Constant Power Control Research Articles

Simulation Analysis of Simulink-based Inverter Controller in Micro-grids

As environmental awareness increases and new energy technologies develop, microgrid systems have garnered significant attention as an important method for operating new energy sources. This trend reflects the growing emphasis on environmental protection. In the process of achieving both independent operation and grid-connected operation, the internal microgrid needs to incorporate an inverter control system equipped with various control methods. The inverter control system is responsible for regulating the inner loop parameters, and the coupling of these parameters will directly impact system stability. The research focus of this article is on microgrid systems that include wind-solar-storage systems. The study primarily employs three control types—constant power control (PQ), virtual synchronous generator control (VSG), and a combination of PQ and VSG control (PQ+VSG)—for simulation analysis to explore system stability. By conducting an in-depth stability analysis, we further understand the characteristics of inverter internal control and grid-connected inverter operation, thereby providing guidance for the design of control systems and ultimately achieving their effective application in power systems.

Compact Laser-Induced Fluorescence Detector with Adjustable Laser Focal Spot for Multiple Purposes.

In many research fields, the demand for miniaturized laser-induced fluorescence (LIF) detection systems has been increasing. This work has developed a compact LIF detector, employing a laser diode as the excitation source and a photodiode as the photodetector with an adjustable laser focal spot, to meet the diverse requirements of various observation targets, such as capillaries, PCR tubes, and microfluidic chips. It features the functionalities of background fluorescence correction, the adaptive adjustment of the dynamic range, and constant power control for the laser. The influence of the excitation power on the detection limit was studied through experiments, and the configuration results for LED/LD as light sources and 487/450 nm wavelengths were compared and optimized. A fully integrated, compact, modular epifluorescence LIF detector was subsequently constructed, measuring 40 × 22 × 38 mm3 in total size, with a cost of USD 320, and achieving a detection limit of 0.4 nM for fluorescein sodium. Finally, the detector was integrated into a nucleic acid detection system with a microfluidic chip on the Chinese Space Station (CSS) and was also tested with PCR tubes and capillaries, proving its broad practicality and adaptability to various analytical systems.

A 15 KW level 3 inductive power transfer charger for fast charging and maximum efficiency

This paper aims to design and simulate a Wireless Power Transfer charger that can achieve fast charging, thereby improving the EV users’ experience and bypassing the disadvantages of Level 1 and 2 chargers. We attend to this objective by presenting a Two-Stage Inductive Power Transfer system controlled by the constant power (CP) control strategy. Key innovations include the integration of an LCC-C compensation network with a Switched-Controlled Capacitor (SCC) and a DC/DC Buck converter. To validate our proposed system, we simulate a prototype using SimScape library. The simulation leads us to design a TSIPT prototype that achieves high-power charging of 15.3 KW and a power efficiency ranging from 92.2 % to 88 %, and an output voltage varying from 523V to 878V. These results are thanks to the DC/DC Buck converter that regulate the output and help to improve the battery life span, and due to the combination between the SCC and the secondary active rectifier (AR) the proposed IPT can maintain with a maximum constant charging output and a maximum power efficiency, that can make the overall system more stable.

An Improved Constant Active Power Control for Three-Phase Buck Rectifier Under Unbalanced Input Voltages and Wide AC Input Frequency

An Improved Constant Active Power Control for Three-Phase Buck Rectifier Under Unbalanced Input Voltages and Wide AC Input Frequency

A speed decoupling control method for multi-channel pressure-flow coupling system

Abstract The main engine of construction machinery often involves the compound action of multi-action, such as excavator bucket rod, shovel bucket, and moving arm. Due to the matching relationship between the constant pressure differential valve and main valve, constant power limitation of a pump, load change, and other factors, it will cause the load with low pressure to move first and the load with high pressure to move later. To solve this problem, the existing speed control (or flow control) in the industry generally adopts pre-valve or post-valve compensation load-sensitive systems, positive flow control, negative flow control, constant power control, and so on. The speed control method can solve the coarse flow distribution under multi-load conditions, but is not suitable for working conditions with high precision of flow control or flow distribution, such as speed tracking, trajectory control, etc., and cannot meet the accurate control of flow or speed. In this paper, a speed decoupling control method based on hydraulic factors (such as pressure drop, flow rate, oil temperature, hydraulic pump speed, system pressure, etc.) is proposed. Through accurate modeling and simulation technology, the accuracy of compound action flow control is improved, and the anti-interference energy of the compound action system is enhanced, which lays a foundation for hydraulic speed tracking, displacement tracking, and so on.

Research and Design of Fixed-Pitch Non-Grid-Connected Wind Power System

Traditional fixed-pitch wind turbine, whose rotational speed is a constant, adjusts its aerodynamic power according to the blade stall characteristic, and it has the advantage of being simple, robust and reliable, with simple and inexpensive electric systems. By introducing MPPT strategy on low wind condition and constant output power control on high wind condition, higher efficiency of fixed-pitch wind turbine can be obtained, which is realized by regulating the turbine rotational speed according to wind speed. In this paper, the variable speed regulation strategy is proposed, the stability characteristic based on the small signal model is analyzed, and the speed control technique based on disturbance observer and Internal Model PID controller is discussed in detail, some experimental results are presented, which show that the dynamic response of speed controller is favorable and efficiency of the plant is improved by tracking the maximum power point on low wind condition and keeping the turbine aerodynamic power at its rated value on high wind condition.

A Novel Constant Power Control for Series-Parallel Resonant Repetitive-Frequency Capacitor Charging Power Supply

A Novel Constant Power Control for Series-Parallel Resonant Repetitive-Frequency Capacitor Charging Power Supply

Constant Power Control Against M/R With Expanded PT-Symmetric Range for Wireless in-Flight Charging of Drones

For the drone wireless in-flight charging system, the challenge is to keep a constant charging power under the large range of continuous fluctuation of mutual inductance ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> ), the variation of battery load ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> ), and the limited payload of drones, which has been rarely studied in previous research. To address the issue, this paper presents a primary-series and secondary-series-inductor-series-parallel-capacitor (SLSPC) high-order topology for the parity-time (PT) symmetric wireless power transfer (WPT) system, which can greatly expand the exact PT-symmetric region (constant power range) by the reduction of critical coupling coefficient in comparison with the traditional series-series topology. Besides, the constant power control scheme is proposed based on the series-SLSPC high-order topology to overcome the change of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">M</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> . With the proposed control method, only the primary current needs to be detected, which enhances the real-time performance of the WPT system and reduces the payload of drones. Simulated and experimental results validate the expansion capability of the PT-symmetric range with the proposed series-SLSPC PT-WPT system and the feasibility of the proposed control scheme.

DC‐side stability analysis of grid‐tied converter with different control modes based on electrical torque analysis

AbstractThe DC‐side stability of the grid‐tied converter under different control modes is fully investigated using electrical torque analysis. The small‐signal model of a single converter connected to an ideal DC bus under various control modes is formulated. Accordingly, the damping and synchronising coefficient contributed by the DC network and controllers of grid‐tied converter are separately accessed using the electrical torque analysis method and the stabilising conditions of the grid‐tied converter operating under different control modes are further derived. The system stability mainly corresponds with DC network dynamics under constant active power control mode. On the contrary, the grid‐tied converter under constant DC‐link voltage control mode has no stability problem. Generally, elevating the DC‐link capacitance or decreasing the droop gain can greatly improve the stability margin reserve of the VSC‐HVDC links. In addition, the control gains of the classical PQ controller are proven to have limited impacts on DC‐side system stability. Finally, the results of numerical simulation prove the validity of the proposed stability analysis method and the stable boundary for the grid‐tied converter with different control modes.

Frequency Support Control of Multi-Terminal Direct Current System Integrated Offshore Wind Farms Considering Direct Current Side Stability

The frequency stability of modern power systems is challenged due to widespread application of large-scale renewable energy systems, of which the offshore wind farm (OWF) is one of the dominant resources. The OWFs are usually integrated into the grid by multi-terminal direct current (MTDC) transmission systems, which makes the energy flow complicated and the frequency control design challenging. A frequency support control method of MTDC system integrated OWFs (referred to as the OWF-MTDC system) is proposed in this paper. First, the wind turbine generation system (WTGS) is controlled to reserve a certain amount of available power according to the real-time wind speed for more comprehensive frequency regulation. Then, the frequency support control of OWFs is designed, and they can release the rotor kinetic energy and reserved power to support the onshore grid frequency. In addition, the virtual inertia control of a modular multi-level converter (MMC) is designed, which can also provide frequency support in an emergency by use of the DC capacitor. To ensure that the frequency control of the OWF-MTDC system does not degrade the stability of the system, a detailed DC impedance model of the MMC-based MTDC systems is developed, considering the constant power control and DC voltage control. Based on the impedance model, the impact of the frequency control coefficients on the DC side stability of the MTDC system is analyzed. Simulation results validate the stability analysis and verify the proposed frequency control method, which can effectively provide frequency support to the onshore power grid.

Fixed Frequency LCC Resonant Converter Modeling and Optimal Design for High-Voltage Capacitor Charging Power Supply in Constant Power Control

LCC resonant converter is widely used in high-voltage capacitor charging power supply(CCPS) due to its high efficiency and utilization of parasitic parameters. Since CCPS generally demand a wide voltage variation range, the conventional frequency modulation is difficult to scale up in constant power control. In this paper, a phase-shift(PS) LCC resonant converter in constant power control is proposed. To solve the deviation of the shifted phase of the traditional method in constant power control, an accurate model based on state plane analysis(SPA) is built. On this basis, an optimal design method of PS-LCC for CCPS is proposed, which is helpful to realize the soft switching and reduce the current peak. Finally, a 10kV CCPS prototype is built. And experiment designed by proposed method realizes the constant power charging in PS-LCC for the first time. Experimental results show that the charging speed is increased by 44.3% compared with the traditional constant current charging. Besides, the current stress is reduced by 24.1% and the soft-switching range is extended by 6.9%. There is valuable engineering guidance for realizing high-efficiency and high-speed CCPS by the design method proposed.

Error-Based Active Disturbance Rejection Control for Wind Turbine Output Power Regulation

The intermittence and randomness of wind speed often lead to the fluctuation of wind turbine output power especially when operating in high wind speed areas. In this paper, a holistic framework of error-based ADRC for wind turbine is proposed to achieve the output power regulation, by designing an extended state observer and parameter optimization to estimate and compensate the total disturbances. A stability theorem of closed-loop system with error-based ADRC is proposed by the Lyapunov function, and the feasible region of the controller parameters is deduced accordingly. To achieve the best performance of error-based ADRC, the optimal solution of the controller parameters is determined by the proposed Aquila Optimizer fused Golden Sine Algorithm. Finally, the superiority of proposed control strategy is verified by simulation tests on a 5MW OpenFAST wind turbine. Compared with the traditional control methods adopted in the industry, the error-based ADRC has excellent regulation rapidity and power stability for constant power control of wind turbine.

Jamming Signal Cancellation by Channel Inversion Power Control for Preserving Covert Communications

Uninformed jammers are used to facilitate covert communications between a transmitter and an intended receiver under the surveillance of a warden. In reality, the signals the uniformed jammer emits to make the warden’s decision uncertain have inadvertently interfered with the detection of the intended receiver. In this paper, we apply truncated channel inversion power control (TCIPC) to both the transmitter and the uninformed jammer. The TCIPC scheme used on the uninformed jammer may help the intended receiver remove jamming signals using the successive interference cancellation (SIC) technique. Under the assumption that the warden knows the channel coefficient between two intended transceivers and achieves the optimal detection power threshold, we form the optimization problem to maximize the effective transmission rate (ETR) under covertness and decoding constraints. With the aim of enhancing covertness-related performance, we achieve the optimal power control parameters and determine system parameter-related constraints required for the existence of these solutions. According to the simulations, the use of the TCIPC scheme on the uninformed jammer significantly improves covertness-related performance in comparison to that of random power control (RPC) and constant power control (CPC) schemes. In addition, simulation results show that, for the TCIPC scheme: 1) the maximum ETR tends to converge as the transmitter’s or the uninformed jammer’s maximum transmit power increases, and 2) there exists an optimal value of the transmitter’s predetermined transmission rate to achieve the optimal performance.

Multiobjective Optimization and Multiphysics Design of a 5 MW High-Speed IPMSM Used in FESS Based on NSGA-II

The flywheel energy storage system (FESS) has high-power density and fast response speed, hence it is widely used as a pulse power supply. For the high-speed permanent magnet synchronous machine (HSPMSM) used in high-power FESS, there are two technical problems that need to be solved, including huge centrifugal forces of the rotor at a high-speed operation region and large phase currents at a low-speed operation region. In this paper, a 5 MW high-speed interior PMSM (HSIPMSM) is designed for FESS. The design goal of this electric machine is to reduce the maximum phase current at the lowest speed as much as possible while ensuring the rotor mechanical strength. Based on the response surface (RS) model and non-dominated sorting genetic algorithm II (NSGA-II), the multiobjective design of the HSIPMSM is accomplished using 29 groups of multiphysical field finite element analysis (FEA) sampling experiments. The computational cost is effectively reduced. In addition, the constant power optimal trajectory and control switching speed of the HSIPMSM are analyzed and discussed, and the reason that the constant power flux weakening region of the designed HSIPMSM is not wide and the maximum torque per ampere (MTPA) mode is adopted at a low-speed operation region is further illustrated.

Research on Control Strategy of Constant Power Output in MCRWPT System

During wireless charging, the change of battery resistance will cause the fluctuation of output power, which will shorten the battery life and affect the charging safety. According to the theoretical analysis of WPT, when the load resistance changes, the output power can be stabilized by adjusting the input voltage of the system. Aiming at the variable load MCRWPT system, that is, only the load resistance changes under the resonant state, this paper designs the MCRWPT constant power control system by using the principle of reflective impedance and using the phase-shifting control voltage regulation and builds a simulation model through Matlab/Simulink platform to verify that the output power is kept in a certain range, without additional communication loops, which reduces the volume of electrical equipment and saves costs.

A Comprehensive Evaluation of Different Power Quantities in DC Electric Arc Furnace Power Supplies

Conventionally, DC arc furnaces are fed by thyristor rectifiers to control the level of current or power transferred to the load. With the advancement of high-power transistors, other structures such as diode rectifiers and DC choppers have been introduced and developed for the feeding system of DC electric arc furnaces. In this paper, the effect of different power supply systems on power quality indexes is discussed. In this regard, two types of feeding systems are considered, including a power supply system based on thyristor rectifiers and a power supply system based on diode rectifiers and DC choppers. In addition, different control methods, including constant current control (CCC) and constant power control (CPC), on DC electric arc furnaces are applied. For evaluating the power quality indexes, voltage and current harmonic distortion, unbalance of voltage and current, and power factor on the AC side are investigated for different power supply systems. Simulation results were performed with PSCAD/EMTDC software. It is shown that the power supply systems with diode rectifiers and DC choppers have superiority in comparison to the types based on thyristor rectifiers. According to the results, the average current THD is reduced from 16.55% in the thyristor rectifier to 8.40% in the chopper rectifiers with the CCC method and from 19.27% in the thyristor rectifier to 7.38% in the chopper rectifiers with the CPC method. Moreover, the average voltage THD is reduced from 5.67% in the thyristor rectifier to 3.02% in the chopper rectifiers with the CCC method. The result is similar to the CPC method. Furthermore, for a specific power supply system, the harmonic distortion is lower in the case of the CPC method than in the CCC method.

Weldability of Additive Manufactured Stainless Steel in Resistance Spot Welding

The manufacture of complicated automobile components that are joined by resistance spot welding requires considerable cost and time. The use of additive manufacturing technology to manufacture automobile components helps reduce the overall time consumption and yields high accuracy. In this study, the weldability of conventional (C) 316L stainless steel and additive manufactured (AM) 316L stainless steel was evaluated and analyzed. After deriving the lobe diagram for both the materials, the monitoring data, nugget diameter, tensile shear strength, and hardness were analyzed. The findings of the study have opened up a massive potential for use in resistance spot welding technology for additive manufactured materials’ industries in the forthcoming years. When AM 316L stainless steel was welded in the constant current control mode, a nugget diameter of up to 4.7 mm, which is below the international standard, could be secured. Through the constant power control mode, however, the nugget diameter could be improved to a sufficient level of 5.8 mm.

Investigation of the wave–photovoltaic-battery​ hybrid power generation platform’s control strategy

This paper proposes a wave–photovoltaic-battery hybrid power generation platform which based on the distributed DC collection and AC inverter grid structure. To be able to simplify the control structure of the power generation system and improve the anti-interference ability of the system, a one-step delay compensation model predictive current control (MPCC) method is proposed for the wave power generation rectifier unit and the perturbation and observation (P&O) fuzzy logic maximum power point tracking (MPPT) algorithm is applied in the photovoltaic power generation unit. Meanwhile, the constant power control method is used to realize the charge and discharge control of the energy storage system to achieve the grid-connected goal of tracking the load power demand. Finally, the MATLAB/Simulink software is applied to simulate the grid-connected operation characteristics of the wave energy power generation unit in continuous power generation modes, as well as the photovoltaic power generation unit at constant temperature and variable irradiance. The results illustrate that the suggested technique for controlling the power generating unit is straightforward and feasible, DC bus voltage stability effect is effective, and the inverter output satisfies the grid-connected operating requirement, which verifies the feasibility of the proposed scheme and can provide some theoretical support for the subsequent high-capacity wave–photovoltaic-battery hybrid power generation platform.

Influence of different testing positions of sensors on the dynamic response of load sensing hydraulic systems

This paper first introduced the load sensing hydraulic system and elaborated on its load feedback, pressure cut-off, and constant power control principles. Moreover, based on the response hysteresis of the load sensing hydraulic system in the actual commissioning of the project, this paper proposed the possible influence of the sensor on the response of the hydraulic system through troubleshooting analysis. Third, experiments were conducted to obtain the system dynamic response curves given different sensor positions and to prove the hypothesis. Meanwhile, the influence mechanism and improvement measures were analyzed. Finally, the optimal installation positions of the sensor based on different operating conditions were discussed.

Grid-Connected Microbial Fuel Cell Modeling and Control in Distributed Generation

Water shortages and water pollution have seriously threatened the sustainable development of the community. The grid-connected microbial fuel cell is an effective way to control the cost of wastewater treatment plants. Moreover, it solves the problem of low efficiency and high energy consumption. In view of the characteristics of strong coupling, non-linearity, and internal load in the process of microbial fuel cell grid connection, it is necessary to design the grid-connected unit of power electronic device. Based on the establishment of the microbial fuel cell stack model, the stability control and the constant power control scheme were designed for the chopper and inverter, respectively. The simulation results showed that the control strategy with the combination of voltage stabilizer and constant power can make a grid-connected system of all phase voltage and frequency output. The three-phase voltage Uabc was steady at 7 h and the voltage amplitude was controlled at roughly 380 V, according to the output voltage waveform. The value was 50 Hz, which satisfies the criteria for grid connection.