• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.10 no.4
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• pp.135-142
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• 2011

This paper proposes a performance evaluation method for power consumption of set-top box (STB) stand-by mode transition schemes. A stand-by mode transition scheme characterizes the timing of mode transition. The timing of mode transition affects the duration of stand-by mode operation, and the power consumptions of STB as well. Recently a fast stand-by mode transition scheme (FMT) has been proposed based on user input for selecting the device to be connected to TV. In this paper, we evaluate power consumption of FMT and a conventional mode transition scheme. For the computation of the duration of stand-by mode operation, the user input events are modeled as Poisson process. Simulation results based on the modeling reveals that the proposed scheme is more effective in power saving than the conventional scheme by up to 30%.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.5
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• pp.440-448
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• 2017

This paper proposes a controller design of a distributed source inverter in stand-alone mode or grid-connected mode to compensate the current or voltage harmonics caused by local nonlinear load. The PR-based multi loop controller has been used to improve the dynamic performance of the system and to compensate the output voltage or grid current harmonics. The multi-loop controller consists of an outer current controller and an inner voltage controller for the output voltage control in stand-alone mode. In grid-connected mode, an outer current controller is added to the output voltage controller for the grid current control. The design performance of each controller is described through the Root locus and Bode plot of the transfer functions. The validity of the proposed control algorithm and design parameters has been verified through the PSiM simulation and experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.28 no.1
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• pp.22-29
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• 2023

A grid-connected inverter can be used in grid-connected or stand-alone modes. Generally, a grid-connected inverter operates in a grid-connected mode, but the inverter operates in stand-alone mode if grid faults occur. In the stand-alone mode, the grid-connected inverter must supply electric power to a critical load that needs to receive stable power even though grid faults occur. Generally, three-phase loads are used as critical loads, but a single phase is configured in some cases. In these conditions, the critical load is required to unbalance the load power consumption, which makes the three-phase load voltage unbalancd. This unbalanced voltage problem can cause fatal problems to the three-phase critical loads, and thus must be addressed. Hence, this paper proposes an algorithm to solve this unbalanced voltage problem by the individual phase current control. The proposed method is verified using Psim simulation and experiments.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.4
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• pp.369-378
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• 1992

This paper proposes a utility parallel processing inverter system, which consists of a voltage source PWM inverter, isolation transformer and a reactor linking the inverter to utility line. This system realizes following functions : (1) voltage phase frequency and amplitude synchronization between inverter and utility line at stand-alone mode. (2) current phase synchronization between inverter and load at parallel mode. Therefore, despite sudden increase in load current over setting point at stand-alone mode, inverter system can be transferred into parallel mode immediately without transient current. Furthermore, high frequency(18KHz) PWM control and sinusoidal filtering improve the inverter output waveform by eliminating high order harmonic components as well as low order. As a switching device, IGBT is used for high frequency switching and large current capacity.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.4
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• pp.567-575
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• 2016

This paper proposed the voltage control of stand-alone inverter for power quality improvement under unbalanced and non-linear load. The 3-phase DC-AC inverter controls CVCF(Constant Voltage Constant Frequency) and selective harmonic eliminate method in stand-alone mode by PR controller, and the stand-lone inverter supplies stable sinusoidal voltage to balanced, unbalanced and non-linear loads. The total harmonic distortion(THD) of line-to-line load voltage($V_{LL}$) is 1.2% in the balanced load. THD of $V_{LL}$ is reduced from 5.2% to 1.4% and 6.7% to 3.5%, respectively unbalanced and non-linear load. The stand-alone inverter can be supplies sinusoidal balanced voltage to unbalanced load because the voltage unbalanced factor(VUF) of $V_{LL}$ is reduced from 5.2% to 1.4% in the unbalanced load. Feasibility of control method for a stand-alone inverter will be verified through 30kW stand-alone inverter system.

• Journal of Environmental Science International
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• v.17 no.6
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• pp.647-655
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• 2008

The purpose of the study is to find the problems related to the current state of the stand age classes and the method of calculating it defined in the existing forest type map and propose the more accurate method of calculating the stand age classes. The object for the study was selected as the forest scattered around the Geesan village Paju city in Kyunggi province. For the accurate method of calculating the stand age classes, such items as, the type of actual vegetation, establishment of grid-type standard area scaled down at the level of the 5% of the actual area, the types, number, DBH and age of tree found by the plots, were investigated. It was found out actual vegetation was divided into the total 24 types and the 20 types of them belonged to the growing tree areas. As the plots, the 125 places(unit area: $400m^2$) were established the types of the trees found were distributed in the range where the minimum was 1 type, the maximum was 9, the mean was $4.4{\pm}1.5$, and the mode was 4 types. The number of the trees found was distributed in the range where the minimum was 17, the maximum was 125, the mean was $4.4{\pm}1.5$, and the mode was 70. In the DBH, the minimum was 6 cm, the maximum was 30 cm, the mean was 13 cm and the mode was 10 cm. As the result of measuring the age of the 5 trees corresponding to the value of the mode in DBH, selected among the dominant species by the plots, less than 20 years was 17 places, the 115 places were included in the range from 21 to 30 years, and more than 31 years was the 6 places.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.1
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• pp.54-60
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• 2011

The flight control law designed for prototype aircraft often leads to degraded stability and performance, although developed control law verify by non-real time simulation and pilot based evaluations. Therefore, the proper evaluation methods should be applied such that flight control law designed can be verified in real flight environment. The one proposed in this paper is IFS (In-Flight Simulator). Currently, this system has been implemented into the F-18 HARV (High Angle of Attack Research Vehicle), SU-27 and F-16 VISTA (Variable stability In flight Simulation Test Aircraft) programs. The IFS necessary switching control law such as fader logic and integrator stand-by mode to reduce abrupt transient and minimize the integrator effect for each flight control laws switching. This paper addresses the concept of switching mechanism with fader logic of "TFS (Transient Free Switch)" and stand-by mode of "feedback type" based on SSWM (Software Switching Mechanism). And the result of real-time pilot evaluation reveals that the aircraft is stable for inter-conversion of flight control laws and transient response is minimized.

• Fire Science and Engineering
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• v.26 no.1
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• pp.74-79
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• 2012

This study is described for development of the stand-alone smoke and heat detector (SASHD) according to the revised in 2011 type approval and performance inspection code for detector. The main improvement of the revised regulation is source. CMOS microcontroller with nano watt technology is use for development of the workable SASHD over 10 years. The low-power SASHD is developed by using the power-saving sleep mode of microcontroller, by making the low-power source voltage checker, heat detector and smoke detector. The stand-alone detector is developed by smoke and heat detector type for reduce false fire alarm. User can choose type of work between the heat detection mode and smoke & heat detection mode. The SASHD can communicate with each them using RS-485 communication supported from microcontroller. So, this study can develop the SASHD that is able to alarm more wide area when fire occurs and reduce a flash fire alarm.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.5
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• pp.448-457
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• 2013

This paper proposes a control method under stand-alone operating mode for distributed-module type photovoltaic power conditioners. In conventional schemes, there are some problems of a controller saturation in the DC-link (or load) voltage controller when overly-heavy load, light load, and the generated PV power reduction occurs, as well as when a transition occurs from an overly-loaded to normal conditions. To overcome these problems, the proposed controller method switches the main control target from DC-link voltage to the maximum power point, which is closer to the stable operating point when it returns to normal operating conditions. For the analysis, a state-plane trajectory was given and the circuit analysis by PSIM simulation was done. For the verification, a prototype hardware with 110[W] and 50[W] dual photovoltaic modules has been implemented. From the results, it can be seen that PV power tracking is successfully done with the proposed method even under a stand-alone operation mode.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.210-216
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• 2009

Distributed Generation (DG) is predicted to play a important role in electric power system in the near future. insertion of DG system into existing distribution network has great impact on real-time system operation and planning. It is widely accepted that micro turbine generation (MTG) systems are currently attracting lot of attention to meet customers need in the distributed power generation market. In order to investigate the performance of MT generation systems, their efficient modeling is required. This paper presents the modeling and simulation of a MT generation system suitable for stand-alone operation. The system comprises of a permanent magnet synchronous generator driven by a MT. A brief description of the overall system is given, and mathematical models for the MT and permanent magnet synchronous generator are presented. Also, the use of power electronics in conditioning the power output of the generating system is demonstrated. Simulation studies with MATLAB/Simulink have been carried out in stand-alone operation mode of a DG system.