Yeonchan Lee

Development of Reliability Contribution Function of Power System including Wind Turbine Generators combined with Battery Energy Storage System

Abstract - This paper presents a study on reliability assessment and new contribution function development of power system including Wind Turbine Generator(WTG) combined with Battery Energy Storage System(BESS). This paper develops and proposes new reliability contribution function of BESS installed at wind farms. The methodology of reliability assessment, using Monte Carlo Simulation(MCS) method to simulate sample state duration, is proposed in detail. Forced Outage Rate(FOR) considered probabilistic approach for conventional generators is modelled in this paper. The penetration of large wind power can make risk to power system adequacy, quality and stability. Although the fluctuation of wind power, BESS installed at wind farms may smooth the wind power fluctuation. Using small size system as similar as Jeju island power system, a case study of reliability evaluation and new proposed contribution function of power system containing WTG combined with BESS is demonstrated in this paper, which would contributes to BESS reliability contribution and assessment tools of actual power system in future. Key Words : Wind turbine generator(WTG), Battery energy storage system(BESS), Monte carlo simulation(MCS), Reliability evaluation, ESS reliability contribution † Corresponding Author : Dept. of Electrical Eng., RIGET, ERI, Gyeongsang National University, Korea E-mail : jschoi@gnu.ac.kr* Dept. of Electrical Engineering, Gyeonsang National University , Korea ** KEPRI, KEPCO*** Dept. of Electrical Engineering, Daejin University, Korea Received : September 9, 2015; Accepted : February 19, 2016

Reliability Evaluation with Wind Turbine Generators and an Energy Storage System for the Jeju Island Power System

This paper proposes probabilistic reliability evaluation model of power system considering Wind Turbine Generator(WTG) integrated with Energy Storage System(ESS). Monte carlo sample state duration simulation method is used for the evaluation. Because the power output from WTG units usually fluctuates randomly, the power cannot be counted on to continuously satisfy the system load. Although the power output at any time is not controllable, the power output can be utilized by ESS. The ESS may make to smooth the fluctuation of the WTG power output. The detail process of power system reliability evaluation considering ESS cooperated WTG is presented using case study of Jeju island power system in the paper.

Development of One Day-Ahead Renewable Energy Generation Assessment System in South Korea

This paper proposes a probabi listic generatio n assessment mo del of renewable energy generators(REGs) considering uncertainty of resources, mainly focused on Wind Turbine Genera tor(WTG) and Solar Cell Generator(SCG) which are dispersed widely in South Korea The propos ed numerical analysis method as sesses the one day-ahead generation by combining equivalent generation characteristics function and probabilisti c distribution function of wind speed(WS) and solar radiation(S R) resources. The equivalent generat ion functions(EGFs) of the win d and solar farms are established by grouping a lot of the farms appropriately centered on W eather Measurement Station(WMS ). First, the EGFs are assessed by using regression analysis method based on typical least squ are method from the recorded a ctual generation data and hist orical resources(WS and SR). Second, the generation of the REGs is assessed by adding the on e day-ahead resources forecast, announced by WMS, to the EGFs which are formulated as third order degree polynomials usi ng the regression analysis. Third, a Renewable Energy Generation Assessment System(REGA S) including D/B of recorded a ctual generation data and hist orical resources is developed using the model and algorithm pre dicting one day-ahead power ou tput of renewable energy generators.

Hourly Average Wind Speed Simulation and Forecast Based on ARMA Model in Jeju Island, Korea

This paper presents an application of time series analysis in hourly wind speed simulation and forecast in Jeju Island, Korea. Autoregressive – moving average (ARMA) model, which is well in description of random data characteristics, is used to analyze historical wind speed data (from year of 2010 to 2012). The ARMA model requires stationary variables of data is satisfied by power law transformation and standardization. In this study, the autocorrelation analysis, Bayesian information criterion and general least squares algorithm is implemented to identify and estimate parameters of wind speed model. The ARMA (2,1) models, fitted to the wind speed data, simulate reference year and forecast hourly wind speed in Jeju Island.

Power Supply Assessment Model of Renewable Energy Generators – Focused on Wind Turbine Generator and Solar Cell Generator –

This paper proposes power supply assessment model of renewable energy generators(REG). The REGs have uncertainty of resource supply. Therefore, the REGs have probabilistic power characteristics. The analytical probabilistic power assessment model of the REGS is developed in this paper. This paper is focused on Wind Turbine Generator(WTG) and Solar Cell Generator(SCG). The assessment model based on probabilistic model considering uncertainty of resources(wind speed and solar radiation) is developed. The power is assessed from expected value based the proposed model. The proposed model is applied two simple systems, which have a WTG or a SCG in this paper.

GUI of GMS Simulation Tool Using Fuzzy Methods

This study used the fuzzy theory for creating preventive maintenance scheduling of generator (GMS). GMS simulation tool is developed in optimum by the CO2 emission, probabilistic production cost, and reliability criteria LOLE(Loss of load expectation), EENS(Expected energy not served) in the objective functions. GMS has shown in graphical user interface (GUI) for the user-friendliness of the generator. It can be resulted in generator maintenance scheduling, reliability indices of power system, total probabilistic production costs and each power company probabilistic production costs.

Conversion Function and Relationship of Loss of Load Expectation Indices on Two Kinds of Load Duration Curve

This paper develops a conversion function and method transforming from daily peak load curve used LOLED [days/ year] to hourly load curve used LOLEH[hours/year]and describes relationship between LOLED [days/year] and LOLEH [hours/year]. The indices can not only be transformed just arithmetically but also have different characteristics physically because of using their different load curves. The conversion function is formulated as variables of capacity and forced outage rate of generator, hourly load daily load factor and daily peak load yearly load factor, etc. Therefore, the conversion function () can not be simple. In this study, therefore, the function is formulated as linear times of separated two functions. One is an exponential formed conversion function of daily load factor. Another is formulated with an exponential typed conversion function of daily peak load yearly load factor. Futhermore, this paper presents algorithm and flow chart for transforming from LOLED[days/year] to LOLEH[hours/year]. The proposed conversion function is applied to sample system and actual KPS(Korea Power System) in 2015. The exponent coefficients of the conversion functions are assessed using proposed method. Finally, assessment errors using conversion function for case studies of sample system and actual system are evaluated to certify the firstly proposed method.

User friendly generator maintenance scheduling simulation system based on probabilistic methodology

This study develops alternative user friendly generator maintenance scheduling(GMS) considering not only probabilistic reliability maximization but also probabilistic production cost minimization. Furthermore, the proposed GMS system has various kinds of objective functions as like as CO2 minimization. The probabilistic reliability objective includes LOLE(Loss of load expectation), EENS(Expected energy not served) and EIR(Energy index of reliability). Production cost is evaluated with consideration of uncertainties of generators. In actual system case study describes effectiveness and user friendly of generator maintenance scheduling simulation systems proposed in this paper. Additionally, the practicality and effectiveness of the proposed approach are demonstrated in the simulation for a real-size power system model in Korea South-East Power CO.(KOEN).

Probabilistic evaluation of long-term stability considering secondary contingency scenarios

This paper studies the effects of secondary contingency (N-1-1) on stability of power system in long time duration transient state considering state probability. The Vietnam power system which includes all level voltages up to 500 kV is utilized. The only 500 kV level system is analyzed by N-1-1 contingency criterion to define vulnerabilities of power grid. The dynamic simulation is implemented in vulnerability-based power system scenarios to verify long-term stability. The dynamic models of generators, governor, excitation system, maximum excitation limiters, static VAR compensators and load tap changers are built up based on real data of Vietnam power system.

Relation formulation between daily and hourly load curve based loss of load expectation indices

This paper develops a conversion function and method transforming from daily peak load curve used LOLED [days/year] to hourly load curve used LOLEH [hours/year] firstly. The indices can not only be conversed just arithmetically but also have different characteristics physically because of using their different load curves. The conversion function is formulated as variables of capacity and forced outage rate of generator, hourly load daily load factor and daily peak load yearly load factor, etc. Therefore, the conversion function (γ = φ(·)) can not be formulated in simple but in complex and difficult. In this study, therefore, the function is formulated as linear times of separated two functions. One is exponential formed conversion function of daily load factor. Another is formulated exponential typed conversion function of daily peak load yearly load factor. Furthermore, this paper presents algorithm and flow chart for conversing from LOLED [days/year] to LOLEH[hours/year]. The proposed conversion function is applied to sample system and actual KPS(Korea Power System) in 2015. The exponent coefficients of the conversion functions are assessed using proposed method. Finally, assessment errors using conversion function for case studies of sample system and actual system are evaluated to certify the firstly proposed method.