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- Abstract：At 15:48 on March 21, 2018, a large-scale blackout occurred in Brazil, the power grid in the north and northeast of Brazil were disconnected from main power grid. The load shedding was 19760 MW, accounted for 25% of the total load of the power grid, and 85% of the states were affected, resulting in huge economic losses. In order to avoid severe large-scale blackouts, the main process of blackouts in history was introduced, and lessons learned from blackouts were summarized from the aspects of natural conditions, equipment faults, manual mistakes, strategic mistakes and so on. The main causes of large power outage accidents were analyzed and the corresponding measures were put forward. Finally, combined with several development and research highlights of current power systems, such as renewable energy integration, AC/DC hybrid power systems, energy internet, cyber-physical power systems, and artificial intelligence, the main research directions of power system large scale blackouts were proposed.Keywords：power systems;large-scale blackout;cascading faults;energy internet72|1916|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Artificial intelligence was widely used in power systems. It has improved the security, reliability and operation ability of power systems. The related work in the early, middle and late stages was summarized including expert system and neural network and so on in the 1980s and 1990s and relevance vector machine in the early 21st century. The characteristics, principles and application in power systems of relevant vector machines were mainly introduced.Keywords：power system;artificial intelligence;expert system;relevance vector machine144|2763|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Large-scale centralized new energy sending system is a unique form of power grid in China. Due to the high proportion of new energy sources and low tolerance to high-voltage direct current(HVDC) fault disturbance, there are prominent problems in the coordination between source and power network. The major potential risks, such as large voltage fluctuation, large frequency fluctuation and low frequency oscillation were analyzed. It was pointed out that the key problems of modeling include the auxiliary control of excitation system, generator protection concerned with network and generator speed control with dynamic system. The simulation evaluation process and precautions of the source network coordination in large-scale centralized new energy sending system were also proposed, which could be a reference for the actual simulation evaluation operation.Keywords：new energy;wind power uniting thermal power;generator protection concerned with network;low frequency oscillation45|2034|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：With the increasing scale of new energy power generation, longer and longer transmission distances, and access to large-scale distributed generation and DC loads, it is increasingly difficult for existing AC transmission systems to meet the needs of power system development. Due to the technical advantages of high voltage direct current(HVDC), the challenges faced by AC power systems have brought new opportunities for the development of DC power systems. The development status of DC power technologies at different voltage levels in Europe, America, and China were introduced in this paper. The application scenarios of DC power technologies with different voltage levels were described respectively. In light of the shortcomings of existing AC power transmission technologies, the superiority of DC power technologies were analyzed. Finally, the challenges faced by the development of DC power systems under the current state of technology in key equipment R&D, control and protection, and standard setting were introduced.Keywords：new energy generation;DC power technology;power electronics technology62|2097|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：After guideline[2016]392 was issued by the government, smart energy has become a hot pursuit within power system, manufacturers and social capital, while little connotation of which has been known. Understanding of smart energy is often focused on construction of energy infrastructure, distributed power, energy storage, distribution network, which do not belong to consumers. Basic social appeal, strategic framework and systematic implementation plan of smart energy were discussed.Keywords：smart energy;energy transformation;digitalization;whole course;implementation scheme;integrated planning49|171|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Because of the special wiring forms and operation characteristics, it is difficult to monitor the actual running index of power quality for the thermal power plant. In order to grasp the power quality indicators of thermal power plant operation comprehensively and accurately, special testing and evaluation for the power quality is necessary. The current power quality testing for thermal power plants is less and lacks comprehensiveness. Based on the testing of the power quality indicators of several thermal power plants, the power quality data of key monitoring points such as the generator outlet, booster station bus, and factory power bus were calculated and analyzed. Then the test results were correlated with the relevant national standards. Finally, the assessment results and reasonable recommendations were given.Keywords：thermal power plant;power quality test;evaluation analysis88|1532|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
Energy Internet
- Abstract：The energy saving effect of low-pressure(LP) economizer of a 220 MW unit was tested under multivariate factors. Using equivalent enthalpy method, the energy saving effect of LP economizer at different operation modes and different operating parameters has been calculated. For 200MW grade units, when it is necessary to have higher water flow rate and inlet temperature of LP economizer, the condensate water from NO.6 LP heater outlet should be used priority. Under the condition of 220 MW, the optimal flow rate into LP economizer is about 250 t/h, increasing thermal efficiency of the unit by 0.645%. If the inlet water is from the outlet of NO.7 and NO.8 LP heater, the LP economizer inlet temperature is lower, the outlet of the LP economizer should return to the outlet of NO.6 LP heater. And water temperature at LP economizer outlet should be slightly higher than that of NO.6 LP heater outlet. Otherwise, the energy efficiency will decrease compared with the best condition. Under the condition of 220MW, 370 t/h condensate water is extracted from outlet of NO.8 and NO.7 LP heater, entering main condensate water pipe at outlet of NO.6 LP heater after heated. The heating efficiency of the unit increases 2.003%. For different LP economizer operation mode, there are an optimal water returning location and optimal inlet flow.Keywords：boiler;low pressure economizer;energy saving effect;multi-variable factors;equivalent enthalpy method91|1815|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：In order to study the slagging reason of a 600 MW supercritical W-flame boiler, a test study is carried out. The content includes the slagging position detection, gas composition measurement, the temperature distribution measurement and numerical simulation calculation. The results show that the upper part of the down furnace area's temperature is above 1 300 degrees and higher than the softening temperature of the coal; oxygen concentration is low, the concentration of CO is above 10 000 μL/L, showing a strong reducing atmosphere, where is obvious tendency of slagging; the special flow field are also analyzed. According to the analysis of the test results, targeted measures are taken to solve the slagging problem of this W-flame boiler furnace, and the boiler's reliability has been improved obviously.Keywords：W-flame boiler;slagging;gas composition;temperature;flow field33|1868|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：Large scale wind power integration needs thermal generator regulate output power flexibly; during the reform of boiler for flexibility, the normal operation condition should be kept.To reduce the disturbance to the heat load of the boiler furnace, reduce the expansion of the boiler, and to protect the output power flexibly, the operation parameters of the boiler are studied.The long-distance water soot blower of #1 and #2 furnace in a power plant has larger flow rate and great influence on the boiler parameters during the blowing soot process.By replacing the smaller bore nozzle, the disturbance of the water soot blower to the boiler parameters was controlled.The comparison of operation parameters of the boiler before and after the replacement had proved that it is feasible and safe to change the bore nozzle by smaller diameter nozzle.Keywords：boiler;power regulation;long-distance water soot blower;small bore nozzles;parameters48|653|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The low thermal conductivity for most of phase change materials is one of main obstacles in real application. Foam metals can be added into the phase change material to strength heat transfer process because of high thermal conductivity, high porosity and high specific surface area of foam metals. Based on the 3D W-P micro structure model of foam metal, the effect of porosity and pore diameter of foam metals on effective thermal conductivity of the foam metal based composite phase change materials were analyzed. The numerical simulation method was used to predict the thermal conductivity of foam aluminum-air and foam aluminum-water composites.The results show that the W-P model can be used to precisely predict the thermal conductivity of foam metals. The effective thermal conductivity of foam copper-paraffin composite was then analyzed. It is shown that the thermal conductivity of phase change material can be enhanced greatly by adding foam metals, and the thermal conductivity of paraffin has been increased 13 times when the porosity of foam copper is 97.57%. This study has reference value for thermophysical properties enhancement research on phase change materials.Keywords：foam metal;phase change thermal energy storage;effective thermal conductivity;heat transfer enhancement84|672|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
Power Generation and Environmental Protection
- Abstract：As a clean and efficient method of electricity generation, fuel cell is advantageous for high power efficiency, low pollution and noise, and good security, which is one of the most important technologies for distributed power generation. Fuel cell can not only consume the fossil energy like coal or natural gas, but also convert and store renewable energy with its inverse process. In the coal power industry, bulk coal can be utilized cleanly by direct carbon fuel cells, which can solve the problem of low efficiency and severe pollution from bulk coal. Besides, fuel cell can be integrated into natural gas network, forming a micro-combined heat and power system. Compared with the traditional heat and power supply systems, the combined heat and power system has the benefit of energy-step-utilization, with higher efficiency. Furthermore, electrolytic cells can convert the redundant renewable electricity into chemical energy, achieving the energy conversion and storage from the waste hydropower, wind power and solar power, which has great potential in the distributed renewable power system.Keywords：distributed energy supply;fuel cell;combined heat and power65|372|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The randomness of wind power is the reason of wind power abandonment. Considering the grid flow constraints and load frequency regulation ability of hydroelectric power generator, to smooth wind power output, the output of wind power and hydro power could be controlled according to the plan; therefore, the wind farm could be considered as dispatchable node. In order to improve the stability of the total output power of coordinated hydro and wind power generation, a new method based on bird swarm algorithm was proposed. Through the example analysis, before the control system was optimized, the system flow calculation was carried out to ensure the power flow security. It can effectively control the output power of the hydraulic generator on time, and quickly track the desired output power. The influence of high wind abandonment punishment and high power fluctuation punishment on the coordinated operation of wind power and hydropower.Keywords：coordinated hydro and wind power generation;bird swarm algorithm;scheduling;power flow calculation34|133|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The characteristic of working fluids is one of the important factors that affect organic Rankine cycle (ORC) system.Under the different heat source temperature, 11 substances were adopted as the subcritical ORC working fluids, R245fa and R601, as well as 9 non-zeotropic binary mixtures in different mass ratios.The thermal and economic model of the ORC had carried on the analysis.Finally, the method of grey correlation was used to evaluate the system performance.The study shows that the thermodynamic indexes of non-zeotropic binary mixtures are approximately inverse proportional to the temperature glides.When the temperature slip is greater than 5℃, the pure industrial performance is better.The system using the non-zeotropic mixtures is less economical than the pure working fluids.Incombination, when the heat source temperature is fixed, the grey correlation grade increases first and then decreases with the increase of evaporation temperature.The temperature glide of R601/R245fa(0.1/0.9) is the best and its performance is optimal.Using mixed R601 and R245fa as working fluid, system performance is best when the heat source temperature is 160℃.Keywords：solar energy;non-zeotropic mixtures;organic Rankine cycle (ORC);grey correlation grade;heat source temperature32|58|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
- Abstract：The photovoltaic (PV) power station is composed of a large number of photovoltaic modules.Due to the complicated production technology and hard working environment, photovoltaic system DC-side faults occur frequently, directly affecting the photovoltaic system's power generation efficiency.How to extract valid fault sample from the PV array's operating data and identify the fault is an important step to establish a fault model.Therefore, a method based on fuzzy C-means (FCM) clustering to divide and identify the fault samples was proposed.Firstly, the output features of PV array under fault conditions were analyzed and the fault eigenvectors were put forward (open circuit voltage, short circuit current, maximum power point voltage and current).In order to exclude the influence of external excitation conditions on the electrical parameters, the fault eigenvectors were uniformly converted to the standard test condition (STC).Finally, according to the good fuzzy information processing function of FCM, the fault samples of open fault, short fault, shadow fault and abnormal aging fault were clustered.By using the actual operation data, it was proved that this method could accurately and reliably classify the fault samples of the typical fault on the DC side of the PV system and could effectively describe the distribution characteristics of the PV array's electrical parameters in different faults.Keywords：photovoltaic (PV) system;fault samples;fuzzy C-means (FCM) clustering;fault feature extraction57|246|0<HTML><L-PDF> <Meta-XML>Updated：2025-07-04
New And Renewable Energy
