Algorithms in Real-Time Applications

Systems, generally being nonlinear behaves unexpectedly due to external disturbances. Therefore, operation controllers are needed in tracking, chemical engineering, electrical engineering, and other areas. For continuing quality and productivity of industrial firms, the deployment of industrial robots is increasing. Different structures of fuzzy-Proportional Integral Derivative based trajectories for robot manipulators are designed, for various regular and irregular trajectories. Industrial robot’s performance is compared by Proportional Integral Derivative and Fuzzy- Proportional Integral Derivative controller. For tracking the peak power in a Photo Voltaic system, a nonlinear proportional–integral–derivative controller is applied for rapidly changing environmental conditions, particle swarm optimization based Nonlinear-PID, Maximum Power Point Tracking method offers a clean response for Maximum Power Point Tracking. To maintain constant frequency and power variations in power systems the freedom of a three-degree Proportional Integral Derivative controller was designed. For excitation control in Automatic Voltage Regulators, Proportional Integral Derivative and Proportional Integral Derivative -Acceleration controllers are used, Proportional Integral Derivative -Acceleration has more response speed and more stability and it has a good response time and response of frequency by implementing the Particle Swarms Optimization and Gravitational Search algorithm-based Proportional Integral Derivative controller Automatic Voltage Regulator’s voltage response is effective. This paper deals with studying the behavior of various controllers and algorithms in practical applications, comparative analysis of magnetic levitation system response with different controllers and algorithms, and finding the performance of magnetic levitation systems by using a Particle Swarm Optimization algorithm-based Proportional Integral Derivative controller.

Transient stability analysis of the standalone solar‐storage AC supply system based on grid‐forming and grid‐following converters during sudden load variation

AbstractThe standalone solar‐storage AC supply system is an efficient form of utilizing renewable energy. The solar‐storage supply system normally includes two types of converters, grid‐forming (GFM) and grid‐following (GFL) converters. Nevertheless, the incompatibility of the dynamic performance between the GFM and GFL converters due to different control schemes may introduce the transient instability risk to the solar‐storage supply system. To address this issue, it is extremely necessary to perform transient stability analysis and stability‐enhanced control for such a system. In this paper, a sixth‐order model of the dc‐link timescale for the solar‐storage supply system is developed, whose accuracy and applicability are verified by comparing with the detailed electromagnetic model. Based on the derived model, the analysis demonstrates that the solar‐storage supply system faces the potential risk of transient instability under large disturbances of sudden load variation, due to the mismatch of the transient response speeds between virtual excitation control of the GFM converter and dc voltage control of the GFL converter. The transient stability boundary of the system is quantitatively investigated, by depicting the basin of attraction of the post‐disturbance equilibrium point. Furthermore, from the perspective of improving the coordination of the transient behaviours between the GFM converter and the GFL converter, the parameters related to virtual excitation control and dc voltage control are designed to enhance the transient stability of the system. Time‐domain simulations and real‐time simulations are conducted to validate the theoretical analysis.DC–AC power convertors, microgrids, power system control, power system transient stability, renewable energy power conversion

Inhibition of Kv7/M Channel Currents by Fangchinoline

Introduction: Voltage-gated Kv7/M potassium channels play an essential role in the control of membrane potential and neuronal excitability. Fangchinoline, a bisbenzylisoquinoline alkaloid, displays extensive biological activities including antitumor, anti-inflammatory, and antihypertension effects. In this study, we investigated the effects of fangchinoline on Kv7/M channels. Methods: A perforated whole-cell patch technique was used to record Kv7 currents from HEK293 cells and M-type currents from mouse dorsal root ganglion (DRG) neurons. Results: Fangchinoline inhibited Kv7.2/Kv7.3 currents in a concentration-dependent manner, with an IC₅₀ of 9.5 ± 1.2 μM. Fangchinoline significantly inhibited Kv7.1, Kv7.2, Kv7.3, Kv7.4, and Kv7.3/Kv7.5 channels without selective effects. Furthermore, fangchinoline significantly slowed the activation of Kv7.1-Kv7.5 channels and inhibited native M-channel currents of DRG neurons. Conclusion: Taken together, our findings indicate that fangchinoline concentration-dependently inhibited Kv7/M channel currents.

The mechanisms of chromogranin B-regulated Cl- homeostasis.

Chloride is the most abundant inorganic anions in almost all cells and in human circulation systems. Its homeostasis is therefore important for systems physiology and normal cellular activities. This topic has been extensively studied with chloride loaders and extruders expressed in both cell surfaces and intracellular membranes. With the newly discovered, large-conductance, highly selective Cl- channel formed by membrane-bound chromogranin B (CHGB), which differs from all other known anion channels of conventional transmembrane topology, and is distributed in plasma membranes, endomembrane systems, endosomal, and endolysosomal compartments in cells expressing it, we will discuss the potential physiological importance of the CHGB channels to Cl- homeostasis, cellular excitability and volume control, and cation uptake or release at the cellular and subcellular levels. These considerations and CHGB's association with human diseases make the CHGB channel a possible druggable target for future molecular therapeutics.

Research on Adjustable-Speed Asynchronous Condenser with AC Excitation and Its Excitation Control Strategy

In this paper, a speed-adjustable asynchronous condenser with AC excitation and its excitation control strategy are proposed. Through excitation control, the asynchronous condenser not only can adjust the voltage by reactive power output but also can adjust the speed to release rotational kinetic energy and increase the system inertia to smooth system frequency. In this paper, the model of the asynchronous condenser is established, and then a transiently improved control strategy for the asynchronous condenser considering the change of the stator excitation current, is proposed. It is verified by simulation that after the transient improvement control strategy is adopted, the asynchronous condenser can provide reactive power support and a certain frequency support capability to the system.

Dynamic Response of Power Systems With Real GICs: Impact on Generator Excitation Control

Geomagneticallyinduced current (GIC) studies usually focus on transformer response to dc but seldom analyze generator excitation systems. A GIC is driven by an electric field which is induced by a very low-frequency geomagnetic field. It is widely acceptable to model GICs with dc, mostly suitable for static voltage stability analysis, but this does not adequately characterize a power system's dynamic response. Considering this, we studied a multi-machine power system on an OPAL-RT digital real-time simulator (DRTS)-MATLAB/Simulink system. We used real GIC measurement data from high and mid-latitude regions. Wavelet analysis related the frequency components of the GIC to the power system's response. A dynamic generator model with excitation voltage control modelled the source. Our main finding is that excitation system control contributes to reducing the voltage drop caused by increased var demand in saturated transformers with GICs. Measured GICs revealed non-negligible short-term dynamics affecting bus voltages that are not captured with dc-modelling assumptions, yet they are important for voltage stability analysis. This study implies that excitation control creates a buffer for high GICs to flow without violating the grid codes for minimum operating voltages and this paper demonstrates the optimization of this novel approach.

Study on mechanism analysis, specimen influence, and compensation control of large compound shaking table

In order to realize the wide frequency excitation and high accuracy control of a new type of large load-capacity seismic simulation shaking table (named large compound shaking table, LCST), it is necessary to study the in-depth mechanism, influence factors, and compensation algorithm of the LCST. In this paper, the mechanism model of LCST was established by transfer function matrix and the coupling characteristics were analyzed by Bristol method. Then, the three-variable control simulation analysis was carried out by Simulink. The specimen influence on the LCST was tested by setting different mass, frequencies, and damping ratios of the specimen. A series of simulation studies suggest that the control accuracy of LCST is most sensitive to the frequency of the specimen, and high natural frequency could even lead to system instability. For the sake of high-precision control, this paper proposed a feedforward decoupling compensation control (FDCC) strategy. Through numerical studies, the improved tracking of the FDCC strategy was demonstrated. In addition, the mature compensation methods in the conventional shaking table can be introduced reasonably into the control loop by FDCC strategy so that the LCST can more accurately replicate the characteristics of synthetic and historic earthquakes.

The Relevance of GIRK Channels in Heart Function.

Among the large number of potassium-channel families implicated in the control of neuronal excitability, G-protein-gated inwardly rectifying potassium channels (GIRK/Kir3) have been found to be a main factor in heart control. These channels are activated following the modulation of G-protein-coupled receptors and, although they have been implicated in different neurological diseases in both human and animal studies of the central nervous system, the therapeutic potential of different subtypes of these channel families in cardiac conditions has remained untapped. As they have emerged as a promising potential tool to treat a variety of conditions that disrupt neuronal homeostasis, many studies have started to focus on these channels as mediators of cardiac dynamics, thus leading to research into their implication in cardiovascular conditions. Our aim is to review the latest advances in GIRK modulation in the heart and their role in the cardiovascular system.

Power System Stability Improvement of FACTS Controller and PSS Design: A Time-Delay Approach

The existence of low-frequency oscillations in power systems is the cause of power angle instability, limiting the transmission of maximum tie-line power. One of the effective ways to improve the stability limits is by installing a power system stabilizer and supplementary excitation control to augment with an automatic voltage regulator (AVR) supplemental feedback stabilizing signal. This paper proposes a new strategy for simultaneously tuning the power system stabilizer (PSS) and FACTS controller, considering time delays. The design of the proposed controller is modeled as an optimization problem, and the parameters of the controller are optimized through the grasshopper optimization algorithm (GOA). The suggested controller’s efficacy is evaluated for both single-machine infinite bus systems and multi-machine power systems under various disturbances. It also investigated the performance of the proposed controller with variations in signal transmission delays. The results obtained from GOA optimized proposed controller are compared with those obtained from the differential evolution algorithm, genetic algorithm, and whale optimization algorithm. In this context, the proposed GOA optimized controller reduced the objective function value by 16.32%, 14.56%, and 13.72%, respectively, in the SMIB system and 1.41%, 9.98%, and 13.31%, respectively, for the multi-machine system compared with the recently published WOA, and the well-established GA and DE. Further, the proposed controller is found to be stable and effectively increases stability even under small disturbances.

DSE-assisted DEF strategy for locating forced oscillations in synchronous generators

We present a new methodology to identify if forced oscillation (FO) sources are located in excitation systems or turbine governors. In this context, we propose to harness the information that dynamic state estimation (DSE) provides to be able to apply a dissipating energy flow (DEF) method. Measurements from phasor measurement units (PMUs) are used to estimate the internal states of different generators connected to the same bus. Using these estimations, we compute energy functions for the mechanical control loop and for the excitation control loop to determine where the FO was originated. Simulated signals from the IEEE-NASPI Oscillation Source Location (OSL) Contest are used to show that our proposal provides an online systematic methodology for identification and location of power systems forced oscillations, even when current measurements of the generator causing the FO are missing.

Power Tracking Excitation Control and Its Parameter Optimization of Dual-Excited Synchronous Generator

A dual-excited synchronous generator (DESG) with two field windings on the rotor has better dynamic characteristics and high stability. However, the realization of the function needs a reasonable excitation control strategy. In this article, a power tracking excitation control (PTEC) is proposed to improve the operating performances of the DESG. The dynamic processes of a 300-MW DESG with the PTEC are calculated after the disturbance of the torque and reactive power by the time-stepping finite element model, and the results are superior to those adopting the traditional dual-channel excitation control. To further improve the dynamic characteristic of the DESG, the sensitivities of the control parameters of the PTEC to the dynamic characteristic indices are studied. The fuzzy control rules are built based on the sensitivity analysis results and the control parameters are optimized by the fuzzy control method. It revealed the variation laws of the optimized control parameters along with the active and reactive power deviations and their variable rates. The results show that the DESG adopting the optimized control parameters has better dynamic characteristics. The study can provide the theoretic basis for enhancing the system damping effect and suppressing the system oscillation.

Social deficits via dysregulated Rac1-dependent excitability control of prefrontal cortical neurons and increased GABA/glutamate ratios.

Identifying symptom-specific convergent mechanisms for neurodevelopmental disorders is a promising strategy in advancing therapies. Here, we show that bidirectional dysregulation of Rac1 activity in the medial prefrontal cortex (mPFC) dictates shared social deficits in mice. Selective upregulation or downregulation of Rac1 activity in glutamatergic or fast-spiking GABAergic neurons results in excessive or inadequate control of excitability combined with a decrease in glutamate or an increase in GABA concentrations and an increase in the GABA/glutamate ratio, which is responsible for social deficits. Notably, the autism model of Shank3B knockout mice exhibits aberrantly enhanced Rac1 activity, reduced glutamate concentrations, and pyramidal neuron excitability in mPFC accompanied with social deficits, which were corrected by either excitatory-neuron-specific downregulation of Rac1 activity or upregulation of neuronal excitability. Thus, this work shows a convergence between genetic autism risk factors, dysregulation of Rac1 signaling, and excitation-inhibition imbalance, enabling mechanism-based stratification of patients with social deficits.

The Self-Correcting Control Strategy of a Single Flux Linkage Closed Loop for a Contactor

For the first time, a single flux linkage closed-loop control scheme for contactors using fast excitation control is proposed. The integrated observer and closed-loop state observer are designed to observe the flux linkage during the making and closing processes, respectively. After the contactor finishes the making and closing processes under the initial flux linkage control, it enters a self-correcting process that involves decreasing the flux linkage step by step. Two observers are used interchangeably to ensure the accuracy of flux linkage observation in this process; once the decrease in flux linkage becomes insufficient for maintaining the contactor in the closing state, the movable core separation signal is captured in time, and the critical flux linkage is determined based on the flux linkage jump of the closed-loop state observer. Then, the fast response of the single flux linkage closed-loop control can ensure the timely application of short-time and intense excitation and prevent the continued rebound of the movable core before contactor separation. Comprehensive use of the above methods enables the development of the self-correcting control strategy of a single flux linkage closed loop for a contactor. This result is of great significance for automatic bouncing inhibition and energy-saving optimization of contactors.

Speed Control of Direct Current Motor via Pole Placement Control

This paper describes a separately excited DC motor speed control using armature voltage control method, based on traditional Proportional- Integral- Derivative (PID) controller, and pole assignment, feedback control technique. The main objective of the proposed controller is to control the speed of a DC motor shaft rotation and overcome problems like overshoot, and increasing the system model order, that are caused by PID controller, with a step response. Results obtained with Ziegler – Nichols PID controller were compared with those obtained using pole placement. DC motor response contains a 24% overshoot with PID controller; compared with 0.0286% overshoot. In the response of pole placement controller, it is found that pole placement reduces system overshoot to 0.0015% ofthe closed loop system.