Reliability model is the foundation of reliability analysis. Conventional reliability modeling takes the entire system as the research object, and uses all fault data to fit the distribution function of the system, estimate parameters, and optimize the model, thus to determine the distribution type and distribution function of the system, and then to calculate the reliability indicators of the system. Wind turbine is a typical complex electromechanical system, with different functions, structures, and fault forms of each subsystem. It is obviously inappropriate to use one distribution function to determine the fault distribution of the entire system. Therefore, based on the collected and sorted fault data of wind turbines, the distribution function optimization-based reliability modeling and analysis technology of wind turbines is proposed. By applying the commonly used exponential distribution, normal distribution, log-normal distribution, Weibull distribution and gamma distribution, the distribution function fitting, parameter estimation and goodness of fit analysis of the fault interval of each subsystem of wind turbines are carried out, and the distribution function and subsystem reliability function of the fault interval time of each subsystem are determined. On this basis, a Copula connection function is used to establish the reliability function model for wind turbines, taking into account the fault correlation between subsystems. Moreover, an example analysis is conducted on the fault data of an offshore wind turbine, which verifies the feasibility of the proposed method.

Aiming at the case of large frequency fluctuation in natural gas unit black start project, combining with the gas black start system and the waveform diagram during static frequency convertor (SFC) startup, the failure phenomenon is described in detail and the specific cause of the failure is analyzed. On the basis of considering the slow response speed of diesel generator unit, a super capacitor-assisted black start frequency modulation (FM) strategy is proposed. The SFC power is divided into base power and frequency fluctuation power, among which the base power is borne by the diesel generator unit to ensure stable operation of the system, and the frequency fluctuation power is quickly responded by the supercapacitor to suppress the frequency fluctuation effectively. Through the black start experiment of a 4F gas unit, the strategy not only effectively reduces the frequency fluctuation during the black start process, but also avoids the overcurrent fault during ramp-up and load-change phase, thus the reliability and safety of black start of the gas unit is improved.

Based on a typical 600 MW coal-fired cogeneration unit, novel systems with integrated steam jet and external steam cooler are proposed. In novel system I, the waste heat from exhaust steam is recovered through a steam jet, in which reheat steam is chosen as the working fluid. In novel system II, an external steam cooler is used to reduce the superheat of the mixed steam and the heat load of the boiler. Based on EBSILON professional modeling, the system is analyzed considering the peak shaving performance and thermodynamic performance under the maximum heating condition (extracted steam for heating: 800 t/h) and variable conditions. Moreover, the effects of mixed steam pressure and heat exchanger end difference on the system performance are also investigated. The results show that, under the maximum heating condition, compared with those of the reference system, the heating capacities of the novel system I and II increase by 21.59 and 14.47 percentage points, and the power generation efficiencies are increase by 2.48 and 2.78 percentage points, respectively. With the heating load of 300 MW, the power load regulation ratios of the novel system I and II improve by 6.00 and 3.91 percentage points compared with the reference system, and the lower limits of generation reduce by 84.75 MW and 74.32 MW. The gross efficiency of the novel system I and II improve by 3.02 and 2.65 percentage points, respectively, when the mixing steam pressure is increased from 50 kPa to 85 kPa. With the upper temperature difference increasing from 1 ℃ to 9 ℃, the gross efficiencies of the novel system I and II decrease by 1.67 and 1.51 percentage points, respectively. The result can provide technical references for expanding heating capacity and deep peaking of coal-fired cogeneration systems.

In order to solve the problems of waste heat utilization, carbon capture and liquid natural gas (LNG) cold energy utilization of solid oxide batteries fueled by methane, a new type of combined cooling, heating and power system was established. The system includes the improved recompression supercritical mixed working fluid Brayton cycle, the transcritical CO₂ heat recovery Rankine cycle and the secondary mixed working fluid organic Rankine cycle. The thermodynamic analysis, equipment exergy analysis, economic cost analysis of the circulation system, and the multi-objective optimization of the system by using the genetic algorithm in MATLAB. The results show that, increasing P1, T16 and the mass fraction of R14 in the second-stage Rankine cycle can improve the network, thermal efficiency, and exergy efficiency of the system, and reduce the average unit cost. P1 is the pressure at inlet the expander in the compressed supercritical mixed working fluid Brayton cycle, T16 is the inlet temperature of the expander in the transcritical CO₂ regenerative Rankine cycle. Under the optimal working conditions, the thermal efficiency, exergy efficiency and average unit cost of the system are 64.70%, 47.85% and 24.20 dollars/GJ.

This paper focuses on aggregating decentralized demand-side resources through virtual power plants (VPPs) to enhance the peak load management capability in the construction of new electric power systems. The research centers on the core issue of “load-based” virtual power plants participating in power source planning. It investigates the modeling methods for the adjustable potential of virtual power plants, including electric vehicles, air conditioning loads, and industrial loads. Moreover, the paper delineates the economic and operational technical constraints of virtual power plants in power source planning and constructs a power source planning model that accounts for VPPs. Considering the prediction errors of renewable energy and the characterization errors of the VPPs’ response potential, the paper utilizes interval optimization theory to reformulate the model into an interval planning model and completes the deterministic transformation of the model through interval order relations and interval possibility. The rationality of the proposed power source planning method is verified through a case study. The results show that the proposed method can effectively aggregate VPP resources, significantly enhancing the system’s peak load management capability. The constructed interval planning model can effectively handle forecast errors, ensuring the reliability of planning. This method provides an economically feasible solution for the transformation of the source-load structure in new electric power systems. It is evident that the aggregation and optimized dispatch of VPPs can significantly enhance the flexibility and reliability of the power system.

In order to enhance the wind power consumption rate, achieve the goal of energy and power carbon peak and carbon neutral, with the goal of the lowest comprehensive cost of the power system, a new energy power system low carbon economic optimization method is proposed to establish the source and load side of the planning model. Firstly, on the source side of thermal power units, low-carbon transformation is performed, and a solution memory and flue gas bypass system is set up to make the unit become a liquid storage carbon capture unit, and dispatchable resources of photovoltaic power plant (concentrating solar power, CSP) and storage battery is introduced to coordinated with wind power. Then, on the load side, the price and incentive-type demand response resources are used for peak shaving and valley filling, and adjusting the users’ power consumption behaviors and power consumption. Finally, four cases are verified, and the results show that, the decarbonization of the power system from both the source and load sides can help promote wind power consumption, increase the share of renewable energy generation, enhance the low-carbon performance of the system, and save costs.

Under the premise that deep peaking of thermal power units has become normal operation, it poses a higher challenge to transformation of industrial steam supply of thermal power units. Three steam supply schemes using reheater recirculation cooling as the core technology are proposed to meet the requirements of high-pressure steam supply transformation of 660 MW supercritical units. Moreover, the feasibility and economy of these schemes are analyzed by thermodynamic calculation under varying working conditions. The calculation results show that, all the three schemes can ensure the safe operation of the reheater under non-overtemperature conditions, and greatly improve the wide load high pressure steam supply capacity of the unit at 30% rated power load or above and under conditions that meet the demand of single unit with 200 t/h, 6.0 MPa and 480 ℃ steam supply. In order to avoid overspeed of the flow rate at the reheater outlet, it is necessary to coordinate the operation of the immediate pressure (IP) control valve to reduce the flow rate of the reheated steam by increasing the pressure of the reheated steam. With the decrease of the load, the reheater recirculation flow rate under the rated steam supply flow rate will increase. The recirculation flow rate under the whole working conditions of scheme 1 and scheme 3 is not much different, and the ratio of the recirculation flow rate under the high and low load of scheme 2 can reach more than 5 times. Among the three steam supply transformation schemes, scheme 2 is the most energy efficient, scheme 3 is second, and the three schemes can produce economic benefits of 39.51, 44.45 and 41.78 million yuan each year, but in the implementation process, the selection of schemes should consider factors such as investment cost, operation and maintenance amount and energy saving income.

The fuel management system of power plants is the core of coal management in thermal power plants, of which domestic substitution is a necessary path for the power plant informatization, and the localization of databases is the key. Data migration plays an important role of the handover between the old system and the new one. An optimized data migration scheme is proposed based on a thorough study on data migration methods and the data characteristics of fuel management system in power plants. Focusing on the test study of methods for verifying data consistency, the characteristics of sequential comparison and dichotomy are analyzed, and it is proved that dichotomy has certain performance advantages when the proportion of corrupt data is relatively small and the distribution is concentrated. Enlarging the proportion and decentralizing the distribution, dichotomy costs more time obviously. A data migration tool for plant fuel management system is designed and implemented, which realizes visualization of data verification. The tool supports batch operations for functions like configuring verification rules, setting execution methods and providing feedback on results. It also enriches verification rules, supports customized rules and adds the mechanism for exceptions and so on. Divided into user layer, service layer and data layer, this tool achieves data migration of plant fuel management system.

Based on the time-of-use electricity price and the cost of wind-PV-energy storage system, technical and economic research of source-grid-load-storage system is studied. Firstly, a microgrid system model integrating renewable energy and energy storage system is proposed, which includes PV, wind power, energy storage system, grid, and load. Then, under the premise of ensuring reliable power supply to the load, an optimization model of the source-grid-load-storage system is established with the goal of optimizing the system economy based on load data, irradiation data, wind speed data, time-of-use electricity price data, and the costs of each unit of the system. Finally, the optimal capacity and economic feasibility of configuring a wind-PV-storage system in a certain region are analyzed in detail through a numerical example. The analysis results indicate that, the energy storage systems store energy at low electricity prices and release energy at high electricity prices, thereby avoiding users from purchasing electricity from the grid at high electricity prices and reducing the cost of purchasing electricity from the grid. The configuration of a wind-PV-energy storage system can effectively reduce the annual cost of purchasing electricity from the grid.

For the integrated energy system composed of photovoltaic power generation, energy storage battery storage and discharge, and coal-fired heating boiler and cogeneration, the power and heat power systems operate in isolation. To analyze the relationship between the information interaction and economic coordination and dispatch of the integrated energy system, by using the J.F.Benders mixed variable target decomposition method, the physical model of the cogeneration photovoltaic storage thermal power system is decomposed according to the main thermal system and the power subsystem. The information interaction between the sub-objectives is analyzed by the objective function and the system boundary conditions, and the mathematical model of the coordinated scheduling operation of photoelectric consumption and storage and cogeneration is obtained. The protection information is isolated and redirected, and the multi-dimensional variable problem of mixed integer programming is iteratively calculated by Gurobi solver. Based on the case of the integrated energy system, three operating conditions under different load requirements of power and heat are analyzed, and it is found that, the economic benefits of the thermal power operation system are synergistic and complementary, and the information interaction expands the space for photovoltaic consumption. The net load of the system reduces by 13.63% on average, the interactive power loss decreases by 9.480 7 million yuan/year, and the energy utilization efficiency rises by 4.48 percentage points, which shows that this model can serve the economic coordination and scheduling optimization and energy efficiency improvement of the integrated energy system.