Fast Voltage Control Research Articles

Fast and Accurate Neutral-Point Voltage Control Under Balanced and Unbalanced Neutral-Point Voltage for Coupled Ten-Switch Three-Phase Three-Level Inverter

Fast and Accurate Neutral-Point Voltage Control Under Balanced and Unbalanced Neutral-Point Voltage for Coupled Ten-Switch Three-Phase Three-Level Inverter

Fast dynamic DC-link voltage control strategy for dual three-phase PM-assisted synchronous reluctance starter/generator system

Fast dynamic DC-link voltage control strategy for dual three-phase PM-assisted synchronous reluctance starter/generator system

Design and Implementation of Single-Phase Grid-Connected Low-Voltage Battery Inverter for Residential Applications

Integrating residential energy storage and solar photovoltaic power generation into low-voltage distribution networks is a pathway to energy self-sufficiency. This paper elaborates on designing and implementing a 3 kW single-phase grid-connected battery inverter to integrate a 51.2-V lithium iron phosphate battery pack with a 220 V 50 Hz grid. The prototyped inverter consists of an LCL-filtered voltage source converter (VSC) and a dual active bridge (DAB) DC-DC converter, both operated at a switching frequency of 20 kHz. The VSC adopted a fast DC bus voltage control strategy with a unified current harmonic mitigation. Meanwhile, the DAB DC-DC converter employed a proportional-integral regulator to control the average battery current with a dynamic DC offset mitigation of the medium-frequency transformer’s currents embedded in the single-phase shift modulation scheme. The control schemes of the two converters were implemented on a 32-bit TMS320F280049C microcontroller in the same interrupt service routine. This work presents a synchronization technique between the switching signal generation of the two converters and the sampling of analog signals for the control system. The prototyped inverter had an efficiency better than 90% and a total harmonic distortion in the grid current smaller than 1.5% at the battery power of ±1.5 kW.

Fast DC-link voltage control based on power flow management using linear ADRC combined with hybrid salp particle swarm algorithm for PV/wind energy conversion system

Hybrid Energy Systems (HESs) are offering several advantages over conventional generation systems because of the rising need for Renewable Energy Resources (RERs) and its high capability and flexibility of achieving the desired performance for both urban and rural areas. The main goals of HESs are to improve the system performance by increasing its flexibility, reliability and reducing generation instability. In the current work, a hybrid Photovoltaic/Wind Energy Conversion System (PV/WECS) is proposed to supply and support the utility grid. The generated power from the system is greatly responding to the change in both the wind speed and PV irradiance level, and as a result impacting the DC-Bus voltage of the system converters. Therefore, precise, fast and optimum controllers are required for the PV/WECS system to ensure the extraction and generation of stable maximum power during weather variations along with maintaining the DC-Link voltage at the desired value. Further, this study proposes a novel Linear Active Disturbance Rejection Control (LADRC) combined with a hybrid Salp Particle Swarm Algorithm (SPSA) to a grid-connected PV/WECS for extracting the Global Maximum Power (GMP), regulating the DC-Link voltage, and enhancing the active and reactive powers control. The capability of the proposed SPSA-LADRC based-MPPT approach is examined according to the tracking time, accuracy and response to internal and external disturbances and then comparing its performance with other techniques such as SPSA-SMC, SPSA-PID and SPSA-PI controllers respectively. The findings revealed that the LADRC can track and keep the DC-Link voltage as the desired reference value,1500 V, respond much faster than the PI, SMC, and PID controllers as well as keep the THD of the injected current into the grid at a low level of 2.25%. Finally, the performance of the proposed system is experimentally verified using Hardware-In-Loop (HIL). The obtained findings verify the capability and accuracy of the system and its great potential in the management of HESs.

A Fast Primary-Side Current and Voltage Control for Direct Wireless Battery Chargers

A Fast Primary-Side Current and Voltage Control for Direct Wireless Battery Chargers

Distributed fast finite-time secondary control of islanded microgrids: A disturbance observer-based approach

For islanded microgrids with inverter-based distributed generators (DGs), this article focuses on the fast finite-time secondary voltage and frequency control problem considering system uncertainties. The distributed controller is designed based on the command filtered backstepping procedure, and a disturbance observer is constructed to estimate the lumped system uncertainties (including parameter perturbations, unmeasurable variables, etc.). In addition, the singularity issue derived from differentiating the virtual control law is avoided by using a smooth switch function. The proposed controller guarantees that the tracking errors of voltage and frequency converge to a small region around the origin in a finite time, while achieving desired active power sharing ratio. Case studies are conducted on a microgrid system to demonstrate the effectiveness of the proposed strategy in the presence of load changes and parameter perturbations.

A Communication-Free Fast Constant Current and Voltage Control Method for Dynamic Wireless Power Transfer System

A Communication-Free Fast Constant Current and Voltage Control Method for Dynamic Wireless Power Transfer System

Fast and Precise Output Voltage Control of the Buck Converter Without Increasing the System’s Order

Fast and Precise Output Voltage Control of the Buck Converter Without Increasing the System’s Order

A linear Distflow model considering line shunts for fast calculation and voltage control of power distribution systems

The line shunts are usually ignored by various linear power flow (PF) models in power distribution system analysis, planning and optimization. However, “charging effects” from line shunts of underground/submarine power cables would cause non-negligible model errors for these commonly used PF models. In this paper, we propose a modified Linear Distflow model (LinDist) with line shunts, i.e., LinDistS. We also further propose its extensions considering the ZIP load, weakly-meshed topology and unbalanced three-phase systems. Moreover, the linearization error of voltage component is theoretically analyzed. Case studies show that compared with other models, the proposed LinDistS achieves the descent calculation accuracy and efficiency. We also show the application scope of LinDistS by a Volt/VAr control (VVC) framework with distributed generators, mainly photovoltaic (PV), and the non-negligible “charging effect”. Simulation exhibits that with LinDistS, the VVC can optimally dispatch the shunt capacitors and also optimize the real-time reactive power output of PV. Moreover, with LinDistS, the VVC shows better solutions’ consistency and higher computing efficiency compared to traditional VVC methods.

Nonlinear control of permanent magnet synchronous generators (PMSG) using feedback linearization

This paper presents nonlinear control of permanent magnet synchronous generators using feedback linearization. Permanent-magnet synchronous generators (PMSGs) are commonly used for small variable-speed wind turbines to produce highefficiency, high-reliability, and low-cost wind power generation. To eliminate the effects of nonlinearity caused by magnetic saturation, an input–output feedback linearization technique is applied to design the high-performance nonlinear current controllers. With this nonlinear control scheme, output voltage responses become faster than those in cascade control structures. Thus, the size of the output filter capacitor can be much reduced since fast voltage control is feasible. As with usual PWM power converters, in addition, the input current is regulated in a sinusoidal waveform. The proposed control scheme provides the wind generation system with the maximum efficiency and high dynamic performance.

Fast and robust DC link voltage control of single-phase grid-connected converters supporting 50 Hz and 60 Hz mains with universal magnitudes range

It is well-known that dynamics of single-phase grid-connected power converters employing PI or type-II DC link voltage controllers is limited by the maximum tolerable value of utility-side current total harmonic distortion (THD). Moreover, universal DC link voltage controller must be capable of supporting both 50 Hz and 60 Hz utilities and universal range of magnitudes (85Vrms–265Vrms). As a result, DC link crossover frequency value (and hence corresponding settling time) may vary significantly in case grid voltage magnitude variations are not compensated in the controller. In order to cope with the above-mentioned deficiencies, the paper suggests a design methodology for a novel dual-frequency-tuned utility magnitude insensitive plug-in disturbance observer (DOB), supporting universal utility frequencies and magnitudes so that the transient response of a grid-connected converter is improved without altering the existing PI or type-II DC link voltage controller coefficients. These characteristics are attained by robust modification of DC link voltage loop plant to possess notch-like properties around two frequencies of interest and treating the grid voltage magnitude value as non-measurable uncertainty translated into input disturbance and subsequently cancelled. Analytical design guidelines for obtaining PI + DOB controller coefficients are provided for desired values of utility-side current THD and DC link voltage loop phase margin (PM). Simulations and experimental results are provided to validate the feasibility of proposed design methodology.

Probabilistic approach to investigate the impact of distributed generation on voltage deviation in distribution system

The increasing penetration of renewable-based generation in the distribution network adds randomness to the bus voltage due to its stochastic characteristics. Consequently, the distribution network faces voltage limit violations at multiple buses. In this scenario, the traditional voltage control method fails to maintain the voltage profile of the network due to its slow response time. A fast and dynamic voltage control technique can be achieved by utilizing the voltage-controlling capability of available DGs in the network with the information about the impact of DG-integrated bus on change in voltage at any bus in the network. Evaluating this information using the traditional probabilistic load flow method is computationally inefficient for real-time applications. Therefore, in this paper, a principal component analysis (PCA)-based novel probabilistic voltage sensitivity index (PVSI) is proposed. It ranks the DG-integrated buses by evaluating the impact of power perturbation at DG-integrated buses on changes in voltage at any bus in the network. The PVSI is analytically derived to reduce the computation time for ranking. Further, the proposed PVSI is validated on the 69-bus and the 141-bus distribution systems by comparing it with the traditional Monte Carlo simulation (MCS) and joint differential entropy (JDE) in terms of accuracy and computation time. From the simulation, it is observed that PVSI gives a similar ranking as both methods in less computation time. Due to the advantage in computation time, the proposed method enables the distribution system operator (DSO) to use this information for fast and dynamic voltage control in a real-time scenario.

Phasor measurement units‐based fast voltage control strategy for distribution network with high‐penetration distributed photovoltaic

AbstractAs the penetration of distributed photovoltaic (PV) in the distribution network continues to increase, the problem of voltage violation is becoming increasingly prominent. PV output has strong volatility and uncertainty, leading to higher requirements on speed and accuracy of voltage control. The voltage qualification rate of the distribution network with PV is difficult to guarantee if relying on traditional measuring installation and discrete regulators. Thus, it is necessary to introduce high‐frequency sampling devices and various continuous regulators in real‐time voltage control. In this paper, a fast voltage control strategy by real‐time coordination of dynamic voltage regulators (DVRs) and PV inverters based on phasor measurement units (PMU) and remote terminal unit (RTU) information is proposed. The voltage sensitivity is calculated online based on the fast measurement information of PMU. The equivalent models of rapid voltage regulators including DVR and PV inverter are established for the online extraction of voltage optimal control gradients. According to the model predictive control (MPC) theory, a feeder‐level global voltage control strategy is proposed comprehensively considering the objectives of voltage qualification rate, control cost, and network loss, which can realize real‐time voltage control in the distribution network at the millisecond scale. The effectiveness and rapidity of the proposed global voltage control strategy are verified in the IEEE 33‐bus system and a real representative distribution system for preventing voltage violation.

Control Design of Dynamic Virtual Power Plants: An Adaptive Divide-and-Conquer Approach

In this paper, we present a novel control approach for dynamic virtual power plants (DVPPs). In particular, we consider a group of heterogeneous distributed energy resources (DERs) which collectively provide desired dynamic ancillary services such as fast frequency and voltage control. Our control approach relies on an adaptive divide-and-conquer strategy: first, we disaggregate the desired frequency and voltage control specifications of the aggregate DVPP via adaptive dynamic participation matrices (ADPMs) to obtain the desired local behavior for each device. Second, we design local linear parameter-varying (LPV) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathcal {H}_\infty$</tex-math></inline-formula> controllers to optimally match this local behaviors. In the process, the control design also incorporates the physical and engineered limits of each DVPP device. Furthermore, our adaptive control design can properly respond to fluctuating device capacities, and thus include weather-driven DERs into the DVPP setup. Finally, we demonstrate the effectiveness of our control strategy in a case study based on the IEEE nine-bus system.

Decentralized safe reinforcement learning for inverter-based voltage control

Inverter-based distributed energy resources provide the possibility for fast time-scale voltage control by quickly adjusting their reactive power. The power-electronic interfaces allow these resources to realize almost arbitrary control law, but designing these decentralized controllers is nontrivial. Reinforcement learning (RL) approaches are becoming increasingly popular to search for policy parameterized by neural networks. It is difficult, however, to enforce that the learned controllers are safe, in the sense that they may introduce instabilities into the system.This paper proposes a safe learning approach for voltage control. We prove that the system is guaranteed to be exponentially stable if each controller satisfies certain Lipschitz constraints. The set of Lipschitz bound is optimized to enlarge the search space for neural network controllers. We explicitly engineer the structure of neural network controllers such that they satisfy the Lipschitz constraints by design. A decentralized RL framework is constructed to train local neural network controller at each bus in a model-free setting.

Continuous and fast magneto-ionic control of magnetism in Ta/Co/BiFeO3/SrRuO3 multiferroic heterostructure

Room temperature electric field controlled magnetism is extremely promising for the next-generation high-performance spintronic devices. Here, based on the ferroelectric switching driven oxygen ion migration in the Ta/Co/BiFeO3/SrRuO3 heterostructures, the magnetic moment, magnetic coercive field, exchange bias field, and junction resistance are reversibly manipulated by tuning the ferroelectric polarization of the BiFeO3 layer. All these phenomena are consistently explained by the oxygen ion migration induced CoOx/Co redox effect, which is evidenced by the synchrotron X-ray absorption spectroscopy measurements. Interestingly, owing to the controllable ferroelectric switching dynamics of the BiFeO3 thin film, the magnetic coercive field of the Co thin film can be continuously and precisely tuned by controlling the ferroelectric polarization of the BiFeO3 thin film, and the manipulating speed of the voltage control of magnetism can be fast to 100 ns. This nonvolatile, stable, reversible, fast, and reproducible voltage control of magnetism shows great potential for designing low-power and high-speed spintronics.

Fast Supplementary Voltage Control Strategy to Mitigate Catastrophic Trip-off Risk of Wind Turbines

Fast Supplementary Voltage Control Strategy to Mitigate Catastrophic Trip-off Risk of Wind Turbines

Data-Driven Fast Voltage Control in Non-DPMU Distribution Networks With Microgrids

Traditional voltage control methods for distribution networks assume perfect knowledge of the power system model. Nevertheless, the extensive scale of future distribution networks makes it unrealistic to acquire the overall operation state monitoring. Moreover, with the deregulation of distribution networks, partial controllable resources belong to independent systems, such as microgrids, causing distribution system operators unable to force them to provide voltage support directly. To cope with the previously mentioned problems, a data-driven fast voltage control method for distribution networks with MGs is proposed in this article. First, voltage sensitivity matrices are estimated indirectly by identifying line parameters in a regression approach, without using measurement data of distribution phasor measurement units (DPMUs) in distribution networks. Then, an incomplete information game model is proposed to motivate MGs to provide ancillary services of voltage control. To guarantee privacy, only a little key information is shared among MGs and distribution system operators. Moreover, MGs make voltage control strategies autonomously based on the data-driven deep reinforcement learning algorithms, while maximizing their own profits. Finally, we test the method on the modified IEEE 33-node networks and IEEE 123-node networks. The results demonstrate that the proposed method can provide an accurate voltage estimation in electricity markets with non-DPMU measurement data and increase energy and asset utilization.

Fast Grid Frequency and Voltage Control of Battery Energy Storage System Based on the Amplitude-Phase-Locked-Loop

This paper presents a novel fast frequency and voltage regulation method for battery energy storage system (BESS) based on the amplitude-phase-locked-loop (APLL). In the proposed method, the primary frequency regulation and inertia emulating control are designed based on grid frequency deviation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\Delta }f$ </tex-math></inline-formula> ) and its differential <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$(df/dt)$ </tex-math></inline-formula> signals detected by APLL, avoiding complicated and sensitive differential operation to get better dynamic support performance. Moreover, unlike the traditional voltage control only using grid voltage deviation ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\Delta }V$ </tex-math></inline-formula> ), the proposed method also uses the voltage differential control ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$dV/dt$ </tex-math></inline-formula> -control) to improve dynamic performance of traditional voltage control and behaviors of grid voltage based on the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$dV/dt$ </tex-math></inline-formula> signal from APLL. Finally, simulations and experiments are implemented to validate the effectiveness of the proposed APLL-based BESS on improving the dynamic behaviors of grid frequency and voltage.

Asking for fast terminal voltage control in grid following plants could provide benefits of grid forming behavior

Conventional inverter based resource (IBR) plants generally have control loops with high bandwidth which enable them to maintain tight control of the active and reactive power injected by the IBR device into the grid. These control loops, if not tuned appropriately, can suffer from instability under reduced system stiffness. To bring about an increase in stability of a power network with large percentage of IBRs, recent research done around the world has resulted in the emergence of multiple different types of so-called grid forming inverter control architectures. But, in order for inverter manufacturers to break the circular (or chicken-and-egg) problem, exact performance requirements must be known, which can only be specified either through standards and/or interconnection requirements. Through the use of both electromagnetic transient (EMT) time domain and linearized state space small signal analysis, this paper will provide a way to define interconnection requirements that are agnostic to the specific type of grid forming or grid following IBR control. Further, the benefit of defining grid forming interconnection requirements even when short circuit ratio is not low will be showcased.