Research On Operation Optimization And Energy Storage Capacity Allocation For Storage Integrated Power Plants In Power System

Storage integrated power plants include power generation system and energy storage system,e.g.,concentrating solar power plant with thermal energy storage,coal-fired power plant retrofitted with steam extraction and thermal energy storage.In storage integrated power plants,energy in the power-generation process can be directly stored avoiding conversions between different forms of energy,which could greatly improve the efficiency of energy storage.Therefore,the storage integrated power plant has a high ability for flexible operation,which is an effective scheme to improve the utilization level of stochastic renewable energy generartion.In this paper,the operation model,generation optimization and energy storage capacity allocation for concentrating solar power plants,hybrid solar and biomass power plants and coal-fired power plants retrofitted with steam extraction and thermal energy storage.The main work includes the following four aspects:(1)The operation model and generation optimization of concentrating solar power plants with thermal storage coordination are studied in this paper.Based on the basic structure of concentrating solar power plant,the operation modes of each energy module are analyzed.Meanwhile,the main energy flow modes of concentrating solar power plant are studied.Based on the operation characteristics of each energy module and energy coupling relationship,an accurate operation model of concentrating solar power plant is established.The proposed model in this paper takes into account the non-linear characteristics of thermoelectric efficiency in power block,wich is linearized with the piecewise linearization method.Considering different power system dispatch modes,the self-operation objectives of concentrating power plants for generation scheduling and peak-valley prices are established,respectively.Based on the operation model of concentrating power plant,a low-carbon dispatch model of power system is established,aiming to minimize fuel cost,carbon emission cost and capacity shortage penalty.(2)The operation strategy and weekly schedule optimization of hybrid solar and biomass power plant are studied in this paper.Firstly,the internal structure and energy flow characteristics of hybrid solar and biomass power plant are analyzed.Considering the combustion constraints of biomass boilers,the operation model is proposed.In order to avoid the risk of small probability and low revenue caused by solar irradiance uncertainty,a self-operation strategy considering CVaR is proposed.Based on the weather forecast information,a DNI scenario construction method for weekly schedule optimization is proposed.Considering the alternation of cloudy and sunny day,a weekly schedule and allocation model of biomass fuels is established.The validity of the proposed model is verified by comparing with the daily average allocation method.In addition,the simulation results show that the weekly schedule and allocation of biomass fuels can improve the generation ability of hybrid power plants and the reliability of power supply in rainy and cloudy days.(3)The operation model and benefit evaluation method of coal-fired power plant retrofitted with steam extraction and thermal energy storage are proposed in this paper.Firstly,the flexible operation limitations are analyzed from the three dimensions: lower turndown capability,faster ramping capability and faster start-up capability.Then the technical mechanism of improving the flexibility of coal-fired power plants is studied.Based on the basic structure of retrofitted coal-fired power plant,the new medium circulation process and energy flow characteristics are analyzed.Considering thermal energy coupling relationship between the boiler combustion system,thermal storage system and steam-power generation system,the flexible operation model is established.Considering with the dispatch mode of power system,a benefit evaluation method for combined operation of coal-fired power plants and wind power is proposed based on one year time series simulation,in which the day-ahead stochastic unit commitment model and the economic dispatch model are used.With case study simulations,the impact of steam extraction and thermal energy storage retrofit on the operation of wind integrated power system is analyzed.In addition,the impact of thermal energy storage capacity on the overall benefit of power system with different wind power penetrations is analyzed.(4)The thermal storage capacity allocation method of storage integrated power plants for high-level renewable energy generation integrated power system is studied in this paper.Based on the daily average pattern clustering and sequential sequence clustering of renewable energy scenarios,a renewable energy scenario construction method is proposed for a mid-and long-term planning problem considering the consistency of mathematical moments and wind-solar correlation between the original scenario set and the typical scenario set.Considering the energy coupling relationship,a collaborative capacity optimization method of solar field and thermal storage system is proposed for concentrating solar power plant.The necessity of the collaborative capacity optimization is analyzed by numerical simulation.Based on the retrofitted operation model of coal-fired power plants,a planning model for steam extraction and thermal energy storage retrofits to promote high-level wind power utilization is proposed.Based on PSO algorithm and commercial MILP solver,a solution framework of the planning model is proposed.The planning problem is decomposed into two-level optimization model,which could effectively reduce the scale of a single optimization problem and improve the calculation speed.