Issue Ebookcover story
List of IssuesDocument Types
- Abstract：HVDC transmission systems present a risk of commutation failure. For multi-infeed HVDC transmission systems, due to the interaction between AC and DC systems, the commutation failure of a single inverter station may cause multiple inverter stations to fail at the same time or in succession, which poses a threat to the safe and stable operation of the power grid. Based on the mechanism of commutation failure, the multi-infeed interaction factor was introduced to analyze the influencing factors and criteria of commutation failure in multi-infeed HVDC transmission systems, and the current methods and strategies for suppressing commutation failure were summarized. Finally, it pointed out that the mathematical model, the commutation failure coupling mechanism and the suppression measures were worthy of further discussion and research.Keywords：multi-infeed HVDC transmission system;commutation failure;multi-infeed interaction factor68|224|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：In order to deal with the problem of multi-state frequency stability at DC receiving end, this paper studied the variation of inertia time constant and static characteristic coefficient of equivalent machine with or without pumped storage power generation by using the performance indexes of transient, dynamic and static frequency stability, namely reciprocal of instantaneous change rate, damping ratio and reciprocal of static deviation. The influence of pumped storage power generation on transient, dynamic and static frequency stability was analyzed. The performance indexes of each state were obtained and compared with those before. Finally, the model was built for simulation. Through theoretical analysis, it is concluded that pumped storage power generation improves the transient, dynamic and static frequency stability of the DC receiving end power grid. The correctness of theoretical analysis was verified by numerical simulation. The research results provid an important theoretical basis for the influence of pumped storage power generation on the multi-state frequency stability of DC receiving end power grid.Keywords：pumped storage;DC access;temporary-dynamic-static frequency stability;performance index39|196|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：There are some operational problems of the πT hybrid structure, such as large workload of operation and maintenance, poor flexibility and scalability, which can not meet the increasing demand for power supply reliability. In this paper, the optimization scheme of the πT hybrid structure connection structure was put forward, and the technical and economic demonstration of the optimization scheme was carried out. The concrete alteration scheme of πT mode to chain π connection mode was studied, and the networking principle of 110 kV power grid was established, which can direct the implementation and landing of the optimization of the 110 kV power grid with πT hybrid structure.Keywords：network structure;πt hybrid;chain type π connection;single-bus section251|234|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：There are certain differences between the quality management of overseas flexible HVDC transmission project and domestic engineering quality management. In the management process, it is necessary to establish a correct quality management concept based on the project quality management ideas of international relevant standards. Combining ISO 9001:2015, ISO 21500:2012 and PMBOK quality management system standards, the project quality management process was improved from six aspects of knowledge management, change management, resource management, stakeholder management, risk management and communication management, and a quality management system suitable for overseas flexible HVDC transmission project was put forward. Finally, the comprehensive evaluation method of quality management maturity of overseas flexible HVDC transmission project was put forward, and the maturity of the system was analyzed and verified, which provides reference for quality management of overseas flexible HVDC transmission project.Keywords：overseas engineering;flexible HVDC transmission technology;quality management;maturity21|51|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
Energy Internet
- Abstract：The problem of lack of fresh water resources becomes more and more serious. The coupling of low-temperature multi-effect distillation (LT-MED) seawater desalination technology in thermal power plants is widely used, because it can effectively reduce the cost of water production. Ebsilon software was used to model the power plant and a LT-MED seawater desalination coupling system. The influences of steam ejectors on the thermal economy of the water and power cogeneration system under wide load were analyzed. The results show that the coupled system has the optimal performance for single-stage steam ejector at the 75% THA condition design of the power plant. For a cogeneration system with a two-stage steam ejector, the system's electricity loss for water production (ELWP) is reduced by 13.65% than the system with single-stage steam ejector, when the plant load is at 75% THA. And the two-stage steam's ELWP is also lower than that of the single stage steam ejector system when the plant load is above 50% THA.Keywords：wide load of power plant;steam ejector;low-temperature multi-effect distillation (LT-MED);seawater desalination;thermal economy45|305|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：The reduction and uneven distribution of water resources has promoted the generation of air-cooled technology for thermal power systems, but the energy consumption of air-cooled units is higher. Condenser is the core equipment of air-cooled units, and its exhaust pressure is one of the most important indicators affecting the performance of the whole system. Taking a 600 MW unit of a power plant as an example, a simple calculation method for the back pressure of the condenser was put forward, and the influence of upwind speed, ambient temperature, condensate flow rate and fouling thermal resistance on the exhaust pressure of the condenser was analyzed, which can provide reference for optimizing air-cooled units operation, energy saving and consumption reduction.Keywords：direct air-cooled units;condenser;back pressure;variable working conditions29|217|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：In order to realize the life cycle monitoring of exfoliated oxide, a real-time on-line monitoring system for exfoliated oxide of supercritical boilers was developed. The monitoring system installs measuring probes at the outlet of superheater and reheater. By using the impact vibration wave measurement technology, the mass content, particle size distribution and particle flow of exfoliated oxide particles can be directly measured online, real-time and continuously, and the flow of exfoliated oxide in steam pipeline can be effectively monitored. The system is applied in supercritical generating units. By analyzing particle characteristics data, and the variation trend of solid particle concentration with time and load in steam pipeline, the severity of oxide shedding is monitored, and the operation control is evaluated. The purpose of reducing oxide shedding and preventing solid particle erosion is realized. At the same time, the system is used to monitor the quality of steam impurities during the start-up and operation of the unit, and to study the flow of iron in the steam-water cycle of the unit.Keywords：supercritical boilers;exfoliated oxide;life cycle;on-line monitoring;characteristic data27|111|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
Research on Technical Scheme for Shutdown Maintenance Design of 9F Class Combined Cycle Heating Unit
Abstract：In thermal power plants, the corrosion of main equipment can cause major safety hazards and economic losses. Thus, it is very important to take proper maintenance for thermal equipment in power plant during shutdown. A maintenance method of hot air combined with vapor phase corrosion inhibitor was developed for the water vapor system of waste heat boiler in the 9F class gas-turbine combined cycle generation unit. The protection for the thermal equipment was achieved by reducing the inner moisture and injecting vapor phase corrosion inhibitor. The design and implementation of the shutdown maintenance system were described in detail. The actual operation of this maintenance in electric power plant shows the advantages of low cost, simple operation and high protection efficiency. The maintenance of hot air combined with vapor phase corrosion inhibitor has the great guiding significance for the protection of thermal equipment and other related machinery during shutdown.Keywords：9F gas-steam combined cycle generation unit;vapor phase corrosion inhibitor;shutdown maintenance29|414|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06- Abstract：Supercritical carbon dioxide cycle can be utilized in thermal power generation, nuclear power generation, solar thermal power generation and other fields of power generation technology. As a novel power cycle system, it can replace the current widely used steam turbine or gas turbine generators. Before entering commercial application, the advantages of supercritical carbon dioxide cycle technology in various application scenarios and its potential social and economic benefits have to be discussed. By analyzing the characteristics and advantages of supercritical carbon dioxide cycle, this paper explored the feasibility of combining supercritical carbon dioxide cycle with fossil energy, nuclear energy, solar energy, biomass energy, waste heat and other heat sources. A variety of power generation system schemes were put forward, which can provide a reference for future commercial application of supercritical carbon dioxide cycle. With the development of supercritical carbon dioxide cycle technology and the further reduction of equipment cost, the benefits of simplified system, compact structure and high efficiency will become more prominent.Keywords：supercritical carbon dioxide cycle;thermal power generation;nuclear power;solar thermal power generation174|1569|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：The nonlinear terms of the hydro-turbine governing system (HTGS) were approximated based on Maclaurin series. Takagi-Sugeno (TS) fuzzy control was introduced to handle the nonlinear terms of the Maclaurin series, and TS models of the HTGS were developed resultantly. Based on the TS fuzzy models and the defined cost function, a nonlinear model predictive control (NMPC) strategy was designed for the HTGS. Considering the constraints of the HTGS, quadratic programming (QP) was utilized to solve the optimal controller output under the system constraints. Simulations were conducted to assess the performance of the designed QP-based NMPC (QPNMPC) controller. Simulation results reveal that the proposed QPNMPC controller can effectively regulate the output power of the HTGS and that compared with the conventional PID controller the advantages of the proposed QPNMPC controller are demonstrated.Keywords：hydro-turbine governing system;Takagi-Sugeno fuzzy control;model predictive control;quadratic programming;system constraint59|338|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
Power Generation and Environmental Protection
- Abstract：Solar thermochemical energy storage can effectively solve the uneven distribution of solar energy in time and space. Based on the model of industrial methane steam reforming reactor, the model of steam methane reforming reactor heated by molten salt (MS-SMRR) was established by using finite time thermodynamics, and the design parameters of MS-SMRR were obtained. The effects of geometric parameters and operation parameters of MS-SMRR on hydrogen production and total entropy production were analyzed. The results indicate that the total entropy generation rate and the consumption of the molten salt in a counter-flow reference reactor are smaller than those in a parallel-flow reference reactor when the hydrogen production rate is constant. The hydrogen production rate can be enhanced observably by increasing the inlet temperature of the molten salt and decreasing the inlet pressure of the mixture gas. The research results have certain theoretical guiding significance for the optimization design of actual MS-SMRR.Keywords：thermochemical energy storage;steam methane reforming reactor;molten salt;entropy generation rate;hydrogen production rate;finite-time thermodynamics38|200|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：Impedance analysis is the leading method of solving the stability issues of grid-connected renewable energy generation systems. Taking the grid-connected system of direct drive permanent magnet synchronous generator (D-PMSG) as an example, the characteristics and application scope of the existing Nyquist stability criterion were analyzed. In order to make up for the deficiency of the existing impedance stability criterion, a quantitative stability criterion based on the fitting of fractional polynomial function of impedance characteristic was proposed, which applied port impedance characteristics of wind turbine derived or measured by equivalent fitting theory of fractional polynomial function. Within the fitting frequency band, the fractional polynomial was equivalent to original impedance characteristic. The oscillation frequency and the damping level of the given system were calculated by finding the zero point of fitting polynomial, which could analyze quantitatively the stability characteristics of the system. Finally, the correctness and effectiveness of the fractional polynomial fitting criterion were verified by theoretical analysis and time domain simulation.Keywords：direct drive permanent magnet synchronous generator (D-PMSG);sequence impedance characteristic;polynomial fitting;sub/super-synchronous oscillation;stability criterion34|294|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：Aiming at the insecurity of photovoltaic (PV) grid-connected system and the high cost of traditional reserve configuration, a reserve optimization model in different scenes of the system was established to improve security and economy. The risks of loss load and solar power curtailment were introduced in the model. The objective function of the model was to minimize the generation and reserve costs within the constraints of power balance, generation unit characteristics and interruptible load. The inverse-time characteristic of line protection was utilized to transform the power flow constraints into the thermal stability limit. The optimal reserve dispatch model with different responding speed of PV grid-connected system was obtained. The rationality of the model and the effectiveness of the method were verified by an IEEE 30 test system with PV.Keywords：PV grid-connected;inverse-time characteristic;reserve configuration;risk indicator;thermal stability limit23|217|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：Improving the accuracy of wind power data is of great significance for building ubiquitous power internet of things (UPIoT). Wind power prediction has a high demand for historical data sets. Most of research was focused on improving the prediction accuracy by establishing different prediction models or proposing different prediction algorithms. There is not much attention on noise data elimination. Thus, a noise reduction method for the historical wind power data was proposed, which was mainly applied to the data set, by eliminating the distorted data in the historical wind power data, the amount of useless data was reduced, the accuracy of wind power prediction was improved, and the data modeling and prediction time was shortened.Keywords：wind power prediction;data noise reduction;data set processing32|153|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
- Abstract：Due to the intermittent and fluctuant of wind power, large-scale wind power grid-connected poses a challenge to the safe and stable operation of the power grid. Therefore, a wind power fluctuation suppression control strategy based on doubly-fed variable-speed pumped storage unit was proposed. Firstly, based on DIgSILENT/PowerFactory software, the simulation models of doubly-fed variable-speed pumped storage unit under the conditions of power generation and pumping were established to verify its fast power control capability. Secondly, based on the principle of low-pass filtering, combined with the wind power prediction, the control models of the doubly-fed variable-speed pumped storage unit were established to suppress wind power fluctuation under the conditions of power generation and pumping. Finally, a simulation example was given to verify the control strategy. The results show that the doubly-fed variable-speed pumped storage unit has fast power response characteristics. Under the conditions of power generation and pumping, the fluctuation of wind power can be effectively suppressed, the regulation pressure of conventional units can be reduced, and the stability of regional power grid can be improved.Keywords：doubly-fed variable-speed pumped storage unit;low-pass filtering;prediction power;wind power fluctuations65|508|0<HTML><L-PDF> <Meta-XML>Updated：2025-06-06
New and Renewable Energy
