Thermal Power Units Research Articles

Simulation and experimental research on trace detection of ammonia escape based on TDLAS

With the raising of NOX emission control standards, selective catalytic reduction (SCR) denitrification technology has been widely used in thermal power units·NH3 as a kind of important reducing agent, can reduce NOX to N2·NH3 escaped from the flue gas treatment process is directly discharged into the atmosphere, which will not only cause environmental pollution, but also block the catalyst and affect the performance of thermal power units. Therefore, the online monitoring technology for concentration of ammonia is significant. Considering the actual situations, absorption spectrum line around 970.9 cm−1 located in the mid-infrared for NH3 was selected for measurement simulation and experimental research based on TDLAS. The results show that the measuring system has good linear response, repeatability and stability, and the detection limit reached 8.3 and 30 ppbv (10–9), when the integral time was 30 and 1 s respectively, which is suitable for online monitoring of the concentration of ammonia.

Improving the Frequency Response of Hybrid Microgrid under Renewable Sources’ Uncertainties Using a Robust LFC-Based African Vulture Optimization Algorithm

Power systems have recently faced significant challenges due to the increased penetration of renewable energy sources (RES) such as frequency deviation due to fluctuations, unpredictable nature, and uncertainty of this RES. In this paper, a cascaded controller called (1+PD)-PID is proposed to reduce the influence of RES uncertainties on the system and to maintain the system’s reliability during fluctuations. The proposed controller is a combination of (1+PD) and PID controllers in order. The output signal of the (1+PD) controller along with the frequency deviation and the power difference between adjacent areas are used as inputs to the PID controller to create the load reference signal. The parameters of the suggested controller are optimally tuned using the African Vulture Optimization Algorithm (AVOA) to ensure the best performance of the controller. A two-area interconnected system with non-reheat thermal power units combined with RES such as solar and wind energy is modeled using MATLAB/Simulink to evaluate the system response. The controller effectiveness is verified by subjecting the studied system to various types of fluctuations such as step load disturbance, variable load perturbation and RES penetration. The obtained simulation results prove that the proposed (1+PD)-PID controller in integration with AVOA offers a significant improvement in the system performance specifications. Moreover, the proposed AVOA-based (1+PD)-PID controller has proven its superiority over other comparable controllers having the least fitness function of 6.01 × 10−5.

Wind-Thermal-Energy Storage System Optimization: Evidence from Simulations of the Economical Consumption of Wind Energy

To realize the economical consumption of wind energy (WE), an optimal dispatch strategy for wind-thermal-energy storage systems (WTESSs) is proposed. The scheduling model is divided into two stages. In the first stage, the strategy aims to shave peaks and fill valleys in the load curve using a time-of-use (TOU) electricity price and to reduce the variance of the net load and use the energy time-shift characteristics of energy storage systems (ESSs) to optimize their charging and discharging power. In the second stage, the strategy minimizes the cost of WTESSs, obtaining the output power of the thermal power units (TPUs) in each period. Considering the actual need for carbon reduction, a method for calculating the TPUs’ life loss cost under different variable load amplitudes is introduced, and a thermal power peaking cost model considering the ladder-type carbon trading model is constructed to calculate the cost accurately. In addition, to account for the fact that connecting all wind power outputs to the grid will significantly increase the grid peak regulation pressure and operational risk, a mathematical model for WE utilization is established to find the optimal power value for wind power grid connection in each period, which enables economical and practical WE scheduling. According to the simulation results, the overall peak-shaving cost of the system can be reduced by up to 23.95%, and the thermal power deep peak regulation cost can be reduced by up to 90.06%.

Optimal Dispatch of Wind Power, Photovoltaic Power, Concentrating Solar Power, and Thermal Power in Case of Uncertain Output

The integration of large-scale wind and photovoltaic power into modern power grids leads to an imbalance between the supply and demand for resources of the system, where this threatens the safety and stable operation of the grid. The traditional mode of grid dispatch and the capability of regulation of conventional thermal power units cannot satisfy the demands of grid connection for large-scale renewable energy, where the system requires the compensation and coordinated dispatch of flexible power sources. In light of this problem, this paper establishes a model to quantify the uncertainty in the forecasted outputs of wind and photovoltaic power. This is used to develop forecasts of the output of wind and photovoltaic power for several groups of scenarios, and predictions with the best complementarity are selected as a typical set of scenarios by means of their generation, reduction, and combination. By taking full advantage of the complementarity in the rates of regulation of conventional thermal power and concentrating solar power (CSP), a coordinated model of dispatch for wind power, photovoltaic power, CSP, and thermal power is established for a number of typical combinations of scenarios. The influence of uncertainty in the outputs of wind and photovoltaic power on the dispatch of the power grid is examined, and different modes of dispatch are formulated through simulations to analyze the superiority of the dispatch strategy proposed in this paper in terms of abandoned wind quantity, abandoned solar quantity, and the cost of dispatch.

The Semi-Scheduling Mode of Multi-Energy System Considering Risk–Utility in Day-Ahead Market

The large-scale development of renewable energy has an urgent demand for an adjustable power supply. For a multi-energy system with multiple types of heterogeneous power sources, including wind power, photovoltaic (PV) power, hydropower, thermal power and pumped storage, a novel semi-scheduling mode and a solution method were proposed in this paper. Firstly, based on the load and the reserve demand during the peak load period, the semi-scheduling mode was adopted to determine the start-up combination of thermal power units. Furthermore, by predicting the generating/pumping power, the working state of pumped storage units was determined to realize the independent solution of discrete integer variables. Secondly, the risk–utility function was constructed to quantify the attitude of pumped storage towards the uncertainty of renewable energy output, which completed the quotation and clearing of the pumped storage in the ancillary service market. Finally, by taking the minimum total quotation cost as the objective, the wind–solar–hydro- thermal-pumped storage coordinated (WSHTPC) model was built in the day-ahead market. The feasibility and effectiveness of the proposed model were verified through the simulation of a typical day with different renewable energy penetration rates.

Optimization control and economic evaluation of energy storage combined thermal power participating in frequency regulation based on multivariable fuzzy double-layer optimization

Energy storage auxiliary thermal power participating in frequency regulation of the power grid can effectively improve operating efficiency of thermal power units, but how to realize power distribution between energy storage system and thermal power units is the key to the frequency regulation operation of energy storage and thermal power combined system. Aiming at problems that full power compensation strategy is not conducive to the sustainability of energy storage output, a frequency regulation optimization control strategy of thermal powers and energy storage combined system based on multivariable fuzzy double-layer optimization is proposed in this paper. According to the output and compensation weights of the fuzzy controller, the state of charge for energy storage system can be adjusted adaptively to help thermal power units improve the dynamic frequency regulation performance of power grid. The equivalent cycle life of energy storage system is calculated by the rain-flow counting method, and the economy of system is evaluated by the net present value method in the whole life cycle of energy storage system. The effectiveness of the proposed control strategy is verified by the simulation analysis on the actual operation data which can provide a theoretical basis for frequency regulation of automatic generation control.

Optimal Scheduling Strategy for Power Systems Containing Offshore Wind Farms Considering Wind Power Uncertainty

The wind power interval prediction of offshore wind farms and power plan arrangement of conventional thermal power units are of vital importance in the consumption of offshore wind power, the reduction of greenhouse gas impact on the environment, and the electric power system safe and economic operating. With the purpose of selecting the appropriate Copula function on the basis of the results of wind speed and wind power normal test, establish the mathematical model of wind-fire joint optimal scheduling, and optimize coal-fired power units power generation after comparing the convergence performance of particle swarm optimization method and crow search algorithm. Results indicate that the selected Copula function meets the expected criteria, and the optimized thermal unit climbs more smoothly and through the optimization of CSA the complete economic consumption of running is lessened. An idea is presented by this paper, which considers the uncertainties of offshore wind power generation, and the basis for the operational performance of CSA over PSO, and which provides a joint wind-thermal economic optimal dispatch strategy.

Dispatching method of high energy consuming load participating in peak shaving based on variational modal decomposition

With the rapid development of our country, the construction and development of power system has shown the continuous growth of load, and the proportion of new generation energy has also expanded. The impact of these problems on our life cannot be underestimated. Therefore, the development of new energy has become a necessary way to realize the transformation of energy production to green and renewable energy, which is an important direction and necessary decision-making Energy and economy can achieve sustainable development goals all over the world. In order to improve the peak shaving capacity of the power system, this paper proposes to introduce the load side into high energy consuming enterprises to participate in the regulation, and carry out joint optimal dispatching with conventional thermal power units. The optimization goal is to minimize the sum of all day waste air volume of the next day, and the simulation software is used to optimize it. Compared with the regulation of a single thermal power unit, the effect is better, it plays a positive role in reducing wind abandonment, improves the utilization rate of wind power, and has high economic and environmental benefits.

Rule base construction method of section out of limit disposal strategy for thermal power unit equipment fault

This paper proposes a rule base construction method of section out of limit disposal strategy for thermal power unit equipment fault, which can solve the problems of abnormal power transmission and grid real-time scheduling caused by section out of limit. Through the improved Apriori algorithm, the section out of limit disposal strategy of thermal power unit equipment fault is designed. In the mining result of thermal power unit equipment fault section out of limit, the association rules between section state and unit and load disposal strategy are established. By using the improved Apriori algorithm, the policy data and section state data are set as the preceding and following constraints of the association rules, The strong association rules are obtained, and the rule base of cross section out of limit disposal strategy is constructed according to the association rules. The experimental results show that: the number of association rules obtained by the improved Apriori algorithm mining each database is less than 1000, and the rule effectiveness and analysis efficiency are significantly improved; The rule base built by this method can effectively deal with the out of limit problems of different sections and units, and the sensitivity of each generator node increases greatly after the treatment.

Research on combustion and emission characteristics of circulating fluidized bed during load changes

The conventional design of circulating fluidized bed (CFB) focuses more on high combustion efficiency and low pollutant emission. However, as the proportion of new energy generation in China continues to increase, the power grid is placing higher demands on the operational flexibility of thermal power units. The CFB has the advantage of a wide range of load regulations, and it is an inevitable choice to participate in the deep and flexible peak regulation of the power grid. In order to conduct research on the features of CFB during load changes, this work used 0.1 MWth CFB as the research object and examined its combustion and emission characteristics at different loads, as well as the change in temperature and pollutant emissions during load changes. The results showed that the temperature distribution along the height direction of the furnace was not uniform at lower load, while the inhomogeneity of the temperature distribution decreased, and both the temperature and pressure of the furnace increased as the load increased. Moreover, NOx emission and combustion efficiency both rose with the load. When the load increased from 30% to 100%, the NOx emission increased from 228 mg/m3 to 324 mg/m3, the CO emission decreased from 1422 mg/m3 to 104 mg/m3, and the carbon content of the fly ash decreased from 39.2% to 27.6%. If the temperature stability was used as the reference standard for load stability, the load-change rates on the combustion side of the experiment platform from 50% load to 75% load and from 75% load to 100% load under conventional combustion were 0.69%/min and 0.81%/min, respectively. In general, the load variation range of the CFB was wide, but the load-change rate on the combustion side and the combustion efficiency at low loads need to be further improved.

Simulation study on carbon emission of China's electricity supply and demand under the dual-carbon target

As the world's largest developing country, China has set the target of “reaching carbon peak by 2030 and carbon neutrality by 2060”. China's power sector faces many challenges in reducing carbon emissions. This article forecasts electricity consumption from 2021 to 2060 by selecting five influential elements on power demand. Furthermore, the system dynamics model simulates the carbon emission system on the supply and demand side of the power industry. This paper innovatively incorporates the technology factor of carbon capture, utilization, and storage (CCUS) into the supply-side model. In this study, the process of carbon neutrality is separated into three stages, including carbon peak stage (2020–2030), deep low-carbon stage (2030–2050) and zero-carbon stage (2050–2060). The factors of energy storage technology and CCUS technology make significant contributions in the latter two stages. Based on the different development levels of the variables, three scenarios are set as business-as-usual scenario (BAU), low carbon scenario(LC) and ultra-low carbon scenario (ULC). Then scenario analysis is employed to simulate the carbon emission in the future. The scheme under the ULC scenario is the optimal solution to achieve carbon neutrality. Improving flexible transition of thermal power units and promoting the growth of renewable energy are China's primary strategies of achieving carbon peak and carbon neutrality.

Optimal scheduling for unit commitment with electric vehicles and uncertainty of renewable energy sources

The unit commitment (UC) problem is a typical mixed integer nonlinear programming problem related to power systems. As electric vehicles (EVs) and renewable energy sources (RESs; e.g., wind and solar power) have become integrated into the power system, the UC problem has become increasingly complex. With the continuous growth of the proportion of renewable energy based on wind and solar energy in the power supply structure on the supply side in the future, the random characteristics of the supply and demand sides of the power system will become more obvious, which will inevitably bring about the safety, stability and economic operation of the power system. The study of UC not only has great academic value, but also has important practical significance. The optimal scheduling of UC, including thermal, wind, solar, and EV power units was investigated. The objective function of optimal scheduling was to minimize the operating cost of the unit and optimize the charging and discharging costs of EVs. In view of power generation characteristics of RESs, an interval number was introduced to describe the uncertainties in the outputs of wind and solar power generation. The enhanced-interval linear programming is introduced to deal with the UC problem including EVs and uncertainty of RES. For better accuracy, wind power was considered for each of the four seasons (spring, summer, autumn, and winter) and solar power was divided into sunny, cloudy, and rainy conditions. To reflect the influence of EV charging and discharging on UC, three different charging and discharging pricing schemes were considered. Various scenarios were simulated using the CPLEX solver. The results showed that costs can be affected by season and climate. The interval number solution sets of the total cost and of the charging and unit costs were obtained by using interval number theory to describe the uncertainty of output in RESs; this provides a new approach for solving the UC optimization problem by integrating RESs. The charging and discharging of EVs can also affect costs. By encouraging the orderly charging and discharging of EVs, power load fluctuations could be reduced and peak-load shifting could be achieved. Different pricing schemes had different impacts on cost. The pricing scheme can not only effectively reduce the charging cost borne by EV owners, but could also make EVs profitable. This discovery provides a theoretical basis for guidance on the charging and discharging of EVs through charge and discharge price schemes. The simulation results reflect the relationship between economic cost and seasons/climate and confirm the suitability of using an interval number to describe uncertainty in energy generation.

Combined thermal power and battery low carbon scheduling method based on variational mode decomposition

A renewable energy consumption method based on variational mode decomposition and combined regulation of thermal power and storage system is presented in this paper. By decomposing the equivalent load curve using variational mode decomposition, the equivalent load curve is divided into parts with different center frequencies and energy system constraints and solved separately. We then take the maximum wind power absorption rate as the upper model target and solve it. At the same time, through the operation curves of the thermal power unit and battery storage system, the lower optimization model is established to minimize the system’s operating cost with carbon emission costs. The example shows that the regulation method with a storage system improves the consumption rate of wind power and reduces carbon dioxide emission compared with the regulation method without a storage system. Compared with the method without decomposition, the power output curve of the thermal power unit is smoother under the new method, effectively improving the solving speed. It reduces the operating cost of the system and its carbon dioxide emissions.

Evaluation of a modernization project of the main condensate scheme at CHP-10 power unit No. 5 using its customized simulation model

We investigate the effect of modernizing the main condensate scheme applied at the power unit No.5, CHP-10 of Baikal Energy Company LLC, on its energy and economic efficiency using a customized simulation model. Simulation modelling was carried out in the Machine Program Building System software environment. The constructed model was verified using the results of measuring control parameters in several operating modes according to a three-stage procedure of verifying the mathematical models of complex thermal power units. We propose an original approach to modernizing the main condensate thermal scheme at the power unit under study in order to reduce the specific fuel consumption for balance-of-plant needs. The idea was to expand the main condensate scheme by including an additional sealing pump to the feedwater electric pumps of the 1Кs-20-110 unit in order to avoid the incorrect selection of condensate pumps. The study showed that the redistribution of the main condensate flow between the existing condensate pumps and the proposed 1Ks-20-110 sealing pump leads to a reduction in the specific fuel consumption for the electric energy generation to 0.32 g of fuel per kWh across the range of electrical loads from 137 to 150 mW. As a result, the net efficiency of the power unit can be raised by 0.03%. It should be noted that the proposed modernization project may reduce the consumption of electricity for balance-of-plant needs when the feedwater electric pump is switched to the standby mode during an emergency shutdown of the power unit. Based on the performed energy and economic calculations, energy savings for the period of 2019 comprise 82,653 kWh, while the total annual savings are estimated at 78,030 rubles. Thus, the conducted research demonstrates the high efficiency of applying simulation modelling in the study and optimization of existing thermal power plants.

Three-stage Coordinated Dispatching of Wind Power-Photovoltaic-CSP-Thermal Power Combined Generation System

Aiming at the problem that the grid connection of intermittent renewable energy such as wind power and photovoltaics brings great uncertainty to the power system, a three-stage coordinated scheduling strategy of wind power-photovoltaic-concentrated solar energy is proposed. CSP Combined heat and power system. In the first stage, based on the day-ahead forecast data of wind power, photovoltaics and load, a “peak shaving” model of the combination of wind power-photovoltaic-CSP was established. In the second stage, according to the value of the remaining load after optimization in the first stage, a day-ahead economic dispatch model for thermal power units is established. In the third stage, based on the start-stop status and output of thermal power units in the first and second stages, the output of CSP plants and the intraday forecast data of wind power, photovoltaics, and loads, the establishment of an intraday thermal power joint regulation model and the establishment unit and CSP stations are established, and intraday scheduling plans are arranged. Case analysis shows that the proposed CHP system scheduling strategy can be supplemented by thermal power and CSP during load peak and trough periods, thereby minimizing the uncertainty brought by grid integration of wind power and photovoltaics. Introduce.

Optimization of Reserve With Different Time Scales for Wind-Thermal Power Optimal Scheduling Considering Dynamic Deloading of Wind Turbines

In the power system with high proportion of wind power, a day-ahead and intraday coordinated optimal scheduling model of wind power and thermal power units (TPUs) is established considering variable virtual inertia. Firstly, the frequency regulation characteristics of wind turbines (WTs) are analyzed, the feasibility of reserve of WTs is elaborated, and the dynamic deloading strategies of WTs in different wind speed zones are proposed. Then, the feasibility of variable virtual inertia realized by rotor overspeed control (ROC) of WTs is analyzed, which is combined with synchronous inertia of TPUs to deduce the deloading level constraints of WTs and minimum inertia constraints of power system considering inertia demand. Referring to the characteristics of reserve resources in different time scales on the generation side, the reserve capacities of TPUs are divided into minute and second levels according to response time, and the scheduling strategy of reserve capacity in different time scales is proposed, so as to improve the flexibility of TPUs and realize the refined management of reserves. Simulations indicate that the proposed model and method can effectively improve the inertial support capability of the system and reduce the operation cost.

Research on the influence of secondary heat network characteristics on wind power consumption in the combined electric and heat system

With the large-scale investment of thermal power units in the “Three Norths” area, the coupling of the combined electric and heat system has become more and more close, leading to a huge number of abandoned wind. On the basis of the traditional thermal system model, physical characteristics of the secondary heat network are added, and an optimal scheduling model of the combined electric and heat system considering the operation characteristics of the secondary heat network is established. The influence of the operation characteristics of the secondary heat network on the heat loss and wind power consumption of the thermal system is studied. Based on this, different conditions are set up to study the influence of heat-exchange efficiency of heat exchange stations and the diameter of secondary heat network pipes on the combined electric and heat system. The simulation analysis shows that the heat network characteristics of the secondary heat network need to be considered in the scheduling analysis of the combined electric and heat system. In addition, the system air curtailment rate can be reduced by improving the heat exchange efficiency of the heat-exchange station and changing the diameter of the secondary heat network pipeline.

Low-Carbon Economic Dispatching of Multi-Energy Virtual Power Plant with Carbon Capture Unit Considering Uncertainty and Carbon Market

Multi-energy virtual power plants (MEVPPs) effectively realize multi-energy coupling. Low-carbon transformation of coal-fired units at the source side and consideration of demand response resources at the load side are important ways to achieve carbon peak and carbon neutralization. Based on this, this paper proposes a low-carbon economic dispatch model for the MEVPP system considering source-load coordination with comprehensive demand response. Combined with the characteristics of organic Rankine cycle (ORC) waste heat power generation and comprehensive demand response energy to increase the flexibility on both sides of the source and load, the problem of insufficient carbon capture during the peak load period in the process of low-carbon transformation of thermal power units has been improved. First, the ORC waste heat recovery device is introduced into the MEVPP system to decouple the cogeneration unit’s “heat-based electricity” constraint, which improves the flexibility of the unit’s power output. Secondly, we consider the synergistic effect of the comprehensive demand response and ORC waste heat recovery device and analyze the source-load coordination low-carbon dispatch mechanism. Finally, an example simulation is carried out in a typical system. The simulation example shows that this method effectively improves the carbon capture level of carbon capture power plants, takes into account the economy and low carbon of the system, and can provide a reference for the low-carbon economic dispatch of the MEVPP system.

Bidding modes for renewable energy considering electricity-carbon integrated market mechanism based on multi-agent hybrid game

The proposal of carbon peak and carbon neutrality goals will inevitably promote the large-scale development of renewable energy, and the market mechanism is also being pushed forward to absorb more renewable energy in China. Considering electricity-carbon integrated market mechanism, this paper constructs a hybrid game model to study the evolutionary process of renewable energy generation companies (GENCOs) in market trading by setting up three renewable energy bidding modes. Among them, the leader-follow relationship between GENCOs and the day-ahead electricity market is reflected by the Stackelberg game model, and the bidding behavior of different GENCOs is described by cooperative and non-cooperative game models. The role of different stages for the carbon emissions trading (CET) market on the electricity market is discussed based on the sensitivity analysis. The simulation results show that the bundled sales between wind, photovoltaic and thermal power GENCOs could improve the expected profits of each GENCO and reduce the total carbon emissions. As the proportion of renewable energy in the electricity market increases, the clearing prices will decrease. Meanwhile, the peak-shaving times of thermal power units will raise, and thermal power GENCOs are more willing to participate in the auxiliary service market. Besides, the complete marketization of renewable energy GENCOs will affect the recovery of the initial investment. Moreover, it can be found that lower free carbon quota, higher CET and Chinese certified emission reduction (CCER) prices can effectively guide the electricity market to be cleaner.

Design and analysis on different functions of battery energy storage system for thermal power units frequency regulation

Currently, as more and more new energy sources are connected to the power grid, the pressure on the frequency regulation (FR) of thermal power units (TPU) is increasing. The battery energy storage system (BESS) is used in the scene of auxiliary TPU-FR with its rapid response and accuracy, which has attracted many scholars to study it. However, most scholars only studied the system under normal operating conditions, and did not involve too much on the operating strategy of the system in the event of a failure. In this article, a simulation model of energy storage battery auxiliary FR is built in MATLAB/Simulink, which not only analyzes the response characteristics of the system during normal operation, but also verifies the operation strategy of the system during faults. It is revealed that the existence of energy storage battery reduces the grid frequency offset by 38.1% and increases the power response speed by at least 25 times at normal operation. In addition, the total harmonic distortion of grid-connected voltage and current are 2.54% and 1.72%, respectively, which implies high power quality. When a fault occurs, the energy storage battery is protected by reasonably connecting or removing the BESS based on certain boundary conditions to prolong its life and reduce equipment maintenance costs.