マイクログリッドのためのバッテリーエネルギー貯蔵システムの最適化

九州工業大学博士学位論文（要旨）学位記番号：工博甲第423号 学位授与年月日：平成28年9月23

Robust Control of Hydro-Thermal Power System Considering Energy Capacitor System

This article proposes a robust controller design of hydro-thermal power system considering of the thermal power plant area connected to the hydro power plant area. The automation generation control of an interconnected hydro-thermal power system with a small Energy Capacitor System (ECS) augmented to both area has been investigated. The controller is used in order to control the frequency robustly and to improve the power system stability due to the uncertainties in load change and energy capacitors in the system. The power from the load changes are introduced into the system and treated it as the uncertainty during the design process. The H-infinity loop-shaping design procedure (H-infinity LSDP) is adopted as the control design procedure in this study. The results reveal that H-infinity LSDP can achieve higher performance and more robustness compared with PID controller

Laboratory Study of Polypropylene-based Honeycomb Core for Sandwich Composites

Nowadays, a structure of sandwich composites can be reinforced by with hybrid materials such as polypropylene core. Due to its high strength properties, the polypropylene is widely used in various fields of science, technology and engineering including aerospace applications. This research studies the well-known hybrid composites of a carbon fiber (CF) and glass fiber (GF) to evaluate the mechanical properties under the presence of sandwich composites reinforced with such fibers. The different curing-pressure values of each material workpiece have been investigated to determine the curing pressure, resulting in the superior performances and properties. The specimens are moulded by the hand lay-up (i.e., cloth laying angle) of the carbon fiber. By changing direction, the specimens are determined the greatest load-bearing direction based on the bending test. According to the ASTM standard on the strength determination, it is found that when the curing pressure increases, the flexural stress increases. By placing the material orientation in the order (i.e., [CF90 / CF0 / GF0 / Core / GF0 / CF0 / GF0]) provides the highest strength. When the strain reaches its maximum value, the specimens actually fracture. The fracture propagation is generally followed the fiber orientation of the fabric. The experimental results are observed that the lower curing pressure the thicker of the work piece and the fiber volume fraction decreases. The obtained results show that changes in the curing pressure and laying angle significantly affect the mechanical properties of the sandwich composite

Experimental Manufacturing Methods of Glass Fiber Composites Considering Flexural Behaviour

Fiber-reinforced plastic laminates (FRPL) and sandwich composites are outstanding materials due to its mechanical properties (i.e., light weight, low density and high strength to weight ratio). These applications are widely used in the fields of aviation, automotive and construction industries. The superior mechanical properties depend on the properties of reinforcing materials, matrixes and manufacturing processes. This research proposes the comprehensive study of mechanical properties of epoxy resin reinforced by glass fibers under different processes. Glass-fiber sandwich composites were manufactured by the hand lay-up process and cured in different methods (i.e., with and without vacuum bagging). The comparison between curing temperature and pressure is investigated using the vacuum bagging process to determine the mechanical properties under flexural tests. Experimental tests are performed using the universal testing machine (UTM). As a result, it is confirmed that the hand lay-up process affects the flexural stress, deflection and internal force of both fiber-reinforced plastic laminates and sandwich composites. At the high curing temperature, the vacuum bagging method significantly provides the greater flexural stress, deflection and loa

Self-Adaptive Virtual Inertia Control-Based Fuzzy Logic to Improve Frequency Stability of Microgrid With High Renewable Penetration

Maintaining frequency stability of low inertia microgrids with high penetration of renewable energy sources (RESs) is a critical challenge. Solving this challenge, the inertia of microgrids would be enhanced by virtual inertia control-based energy storage systems. However, in such systems, the virtual inertia constant is fixed and selection of its value will significantly affect frequency stability of microgrids under different penetration levels of RESs. Higher frequency oscillations may occur due to the fixed virtual inertia constant or unsuitable selection of its value. To overcome such a problem and provide adaptive inertia control, this paper proposes a self-adaptive virtual inertia control system using fuzzy logic for ensuring stable frequency stabilization, which is required for successful microgrid operation in the presence of high RESs penetration. In this concept, the virtual inertia constant is automatically adjusted based on input signals of real power injection of RESs and system frequency deviations, avoiding unsuitable selection and delivering rapid inertia response. To verify the efficiency of the proposed control method, the contrastive simulation results are compared with the conventional method for serious load disturbances and various rates of RESs penetration. The proposed control method shows remarkable performance in transient response improvement and fast damping of oscillations, preserving robustness of operation

Robust Virtual Inertia Control of a Low Inertia Microgrid Considering Frequency Measurement Effects

Virtual inertia emulation could be regarded as an inevitable component of microgrids with renewable energy, enhancing microgrid inertia and damping properties. In applying this control technique, a phase-locked loop (PLL) is necessary to obtain the estimation of the system frequency data. However, the employment of PLL could cause larger frequency oscillation to the microgrid due to its dynamics. This issue would be exacerbated in a low-inertia microgrid driven by high renewable penetration, severely deteriorating the frequency stability. Thus, the effect of PLL with measurement delay is a critical issue in utilizing the virtual inertia control. To overcome such problem, this paper proposes a robust virtual inertia control for a low-inertia microgrid to minimize the undesirable frequency measurement effects, improving the microgrid frequency stability. The robust H ∞ control design using a linear fractional transformation (LFT) technique is used to develop the virtual inertia control loop, considering the dynamics of PLL with measurement delay and the uncertainties of system inertia and damping. The efficacy of the proposed H ∞ control method is compared to the conventional and optimum proportional-integral (PI)based inertia control. The results show that the H ∞ -based robust virtual inertia control is superior to both conventional virtual inertia control and optimum PI-based virtual inertia control against a wide range of microgrid operating conditions, disturbances, and parametric uncertainties

Forced oscillation suppression using extended virtual synchronous generator in a low-Inertia microgrid

Effects of forced oscillations (FOs) in well-damped power systems are relatively smaller than those of microgrids (MGs) in which the severity of the FOs may be intensified by converter interfaced generators (CIGs). According to the distinct system characteristics, the FOs in MGs will be challenging problems in future research topics. Without proper controls of the CIGs, the FOs may be exhibited extremely higher amplitude, resulting in the MG instability. Such influences will be exacerbated in a low-inertia MG, which can trigger critical frequency oscillation and system collapse. This paper introduces an extended virtual synchronous generator (VSG) with virtual forced components to attenuate the dynamic FO effects in the presence of a low-inertia MG. Contrastive scenarios, i.e., periodic, combined, full sine, and high-frequency FOs are conducted to validate the performances of VSG control in both stand-alone and interconnected MG environments. Numerical results verify that the extended VSG control provides promising benefits in a low-inertia MG not only for the sake of MG stability improvement but also the further FO suppression. © 2023 Elsevier Lt

Comparative Manufacturing of Hybrid Composites with Waste Graphite Fillers for UAVs

Materials of Unmanned Aerial Vehicles (UAVs) parts require specific techniques and processes to provide high standard quality, sufficiently strong, and lightweight materials. Composite materials with a proper technique have been considered to improve the performance of UAVs. Usually, the hybrid composite is developed by mechanical properties with the addition of the filler component (i.e., particle) in a matrix. This research work aims to develop the effective composite materials with better mechanical properties. Considering the manufacturing of hybrid composite materials, the vacuum process is an affecting factor on mechanical properties. The comparison of the hand lay-up process (HL) and vacuum infusion process (VI) with controlled pressure and temperature are studied in this research. In addition, graphite fillers (i.e., 5 wt%, 7.5 wt%, 10 wt%, and 12.5 wt%) are added to the studied matrix. Obviously, the ply orientation is one of the factors that affects mechanical properties. Moreover, two types of ply orientation (i.e., [0°/90°]4s and [−45°/45°]4s) are comprehensively investigated to improve mechanical properties in the three-point bending test. The experimental results show that the vacuum infusion process of ply orientation [0°/90°]4s with the addition of 10 wt% graphite filler exhibits remarkable flexural strength from 404 MPa (without filler) to 529 MPa (10 wt% filler). Especially, the ply orientation of [0°/90°]4s has higher flexural strength than [−45°/45°]4s in both processes. Considering the failure, the fracture of the specimen propagates along the trajectory of fiber fabric orientation, leading to the breakage. Subsequently, the flexural strength under the vacuum infusion process is more significant than in the hand lay-up process. Effectively, it is found that the hybrid composite in this manufacturing has a higher strength-to-weight ratio to use in the structure of UAV instead of pure aluminum. It should be noted that the proposed hybrid composite strategy used in this study is not only limited to the UAV parts. The contribution can be extended to use in other applications such as automotive, structural building, and so on

Virtual Inertia Control Application to Enhance Frequency Stability of Interconnected Power Systems with High Renewable Energy Penetration

Due to a rapid increase in the utilization of power converter-based renewable energy sources (RESs), the overall system inertia in an interconnected power system might be significantly reduced, increasing the vulnerability of the interconnected power system to the system instability. To overcome problems caused by the significant reduction in system inertia, this paper proposes a new application of virtual inertia control to improve frequency stability of the interconnected power system due to high penetration level of RESs. The derivative control technique is introduced for higher-level applications of virtual inertia emulation. Thus, the proposed virtual inertia control loop has a second-order characteristic, which provides a simultaneous enabling of damping and inertia emulations into the interconnected power system, enhancing frequency stability and resiliency. System modeling and simulation results are carried out using MATLAB/Simulink® (R2016b, MathWorks, Natick, MA, USA). Trajectory sensitivities are also performed to analyze the dynamic effects of virtual inertia control’s parameters on the system stability. The effectiveness of the virtual inertia control concept on stability improvement is verified through a multi-area test system with high RESs penetration level for different contingencies