Synchronous Generator System Research Articles

Enhanced MPPT in Permanent Magnet Direct-Drive Wind Power Systems via Improved Sliding Mode Control

Addressing the challenges of significant speed overshoot, stability issues, and system oscillations associated with the sliding mode control (SMC) strategy in maximum power point tracking (MPPT) for permanent magnet synchronous wind power systems, this paper introduces a fuzzy sliding mode control (FSMC) method employing an innovative exponential convergence law. By incorporating a velocity adjustment function into the traditional exponential convergence law, a novel convergence law was designed to mitigate oscillations during the sliding phase and expedite the convergence rate. Additionally, a fuzzy controller was developed to implement a fuzzy adaptive SMC strategy, optimizing the MPPT for permanent magnet synchronous wind power generation systems. Simulation results indicated that this approach offered a faster response and superior interference rejection capabilities, compared to conventional and modified SMC strategies. The improved FSMC strategy demonstrated a swift, dynamic response and excellent steady-state performance, improving the efficiency of MPPT, thus confirming the effectiveness of the proposed method.

Dual internal model control with improved load current feedback for enhanced dynamic performance in aircraft high‐voltage direct current brushless generator

AbstractIn order to enhance the dynamic performance of aircraft high‐voltage direct current wound rotor synchronous generator (WRSG) system under load variations, a dual internal model control (DIMC) method utilising improved load current feedback (ILCF) is proposed. It employs internal model controllers in both voltage and current loops, thereby significantly augmenting the system's disturbance rejection capabilities. Improved load current feedback is incorporated between the DC voltage loop and the field current loop. Additionally, a method for designing a feedback fitting function is established, enhancing the system's adaptability to changes in operational speed and load. The authors outline parameter design methods for voltage and current loops in DIMC, based on the internal model control principle. Adjustments to these parameters can further enhance the system's disturbance rejection capabilities. Finally, comparative experiments between the PI method with ILCF and the DIMC method with ILCF are conducted on a 15 kW WRSG experimental platform. These experiments demonstrate that the proposed DIMC method with ILCF optimises dynamic performance across the entire speed range, enhancing the competitiveness of WRSG systems in aircraft applications.

Development of an emulation platform for synchronous machine power generation system using a nonlinear functional level model

The article presents the Power Hardware in the Loop (PHIL) approach for an autonomous power system analysis based on the synchronous generator model incorporating magnetic saturation effects. The model was prepared in the MATLAB/Simulink environment and then compiled into the C language for the PHIL platform implementation. The 150 kVA bidirectional DC/AC commercial-grade converter was used to emulate the synchronous generator. It was controlled by the real-time simulation control unit with the prepared synchronous generator model incorporating magnetic saturation effects. The proposed approach was validated on the 125 kVA synchronous generator connected to the active and reactive loads of different values for the steady-state and the transient-state performance studies.

A new passive‐based active disturbance rejection control for PMSG system with saturation constraints

AbstractThe disturbance in wind energy conversion system has a serious negative impact on the maximum power tracking performance of the system, and the saturation constraint problem also seriously restricts the stability of the control system. Therefore, a novel model compensation passive‐based active disturbance rejection control strategy is proposed to suppress the disturbance and saturation constraints, thus improving the tracking performance of the permanent magnet synchronous generator system in this paper. Taking advantage of the fact that active disturbance rejection control technology can estimate and compensate for the disturbances of the system in real time, a model compensation active disturbance rejection control method is proposed to make the system more robust to the changes in its own parameters and external disturbance. At the same time, the control input signal of the controller is given. A model compensation passive‐based active disturbance rejection controller is designed by using the passive control method, and the nonlinear sector method is introduced to solve the saturation constraint problem of the system. Simulation results show that the control strategy can effectively reduce overshoot, improve the system's response speed, have a good anti‐interference ability, and effectively suppress the influence of saturation constraints on the system.

Effective numerical simulations of synchronous generator system

Synchronous generator system is a complicated dynamic system for energy transmission, which plays an important role in modern industrial production. In this article, we propose some predictor-corrector methods and structure-preserving methods for a generator system based on the first benchmark model of subsynchronous resonance, among which the structure-preserving methods preserve a Dirac structure associated with the so-called port-Hamiltonian descriptor systems. To illustrate this, the simplified generator system in the form of index-1 differential-algebraic equations has been derived. Our analyses provide the global error estimates for a special class of structure-preserving methods called Gauss methods, which guarantee their superior performance over the PSCAD/EMTDC and the predictor-corrector methods in terms of computational stability. Numerical simulations are implemented to verify the effectiveness and advantages of our methods.

A Temporary Frequency Response Strategy Using a Voltage Source-Based Permanent Magnet Synchronous Generator and Energy Storage Systems

A Temporary Frequency Response Strategy Using a Voltage Source-Based Permanent Magnet Synchronous Generator and Energy Storage Systems

Dynamic Coupling Mechanism Analysis Between Voltage and Frequency in Virtual Synchronous Generator System

Dynamic Coupling Mechanism Analysis Between Voltage and Frequency in Virtual Synchronous Generator System

Frequency regulation strategy of direct drive permanent magnet synchronous wind power generation system based on RPC principle

Frequency regulation strategy of direct drive permanent magnet synchronous wind power generation system based on RPC principle

A Virtual Synchronous Generator Secondary Frequency Modulation Control Method Based on Active Disturbance Rejection Controller

In order to solve the frequency modulation (FM) problem caused by load in the virtual synchronous generator (VSG) system under an islanding state, this paper proposes a frequency modulation method based on active disturbance rejection control (ADRC). Firstly, design a nonlinear function using the design rules of nonlinear functions. Then, the extended state observer (ESO) and nonlinear feedback control law (NLSEF) of ADRC are designed based on the nonlinear function. By introducing ADRC into the power–frequency control loop of VSG, error-free frequency modulation of VSG is achieved. Finally, the superiority of the proposed method was verified through experimental comparison.

Direct Predictive Voltage Control for Grid-Connected Permanent Magnet Synchronous Generator System

In this paper, a direct predictive voltage control (DPVC) is proposed for the grid-connected permanent magnet synchronous generator (PMSG) system. In the proposed strategy, the dc-link voltage regulation and power regulation terms are merged into one cost function, thereby eliminating the conventional cascade control structure. The strategy selects the voltage vector that not only will generate a dc-link voltage closer to the setpoint at instant <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$k+2$</tex-math></inline-formula> , but will generate an active power that can further reduce that voltage error for the future instant. To cope with the mismatch between the actual and nominal parameters, Kalman filter has been added to compensate for the steady-state error. Besides, to enhance the dynamic performance and to save the effort of parameter tuning, the weighting factor is further eliminated from the cost function by sorting the terms into two groups and independently evaluating each group in turn. To fully validate the effectiveness of the proposed strategy, the experimental test waveforms of the DPVC strategy with and without weighting factor have been presented and compared with that of the conventional PI-MPC strategy in various testing conditions.

Power electronic transformers in wind power generation systems

Power electronic transformers (PET) have received extensive attention due to their advantages of compensating reactive power, improving power quality, limiting fault current, and reducing the number of traditional transformer materials. At present, it is also an important research topic to replace conventional power frequency transformers in wind power generation systems. This paper first analyzes the topology of the primary circuit of the power electronic transformer. Several common PET topologies are introduced, and their advantages and disadvantages are analyzed. The module cascade topology and modular multilevel topology are mainly introduced, and the topological circuit diagram is given. The paper also comprehensively introduced the research status quo of wind power generation systems based on the interface of PET, permanent magnetic wind turbines and dual-feed fan wind turbines. The traditional structure of the permanent magnet synchronous generator (PMSG) system and the doubly fed induction generation (DFIG) system is shown. Finally, the problems in PET and the future development direction are summarized.

Optimal frequency fault‐tolerant control of virtual synchronous generator based on adaptive dynamic programming with fuzzy critic estimator

AbstractWith the popularity of renewable energy sources, fault‐tolerant frequency stability of distributed generation systems has become a major challenge. This paper proposes an optimal frequency fault‐tolerant control method in the distributed generation system, utilizing adaptive dynamic programming combined with fuzzy critic estimation. First, based on the operational state of the system, a non‐linear dynamic model for the virtual synchronous generator is established. Then, considering the occurrence of actuator faults, the fault‐tolerant control problem is formulated as an optimal control problem, where a fault observer is designed to estimate the fault signals. Furthermore, the proposed adaptive dynamic programming method based on fuzzy critic estimation is employed to effectively solve the highly coupled nonlinear Hamilton–Jacobi–Bellman equation and ensure the state convergence of the system with uniform ultimate boundedness. The optimal fault‐tolerant control law ensures a bounded frequency error for the virtual synchronous generator system in the event of faults. Finally, the effectiveness of the optimal control method is verified by two sets of simulations.

A fuzzy control and neural network based rotor speed controller for maximum power point tracking in permanent magnet synchronous wind power generation system

When the wind speed changes significantly in a permanent magnet synchronous wind power generation system, the maximum power point cannot be easily determined in a timely manner. This study proposes a maximum power reference signal search method based on fuzzy control, which is an improvement to the climbing search method. A neural network-based parameter regulator is proposed to address external wind speed fluctuations, where the parameters of a proportional-integral controller is adjusted to accurately monitor the maximum power point under different wind speed conditions. Finally, the effectiveness of this method is verified via Simulink simulation

Robust Unknown Input Reconstruction Observer for Hierarchical Parameter Estimation of Synchronous Generator and Brushless Excitation System

This paper copes with the parameter estimation (PE) of the synchronous generator (SG) and the excitation systems. The field winding signals are not available for accurate measurement in the proposed strategy. To this end, a robust unknown input reconstruction (UIR) observer is exploited to determine both SG unknown inputs, including the mechanical torque and field voltage, under disturbances influence. Moreover, the gathered data from one of the SG identification tests, such as a power system stabilizer (PSS)-based method, is deployed for PE of the SG and excitation system hierarchically in the way that the excitation system identification is conducted after reconstructing the field voltage and current. The recommended approach is applied to a 150 MW gas unit, and the comparisons of the simulation and measurement data during validation tests demonstrate the high accuracy of the resultant parameters.

Fuzzy control based adaptive rotational inertia VSG grid integration research

Compared with the traditional inverter grid-connected control strategy, virtual synchronous generator (VSG) has received attention because it can effectively reduce the current shock to the grid caused by load fluctuation during grid-connected process by adding rotational inertia and damping parameters. A fuzzy control scheme is added to the rotor equation of motion of VSG to establish fuzzy rules by finding the relationship between frequency fluctuation and rotational inertia during grid connection. To improve the immunity of the frequency converter to interference during grid connection, and then improve the stability of the output power in the grid-connection process. The feasibility of the proposed method is verified by simulink model construction for simulation and comparison with the conventional virtual synchronous generator system.

Coupling stability analysis of synchronous generator and virtual synchronous generator in parallel under large disturbance

With the development of virtual synchronous generators (VSG), microgrids can choose a synchronous generator (SG) or a virtual synchronous generator (VSG) as the main power supply of an isolated island system. The governor of a synchronous generator and the active power control loop of a virtual synchronous generator may cause the transient power angle instability of the system, while the excitation device and reactive power control loop may cause the transient voltage instability. At present, there have been many studies on these two aspects. However, when a synchronous generator and a virtual synchronous generator are used as the main power sources to supply power to the isolated island system, the mutual coupling between the synchronous generator and the virtual synchronous generator may cause transient power angle and voltage instability. At present, there is little research in this field. Therefore, this paper focuses on the influence of the parallel mutual coupling of synchronous generator and virtual synchronous generator on the system stability, derives the mutual coupling model of a parallel system, it is also revealed that the coupling relationship between the SG and VSG parallel systems will produce a positive feedback mechanism that will be constantly amplified, which will greatly affect the system's stability. At the same time, the influence of coupling on the stability of a parallel system is carefully analyzed using large signal analysis, and the corresponding coupling suppression strategy and adaptive inertia control (AIC) is proposed. Finally, the correctness and feasibility of the proposed method are verified by time-domain simulation, and the experimental results are analyzed.

Fuel Consumption Efficiency Enhancement of Synchronous Diesel Generator Operating at Adjustable Speed using Adaptive Inertia Weight Particle Swarm Optimization Algorithm

Diesel generator is a reliable source of electricity, but requires quite high operational costs, especially for fuel. This paper describes a technique for reducing fuel consumption in Diesel Engine Synchronous Generator systems. The system is originally a Constant Speed Diesel Synchronous Generator (CSD-SG), but during certain conditions, the speed is reduced to minimize fuel consumption by adjusting the Specific Fuel Consumption (SFC) map. SFC is defined as the amount of fuel consumed by a diesel engine generator for each unit of power output. It shows various numbers depending on the speed and operating power. In this paper, we use the Adaptive Inertia Weight Particle Swarm Optimization (AIWPSO) algorithm to select of the proper SFC curve at a certain speed and operating power. AIWPSO employs an adaptive inertial weight adjustment method, which enables this algorithm to achieve faster convergence than conventional Particle Swarm Optimisation (PSO) algorithms. The system is embedded with AC/DC/AC power electronics converter to regulate the frequency. Data set of 1000 kVA Cummins diesel engine generator from the oil and gas company in Central Java, Indonesia was taken for simulations. The results show that the AIWPSO algorithm calculates the fuel consumption as 1,678 liters per day on a typical condition, whereas the previous method, the linear line needs 1,693 liters per day. Therefore, using AIWPSO method can save up to 450 liters of fuel per month. The simulation results show that the proposed method can improve fuel efficiency compared to the previous model.

Dynamic Analysis and Fuzzy Fixed-Time Optimal Synchronization Control of Unidirectionally Coupled FO Permanent Magnet Synchronous Generator System

This paper focuses on dynamic analysis and the fuzzy fixed-time optimal synchronization control problem of unidirectionally coupled fractional-order (FO) permanent magnet synchronous generator (PMSG) system. The synchronization model between FO master and slave PMSGs with capacitive and resistive couplings is built. The dynamic analysis fully reveals its abundant dynamical behaviors including chaotic oscillations and gives stability/instability boundaries with the designed numerical method. In controller design, the hierarchical type-2 fuzzy neural network (HT2FNN) with a transformation is designed to approximate unknown functions, the fixed-time command filter matched up with the compensating signal is proposed to achieve precise estimate and fast convergence, and a fixed-time preconfigured performance function integrated with a smooth and invertible function is built to realize fixed-time convergence and performance constraint. Then a fuzzy fixed-time optimal synchronization control scheme fusing with the HT2FNN, filter, performance function and optimal control is developed under the FO backstepping theory. The stability analysis proves that all signals of the closed-loop system are bounded along with the cost function being minimized. Finally, numerical simulation results verify the feasibility and advantages of our scheme.

Study of Resistive SFCLs for Transient Stability Enhancement of Paralleled Synchronous and Virtual Synchronous Generators in Weak Grid

Regarding a paralleled synchronous generator (SG) and virtual synchronous generator (VSG) system connected to a weak grid, the transient stability should be given more concern. This paper proposes applying resistive superconducting fault current limiters (R-SFCLs) to boost the paralleled SG-VSG system's transient stability while meeting the current limitation requirement (CLR). Firstly, the theoretical modeling is carried out, and the influencing mechanism of the grid strength on the transient stability is clarified. Then, the functions of the R-SFCLs to the paralleled system are analyzed, and the parameter design guidelines for the R-SFCLs are stated. Time-domain simulations are implemented in MATLAB, and a detailed comparison of using the R-SFCLs and the additional torque control for the paralleled system is made. From the simulations, the proposed approach offers a more significant stabilization effect. It outperforms the additional torque control to decrease the unbalanced power, eliminate the power angle oscillation, and handle the short-circuit fault with a longer duration for the paralleled system. The viability and appropriateness of the proposed approach are well confirmed.

Stability Analysis of Active Front End and Permanent Magnet Synchronous Generator With Back EMF-Based Sensorless Control for DC Marine Vessels

This article studies the influence of sensorless control on the permanent magnet synchronous generator (PMSG) and pulsewidth modulation (PWM) converter (active front end rectifier, AFE) system for dc marine vessels. Back EMF-based sensorless control is adopted in this article because the minimum speed of PMSG in a dc marine vessel is enough for obtaining a sufficient back EMF signal. First, the output impedance of “PMSG+AFE” system with a typical topology and controller is deduced by small-signal analysis. The stability analysis with constant power load (CPL) is analyzed, including the influence of sensorless control bandwidth on PMSG with a significant per-unit impedance value. Since the inductance parameter affects both the current control and sensorless control, the influence of error in the estimated inductance parameter on the stability of “PMSG+AFE” system is analyzed. To verify the proposed impedance model, output impedance is measured in the simulation and experiment. The stability analysis with the proposed impedance model and load impedance of CPL is provided in MATLAB, and simulation results and experimental measurements are given to verify the analysis.