Grid-connected Control System Research Articles

Application of optimized photovoltaic grid-connected control system based on modular multilevel converters

Photovoltaic power generation is a promising method for generating electricity with a wide range of applications and development potential. It primarily utilizes solar energy and offers sustainable development, green environmental benefits, and abundant solar energy resources. However, there are many external factors that can affect the output characteristics of Photovoltaic cells and the effectiveness of the grid-connected control system. This study describes the introduction of Modular Multilevel Converter (MMC) technology into photovoltaic power generation systems to improve power generation efficiency. It proposes optimizing and improving the technology by adjusting the temperature and magnitude of lighting and combining traditional algorithms to propose a composite control algorithm. The photovoltaic power generation system employs the modular multi-level converter technology to enhance power generation efficiency alongside optimization and improvement. The temperature and size of light are regulated alongside the traditional algorithm to introduce the composite control algorithm. The improved composite algorithm surpasses the traditional one after experimental comparison of the results. The testing of a model photovoltaic power grid-connected system shows that the combination of modular multi-level converter technology and a photovoltaic grid-connected system, incorporating composite proportional integral control and quasi-proportional resonant control algorithms, yields improved results and feasibility. With rationality and effective control. The simulation results show that at 0.5 s, the light intensity suddenly increases from 750 to 1000 W/m2, and the direct-current voltage suddenly increases for a short time, but then decreases rapidly and finally returns to a stable level close to the rated voltage. From this, it can be seen that when the light intensity continues to change, the voltage value on the direct-current bus side of this MMC grid-tied photovoltaic system can still be maintained close to the rated value, ensuring the operational stability of the entire system. Sensibly and effectively controlled. The implementation of MMC technology in photovoltaic power generation systems enhances power generation efficiency, whilst simultaneously supporting the advancement of photovoltaic power generation and contributing towards environmental protection in the long term.

Smart Grid Sensor Monitoring Based on Deep Learning Technique with Control System Management in Fault Detection

The smart grid environment comprises of the sensor for monitoring the environment for effective power supply, utilization and establishment of communication. However, the management of smart grid in the monitoring environment isa difficult process due to diversifieduser request in the sensor monitoring with the grid-connected devices. Presently, context-awaremonitoring incorporates effective management of data management and provision of services in two-way processing and computing. In a heterogeneous environment context-aware, smart grid exhibits significant performance characteristics with the grid-connected communication environment for effective data processing for sustainability and stability. Fault diagnoses in the automated system are formulated to diagnose the fault separately. This paper developed anoptimized power grid control model (OPGCM) model for fault detection in the control system model for grid-connected smart home appliances. OPGCM model uses the context-aware power-awarescheme for load management in grid-connected smart homes. Through the adaptive smart grid model,power-aware management is incorporated with the evolutionary programming model for context-awareness user communication. The OPGCM modelperforms fault diagnosis in the grid-connected control system initially, Fault diagnosis system comprises of a sequential process with the extraction of the statistical features to acquirea sustainable dataset with effective signal processing. Secondly, the features are extracted based on the sequential process for the acquired dataset with a reduction of dimensionality. Finally, the classification is performed with the deep learning model to predict or identify the fault pattern. With the OPGCM model, features are optimized with the whale optimization model to acquire features to perform fault diagnosis and classification. Simulation analysis expressed that the proposed OPGCM model exhibits ~16% improved classification accuracy compared with the ANN and HMM model.

Design of A Grid-connected Control System for Distributed Photovoltaic Power Generation Based on PLC

Distributed photovoltaics interfere with continuous power generation after grid connection. In the face of the failure of a single module, the current grid-connected control system needs to readjust system parameters to flexibly adapt to equipment operating conditions. Therefore, this paper is researching a photovoltaic power generation grid-connected control system based on PLC. In the hardware part, PLC is used to complete power generation control, monitoring MCU, data acquisition, control, and other modules. In the software part, the grid-connected state is optimized and controlled according to the distributed photovoltaic output power and the remaining energy storage capacity. The PLC is the execution center, which will control the on-off state of the equipment switch after the data operation. The experimental results show that the designed system can optimally control the power generation and energy storage units according to the power change, reduce the cost of electricity consumption through the adjustment of charge and discharge, reduce the IO usage rate, and improve the concurrent response ability of users. The design system not only guarantees the quality and efficiency of photovoltaic grid connection but also realizes rapid networking and independent tracking of power points to meet the requirements of flexible communication.

Current PIλ Control of the Single-Phase Grid Inverter

In a grid-connected power generation system, the grid-connected current of the inverter is sensitive to nonlinear factors such as periodic disturbance of grid voltage, which results in grid-connected current waveform distortion. By establishing a single-phase photovoltaic grid-connected inverter control system model, designing an inverse current fractional-order PI (PIλ or FO-PI) controller and the dynamic and steady-state performance, antidisturbance and grid connection inversion characteristics of the system are simulated and compared under the action of the integer-order PI controller and fractional-order PI controller. The quality of the inverter grid-connected current is analyzed by using the fast Fourier transform (FFT). The simulation results show that the fractional-order control system can reduce the total harmonic distortion (THD) of the grid-connected current and dynamic performance and antidisturbance ability of the improving system while satisfying the steady-state performance indexes.

Optimization method and stability analysis of MMC grid-connect control system based on virtual synchronous generator technology

Aiming at the issue of how to design controller parameters and analyze system stability when modular multilevel converter (MMC) adopts virtual synchronous generator (VSG) control technology. Firstly, this paper derives the parameter correspondence between the grid-connected MMC system and the synchronous generator (SG) system, and obtains the relationship between the virtual inertia parameter and damping parameter with specific structural parameters of MMC, then the optimization method of key parameters in the main controller of MMC grid-connected system is determined. That is to add the optimized inertia parameters and damping parameters to the active-frequency controller, the flux linkage feedback loop and the reactive differential compensation link to the reactive-voltage controller, the stability of MMC grid-connected system was analyzed by adjusting key parameters, and the optimal inertia parameters and damping parameters of the MMC grid-connected system during stable operation was analyzed. Finally, using MATLAB/Simulink to build a simulation model of MMC grid-connected system based on VSG control, the feasibility and correctness of the proposed optimization method for key parameters were verified, and the stability of the system was analyzed. The results showed that the key parameters of the main controller combined with the MMC unique structure were more suitable for the MMC grid-connected control system, which improved the stability of the system.

Second-Order Linear Active Disturbance Rejection Control and Stability Analysis of Energy Storage Grid-Connected Inverter

At present, which has gradually become a technical development trend that the energy storage grid-connected inverter system is connected to the grid to ensure the stable operation of the whole system. However, the stability of the energy storage system itself is also very important for the safe operation of the power grid. Therefore, improving the stability of grid-connected energy storage system is still the key technology of current research. Aiming at the strong coupling and low-voltage ride-through fault of grid-connected system, a second-order mathematical model of grid-connected control system is established. Based on its state space model, a linear extended state observer (LESO) for state observation and a linear state error feedback (LSEF) control law for disturbance estimation are designed. The second-order linear active disturbance rejection control (LADRC) is introduced into the voltage loop, the stability of the second-order LADRC controller is proved by the Lyapunov stability theory, and the stability conditions are given. Finally, the simulation model of the grid-connected energy storage system is built on the MATLAB/Simulink digital platform, and the low-voltage ride-through fault is designed on the grid-side. The simulation results show that the effect of the second-order LADRC control is better than that of the traditional PI control obviously, which reflects the superiority of the second-order LADRC in controlling the grid-side low-voltage ride-through fault.

Simulation Analysis of Wind Turbine Grid Operation Based on PSCAD

With its advantages of pollution-free and low cost, wind power has considerable market and huge development space in many new energy power generation systems. With the increasing installed capacity of wind power, the grid’s acceptance of large-scale wind power has become a new problem. It is very necessary to study the operation characteristics of wind turbines and the related characteristics of grid-connected wind turbines. By analyzing the basic structure and working principle of wind turbine, this article studies the grid-connected control system with permanent magnet motor as the core, designs the corresponding grid-connected control circuit and simulates the grid-connected situation of wind turbine by building PSCAD model.

Grid-Connected Control System for Three-Phase Bidirectional DC/AC Converter to Exploit Photovoltaic Power Generation

A grid-connetected control system is proposed in this paper to regulate three-phase bidirectional DC/AC converters in distribution grid exploiting photovoltaic power generation and not having energy storage at the DC side. To interact power flow at two its sides, statbilize voltage at the DCbus and synchronize with the grid, it includes an inner current controller and an outer voltage controller in a cascaded structure. Using small signal modeling and information about voltage at the point of common coupling and DCbus, control parameters for controllers are determined to balance power between photovoltaic system side and grid side. Simulation results show that the grid-connected control system helps the three-phase bidirectional DC/AC converter meet all requirements very well due to the balance of power at its sides to hold voltage at DC side at a fixed value, grid synchronization and low harmonic distortion total for current and voltage waveforms. They also represents the capability to exploit maximum available power of photovoltaic power generation under any operational condition.

Active control strategy based on vector‐proportion integration controller for proton exchange membrane fuel cell grid‐connected system

Considering the influence of slow response characteristic of a high-power proton exchange membrane fuel cell (PEMFC) on a grid-connected system adequately, a 150 kW PEMFC grid-connected system, including a PEMFC power unit based on a Ballard Stack Modules-FCvelocity™ HD6 is developed in this study. Moreover, then an active control strategy with vector-proportion integration controller is proposed to regulate the cascade system actively and improve the performance of compensating low-order harmonics. The comparisons with conventional active/reactive power (PQ) control are carried out to verify the validity of the proposed method under different conditional tests. The results demonstrate that the proposed strategy can not only track the grid power demand quickly, but also prevent the unsteady phenomena which are aroused by PQ control method from the relatively slow response of high-power PEMFC power unit. Furthermore, the total harmonic distortion of grid-connected current is measured by means of the criterion of IEEE Std1547-2003 and the result of fast Fourier transform analysis testifies that the proposed strategy can decrease the total harmonic content of currents better. Therefore, this proposed method will be an optional effective technique for the design of advanced high-power PEMFC grid-connected control system.

Design of proton exchange membrane fuel cell grid-connected system based on resonant current controller

Because of its high efficiency, low pollution and good stability, proton exchange membrane fuel cell (PEMFC) is considered as one of the most promising technologies for a wide range of applications, such as distributed power generation, transportation, portable power source and automobile. In a PEMFC grid-connected system, the proportion integration (PI) regulator can achieve zero error for the dc components in the rotating frame, but cannot achieve zero error for the ac components in the rotating frame. Hence, the PEMFC grid-connected system will produce a large number of harmonics. In order to overcome this shortcoming, a proportion integration resonant (PIR) controller is utilized to realize zero magnitude error and selective disturbance rejection. Instead of the PIR controller, a vector proportion integration (VPI) controller is designed to quickly and accurately regulate current which achieve zero both amplitude and phase frequency response at the resonant frequency simultaneously. In this paper, the PEMFC grid-connected system based on PIR and VPI controllers are developed according to the operating characteristics of a PEMFC generation system, then analyze and compare the performance of compensation harmonics between them. The total harmonic distortion (THD) of grid-connected voltage and current are measured by means of the criterion of IEEE Std1547-2003. This proposed grid-connected method will provide a novel approach for the design of advanced PEMFC grid-connected control system.

The Simulative Research of Three-Phase PV Grid-Connected Control System Based on SVPWM Inverter

The PV grid-connected control system is mainly related to a few key issues that are characteristics of photovoltaic cells, maximum power point tracking and grid-connected control of three-phase inverter. In this paper, simulation analysis and study of the three-phase grid-connected PV system control strategy. The control strategy of the three-phase PV grid-connected system is analyzed and studied by simulative experiment in this paper. First, a mathematical model of solar cells is established, then the algorithms based on perturb & observe to track maximum power point is used; Secondly, the structure of three-phase PV grid-connected system is introduced, and the space vector SVPWM controller is used to control the grid-connected inverter; Finally, the simulative results on Matlab/Simulink software show that SVPWM inverter control strategy is superior to the traditional hysteresis current inverter control strategy, which illustrates the reliability and superiority of SVPWM control strategy.

The Research of Control Strategy for Three-Phase Photovoltaic Grid-Connected VSI Using Space Vector Pulse Width Modulation and P-Q Theory

This paper investigates the operation of a PV unit which is connected via a three-phase voltage-source inverter to the grid. The PV grid-connected control system is mainly related to a few key issues that are characteristics of photovoltaic cells, maximum power point tracking and grid-connected control of three-phase inverter. The control strategy of the three-phase PV grid-connected system is analyzed and studied by simulative experiment in this paper. A mathematical model of solar cells is established. Then the algorithms based on perturb & observe to track maximum power point is used. The structure of three-phase PV grid-connected system is introduced, and the current control method with Space Vector pulse width modulation (SVPWM) is examined and compared to other current control methods. The p-q theory is used to achieve uninterrupted compensation of the reactive power of the system. Simulative results on Matlab/Simulink software illustrate the reliability and superiority of this control strategy.