• 제목/요약/키워드: DG (Distributed Generation)

검색결과 162건 처리시간 0.027초

Effects of an Angle Droop Controller on the Performance of Distributed Generation Units with Load Uncertainty and Nonlinearity

  • Niya, M.S. Koupaei;Kargar, Abbas;Derakhshandeh, S.Y.
    • Journal of Power Electronics
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    • 제17권2호
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    • pp.551-560
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    • 2017
  • The present study proposes an angle droop controller for converter interfaced (dispatchable) distributed generation (DG) resources in the islanded mode of operation. Due to the necessity of proper real and reactive power sharing between different types of resources in microgrids and the ability of systems to respond properly to abnormal conditions (sudden load changes, load uncertainty, load current disturbances, transient conditions, etc.), it is necessary to produce appropriate references for all of the mentioned above conditions. The proposed control strategy utilizes a current controller in addition to an angle droop controller in the discrete time domain to generate appropriate responses under transient conditions. Furthermore, to reduce the harmonics caused by switching at converters' output, a LCL filter is used. In addition, a comparison is done on the effects that LCL filters and L filters have on the performance of DG units. The performance of the proposed control strategy is demonstrated for multi islanded grids with various types of loads and conditions through simulation studies in the DigSilent Power Factory software environment.

Comprehensive Evaluation of Impacts of Connecting Distributed Generation to the Distribution Network

  • Jin, Wei;Shi, Xuemei;Ge, Fei;Zhang, Wei;Wu, Hongbin;Zhong, Chengyuan
    • Journal of Electrical Engineering and Technology
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    • 제12권2호
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    • pp.621-631
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    • 2017
  • In this paper, we study the various impacts of connecting distributed generation (DG) to the distribution network. The comprehensive evaluation index system (CEIS) of four hierarchies is established, considering economy, reliability and voltage quality, and the calculation methods of different indexes are presented. This paper puts forward an improved triangular fuzzy number analytic hierarchy process (ITFNAHP) to weight the second level indexes (SLI) and the third level indexes (TLI), and calculates the variation coefficient to weight the fourth level indexes (FLI). We calculate the comprehensive weight coefficients based on the weight coefficients of the SLI, TLI and FLI, and then calculate the comprehensive evaluation of satisfaction (CES) of different access schemes. On the basis of the IEEE 33-bus example system, simulations of the calculation methods and the comprehensive evaluation method are carried out under different DG access schemes according to the same total investment cost and the same permeability, respectively, and the simulation results are analyzed and discussed.

A novel approach for optimal DG allocation in distribution network for minimizing voltage sag

  • Hashemian, Pejman;Nematollahi, Amin Foroughi;Vahidi, Behrooz
    • Advances in Energy Research
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    • 제6권1호
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    • pp.55-73
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    • 2019
  • The cost incurred by voltage sag effect in power networks has always been of important concern for discussions. Due to the environmental constraints, fossil fuel shortage crisis and low efficiency of conventional power plants, decentralized generation and renewable based DG have become trends in recent decades; because DGs can reduce the voltage sag effect in distribution networks noticeably; therefore, optimum allocation of DGs in order to maximize their effectiveness is highly important in order to maximize their effectiveness. In this paper, a new method is proposed for calculating the cost incurred by voltage sag effect in power networks. Thus, a new objective function is provided that comprehends technical standards as minimization of the cost incurred by voltage sag effect, active power losses and economic criterion as the installation and maintenance costs of DGs. Considering operational constraints of the system, the optimum allocation of DGs is a constrained optimization problem in which Lightning Attachment procedure optimization (LAPO) is used to resolve it and is the optimum number, size and location of DGs are determined in IEEE 33 bus test system and IEEE 34 bus test system. The results show that optimum allocation of DGs not only reduces the cost incurred by voltage sag effect, but also improves the other characteristics of the system.

Active Distribution Network Expansion Planning Considering Distributed Generation Integration and Network Reconfiguration

  • Xing, Haijun;Hong, Shaoyun;Sun, Xin
    • Journal of Electrical Engineering and Technology
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    • 제13권2호
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    • pp.540-549
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    • 2018
  • This paper proposes the method of active distribution network expansion planning considering distributed generation integration and distribution network reconfiguration. The distribution network reconfiguration is taken as the expansion planning alternative with zero investment cost of the branches. During the process of the reconfiguration in expansion planning, all the branches are taken as the alternative branches. The objective is to minimize the total costs of the distribution network in the planning period. The expansion alternatives such as active management, new lines, new substations, substation expansion and Distributed Generation (DG) installation are considered. Distribution network reconfiguration is a complex mixed-integer nonlinear programming problem, with integration of DGs and active managements, the active distribution network expansion planning considering distribution network reconfiguration becomes much more complex. This paper converts the dual-level expansion model to Second-Order Cone Programming (SOCP) model, which can be solved with commercial solver GUROBI. The proposed model and method are tested on the modified IEEE 33-bus system and Portugal 54-bus system.

제어 가능한 전류원 기반의 인버터를 이용한 실제적 태양광 발전 시스템 모델링 (Modeling of Practical Photovoltaic Generation System using Controllable Current Source based Inverter)

  • 오윤식;조규정;김민성;김지수;강성범;김철환;이유진;고윤태
    • 전기학회논문지
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    • 제65권8호
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    • pp.1340-1346
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    • 2016
  • Utilization of Distributed Generations (DGs) using Renewable Energy Sources (RESs) has been constantly increasing as they provide a lot of environmental, economic merits. In spite of these merits, some problems with respect to voltage profile, protection and its coordination system due to reverse power flow could happen. In order to analyze and solve the problems, accurate modeling of DG systems should be preceded as a fundamental research task. In this paper, we present a PhotoVoltaic (PV) generation system which consists of practical PV cells with series and parallel resistor and an inverter for interconnection with a main distribution system. The inverter is based on controllable current source which is capable of controlling power factors, active and reactive powers within a certain limit related to amount of PV generation. To verify performance of the model, a distribution system based on actual data is modeled by using ElectroMagnetic Transient Program (EMTP) software. Computer simulations according to various conditions are also performed and it is shown from simulation results that the model presented is very effective to study DG-related researches.

Operation Analysis of a Communication-Based DC Micro-Grid Using a Hardware Simulator

  • Lee, Ji-Heon;Kim, Hyun-Jun;Han, Byung-Moon
    • Journal of Power Electronics
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    • 제13권2호
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    • pp.313-321
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    • 2013
  • This paper describes the operation analysis results of a communication-based DC micro-grid using a hardware simulator developed in the lab. The developed hardware simulator is composed of distributed generation devices such as wind power, photovoltaic power and fuel cells, and energy storage devices such as super-capacitors and batteries. Whole system monitoring and control was implemented using a personal computer. The power management scheme was implemented in a main controller based on a TMS320F28335 chip. The main controller is connected with the local controller in each of the distributed generator and energy storage devices through the communication link based on a CAN or an IEC61850. The operation analysis results using the developed hardware simulator confirm the ability of the DC micro-grid to supply the electric power to end users.

Islanding Detection Method for Inverter-Based Distributed Generation through Injection of Second Order Harmonic Current

  • Lee, Yoon-Seok;Yang, Won-Mo;Han, Byung-Moon
    • Journal of Power Electronics
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    • 제18권5호
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    • pp.1513-1522
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    • 2018
  • This paper proposes a new islanding detection method for inverter-based distributed generators by continuously injecting a negligible amount of 2nd order harmonic current. The proposed method adopts a proportional resonant (PR) controller for the output current control of the inverter, and a PR filter to extract the 2nd order harmonic voltage at the point of common coupling (PCC). The islanding state can be detected by measuring the magnitude ratio of the 2nd order harmonic voltage to the fundamental voltage at the PCC by injecting a 2nd order harmonic current with a 0.8% magnitude. The proposed method provides accurate and fast detection under grid voltage unbalance and load unbalance. The operation of the proposed method has been verified through simulations and experiments with a 5kW hardware set-up, considering the islanding test circuit suggested in UL1741.

연속적인 운전모드의 전환을 위한 계통연계형 인버터의 간접 전류 제어기법 (Indirect Current Control of Utility Interactive Inverter for Seamless Transfer)

  • 유태식;배영상;김효성;최세완
    • 전력전자학회논문지
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    • 제11권1호
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    • pp.72-78
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    • 2006
  • 분산발전시스템에 비상부하 등의 전용부하가 접속되어 있는 경우, 주전원에 고장이 발생하러라도 비상전용부하에는 지속적인 전력을 공급하기 위하여 의도적인 단독운전을 하게 된다. 기존의 계통연계형 인버터는 주전원에 전력을 주입하기 위하여 평소에 전류제어모드로 운전을 하기 때문에, 의도적인 단독운전 상황이 발생하는 경우 비상부하에 안정된 전압을 공급해 주기 위하여 전압제어모드로 운전을 전환하여야한다. 이러한 운전모드의 전환시 인버터의 출력단 전압에 심각한 과도문제가 발생된다. 본 논문에서는 의도적인 단독운전 발생시 인버터 운전모드 전환에 따른 출력전압의 과도현상을 최소화하기 위한 인버터 토폴로지와 제어알고리즘을 제안한다. 제안된 간접전류제어 알고리즘에 적합한 LCL필터 설계방법과 설계데이터를 제시한다.

Modeling, Control and Simulation of Microturbine Generator for Distributed Generation System in Smart Grid Application

  • Hong, Won-Pyo;Cho, Jae-Hoon
    • 조명전기설비학회논문지
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    • 제23권7호
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    • pp.57-66
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    • 2009
  • Microturbines system (MTS) are currently being deployed as small scale on-site distributed generators for microgrids and smart grids. In order to fully exploit DG potentialities, advanced integrated controls that include power electronics facilities, communication technologies and advanced modeling are required. Significant expectations are posed on gas microturbines that can be easily installed in large commercial and public buildings. Modeling, control, simulation of microturbine generator based distributed generation system in smart grid application of buildings for both grid-connected and islanding conditions are presented. It also incorporates modeling and simulation of MT with a speed control system of the MT-permanent magnet synchronous generator to keep the speed constant with load variation. Model and simulations are performed using MATLAB, Simulink and SimPowerSystem software package. The model is built from the dynamics of each part with their interconnections. This simplified model is a useful tool for studying the various operational aspects of MT and is also applicable with building cooling, heating and power (BCHP) systems

Islanding Detection Method for Inverter-based Distributed Generation Systems using a Signal Cross-correlation Scheme

  • Bae, Byung-Yeol;Jeong, Jong-Kyou;Lee, Ji-Heon;Han, Byung-Moon
    • Journal of Power Electronics
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    • 제10권6호
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    • pp.762-768
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    • 2010
  • This paper describes the development of a new islanding detection method for inverter-based distributed generation systems, which uses a signal cross-correlation scheme between the injected reactive current and the power frequency deviation. The proposed method injects 1% of the reactive current to the rated current which brings about a negligible degradation of the power quality. It discriminates the islanding state, when the calculated cross-correlation index is larger than 0.5. The operational feasibility was verified through computer simulations with PSCAD/EMTDC software and experimental research with a hardware prototype. The proposed method can detect the islanding state without degrading the power quality at the point of common connection. Further study is required to overcome the cancellation of the injected reactive current from multiple distributed generation units interconnected with the utility grid.