마이크로그리드에서 하이브리드 시스템의 Feeder Flow Mode 운영을 위한 제어 알고리즘

문대성(Dae-Seong Moon),서재진(Jae-Jin Seo),김윤성(Yun-Seong Kim),원동준(Dong-Jun Won) 대한전기학회 2011 전기학회논문지 Vol.60 No.1

Active power control scheme for distributed generation in microgrid consists of feeder flow control and unit power control. Feeder flow control is more useful than the unit power control for demand-side management, because microgrid can be treated as a dispatchable load at the point of common coupling(PCC). This paper presents detailed descriptions of the feeder flow control scheme for the hybrid system in microgrid. It is divided into three parts, namely, the setting of feeder flow reference range for stable hybrid system operation, feeder flow control algorithm depending on load change in microgrid and hysteresis control. Simulation results using the PSCAD/EMTDC are presented to validate the inverter control method for a feeder flow control mode. As a result, the feeder flow control algorithm for the hybrid system in microgrid is efficient for supplying continuously active power to customers without interruption.

UPFC Control based on New IP Type Controller

Shirvani, Mojtaba,Keyvani, Babak,Abdollahi, Mostafa,Memaripour, Ahmad The Korean Institute of Electrical Engineers 2012 Journal of Electrical Engineering & Technology Vol.7 No.5

This paper presents the application of Unified Power Flow Controller (UPFC) in order to simultaneous control of power flow and voltage and also damping of Low Frequency Oscillations (LFO) at a Single-Machine Infinite-Bus (SMIB) power system installed with UPFC. PI type controllers are commonly used controllers for UPFC control. But for the sake of some drawbacks of PI type controllers, the scope for finding a better control scheme still remains. In this regard, in this paper the new IP type controllers are considered as UPFC controllers. The parameters of these IP type controllers are tuned using Genetic Algorithms (GA). Also a stabilizer supplementary controller based UPFC is considered for increasing power system damping. To show the ability of IP controllers, this controller is compared with classical PI type controllers. Simulation results emphasis on the better performance of IP controller in comparison with PI controller.

UPFC Control based on New IP Type Controller

Mojtaba Shirvani,Babak Keyvani,Mostafa Abdollahi,Ahmad Memaripour 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.5

This paper presents the application of Unified Power Flow Controller (UPFC) in order to simultaneous control of power flow and voltage and also damping of Low Frequency Oscillations (LFO) at a Single-Machine Infinite-Bus (SMIB) power system installed with UPFC. PI type controllers are commonly used controllers for UPFC control. But for the sake of some drawbacks of PI type controllers, the scope for finding a better control scheme still remains. In this regard, in this paper the new IP type controllers are considered as UPFC controllers. The parameters of these IP type controllers are tuned using Genetic Algorithms (GA). Also a stabilizer supplementary controller based UPFC is considered for increasing power system damping. To show the ability of IP controllers, this controller is compared with classical PI type controllers. Simulation results emphasis on the better performance of IP controller in comparison with PI controller.

Analysis of Control Conflict between UPFC Multiple Control Functions and Their Interaction Indicator

Wang H. F.,Jazaeri M.,Cao Y. J. Institute of Control 2005 International Journal of Control, Automation, and Vol.3 No.S

Interactions among multiple control functions of a UPFC installed in a power system have been observed in power system simulation and been reported in authors' previous publications [1,2]. This paper presents new analytical results about these observed interactions and concludes that they are due to the control conflict between the series and shunt part of the UPFC, which are connected through the internal common capacitor inside the UPFC. Investigation in the paper reveals, for the first time as far as the authors are aware of, that the linkage pattern of UPFC series and shunt part decides whether the control functions implemented by the UPFC series and shunt part conflict each other or not. This linkage pattern of UPFC series and shunt part can be described by the flow of active power through the UPFC at steady-state operation of the power system. Hence in order to predict the possible interactions among multiple control functions of the UPFC, an interaction indicator is proposed in the paper which is the direction and amount of active power flow through the internal link of the UPFC series and shunt part at steady-state operation of the power system. This proposed interaction indicator can be calculated from power system load flow solution without having to run simulation of the power system with UPFC controllers installed. By using the indicator, the interactions among multiple control functions of the UPFC caused by badly set controller's parameters are excluded. Therefore the indicator only identifies the possible existence of inherent control conflict of the UPFC.

Strategy based PSO for Dynamic Control of UPFC to Enhance Power System Security

Belkacem Mahdad,Tarek Bouktir,Kamel Srairi 대한전기학회 2009 Journal of Electrical Engineering & Technology Vol.4 No.3

Penetration and installation of a new dynamic technology known as Flexible AC Transmission Systems (FACTS) in a practical and dynamic network requires and force expert engineer to develop robust and flexible strategy for planning and control. Unified Power Flow Controller (UPFC) is one of the recent and effective FACTS devices designed for multi control operation to enhance the power system security. This paper presents a dynamic strategy based on Particle Swarm Optimization (PSO) for optimal parameters setting of UPFC to enhance the system loadability. Firstly, we perform a multi power flow analysis with load incrementation to construct a global database to determine the initial efficient bounds associated to active power and reactive power target vector. Secondly a PSO technique applied to search the new parameters setting of the UPFC within the initial new active power and reactive power target bounds. The proposed approach is implemented with Matlab program and verified with IEEE 30-Bus test network. The results show that the proposed approach can converge to the near optimum solution with accuracy, and confirm that flexible multi-control of this device coordinated with efficient location enhance the system security of power system by eliminating the overloaded lines and the bus voltage violation.

Analysis of Control Conflict between UPFC Multiple Control Functions and Their Interaction Indicator

H. F. Wang,M. Jazaeri,Y. J. Cao 대한전기학회 2005 International Journal of Control, Automation, and Vol.3 No.2

Interactions among multiple control functions of a UPFC installed in a power system have been observed in power system simulation and been reported in authors' previous publications [1,2]. This paper presents new analytical results about these observed interactions and concludes that they are due to the control conflict between the series and shunt part of the UPFC, which are connected through the internal common capacitor inside the UPFC. Investigation in the paper reveals, for the first time as far as the authors are aware of, that the linkage pattern of UPFC series and shunt part decides whether the control functions implemented by the UPFC series and shunt part conflict each other or not. This linkage pattern of UPFC series and shunt part can be described by the flow of active power through the UPFC at steady-state operation of the power system. Hence in order to predict the possible interactions among multiple control functions of the UPFC, an interaction indicator is proposed in the paper which is the direction and amount of active power flow through the internal link of the UPFC series and shunt part at steady-state operation of the power system. This proposed interaction indicator can be calculated from power system load flow solution without having to run simulation of the power system with UPFC controllers installed. By using the indicator, the interactions among multiple control functions of the UPFC caused by badly set controller's parameters are excluded. Therefore the indicator only identifies the possible existence of inherent control conflict of the UPFC.

Centralized Control Algorithm for Power System Performance using FACTS Devices in the Korean Power System

Sang-Gyun Kang,Sangsoo Seo,Byongjun Lee,Byunghoon Chang,Rohae Myung 대한전기학회 2010 Journal of Electrical Engineering & Technology Vol.5 No.3

This paper presents a centralized control algorithm for power system performance in the Korean power system using Flexible AC Transmission Systems (FACTS) devices. The algorithm is applied to the Korean power system throughout the metropolitan area in order to alleviate inherent stability problems, especially concerns with voltage stability. Generally, control strategies are divided into local and centralized control. This paper is concerned with a centralized control strategy in terms of the global system. In this research, input data of the proposed algorithm and network data are obtained from theSCADA/EMS system. Using the full system model, the centralized controller monitors the system conditionand decides the operating point according to the control objectives that are, in turn, dependenton system conditions. To overcome voltage collapse problems, load-shedding is currently applied in the Korean power system.In this study, the application of the coordination between FACTS and switch capacitor (SC) canrestore the solvability without load shedding or guarantee the FV margin when the margin is insufficient.Optimal Power Flow (OPF) algorithm, for which the objective function is loss minimization, isused in a stable case. The results illustrate examples of the proposed algorithm using SCADA/EMS data of the Korean power system in 2007.

조향펌프 유량계 시험제어기 개발

정규홍(G. H. Jung) 유공압건설기계학회 2016 유공압건설기계학회 학술대회논문집 Vol.2016 No.6

Owing to the large steering effort, most of heavy-duty commercial vehicles adopt power steering system of which core components are the steering pump and steering gear. Conventionally, diagnosis and correction of commercial vehicle steering related problems are handled by properly trained mechanics who have the proper equipment or tools. However, recent automotive technology introduces various kind of sensors and actuators those are linked with ECUs for the purpose of intelligent control and smart diagnosis of malfunctions. Steering flow indicator is a type of flow switch which detects the specific level of steering pump flow. It is used to monitor the flow of power steering fluid as a diagnostic tool to ensure that the power steering system is not fail. This work deals with a controller design of test equipment for the steering pump which is newly-developed by domestic company. The controller hardware interfaces the hydraulic test-rig to impose the test conditions on the steering flow indicator and the embedded software is designed to manage the test procedure according to the test specifications. Although initial flow control by the proportional solenoid valve is replaced by the speed control of piston pump due to the jittering of control flow, overall functions are verified as it is expected.

Centralized Control Algorithm for Power System Performance using FACTS Devices in the Korean Power System

Kang, Sang-Gyun,Seo, Sang-Soo,Lee, Byong-Jun,Chang, Byung-Hoon,Myung, Ro-Hae The Korean Institute of Electrical Engineers 2010 Journal of Electrical Engineering & Technology Vol.5 No.3

This paper presents a centralized control algorithm for power system performance in the Korean power system using Flexible AC Transmission Systems (FACTS) devices. The algorithm is applied to the Korean power system throughout the metropolitan area in order to alleviate inherent stability problems, especially concerns with voltage stability. Generally, control strategies are divided into local and centralized control. This paper is concerned with a centralized control strategy in terms of the global system. In this research, input data of the proposed algorithm and network data are obtained from the SCADA/EMS system. Using the full system model, the centralized controller monitors the system condition and decides the operating point according to the control objectives that are, in turn, dependent on system conditions. To overcome voltage collapse problems, load-shedding is currently applied in the Korean power system. In this study, the application of the coordination between FACTS and switch capacitor (SC) can restore the solvability without load shedding or guarantee the FV margin when the margin is insufficient. Optimal Power Flow (OPF) algorithm, for which the objective function is loss minimization, is used in a stable case. The results illustrate examples of the proposed algorithm using SCADA/EMS data of the Korean power system in 2007.

Optimal Power Control Strategy for Wind Farm with Energy Storage System

Cong-Long Nguyen,Hong-Hee Lee 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

The use of energy storage systems (ESSs) has become a feasible solution to solve the wind power intermittency issue. However, the use of ESSs increases the system cost significantly. In this paper, an optimal power flow control scheme to minimize the ESS capacity is proposed by using the zero-phase delay low-pass filter which can eliminate the phase delay between the dispatch power and the wind power. In addition, the filter time constant is optimized at the beginning of each dispatching interval to ensure the fluctuation mitigation requirement imposed by the grid code with a minimal ESS capacity. And also, a short-term power dispatch control algorithm is developed suitable for the proposed power dispatch based on the zero-phase delay low-pass filter with the predetermined ESS capacity. In order to verify the effectiveness of the proposed power management approach, case studies are carried out by using a 3-MW wind turbine with real wind speed data measured on Jeju Island.