Operational Reliability Evaluation Of Composite Generation And Transmission Systems Considering Multiple Meteorological Factors And Decommissioned Battery Storage

The basic function of a modern electric power system is to provide electric energy to its customers at the lowest possible cost and at an acceptable risk level.With the development of society and the improvement of living standards,the power demand of the whole society is growing,and the requirement for reliability of power supply is also increasing.Power system is a typical large-scale system across regions.A large number of electrical devices are directly exposed to external environment,and are vulnerable to external weather conditions.Existing models fail to accurately consider the impact of multiple meteorological factors,and thus cannot fully catch up the comprehensive influences of weather on a power system that includes generation,transmission,and load.On the other hand,there are several uncertainties existing in all parts of power system.With the increase of installed renewable energy in power systems,the system uncertainties increase due to the significant fluctuation of renewable generation output,which lead to an urgent need in connecting energy storage systems to power systems in order to balance the uncertainties caused by meteorological and other factors.However,conventional energy storage is expensive,so it is necessary to find a new battery storage scheme considering the balance of reliability and economy.Reusing decommissioned batteries of electric vehicles,which has become a serious environmental challenge,provides an opportunity to solve environmental problems and promote the economic reliability of power systems.This thesis puts the focus on the operational reliability evaluation of composite power generation and transmission systems,including two related issues: real-time meteorological impacts and decommissioned battery energy storage of electric vehicles.The operational reliability evaluation models of power devices and power systems considering the influence of multiple meteorological factors are presented.In addition,with higher proportion of renewable generation in systems,the feasibility and effectiveness of reusing decommissioned batteries as large-scale energy storage systems in power systems are studied from a perspective of operational reliability and backup analysis.To address the issues that the existing reliability evaluation models of power devices considering meteorological impacts cannot fully consider the effects of real-time meteorological conditions and the accuracy is not high enough,an operational reliability model of power devices based on the improved logistic regression model is proposed.Based on a data-driven method,historical fault record data of outdoor power devices and corresponding numerical weather record data are combined to fit a failure probability model of a device group located in the same meteorological region.Such a model can be used for real-time operational reliability evaluation and prediction.The case study results show that compared to the existing models,the proposed model can be utilized to accurately evaluate the impact of real-time numerical meteorological conditions on the failure probability of power devices,leading to more stable practical results.To solve the problem that power systems including generation,transmission and load are all influenced by multiple meteorological factors,while existing models cannot fully consider the comprehensive impacts of multiple meteorological factors and corresponding uncertainties on the operational reliability evaluation of power systems,a nested sampling method for operational reliability evaluation of composite generation and transmission systems considering multiple meteorological factors is developed.In this method,the uncertainties of the variables affected by weather can be traced back to the uncertainties of multiple meteorological factors,and the spatial-temporal consistency of all uncertainties is maintained.A generalized probabilistic modeling method of meteorological factors is also proposed.According to the historical record of meteorological data,the probability distribution of each meteorological factor is determined at any time point through steps of fitting,shifting and domain adjustment,which can be adopted to ensure the accuracy of operation reliability evaluation.The case study results show that with the proposed nested sampling method,the impacts of multiple meteorological factors and their uncertainties at any time point on various random variables are fully considered,including renewable energy outputs,outdoor power device failure probabilities,dynamic thermal ratings of transmission lines,and random variations of loads.And the combination of Latin hypercube sampling and the Gibbs sampler based Markov chain Monte Carlo method can effectively improve the efficiency of operational reliability evaluation.Moreover,the uncertainty importance measures of each random variable obtained via the proposed nested sampling method can be used to provide a guidance for the industrial practice of operational reliability evaluation.To overcome the challenging problem of the increase in power system uncertainties with higher penetration of renewable generation,an innovative idea of reusing decommissioned batteries as a large-scale storage in power system is presented in the thesis,and its feasibility is proved through modeling and analysis.Based on the rapid degradation characteristic of decommissioned batteries,a new battery capacity degradation model suitable for decommissioned batteries is proposed.Literature review indicates that it is also the first capacity degradation model applied to operational reliability evaluation of power systems.A universal generating function is adopted to build a probabilistic model for the capacity of a battery module consisting of hundreds of cells.With the reliability model of battery modules,the operational reliability evaluation model of composite generation and transmission systems with decommissioned batteries is proposed to quantify the influence of decommissioned batteries on operational reliability of the system.The test results show that the proposed capacity degradation model can be used to simulate the process of battery capacity degradation under different operating conditions.By adopting the proposed idea and models,the operational reliability of the composite generation and transmission systems with decommissioned batteries is improved,and a significant investment saving can be reached.Moreover,reasonable second retirement schedule of these decommissioned batteries lead to short-term profits for utilities.Reusing decommissioned batteries in power systems bring some reserve for a system and help improve the operational reliability,but there is no existing reserve analysis index or method for decommissioned batteries.To address this issue,a new equivalent reserve index is presented to quantify the reserve effect of reusing decommissioned batteries in composite generation and transmission systems.Reserve analysis is conducted based on operational reliability evaluation of power systems with decommissioned batteries.The proposed operation strategy on battery energy storage fully characterizes the relative commitment priority of battery discharging and traditional unit generation,and the relative assignment priority of battery charging and load demand.The test results show that the proposed index can quantify the reserve effect of decommissioned batteries in systems.By using the proposed model,decommissioned batteries are able to show their best performance,and load curtailment is reduced in some system contingency states.The feasibility and effectiveness of reusing decommissioned batteries in power systems is further proved from the perspective of reserve analysis,since that the decommissioned batteries can maintain a certain backup effect during one year.