• KIEE International Transactions on Power Engineering
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• 제3A권3호
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• pp.148-154
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• 2003

This paper describes the development of KEPCO's 80MVA UPFC electromagnetic transient model and the analysis of its performance in the actual Korean power system. KEPCO's 80MVA UPFC is currently undergoing installation and will be ready for commercial operation from the year 2003. In order to apply a new FACTS device such as the UPFC to the actual power system, the utility needs, in advance, both load flow stability studies and transient studies. Therefore, KEPRI, the research institute of KEPCO, developed a detailed transient analysis model that is based on the actual UPFC S/W algorithm and H/W specifications. This simulation model is implemented by an EMTDC/PSCAD package. The results of the simulation show the effectiveness of UPFC operation in the KEPCO power system.

• Smart Structures and Systems
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• 제21권4호
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• pp.493-519
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• 2018

This article presents a finite element (FE) model to assess the free vibration and static response of a functionally graded skew magneto-electro-elastic (FGSMEE) plate. Through the thickness material grading of FGSMEE plate is achieved using power law distribution. The coupled constitutive equations along with the total potential energy approach are used to develop the FE model of FGSMEE plate. The transformation matrix is utilized in bringing out the element matrix corresponding to the global axis to a local axis along the skew edges to specify proper boundary conditions. The effect of skew angle on the natural frequency of an FGSMEE plate is analysed. Further, the study includes the evaluation of the static behavior of FGSMEE plate for various skew angles. The influence of skew angle on the primary quantities such as displacements, electric potential, and magnetic potential, and secondary quantities such as stresses, electric displacement and magnetic induction is studied in detail. In addition, the effect of power-law gradient, thickness ratio, boundary conditions and aspect ratio on the free vibration and static response characteristics of FGSMEE plate has been investigated.

• 동력기계공학회지
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• 제21권6호
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• pp.40-45
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• 2017

The objective of this study is the finite element-transfer stiffness coefficient method, which is the combination of the modeling technique of finite element method and the transfer technique of transfer stiffness coefficient method, is applied in the static analyses of two dimensional curved beam structures. To confirm the effectiveness of the applied method, two computational models are selected and analyzed by using finite element method, finite element-transfer stiffness coefficient method and exact solution. The computational results of the static analyses for two computational models using finite element-transfer stiffness coefficient method are equal to those using finite element method. When the element partition number of curved beam structure is increased, the computational results of the static analyses using both methods approach the exact solution. We confirmed that the finite element-transfer stiffness coefficient method is superior to finite element method when the number of the curved beam elements is increased from the viewpoints of the computational speed and the utility of computer memory.

• 복합신소재구조학회 논문집
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• 제4권1호
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• pp.33-39
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• 2013

Structural insulated panels, structurally performed panels consisting of a plastic insulation bonded between two structural panel facings, are one of emerging products with a viewpoint of its energy and construction efficiencies. These components are applicable to fabricated wood structures. In Korea, there are few technical documents regulated structural performance and engineering criteria in domestic market. This study was conducted to identify fundamental performance of both monotonic load and quasi static cyclic load for SIPs in shear wall application. Static test results showed that maximum load was 44.3kN, allowable shear load was 6.1kN/m, shear stiffness was 1.23 M N/m, and ductility ratio was 3.6. Cyclic test was conducted by two kinds of specimens : single panel and double panels. Cyclic test results, which were equivalent to static test results, showed that maximum load was 45.42kN, allowable shear load was 6.3kN/m. Furthermore the accumulated energy dissipation capability for double panels was as 2.3 times as that for single panel. From performance of structural tests, it was recommended that the allowable shear load for panels was at least 6.1kN/m.

• 동력기계공학회지
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• 제18권6호
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• pp.64-69
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• 2014

A circular plate is one of the important structures in many industrial fields. In static analysis of a circular plate, we may obtain an exact solution by analytical method, but it is limited to a simple circular plate. Thus, many researchers and designers have used numerical methods such as the finite element method. The authors of this paper developed the finite element-transfer stiffness coefficient method (FE-TSCM) for static and dynamic analyses of various structures. FE-TSCM is the combination of the modeling technique of the finite element method (FEM) and the transfer technique of the transfer stiffness coefficient method (TSCM). FE-TSCM has the advantages of both FEM and FE-TSCM. In this paper, the authors formulate the computational algorithm for the static analysis of axisymmetric circular plates under lateral loading using FE-TSCM. The computational results for three computational models obtained by FE-TSCM are compared with those obtained by FEM in order to confirm the accuracy of FE-TSCM.

• Journal of Power Electronics
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• 제10권1호
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• pp.85-90
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• 2010

In this paper the effects of a Static Synchronous Series Compensator, which is constructed with a 48-pulse inverter, on the power demand from the grid are studied. Extensive simulation studies were carried out in the MATLAB simulation environment to observe the compensation achieved by the SSSC and its effects on the line voltage, line current, phase angle and real/reactive power. The designed device is simulated in a power system which is comprised of a three phase power source, a transmission line, line inductance and load. The system parameters such as line voltage, line current, reactive power Q and real power P transmissions are observed both when the SSSC is connected to and disconnected from the power system. The motivation for modeling a SSSC from a multi-pulse inverter is to enhance the voltage waveform of the device and this is observed in the total harmonic distortion (THD) analysis performed at the end of the paper. According to the results, the power flow and phase angle can be controlled successfully by the new device through voltage injection. Finally a THD analysis is performed to see the harmonics content. The effect on the quality of the line voltage and current is acceptable according to international standards.

• 전자공학회논문지C
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• 제36C권5호
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• pp.38-47
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• 1999

저전력을 실현하기 위하여 구조, 논리 및 트랜지스터레벨에서 16비트 덧셈기를 설계하였다. 기존의 ELM덧셈기는 입력 비트 패턴에 의해 계산되는 블록캐리발생신호 (block carry generation signal) 때문에 특정 입력 비트 패턴이 인가되었을 때에는 G셀에서 글리치(glitch)가 발생하는 단점이 있다. 따라서 구조레벨에서는 특정 입력 비트 패턴에 대해서 글리치를 피하기 위해 자동적으로 각각의 블록캐리발생신호를 마지막 레벨의 G셀에 전달하는 저전력 덧셈기 구조를 제안하였다. 또한, 논리레벨에서는 정적 CMOS(static CMOS)논리형태와 저전력 XOR게이트로 구성된 저전력 소모에 적합한 조합형 논리형태(combination of logic style)를 사용하였다. 게다가 저전력을 위하여 트랜지스터레벨에서는 각 비트 전파의 논리깊이(logic depth)에 따라서 가변 크기 셀들(variable-sized cells)을 사용하였다. 0.6㎛ 단일폴리 삼중금속 LG CMOS 표준 공정변수를 가지고 16비트 덧셈기를 HSPICE로 모의 실험한 결과, 고정 크기 셀(fixed-sized cell)과 정적 CMOS 논리형태만으로 구성된 기존의 ELM 덧셈기에 비해 본 논문에서 제안된 덧셈기가 전력소모면에서는 23.6%, power-delay-product면에서는 22.6%의 향상을 보였다.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.206-214
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• 2013

This paper proposes a new method for monitoring local voltage stability using the saddle node bifurcation set or loadability boundary in two dimensional power parameter space. The method includes three main steps. First step is to determine the critical buses and the second step is building the static voltage stability boundary or the saddle node bifurcation set. Final step is monitoring the voltage stability through the distance from current operating point to the boundary. Critical buses are defined through the right eigenvector by direct method. The boundary of the static voltage stability region is a quadratic curve that can be obtained by the proposed method that is combining a variation of standard direct method and Thevenin equivalent model of electric power system. And finally the distance is computed through the Euclid norm of normal vector of the boundary at the closest saddle node bifurcation point. The advantage of the proposed method is that it gets the advantages of both methods, the accuracy of the direct method and simple of Thevenin Equivalent model. Thus, the proposed method holds some promises in terms of performing the real-time voltage stability monitoring of power system. Test results of New England 39 bus system are presented to show the effectiveness of the proposed method.

• Journal of Power Electronics
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• 제3권3호
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• pp.185-196
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• 2003

In this paper, the single-phase static VAR compensator (SVC) is applied to regulate and stabilize the generated terminal voltage of the single-phase self-excited induction generator (single-phase SEIG) driven by a variable-speed prime mover (VSPM) under the conditions of the independent inductive load variations and the prime mover speed changes The conventional fixed gain PI controller-based feedback control scheme is employed to adjust the equivalent capacitance of the single-phase SVC composed of the fixed excitation capacitor FC in parallel with the thyristor switched capacitor TSC and the thyristor controlled reactor TCR The feedback closed-loop terminal voltage responses in the single-phase SEIG coupled by a VSPM with different inductive passive load disturbances using the single-phase SVC with the PI controller are considered and discussed herem. A VSPM coupled the single-phase SEIG prototype setup is established. Its experimental results are illustrated as compared with its simulation ones and give good agreements with the digital simulation results for the single-phase SEIG driven by a VSPM, which is based on the SVC voltage regulation feedback control scheme.

• Journal of Power Electronics
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• 제19권1호
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• pp.244-253
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• 2019

Finite control set model-predictive control (FCS-MPC) has received increasing attentions due to its outstanding dynamic performance. It is being widely used in power converters and multilevel inverters. However, FCS-MPC requires a lot of calculations, especially for multilevel-cascaded H-bridge (CHB) static synchronous compensators (STATCOMs), since it has to take account of all the feasible voltage vectors of inverters. Hence, an improved five-segment space vector pulse width modulation (SVPWM) method based on the non-orthogonal static reference frames is proposed. The proposed SVPWM method has a lower number of switching states and requires fewer computations than the conventional method. As a result, it makes FCS-MPC more efficient for multilevel cascaded H-bridge STATCOMs. The partial cost function is adopted to sequentially solve for the reference current and capacitor voltage. The proposed FCS-MPC method can reduce the calculation burden of the FCS-MPC strategy, and reduce both the switching frequency and power losses. Simulation and experimental results validate the excellent performance of the proposed method when compared with the conventional approach.