Large-scale Wind Power Generation Systems Research Articles

Stochastic Modelling and Stability Analysis of Large-Scale Wind Power Generation System with Dynamic Loads

As a result of dwindling fossil fuel reserves and the negative impact of greenhouse gases (GHGs) on the environment, it is important that the search for a power grid that will comprise of only variable renewable energy (VRE) generation sources such as wind or solar energy which is available everywhere for free is given much attention. The main challenge associated with these sources of energy is their variability and random nature. It is as a result of instability introduced by the VRE generation sources, that is why there is a strict control measures put in place by the regulators as to how much VRE generation sources can feed into the power grid in the case of its integration into an existing power grid. It becomes imperative to consider implications for grid stability and reliability when considering a power grid that will consist of VRE generation only. Eigenvalue approach was used to analysed the performance of anticipated large-scale VRE grid to ascertain its behaviour. Eigenvalue approach is one of the methods to examine the stability of a power system’s dynamic performance. The results indicated that it is possible to attain the necessary stability provided the assumptions made during the modelling stage is revised to improve upon the model.

Model Predictive Control Method of hybrid Battery energy storage system for Smoothing Wind Power Fluctuation

In a large-scale wind power generation system, active power fluctuation caused by random wind speed will have a serious impact on the power grid. In order to limit the power fluctuation that wind farm transmits to the power grid and protect the energy storage battery, this paper has proposed a model predictive control method of hybrid energy storage by optimizing the objective function and constraint conditions. Firstly, the mathematical model of predictive control method has been established in a wind power system with hybrid energy storage. Then, with the goal of minimum energy storage output and maximum charging-discharging capacity of the super-capacitor, the predictive control process has been optimized. Meanwhile, the constraint on the output power of the battery has been dynamically changed to reduce its charging-discharging switching frequency, and the model predictive control strategy of the hybrid energy storage has been formed. Finally, compared with the model prediction control method of single energy storage, based on a wind farm data, the simulation results show that the proposed method can smooth wind power fluctuation, reduce the time that the power does not satisfy the fluctuation requirements, ensure the capability of the super-capacitor, and reduce the charging-discharging switching frequency of the energy storage battery.

An Improved Brushless Doubly Fed Generator With Interior PM Rotor for Wind Power Applications

This paper presents a novel interior permanent magnet brushless doubly fed generator (IPM-BDFG) for wind power applications, which is based on the magnetic field modulation theory. The basic structure and working principle of the IPM-BDFG are put forward first. As the rotor structure has a great influence on the performance of the IPM-BDFG, the merits of the IPM rotor are discussed by comparing with the surface-mounted rotor. In order to solve the asymmetry phenomena and reduce the harmonics caused by the introduction of field modulation ring, a three-segmented structure for the outer rotor is adopted. Finally, the performances of the proposed IPM-BDFG are validated by using finite-element analysis (FEA). The FEA results show that the IPM-BDFG with segmented outer rotor has excellent performances and owns good potential in the applications of future large-scale wind power generation systems.

A Brushless Doubly Fed Generator Based on Permanent Magnet Field Modulation

A brushless doubly fed generator (BDFG) for wind power applications with a double-rotor structure is presented in this paper. First, field modulation ring and its application in the proposed BDFG are introduced. The geometric constraints of the field modulation ring are analyzed. Then, the operation principle of a variable-speed constant-frequency BDFG system is presented. The design of the BDFG is discussed, and finite-element analysis for the BDFG is carried out to obtain the performance of the machine. Finally, a small-size prototype machine is designed and manufactured to verify the theoretical analysis. The proposed BDFG has some advantages, such as high efficiency and high reliability. It has good potential on the applications of future large-scale wind power generation systems.

Hardware Integration and Performance Analysis of a 10 kW HTS Wind Power Generator

The use of high temperature superconducting (HTS) generators in a large-scale wind power generation systems has drawn much attention as a contemporary research topic. In this paper, a prototype 10 kW HTS generator was designed based on the suggested design process considering electromagnetic, thermal and mechanical characteristics of the generator. We estimated the output power of the generator and operating current of the HTS field coils was decided considering the critical current and perpendicular magnetic field of the HTS wire. The thermal characteristics of the HTS generator was analysed to confirm that it was cooled to the operating temperature of 30 K. The torque tube and sticks of the HTS rotor part in the generator were designed and analysed to withstand mechanical stress considering the torque and thermal contraction. Based on these results, the HTS generator was built, and tested to prove the adequacy of the established design process of the generator. The measured cooling temperature of the fabricated generator was cooled to the target temperature of 30 K, and the magnetic field values of the HTS field coils and armature were the same as the simulation values. Finally, the output power of the generator was reached to the target output power of 10 kW. In this paper, the detailed results of the operating performance of the 10 kW HTS generator are discussed in detail.

Design, Fabrication, and Analysis of HTS Coils for a 10-kW Wind Power Generator Employing a Brushless Exciter

High-temperature superconducting (HTS) generators for large-scale wind power generation systems attract much research attention. Excitation systems in HTS generators, particularly brushless HTS exciters, are a new challenge. To verify the possibility of a brushless HTS exciter in a large-scale wind power generator, we designed and fabricated HTS coils for a laboratory-scale wind power generator employing a brushless exciter. In order to supply dc current into the HTS coils, a brushless exciter was considered in the generator. All of the field coils were wound with an HTS coated conductor made of 2G GdBCO wire. The conduction cooling test was executed in a cryogenic test chamber to check the performances at 30 K. The detailed results of the operating performance of the HTS coils were discussed in detail.

Design of dual-dimensional controller based on multi-objective gravitational search optimization algorithm for amelioration of impact of oscillation in power generated by large-scale wind farms

This paper studies the impact of high penetration of wind generation technology on dynamic stability of power networks. A mathematical model of a multi-machine power system, including Large-scale Wind Power Generation System (LWPGS) incorporating active power oscillation due to tower shadow and wind shear phenomena is developed. Based on this model, an extended Small-Signal Scrutiny (SSS) procedure to study the impact of oscillatory modes on mechanical vibrations is proposed. The critical operating points that can be dangerous for power system performance are detected. The study is based on modified 16-machine 5-area network with lightly damped electromechanical modes. A dual-dimensional controller for LWPGS is proposed. The first and second dimensions of the designed controller are based on wide-area and local signals, respectively. Selection of the best input of the LWPGS is based on Singular Value Decomposition (SVD) analysis, while the qualified remote control signal is found by geometric approach. Multi-Purpose Gravitational Search Algorithm (MPGSA) based on fuzzy decision making is applied for the coordinated design of LWPGS controller and accelerating power PNS (PNS2B) of the synchronous machines. The simulation results are presented to elucidate the effectiveness of the well-tuned damping controller of the LWPGS.

NOVEL FAULT DIAGNOSIS METHOD BASED ON CHAOS EYES AND EXTENSION NEURAL NETWORK FOR WIND POWER SYSTEMS

This paper proposes a novel approach based on the chaos eye method (CEM) and extension neural network (ENN) for fault diagnosis of wind power systems. First, we used sensors to capture the vibration signals of the wind power system to detect subtle changes. Subsequently, the chaotic synchronization detection method was used to form a chaos error distribution diagram. The distribution diagram centroid, called chaos eye in this paper, was used as the fault diagnosis feature to reduce the number of extracted features. This reduction in diagnostic features enables considerably reducing the computation time and cost of hardware implementation. The ENN-based method was then used to design a fault diagnosis system for the tested wind power generation. The feasibility and practicability of the proposed method were validated using a simulation system. The patent for the proposed method is currently pending, and this method contributes to the key technologies of large-scale wind power generation systems in Taiwan.

Profit payment scheme for service created by hybrid controller of large-scale wind power generation system

The contribution of hybrid controller of large-scale wind power generation system (LWPGS) in system stability and profit is discussed throughout the paper. To this purpose, it is necessary to formulate the impact of high infiltration of wind turbines on the dynamic stability of power networks. A mathematical model of a multi-machine power network is developed first, based on which an extended small-signal stability analysis procedure is projected and discussed to handle the influence of LWPGS on oscillatory modes. This model is then applied for analyzing the damping impact of the LWPGS and ancillary service (AS) associated with its controller. After the model creation, the profit created by LWPGS hybrid controller as AS is analyzed by multi-objective optimization based on low-frequency oscillation stability criterion and generation cost. Two scenarios for the valuation of small-signal stability as an AS provided by LWPGS controller are considered. The study is based on a changed 16-machine 5-area network. The comparative analysis of the results is also presented to elucidate the suggested approach.

Designs of 10 MW Air-core and Iron-core HTS Wind Power Generators

High Temperature Superconducting (HTS) synchronous generators can be designed with either an air-core type or iron-core type. The air-core type has higher efficiency under rated rotating speed and load than the iron-core type because of the iron losses which may produce much heat. However, the total length of HTS wire in the air-core type is longer than the iron-core type because the generated magnetic flux density of the air-core type is low. This paper deals with designs of 10 MW air-core and iron-core HTS wind power generators for wind turbines. Fully air-core, partially iron-core, and fully iron-core HTS generators are designed, and various stator winding methods in the three HTS generators are also considered, such as short-pitch concentrated winding, full-pitch concentrated winding, short-pitch distributed winding, and full-pitch distributed winding. These HTS generators are analyzed using a 3D finite elements method program. The analysis results of the HTS generators are discussed in detail, and the results will be effectively utilized for large-scale wind power generation systems.

Design and Characteristic Analysis of a 10 kW Superconducting Synchronous Generator for Wind Turbines

A superconducting synchronous generator (SCSG) is suitable for designing a large-scale wind power generation system, because of its lighter weight and higher torque as compared to conventional generators. This paper analyzes a 10-kW SCSG designed by the finite element method. The finite element method tool is used to evaluate the designed 10-kW SCSG, which has 16 double pancake coils of race-track type with coated conductor tape according to the component certification (IEC 60034) for a wind power generator. The results show several specific characteristics of the designed SCSG. The results can also effectively evaluate the SCSG for a wind turbine, before the scale-up design and fabrication of the generator.