Pulsed Power Loads Research Articles

A Novel Resilient Control of Grid-Integrated Solar PV-Hybrid Energy Storage Microgrid for Power Smoothing and Pulse Power Load Accommodation

Solar photovoltaics (PVs) are increasingly penetrating remote are a power systems. However, the adverse effect of pulse power loads and fluctuating PV power brings severe grid instability. Therefore, an effort is made to propose a hybrid energy storage system (HESS) that encompasses hydrogen/bromine redox flow battery (RFB) and supercapacitor (SC) for grid-integrated PV systems to facilitate high energy and power support. Furthermore, the system is equipped with an antiwindup mixed-order generalized integrator (AWMOGI), an improved sparrow search algorithm (ISSA) tuned tilt integral–derivative with filter (TIDF) controller, and a fast-acting adaptive dc-link power-based energy management control. AWMOGI extracts fundamental components of grid voltage and is immune to noise and grid disturbances. The ISSA-tuned TIDF controller has better error mitigation ability and quickly settles the actual signal to the reference for dc-link voltage control of the voltage-source inverter, PV maximum power point tracking, and HESS control that improves the overall system dynamics. The energy management system coordinates RFB and SC participation in handling sudden and average changes in power surges resulting in the first dc-link voltage regulation and less current stress on RFB. The proposed system and furnished control effectiveness are confirmed through MATLAB simulation and OPAL-RT real-time simulator test bench.

Active Disturbance Rejection Control Using Artificial Neural Network for Dual-Active-Bridge-Based Energy Storage System

The dual-active-bridge (DAB) converter has become a popular isolated solution to integrate energy storage systems (ESSs) and dc microgrids (MGs). However, constant power loads (CPLs) and pulsed power loads (PPLs) may reduce system damping and cause voltage oscillations in DAB converter-based ESSs (DAB-ESSs). An artificial neural network-based active disturbance rejection control (ANN-ADRC) is proposed to regulate constant output voltage quickly and accurately under different operating conditions. First, the ADRC controller is designed based on the small-signal modeling of the DAB-ESSs. Feedforward compensation and uncertainty estimations of the extended state observer (ESO) help to improve the dynamic performance and to reduce the number of current sensors. Then, after satisfying the conditions of stability analysis, the parameters of the ADRC controller are selected automatically via ANN. The ANN is trained with two inputs (ADRC controller parameters) and two outputs (performance indicators of the ADRC controller). The well-trained ANN can be used as a surrogate model to obtain the optimal solution of the objective function easily and quickly. The proposed ANN-ADRC algorithm with selected parameters is implemented and validated on the hardware experimental setup. The experimental results illustrate that the proposed controller can achieve fast dynamic performance under various operating conditions.

Deep Reinforcement Learning-Based Optimal Control of DC Shipboard Power Systems for Pulsed Power Load Accommodation

To accommodate the pulsed power load (PPL) in the dc shipboard power system, the charging performance of the energy storage system (ESS) specialized for the PPL needs to be guaranteed, which leads to a challenging power system optimal control problem due to multiple objectives, operational constraints, complex nonlinear system structure, and uncertainties. This paper addresses this problem by using a model-free optimal control method based on the deep reinforcement learning (DRL). First, a dc shipboard power system optimal control problem with three control objectives and the input constraints is formulated, where three objectives include the fast ESS charge, the dc bus voltage regulation, and the proportional load current sharing. Then, to solve this problem, a DRL control framework based on the improved twin-delayed deep deterministic policy gradient (TD3) algorithm is developed, which adopts a modified critic network predicting technique and a stack-based data sampling strategy that are suitable for this fast-dynamic power system. The proposed method links the DRL framework with the optimal control. With the reward function being properly designed, the presented DRL control can well realize three control objectives. Case studies considering various operating conditions of the power system verify its effectiveness.

Shipboard Control System Supported by Energy Storage Sizing to Meet the MIL-STD-1399 Limits for Pulsed Power Loads

Shipboard Control System Supported by Energy Storage Sizing to Meet the MIL-STD-1399 Limits for Pulsed Power Loads

Exploring Grid-Edge Computing [From the Editor

Data-driven computing has been a hot topic, AND <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">IEEE Electrification Magazine</i> presented a themed issue on data and cyberphysical systems in March 2021 to cover various data-driven applications in power electronics systems and power grid operations. Examples include synchrophasor-based monitoring; impedance characterization for stability prediction; and pulsed power load monitoring of all-electric ships.

Design of a Multiloop Control Structure for Load-Disturbance Attenuation and Power-Mismatch Mitigation in Isolated Multiport Power Converters

This article proposes a multiloop control structure for isolated multiport power converters (IMPCs), which includes a multiloop load-disturbance attenuation controller (MLDAC) and also an improved multiloop power-mismatch mitigation controller (MPMMC). The inherent capability of the IMPC to use a common magnetic link (CML) instead of multiple magnetic links offers an attractive solution to design a compact multimodule-based IMPC. With the proposed MLDAC, the IMPC can regulate the system voltage for any load disturbance without requiring any feedforward output current sensor. Moreover, the proposed MPMMC effectively mitigates leakage parameter mismatch and strictly balances the power routing in the multiple ports of the IMPC. The proposed MLDAC and MPMMC are decoupled with an improved decoupling mechanism. Additionally, this article develops a control law to indicate a safe operating area of the MPMMC. The strict voltage regulation of the IMPC under random load disturbance facilitates plug-n-play connectivity and supply of power to pulsed power loads. Moreover, eliminating the power-mismatch issues in the CML ensures equal thermal stresses and duty-life cycles of the solid-state switching devices. The performance of the proposed MLDAC is tested and compared with existing disturbance attenuation techniques. The simulation and the experimental results substantiate the superiority of the proposed MLDAC and MPMMC.

MMC Stationary Operating Regimes in Case of Periodic Power Demand on the DC Side

The operation of modular multilevel converters (MMCs) with a periodic dc-side voltage is considered whose fundamental frequency component is linked to the grid frequency. Such a voltage component arises for instance by operating a pulsed power load, which is analyzed in this article as an example for this problem class. This application entails harmonic voltage components, which in conjunction with the ac current, lead to an imbalance of the available arm voltages. Although purely feedback-based balancing schemes can reduce the imbalance, they may fail to mitigate it sufficiently. Considering the balancing problem already during the stationary regime design, new options appear, which are to be investigated. Recent modeling methods are employed in order to analyze and mitigate this imbalance. In particular, the imbalance is already dealt with during the determination of suitable stationary operating regimes. Thanks to this, four regimes are derived, one of which is analogous to an already published regime for the concerned application. The regimes are compared on the basis of their individual advantages and their impact on the converter rating. Three of them avoid the singularity that is present in the already published regime. The findings are supported by numerical and experimental results.

Decentralized Coordination and Stabilization of Hybrid Energy Storage Systems in DC Microgrids

Hybrid energy storage system (HESS) is an attractive solution to compensate power balance issues caused by intermittent renewable generations and pulsed power load in DC microgrids. The purpose of HESS is to ensure optimal usage of heterogeneous storage systems with different characteristics. In this context, power allocation for different energy storage units is a major concern. At the same time, the wide integration of power electronic converters in DC microgrids would possibly cause the constant power load instability issue. This paper proposes a composite model predictive control based decentralized dynamic power sharing strategy for HESS. First, a composite model predictive controller (MPC) is proposed for a system with a single ESS and constant power loads (CPLs). It consists of a baseline MPC for optimized transient performance and a sliding mode observer to estimate system disturbances. Then, a coordinated scheme is developed for HESS by using the proposed composite MPC with a virtual resistance droop controller for the battery system and with a virtual capacitance droop controller for the supercapacitor (SC) system. With the proposed scheme, the battery only supplies smooth power at steady state, while the SC compensates all the fast fluctuations. The proposed scheme achieves a decentralized dynamic power sharing and optimized transient performance under large variation of sources and loads. The proposed approach is verified by simulations and experiments.

A New Approach on Modeling of Pulsed-Power Loads

Pulsed power sources provide high-power waves with high frequency (HF) content for a wide range of applications. Conventionally, a simple resistance is employed for the most prevalent pulsed power loads. However, the load model can highly affect the efficiency of source design. This paper contributes to fill this gap by considering the HF behavior of the loads. Accordingly, a new approach has been proposed to present a general HF lumped-circuit model for pulsed power loads. The frequency response of the loads is identified using the Finite Integration Technique (FIT). Subsequently, an equivalent circuit model is established based on the vector fitting (VF) algorithm. The applicability of the approach has been verified by comparison with two experiments, i.e. Vircator and coaxial reactor as the loads. It is indicated that the HF-based model can significantly improve the simulation results to be in good agreement with experiments. The results present that while a pure-resistive load model could lead to about 30% error in the estimation of the characteristics of output voltage, it is about less than 5% in the case of the proposed HF load model.

Optimal State-Constrained Control of DC Shipboard Power Systems for Online Pulsed Power Load Accommodation

Pulsed power loads (PPLs) consume a huge amount of energy within a short time. An energy storage system (ESS) is usually installed in a shipboard power system (SPS) for PPL accommodation. Online accommodation strategies, where the PPL is connected to the SPS through the ESS all the time, have great advantages in reducing the hardware cost and increasing the PPL deployment frequency. But there is a lack of online accommodation solutions to deal with the operational requirements. This article presents a barrier-Lyapunov-function-based optimal control solution for online PPL accommodation in dc SPSs. By introducing the state-constrained technique, the operational constraints on the supply current for PPL accommodation and the bus voltage are all respected. Three control objectives, including safe and fast ESS charging, high-quality regulation of the dc bus voltage, and generation cost dynamic minimization, are realized simultaneously. The stability and optimality of the control solution are guaranteed rigorously via the Lyapunov synthesis. Simulations based on a switch-level SPS model demonstrate the effectiveness of the proposed control solution.

Deep Reinforcement Learning Control for Pulsed Power Load Online Deployment in DC Shipboard Integrated Power System

Online deployment of pulsed power load (PPL) is one of the most challenging issues in DC shipboard integrated power systems (SIPSs), which leads to a multi-objective optimal control problem subject to various constraints in this paper. Since traditional model-based methods face difficulties in designing the optimal control policy and are prone to model inaccuracy and parameter uncertainty, there is an urgent need for a model-free and also high-performance control approach. Thus, a deep reinforcement learning (DRL) optimal control, which employs the twin-delayed deep deterministic policy gradient (TD3) algorithm, is presented in this paper. The DRL optimal control adopts a stack-based state observation technique to enhance learning and control performance, and it uses a multi-objective reward function design to signify the overall dynamic performance. Besides achieving the safe and fast online deployment of PPL, it also fulfills the regulation of DC bus voltage and the proportional current sharing among distributed generations (DGs). Moreover, the DRL control has an advantage in handling the ramp rate constraints of SIPS. The optimal control satisfying ramp rate constraints can be obtained through a deep learning process. The performance of the proposed DRL control is validated by case studies considering different load conditions.

Coordinated Control and Optimal Flow of Shipboard Mvdc System for Adapting to Large Pulsed Power Load

Coordinated Control and Optimal Flow of Shipboard Mvdc System for Adapting to Large Pulsed Power Load

Mitigation of pulsed power load effect on power system using FLC-SMES

Integration of the pulsed power load (PPL) into the power system leads to high fluctuations in the frequency and voltage at the point of common coupling (PCC). This paper presents an effective solution to overcome these issues related to the PPL using the superconducting magnetic energy storage (SMES) system that has the features of high power capability and fast response. The fuzzy logic control technique (FLC) is employed to control the interfaced DC–DC chopper of the SMES to regulate the active power of the PCC and the state-of-charge (SOC) of the SMES coil. Two scenarios have been addressed with/without integrating the SMES conversion system. The on-time of the studied PPL is 0.1s with a total power of 5.7 MW, which is considered a high power demand in a short period. The simulation results based on MATLAB/Simulink show the high performance of the proposed system based on the FLC-SMES to minimize the voltage and frequency fluctuations during the operation of PPL.

Fault Protection Considerations for MVDC Shipboard Power Systems Operating with Pulsed-Power Loads

Medium Voltage Direct Current (MVDC) power distribution architectures are of immense interest for various shipboard power applications due to their advantages over classical MVAC distribution systems with respect to power quality, power density, and efficiency. However, MVDC are far away from maturity when compared to MVAC with respect to fault detection and isolation. Currently, there are no standards available for applying MVDC protection systems in shipboard applications. Furthermore, due to the absence of zero crossings in DC waveforms and unique transient fault signatures, it is challenging to design effective protection system schemes to isolate faults via conventional protection systems. This paper investigates and analyses various types of shipboard MVDC dynamic fault behaviours and signatures under different DC bus disturbances such as: bus to ground, bus to bus to ground, and impact of Pulsed-Power Load (PPL) with and without faults on a shipboard MVDC distribution system. Furthermore, a communication-based fault detection and isolation system controller that improves upon a directional ac overcurrent relay protection system is proposed offering additional protection discrimination between faults and PPLs in MVDC systems. To validate the effectiveness of the proposed protection controller, different bus current disturbances are simulated within a time-domain electromagnetic transient simulation of a shipboard power system including a PPL system operating with different ramp rate profiles, pulse widths, peak powers, and fault locations

Optimal Flow of MVDC Shipboard Microgrids With Hybrid Storage Enhanced With Capacitive and Resistive Droop Controllers

Hybrid storage system composed of battery energy storage systems (BESSs) and supercapacitors is a promising solution to mitigate the high frequency power fluctuations of pulsed power loads (PPLs) in medium voltage DC (MVDC) shipboard power systems. Due to the presence of multiple storage units, a power sharing algorithm needs to be considered within the energy management system (EMS) in the shipboard power system. In this paper, an optimal power flow problem is formulated for MVDC shipboard power systems with hybrid energy storage systems. Battery energy storage systems (BESSs) and conventional generation units are enhanced with virtual resistive droop controllers to share the steady-state power fluctuations. Supercapacitors are enhanced with virtual capacitive droop controllers to share the high frequency fluctuations in the load. The optimal flow accounts for minimizing the operational cost of the generation units in the shipboard power system considering the constraints of network, load balance, voltage profile, and power/energy limits. Second-order cone programming (SOCP) relaxation is used to approximate the nonconvexity of the optimal flow formulation and necessary conditions for global optimality of the solution are discussed. Results confirm the effectiveness of the proposed formulation in load support and managing the energy between storage units.

Power quality metrics for DC grids with pulsed power loads

&lt;span lang="EN-GB"&gt;DC grids can effectively feed pulsed power loads (PPLs), integrating local energy storage to minimize the impact on other connected loads and implementing buffered sub-grids to isolate susceptible loads even more. The identification of regulatory limits for PPL integration and DC grid response and the assessment of PPL impact necessitate suitable Power Quality (PQ) metrics. Existing indexes and limits (e.g. ripple and distortion, voltage fluctuation) are compared to other metrics, derived from control methods and knowledge of the peculiar characteristics of PPL and interaction with DC grids in some examples. The objective is a unified approach for PQ metrics suitable for a wide range of DC grids and in particular to the behavior of PPLs.&lt;/span&gt;

Modelling and simulation on a novel meat grinder circuit for the dynamic pulsed power load

Compared with the capacitive pulsed power supply (CPPS), the inductive pulsed power supply (IPPS) is considered to have broader prospects because of its theoretically higher energy densities. Most recent researches focus on characteristics of the IPPS with a fixed load, which is rather different from practical applications from the engineering point of view. In this paper, with the purpose of preliminarily verifying the IPPS’s feasibility, the performance of the novel meat grinder circuit with a dynamic load model is presented and analysed under PSpice environment. The analysis model is based on the parameters of the four-module IPPS and the pulsed power load built in Institute of Electrical Engineering. Finally, the comparison between the IPPS and the CPPS with same initial energy is carried out.

Study on harmonic source model of millisecond pulsed power load based on switching functions

Modern radar is a typical millisecond pulse power load (MPPL), which contains a large number of power electronic devices. If the MPPL is connected to the power system, it will cause serious voltage distortion problems. The working mode of the radar pulse load will directly affect the voltage distortion. In order to analyze the influence of MPPL on the system voltage distortion, a harmonic source model of MPPL were proposed based on the switching functions. At the same time, in order to evaluate the degree of voltage distortion, an improved voltage distortion evaluation index-Waveform Relative Deviation Rate (WRDR) is proposed. The harmonic source model is based on the equivalent topology of MPPL, which can theoretically explain the cause of the sub-harmonic and inter-harmonic currents, and can reflect the influence of the parameters of MPPL on its harmonic characteristics. The simulation and experimental results prove that the harmonic source model can be used to calculate the distribution and magnitude of the harmonic current of MPPL, and to explain the cause of voltage distortion. Finally, the improved voltage distortion evaluation index is used to analyze and summarize the influence of MPPL on voltage distortion.

Comparative assessment of supercapacitor bank switching techniques under constant resistor, constant current, and constant power loads

High specific power density and longer cycle life features made the supercapacitors as the most prominent option in managing the transient demands of the pulsed power loads. However, the discharging characteristics of supercapacitors confine them from the utilisation of their entire energy. Reflecting on these concerns, this study aims to provide an extensive review of various bank switching circuits of supercapacitors to enhance their energy utilisation. Also, a comprehensive analysis of these switching circuits in terms of power delivery duration, SC cell energy utilisation, terminal voltage variations, system efficiency, and total cost is carried out for the constant resistor, constant power, and constant current loads.

Self-Healing Predictive Control of Battery System in Naval Power System With Pulsed Power Loads

This article presents a model predictive self-healing control (MPSC) scheme for battery system interfaced dual active bridge (DAB) converter in navy ship power system (NSPS) with pulsed power loads (PPLs). The voltage and frequency of NSPS are vulnerable to PPLs energization. A properly controlled battery system with fast dynamic response can mitigate this vulnerability. Model predictive control (MPC) is a potential solution for the battery system interfaced DAB converter to achieve fast dynamic response and mitigate disturbances imposed to the NSPS by PPLs. However, conventional MPC framework suffers from current prediction error due to the pulsating AC-link inductor's voltage profile in DAB converter. This article proposes a self-healing control loop that utilizes the feasible range of power transfer in conjunction with the AC-link inductor's voltage profile. The proposed method can validate and autonomously correct the predicted current and phase shift in DAB converter interfaced a battery system. The proposed control scheme on DAB converter prevents voltage and frequency collapse in a hybrid AC/DC NSPS particularly during the PPL energization. The system stability is studied based on Lyapunov stability analysis. The theoretical concepts are validated by several case studies implemented on a hardware-in-the-loop (HIL) testbed of a NSPS. The case studies demonstrate voltage and frequency regulation of the NSPS with fast dynamic response during PPLs energization. The proposed MPSC performance is compared with proportional-integral (PI) based control for DAB in NSPS with PPLs.