Direct-drive Wind Power Generation System Research Articles

Improved Maximum Power Point Tracking Control for D-PMSG Systems: Fuzzy Gradient Step Approach

Improved Maximum Power Point Tracking Control for D-PMSG Systems: Fuzzy Gradient Step Approach

Modeling of Direct-Drive Permanent Magnet Synchronous Wind Power Generation System Considering the Power System Analysis in Multi-Timescales

The dynamics of wind power generation cannot be neglected in the modern power system and could have a great impact on the system dynamics, even raising the risk of a blackout. Because of this, power system simulation has to include the model of wind power generation. However, due to the high order of the full model of the wind power generator, it is impossible to model them in detail in the use of the power system dynamic simulation considering the thousands of wind generators in the grid. In this context, a simplified model is normally used with the trade-off in lower accuracy. As a direct-drive permanent magnet synchronous wind power generation system (D-PMSG) would take up a certain occupation in the modern power system, a proper D-PMSG simplified model is needed in the power system simulation. For a different research purpose in a different timescale, a different complexity of the model can be used to maximize the accuracy, in the meantime speeding up the simulation. This paper proposes a set of simplified models of the direct-drive permanent magnet synchronous wind power generation system (D-PMSG) and classifies them according to the timescale of the dynamics and the use cases, i.e., faults (transient stability analysis), system contingencies (voltage and frequency stability analysis) and wind speed variations (energy transformation). The accuracy of the proposed simplified models is verified by comparing them with the detailed D-PMSG electromagnetic transient mode in Matlab/Simulink, and their use case of the power system simulation is validated based on the case study of the IEEE 39-bus system considering the above scenarios.

Optimization of Computer Communication Monitoring System for Wind Turbine Speed

This article first studies the operating principles of wind turbines, focusing on the analysis of the structure and working principles of permanent magnet direct-drive wind turbines. According to the actual needs of the wind power system, the monitoring objects of the monitoring system are determined, and the overall monitoring plan for wind power generation is proposed to realize real-time analysis of the operating characteristics of the wind power system. At the same time, it pointed out the great significance of the wind power generation simulation experiment system and focused on the wind speed modeling. In terms of hardware research and analysis, relevant sensors, high-speed data acquisition cards, etc., were selected, and relevant signal conditioning circuits were designed, and a permanent magnet direct-drive wind power generation system simulation monitoring platform was constructed. In terms of software, LabVIEW was chosen as the design language of the monitoring system, and it pointed out the advantages of using LabVIEW in this monitoring system. Finally, the system uses the laboratory permanent magnet direct-drive wind turbine as the monitoring object. The practicality and accuracy of the system are verified through experiments such as permanent magnet motor power test, motor speed test, database system test, and remote monitoring test. The experimental results show that the monitoring system has a friendly interface and perfect functions and has important practicability and reference in the field of wind power monitoring.

Characteristics Analysis of Inertia Damping of Grid-Connected System of Direct-Drive Wind Power Generation

As large-scale direct-drive wind turbine generator set is connected to the grid, the power system will face problems such as reduced inertia and insufficient frequency modulation capability. The control of wind turbine virtual inertia is an important way to solve this problem. Therefore, this paper takes the direct-drive wind power generation system as the research object, draws lessons from the multi-time scale modeling idea, and based on the electrical torque analysis, establishes the DC voltage time model with the wind turbine virtual inertia control. Based on this, inertia damping characteristics of direct-drive wind power grid-connected system are analyzed. The results show that the dynamic characteristic parameters of the system are affected by many factors, among which the equivalent inertia coefficient of the system is mainly affected by DC capacitance, DC bus voltage and wind turbine virtual inertia control parameters. Damping coefficient is mainly affected by steady-state operating point and DC voltage proportional control parameter K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pu</sub> . The synchronization coefficient is mainly affected by steady-state operating point and DC voltage integration control parameter K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">iu</sub> . The correctness of mechanism analysis of inertia damping characteristics of the whole system is verified by simulation, which provides a certain theoretical reference for inertia damping research of electronic power system.

Simulation study on direct‐drive wind power system

Direct-drive wind turbine is an important type of wind power technology. In recent years, it has also become the development trend of large-capacity wind turbines. It is difficult and expensive to establish physical simulation for wind in reality, which makes the real-time simulation model necessary in the study its power generation control strategy and operation characteristics. Here, the structure and basic principles of the direct-drive wind power system was studied, mathematical model of the dq generator and converter using coordinate transformation was built, and control methods including the wind turbine pitch angle control, maximum power tracking control, and generator-side variable flow control were simulated. Furthermore, a control strategy of generator-side converters and grid-side converters was proposed and studied based on the model in the real-time simulation system RTDS. Different working conditions as grid-connected normal operation and operation with grid fault were simulated within the strategy. Waveforms of current, voltage, power, torque were obtained and analysed. The simulation results showed that the simulation model reflected the operating characteristics of the direct-drive wind power generation system well, the control strategy performed successfully, and the features of the system in normal and faulted operation were preliminarily revealed.

Switched model based control of dual-PWM converters in the direct-drive permanent magnet synchronous wind turbine system

Nowadays, permanent magnet synchronous generator (PMSG) based direct drive wind power generation systems are developing rapidly and are attracting more and more attention. Dual-PWM (pulse width modulation) converters, as full power converters of the direct-drive wind power system, have excellent performance and have been widely used in recent years. The effective control of the back-to-back Dual-PWM converters plays an important role in generating the wind power efficiently. As the back-to-back Dual-PWM converters of the direct-drive wind power generation system can be considered as switched systems according to their working characteristics, this study presents one switched model based control strategy for the control of the Dual-PWM converters. First, the switched dynamic models of the converters on the PMSG side and the grid side are established, respectively. In contrast to the traditional averaged or linearized models, the proposed models can be more precise because no approximation will be introduced when the wind speed changes. Then, in order to realize the highest convergent rate, the min-projection strategy based switched control laws are derived. Furthermore, the stability analysis is done to assure the global stability of the proposed control strategy. Finally, detailed simulations and experiments are available to verify the proposed control method. The simulation and experimental results demonstrate that the proposed models and the control strategy are correct and effective. Comparing with the conventional proportional-integral control method, this paper integrates the back-to-back Dual-PWM converters as part of the proposed controller and utilizes the states of the converters as control variables, and thus, faster torque dynamics can be achieved.

A Review on Low Voltage Ride-Through Solutions for PMSG Wind Turbine

The exiting of wind turbines will cause the adverse effect on the power grid and its assembling unit in network voltage drops. So, direct-drive wind power generation system should meet the requirement of the certain ability of low voltage. This paper introduces the influence of wind power system with different structure by voltage drop as well as the disadvantage and advantage on LVRT. The relate regulations based on LVRT are analyzed. The existing LVRT technologies of direct-drive wind power systems are briefly presented. The characteristics of each scheme from the different LVRT technology are analyzed. Moreover, further study of LVRT for PMSG is pointed out.

Gearless Continuously Variable Transmission Technology and its Application in Wind Power Generation

Based on gearless continuously variable transmission technology, a cascaded wind power generation system with Variable Speed Constant Frequency (VSCF) is presented in this paper. The system has combined the advantages of doubly-fed and direct-drive wind power generation system. The raising-speed gear box has been done away with, and the system reliability has been improved. Reducing the power capacity of the aspects of the variable frequency speed regulation, the function of grid-connected electricity generation can be achieved with less cost. Synchronous generator directly connects to grid, which helps to optimize power quality. The topological structure of system is discussed in this paper, and its operating principle is analyzed, revealing its characteristics and engineering application prospects.

A Space-Vector-Modulated Sensorless Direct-Torque Control for Direct-Drive PMSG Wind Turbines

This paper proposes a space-vector modulation (SVM)-based direct-torque control (DTC) scheme for a permanent-magnet synchronous generator (PMSG) used in a variable-speed direct-drive wind power generation system. A quasi-sliding-mode observer that uses a relatively low sampling frequency, e.g., 5 or 10 kHz, is proposed to estimate the rotor position and stator flux linkage based on the current model of the PMSG over a wide operating range. The optimal torque command is directly obtained from the estimated rotor speed for the DTC by which the maximum power point tracking control of the wind turbine generator is achieved without the need for wind speed or rotor position sensors. Compared with the conventional DTC, the proposed SVM-DTC achieves a fixed switching frequency and greatly reduces the flux and torque ripples, while retaining the fast dynamic response of the system. The effectiveness of the proposed SVM-DTC scheme is verified by simulation studies on a 1.5-MW PMSG wind turbine and is further verified by experimental results on a 2.4-kW PMSG with a 10-kHz sampling frequency.

The Design and Simulation of Improved and Multiplex Boost Converter

In a MW-level and high-power wind power system, the level of current and voltage is easy to exceed the capacity of one switch device, so single boost converter has already can't meet the requirements of system. To solve this problem , for 1.2MW direct drive VSCF wind power system this paper designed a improved and multiplex boost converter , the over-voltage protection circuit branch is inserted into the circuit. The system state equation and control strategy are given, and the input current ripple is analyzed. Finally, in the Matlab environment, build the model of direct-drive wind power generation system to verify the feasibility of this circuit. The results show that: the system can run stably, has high efficiency, low ripple and has a good practical value. DOI : http://dx.doi.org/10.11591/telkomnika.v12i4.5002

A Simulation System of Wind Turbine Based on Labwindows

Wind energy is the worlds fastest growing renewable energy source in recent years, and it has drawn worldwide attention. Due to high efficiency, simple topology and stable operation, variable speed constant frequency (VSCF) direct-drive wind power generation system using permanent magnet synchronous generator (PMSG) is the development trend and one of the focuses of wind power generation system research. The paper introduces the trend of the development wind power generation and the recently research stage on the wind power generation. Based on the VSCF power fundamental principle, the dissertation analyzes the strategy of wind turbine simulation. In the development of wind power generating system, the wind turbine emulator becomes more and more important because it can provide controllable wind turbine characteristics. Simplified mathematical model based on the CT-λ curve is constructed, the system structure and emulation method are analyzing. Hardware and software are designed and implemented, and a laboratory set-up is building which based on DC motor. Experimental results show that the wind turbine emulator is as good as expected.

Investigation of PMSG Fed Diode-Clamped Multilevel Inverter for Wind Energy System

Wind energy has drawn worldwide attention because of its simple structure, high efficiency and stable operation. Recently, variable speed constant frequency (VSCF) direct-drive wind power generation system using permanent magnet synchronous generator (PMSG) has gained popularity. This paper focuses on the simulation of PMSG fed diode clamped MultiLevel Inverter (MLI) for wind applications. A three-level MLI with phase disposition PWM technique has been proposed. Simulation studies on the proposed scheme have been carried out in MATLAB and spectral quality of the output has been investigated.

Parallel Operation of Full Power Converters in Permanent-Magnet Direct-Drive Wind Power Generation System

Parallel operation is an effective way to improve the capacity of full power converter in permanent-magnet direct-drive wind power generation system. But it causes the zero-sequence circulating-current (ZSCC), which brings current discrepancy, current waveform distortion, power losses, and electromagnetic interference (EMI), etc. The paper proposes a new topology of full power converters which are composed of <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> full power converters. The <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</i> converters have the same structures and are in parallel with each other. Besides, the average models of the system are analyzed and the fundamental mechanism of ZSCC generation is given. Based on the above analysis, the control strategy of the system is designed. The simulation and experiment results of two parallel full power converters show the feasibility of the proposed theory and control scheme.

Improved sliding mode model reference adaptive system speed observer for fuzzy control of direct‐drive permanent magnet synchronous generator wind power generation system

This study presents an improved sliding mode model reference adaptive system (SM-MRAS) speed observer for the fuzzy control of direct-drive wind power generation system with a permanent magnet synchronous generator (PMSG). The SM-MRAS speed sensorless observer is described and the corresponding algorithm is derived. The designed fuzzy controller is compared with the conventional PI controller by simulations and experiments. A dc motor is controlled to simulate the wind turbine and an active machine-side converter with space vector pulse width modulation control is adopted to realise the maximum power extraction. A 250-W PMSG experimental platform is built and the experiment results verify the validity of the proposed SM-MRAS speed observer.

Direct driven wind energy conversion system based on hybrid excitation synchronous machine

A novel direct-drive type wind power generation system based on hybrid excitation synchronous machine (HESM) is introduced in this paper. The generator is connected to an uncontrollable rectifier, and a fully controlled voltage-source inverter is used to connect the system to utility grid. An intermediate DC bus exists between the rectifier and inverter. A new control strategy is proposed which achieves the maximum power point tracking (MPPT) with the control of excitation current of HESM and stabilizes the DC link voltage with the control of inverter output current simultaneously. Specially-designed buck circuit is used to control the excitation current of HESM, and grid voltage-oriented vector control strategy is employed to realize the decoupling of the inverter output power. Simulation results and experiment in 3 kW lab prototype show an excellent static and dynamic performance of the proposed system.

Model Predictive Control for Direct-Drive Wind Power Generation Systems

Permanent magnet synchronous generator (PMSG) are commonly used in direct-drive wind power generation systems, which produce high efficiency, high reliability and low cost in wind power generation. This paper presents a new and simple control scheme using predictive control, which is used in PMSGs and grid-connected inverters. The controller uses the models of PMSGs and grid-connected inverters to predict on each sampling interval. A cost function defines the desired behavior of the system. The switching state that minimizes the cost function is selected and applied during the next sampling interval. At any wind speed within the operating range, the PMSG rotor speed can optimally controlled to extract maximum wind power. The simulated results show that the proposed control scheme can provide the direct-drive wind power generation system with the maximum efficiency and high dynamic performance.