Output Power Control Research Articles

Impact of Reactive Current and Phase-Locked Loop on Converters in Grid Faults

The precise control of output power by grid-connected converters relies on the correct identification and tracking of a grid voltage’s phase at the converter terminal. During severe grid faults, large disturbances cause the converter’s operating point to move away from the stable equilibrium point during normal operation. This leads to oscillations of both the active and reactive power fed into the grid. Using large-signal modelling, this study investigated the converter’s dynamic processes during and after such fault situations. The investigation considered the influence of the converter’s phase-locked loop (PLL), responsible for phase tracking, as well as that of the DC link on the converter-grid system, which has a major influence on the active power exchange with the grid. On this basis, this study also focused on the reactive current reference’s influence during and after fault clearing. Furthermore, an easily implementable strategy for reactive current injection, leading to minimum power oscillations, was presented. The results and the optimized strategies were validated via controller hardware-in-the-loop tests.

Magnetosensory Power Devices Based on AlGaN/GaN Heterojunctions for Interactive Electronics

AbstractThe advances in biological magnetoreception and microelectronics have promoted the vigorous development of interactive electronic devices capable of noncontact interaction and control via magnetic fields. Here, a magnetosensory power device (MPD) that integrates a magnetic film ((Fe90Co10)78Si12B10) unit into a cantilever‐structured AlGaN/GaN‐based high‐electron‐mobility‐transistor is presented. The MPD is capable to not only sense external magnetic field, but also control device output power with the emulation of magnetoreception. Specifically, the device can achieve significant control of output power density (18.04 to 18.94 W mm−2) quasi‐linearly with magnetic field stimuli (0–400 mT) at a gate bias of −5 V. In addition, the maximum output power density of the MPD can reach 85.8 W mm−2 when a gate bias of 1 V is applied. The simulation and experimental results show that MPD has excellent orientation and magnetic field sensing functions under 0–400 mT magnetic fields. With the intelligent capabilities of magnetic sense and output power control, such interactive electronic devices will have broad application prospects in the fields of artificial intelligence, advanced robotics, and human‐machine interfaces.

Dual-Output Extended-Power-Range Quasi-Resonant Inverter for Induction Heating Appliances

Induction heating technology provides efficient and reliable heating processes that outperform other classical heating methods based on fossil fuels or resistive heating. Among its many industrial, domestic, and biomedical applications, domestic induction heating appliances are a popular choice due to these advantages. This technology requires high-performance and cost-effective inverters that take most of the power devices and the converter topology. Depending upon the desired performance and output-power range, different power converters are employed. However, currently, most platforms rely on the well-known series resonant half-bridge topology. Single-switch topologies offer a cost-effective implementation but are limited to the low-cost low-performance markets due to their limitations in terms of output power and power control. In this context, this paper proposes a high-performance dual-output quasi-resonant inverter for modern induction heating appliances. Unlike state-of-the-art proposals, this converter achieves a full-output-power operating range of up to 3.6 kW. Consequently, it provides a high-performance cost-effective alternative to current implementations. The proposed converter is analyzed in this paper and experimentally verified using a dual-output 3.6-kW induction heating appliance prototype.

An Isolated SRC-Based Single Phase Single Stage Battery Charger for Electric Vehicles

In this article, a single-phase bridgeless electrolytic capacitor-less single-stage battery charger is proposed. The proposed charger consists of a bridgeless power factor corrector (PFC) circuit and an isolated series resonant converter (SRC). The series resonance circuit provides zero current switching (ZCS) for output diodes, thus reducing losses related to their reverse recovery. The resonant capacitors are designed so that the charger can operate in the range of 120–230-V input voltage, while ZCS is still guaranteed for output diodes. In addition, elimination of low-frequency input diodes decreases the circuit losses. The power factor correction and output power control are simultaneously achieved in one stage by using the proposed control method. The results obtained from a 350-W experimental prototype clearly confirm the correct operation of the proposed charger.

Design of a Dynamic Hybrid Compensator for Current Sharing Control of Parallel Phase-Shifted Full-Bridge Converter

The phase-shifted full-bridge (PSFB) converter has been widely used in power supply modules due to its simple control and high output power. However, with the market’s increasing demand for higher power sources, the PSFB converter needs to face challenges in increasing its output power level. Compared to redesigning a larger power module or a larger single converter, it will be more cost-effective to achieve a higher power output by paralleling the existing converters. However, due to the manufacturing differences in circuit components, the output imbalance in parallel PSFB converter systems may damage the power modules. Thus, the influence of differences in circuit components is analyzed in this paper, and it is found that the leakage inductance and transformer ratio are the main factors resulting in errors in current sharing control. Consequently, a dynamic hybrid compensator (DHC) is proposed in this paper, that can significantly reduce the error in current sharing control via the compensation of the duty cycle of a slave module. Furthermore, the DHC is verified on an 800 W two-phase PSFB converter, which shows that even when the difference in components is as large as 20%, the proposed method can still reduce the error in current sharing control to less than 2% under both half and full load conditions.

A BP-IPSO Algorithm Suitable for Centralized Thermoelectric Generation System Power Tracking under Nonuniform Temperature Distribution

The power-voltage (P-V) characteristic curve of the centralized thermoelectric generation (TEG) system under nonuniform temperature distribution (NTD) exhibits multiple extreme point characteristics, and the traditional maximum power point tracking (MPPT) algorithm is prone to fall into the local maximum power point (LMPP) and takes a long time to track. This paper designs a BP-IPSO algorithm based on back propagation neural network (BPNN) and improved particle swarm optimization (IPSO) for MPPT. The algorithm firstly utilizes the good nonlinear function fitting ability of BPNN to obtain the fitting curve of the relationship between system control input and power output to establish the TEG array power prediction model. Then, the dynamic learning factor and weight coefficient are introduced into the traditional particle swarm optimization (PSO) algorithm to search the output power prediction model and realize MPPT control. MATLAB/Simulink experiment results show that BP-IPSO algorithm can effectively avoid falling into LMPP, quickly and accurately track the global maximum power point (GMPP), and effectively suppress the oscillation of voltage and power during the tracking process. Especially in the start-up test experiment, compared with perturb and observe (P&O), PSO, and grey wolf optimizer (GWO), the energy generated by BP-IPSO increased by 12.84%, 3.18%, and 4.75%, respectively, which improved the system power generation efficiency.

Per-Phase Power Controller for Smooth Islanded Transitions in Three-Phase Three-Wire Systems

This manuscript describes the operation of a droop-based controller for three-phase converters in the case of the absence of a neutral connection to the grid. The controller is capable of output power tracking and smooth transitions into the islanded operation. While independent per-phase control of the converter output power is possible if a neutral connection is present, its absence implies additional constraints to be considered. Focusing on this latter case, the controller described herein allows the independent control of the active power at the output of each phase of the converter and a smooth transition to the islanded operation. These features are paramount in future smart power systems, such as smart microgrids, for implementing demand–response, power-flow management, and uninterrupted power operation.

Impact of inertia response control strategy based doubly fed induction generator on frequency stability of power system

While the doubly fed induction generator (DFIG) is widely applied in the new power system, its decoupled control and fluctuation of output power have led to serious problems in frequency stability. Inertia response control (IRC) of DFIG has attracted significant attention, while its impact has not been clearly researched. In this study, a low-order model of DFIG focusing on frequency stability is proposed. Firstly, the simplified model of DFIG considering the IRC is introduced through Taylor series expansion. The frequency response model considering the energy storage system (ESS) is proposed. Taking the rate of change of frequency (RoCoF) and steady-state frequency deviation (SFD) as the constraint, an analytical solution for the maximum proportion of DFIGs is deduced to reflect the impact of IRC on the system frequency stability. Finally, the accuracy of the proposed method and the effectiveness of IRC is verified on the modified IEEE-9 system.

Measurement of the output power of electrosurgical high-frequency equipment when simulating single fault conditions

The issues of determining the output power of high-frequency electrosurgical equipment by simulation of single fault conditions in accordance with the particular standard DSTU EN 60601-2-2:2015 are considered. It is noted that modern high-frequency equipment is equipped with measuring units to control output current and voltage in order to ensure control of output power. A method for monitoring the performance of built-in protection systems of modern HF equipment is proposed if the output power exceeds the limits of allowable values under single fault conditions. This method is common for most operating modes of HF equipment. Practical examples of such tests are given.

Active blade pitch control and stabilization of a wind turbine driven PMSG for power output regulation

A common strategy in controlling a permanent magnet synchronous generator (PMSG) driven by a wind turbine is the maximization of output power of the wind turbine itself. A control strategy must be adopted, is to deliver a desired reduced amount of power whenever it is required. In order to realize the direct control of wind turbine output power across a wide range of wind speeds, a linearized parameter varying dynamic model of the nonlinear wind turbine system including wind disturbances is developed and used in this paper. The stability of the wind turbine system is analyzed and a blade pitch controller is designed, based on the linearized, parameter-varying, model-predictive control and is validated. Thus, the wind turbine is regulated in a way that the generator delivers the demanded power output to the load. Moreover, the blade pitch control system also performs the key function of augmenting the stability of the wind turbine, for the right choice of the gains.

Selective Monitoring of Power Quality Indicators in Distribution Networks with a Large Share of RES Generation

The development of generation based on renewable energy sources (RES) plays an important role in achieving carbon neutrality. Modern solar and wind power plants are connected to distribution electric networks through inverters, which implement power output control and protection algorithms. With a low load of these inverters, violations of the standardized levels of power quality indicators (PQI) are recorded, such as voltage deviations, fluctuations, dips and non-sinusoidality. This is the case with low levels of solar radiation at solar power plants and small wind heads at wind farms. As a rule, the mix of industrial consumers connected to such distribution networks includes electric loads for which deviations of the PQIs from their standardized values are critical and lead to their disconnection by protections, shutdown of technological processes, damage from spoilage, and under-delivery of products. For identifying the disturbance sources and filing lawsuits to compensate for damages, industrial consumers introduce various PQI monitoring systems. A selective monitoring method for automatically detecting violations of the standardized PQI values is considered. To take into account the combined effect of PQIs on electric loads, it is proposed to use the modulus of the current and voltage mutual correlation coefficient. The PQI monitoring device structural diagram is considered, which is based on the results from simulating various network operation modes, as well as the sequential Wald analysis procedure. The introduction of this device will make it possible to prevent significant and long-term violations of the PQIs, thereby ensuring reliable operation of industrial consumers in distribution networks with a large share of RES based generation.

Output Power Control and Load Mitigation of a Horizontal Axis Wind Turbine with a Fully Coupled Aeroelastic Model: Novel Sliding Mode Perspective

The power control of horizontal axis wind turbines can affect significantly the vibration loads and fatigue life of the tower and the blades. In this paper, we both consider the power control and vibration load mitigation of the tower fore-aft vibration. For this purpose, at first, we developed a fully coupled model of the NREL 5MW turbine. This model considers the full aeroelastic behaviour of the blades and tower and is validated by experiment results, comparing the time history data with the FAST (Fatigue, Aerodynamics, Structures, and Turbulence) code which is developed by NREL (National Renewable Energy Lab in the United States). In the next, novel sensorless control algorithms are developed based on the supper twisting sliding mode control theory and sliding mode observer for disturbance rejection. In region II (the wind speed is between the cut-in and rated wind velocity), the novel sensorless control algorithm increased the power coefficient in comparison to the conventional indirect speed control (ISC) method (the conventional method in the industry). In region III (the wind speed is between the rated and cut-out speed), an adaptive neural fuzzy inference system (ANFIS) is developed to estimate pitch sensitivity. The rotor speed, pitch angle, and effective wind velocity are inputs, and pitch sensitivity is the output. The designed novel pitch control performance is compared with the gain scheduled PI (GPI) method (the conventional approach in this region). The simulation results demonstrate that the flapwise blade displacement is reduced significantly. Finally, to reduce the fore-aft vibration of the tower, a tuned mass damper (TMD) was designed by using the genetic algorithm and the fully coupled model. In comparison to the literature body, we demonstrate that the fully coupled model provides much better accuracy in comparison to the uncoupled model to estimate the vibration loads.

Output power control of nuclear reactor using ant lion optimization-based controller

Power level control is a <span>critical issue in nuclear power stations due to its nonlinear dynamics. One of the most commonly used controllers is fractional order proportional–integral–derivative (FOPID). The FOPID is an enhanced and modern controlling system that has two additional added parameters. In this paper, comparison between particle swarm, gray wolf and ant lion optimization techniques is performed to determine the FOPID controller parameters. The nuclear reactor is a pressurized water reactor which is a fifth order nonlinear reactor model and is simulated using MATLAB software based on the point kinetic model. The integral square error (ISE) performance index is used to evaluate the performance of the three optimization techniques. The simulation results show that ant lion optimization for tuning the FOPID controller parameters gives the best performance and integral square error index better than the two other optimization techniques.</span>

Multi-Energy Acquisition Modeling and Control Strategy of Underwater Vehicles

An autonomous underwater vehicle (AUV) can only carry limited energy for improved flexibility, but this brings the problem of working endurance. The acquisition of environmental energy by an underwater robot is a positive way to supplement energy and increase endurance. However, the instability and difference in power output capacity of different environmental energies will lead to low utilization of environmental energy. In this study, a multi-energy acquisition model is established to manage the AUV’s energy, which includes a heart rate sampling system, a mixed-energy circuit topology, and a maximum power output algorithm of environmental energy based on power trajectory tracking. The simulating results show that the power output control strategy can effectively improve the multi-energy acquisition and utilization efficiency of underwater vehicles, which has a positive significance and could improve endurance time.

Photonic crystal based interferometric design for label-free all-optical sensing applications.

Optical sensing devices has a great potential in both industrial and biomedical applications for the detection of biochemicals, toxic substances or hazardous gases thanks to their sustainability and high-selectivity characteristics. Among different kinds of optical sensors based on such as fibers, surface plasmons and resonators; photonic crystal (PC) based optical sensors enable the realization of more compact and highly efficient on-chip sensing platforms due to their intriguing dispersive relations. Interferometric devices based on PCs render possible the creation of biochemical sensors with high sensitivity since a slight change of sensor path length caused by the captured biochemicals could be detected at the output of the interferometer via the interferences of separated beams. In this study, a new type of Mach-Zehnder Interferometer (MZI) using low-symmetric Si PCs is proposed, which is compatible with available CMOS technology. Intended optical path difference between the two MZI channels is provided by the periodic alignments of symmetry-reduced PC unit cells in the MZI arms. Unlike the conventional symmetrical PC based MZIs, Fano resonances exist for the proposed MZI design, i.e. transmission dips and peaks appear in the output spectrum, and the location of dip and peak frequencies in transmission spectra can be efficiently controlled by utilizing interference phenomenon. Exploiting this effect, any refractive index change at the surrounding medium could be distinctly observed at the transmission spectra. In the view of such results, it is convenient to say that the proposed MZI configuration is suitable for efficient optical sensing of toxic gases as well as liquids. The designed all-dielectric MZI system is numerically investigated in both spectral and spatial domains to analyze its interferometric tunability: an optical sensitivity of about 300 nm/RIU is calculated for gaseous analytes whereas that sensitivity value is around 263.2 nm/RIU in the case of liquid analytes. Furthermore, high quality factor of Q > 45000 is obtained at Fano resonances with Figure-of-Merit (FoM) value of FoM ∼ 8950 RIU-1(7690 RIU-1) in the case of gas analytes (liquid analytes), which is the indication of enhanced optical sensing performance of the proposed MZI design. Considering all the above-mentioned advantages, the proposed interferometric configurations based on low-symmetric PCs could be utilized for efficient photonic sensor applications that require controllable output power or sensing of gaseous and liquid substances.

Kinetics of ventilatory and mechanical parameters of novice male rowers on the rowing ergometer

ABSTRACT Maximal oxygen consumption (VO2max) and maximal power output (Pmax) play a preponderant role in the performance of rowers. This study aims to describe and analyse the kinetics of ventilatory and mechanical parameters in novice male rowers on the rowing ergometer. Twelve male novice rowers were part of the study – descriptive with a selective non-probabilistic cross-sectional design. The variables were VO2max and Pmax. The kinetics of the variables were observed in an Incremental Test (IT) and a 2,000 m time trial (2,000mTT). The differences between the tests were established by Student’s t-test (p < 0.05). In both protocols, the VO2max reached 330–345 s. Between IT and the 2,000mTT there were significant differences in the VO2max (52.7 ± 3.3 vs 55.9 ± 3.4 mLO2·kg−1·min−1, p ˂ 0.01) and Pmax (334.7 ± 20.2 vs 269.5 ± 31.3 W, p ˂ 0.001). The novice rowers’ low physiological capacity and efficiency generated instability in the power output kinetics. A very large delta was observed between the maximum and minimum power output. Exploring tests with a shorter duration for novice rowers (360 s) and improving power output control in the different tests are suggested.

Explosive Electric Actuator and Control for Legged Robots

Unmanned systems such as legged robots require fast-motion responses for operation in complex environments. These systems therefore require explosive actuators that can provide high peak speed or high peak torque at specific moments during dynamic motion. Although hydraulic actuators can provide a large force, they are relatively inefficient, large, and heavy. Industrial electric actuators are incapable of providing instant high power. In addition, the constant reduction ratio of the reducer makes it difficult to eliminate the tradeoff between high speed and high torque in a given system. This study proposes an explosive electric actuator and an associated control method for legged robots. First, a high-power-density variable transmission is designed to enable continuous adjustment of the output speed to torque ratio. A heat-dissipating structure based on a composite phase-change material (PCM) is used. An integral torque control method is used to achieve periodic and controllable explosive power output. Jumping experiments are conducted with typical legged robots to verify the effectiveness of the proposed actuator and control method. Single-legged, quadruped, and humanoid robots jumped to heights of 1.5, 0.8, and 0.5 m, respectively. These are the highest values reported to date for legged robots powered by electric actuators.

A Health-Oriented Power Control Strategy of Direct Drive Wind Turbine

Offshore wind power has great development potential, of which operation and maintenance costs account for a large proportion in the full lifecycle cost. Power output control strategy plays a key role in wind turbine generator system (WTGS). Traditional control strategies, such as maximum power point tracking and unity power factor, which only uses current local information for decision-making, are not the optimal control method when considering the component fatigue. For the reason, this paper proposes a health-oriented power control strategy, which transforms control problem into an equivalent solution to an economic revenue model. The model aimed to maximize the economic revenue of the full lifecycle, and employed physics-of-failure methodology to quantify the remaining useful life, involving detailed mission profiles. Further, a receding horizon predictive controller is designed to flatten the junction temperature fluctuation and extend converter lifespan, for engineering application. A 1.2 MW WTGS is utilized as a benchmark to verify the proposed strategy performance, and the numerical results reveal the mechanism of the optimized control strategies for alleviating the fatigue and aging of the converters.

Dispersion process of highly crystalline single-walled carbon nanotubes focusing on their chemical stability

The purpose of this study is to develop a planar field electron emission source that can be driven stably for a long time with low energy consumption and output power control to realize field-emission–cathodoluminescence (CL) devices with excellent energy efficiency. This was achieved driven by the motivation that the use of CLs with excellent quantum efficiency can create new values for society by realizing energy-saving lighting. We attempted to prepare dispersion coatings of highly crystalline single-walled carbon nanotubes (hc-SWCNTs) with guaranteed chemical stability by an industrial dispersion process. The change in chemical stability owing to the adoption of the dispersion process was traced by quantifying the shape of the thermogravimetric analysis (TGA) curve, and the process suitable for the dispersion of hc-SWCNTs was investigated. As a result, it was shown that the wet jet mill dispersion process could be combined to achieve dispersion with slightly deteriorated chemical stability. This was achieved by reducing the milling effect of foreign matter and by controlling the shear force and the number of shear cycles applied to the dispersion.

Power output control method of small power photovoltaic grid connected power generation under complex illumination

Due to the irregular change of lighting conditions, there is a large error in the control of photovoltaic grid connected power output. Therefore, this paper proposes proposes a power output control method for low-power photovoltaic grid-connected power generation considering complex illumination. Based on the analysis of the basic characteristics of photovoltaic grid connected power generation, the output characteristics of photovoltaic array under complex lighting conditions are studied. Combined with its variation characteristics, based on fuzzy control strategy, the output of photovoltaic grid connected energy storage system is adjusted by filter control with variable time constant, and economic operation and stable operation are taken as constraints. The test results show that the design method has a high degree of fit between the control of photovoltaic grid connected power output and the actual results, and the error is within a reasonable range, which is obviously due to the two groups of comparison methods.