The geographical distribution of energy resources in China is very uneven, whether it is conventional energy or renewable clean energy. In addition, with the growth of electricity demand, the proportion of the grid in the energy transmission system is increasing, and the continuous growth of load size and cross-regional power flow scale promotes the expansion of the grid size and the increase of the grid complexity. The complexity of power grid security and stability control will be greatly increased and the centralized access of large renewable energy bases will bring new technical problems to the safe operation of power grid. The sending end is connected to a large number of renewable energy sources, such as wind power generation, and the power fluctuation is large. In addition, the UHV DC project is in the early stage of operation, the construction of supporting facilities is weak, and the UHV DC near generators are in a critical state for a long time. At this point, generator stator and rotor overcurrents and other limits may operate when renewable energy power fluctuates, and it is difficult to objectively assess the compatibility of limits and protections due to the wide variation in the implementation principles of limits and protections among different manufacturers. When the system fails or fails, the control system of the generator set will participate in the adjustment to restore the system to a stable operating state. If the control system parameters and protection are not properly coordinated, protection may be caused before the control action, and the generator set will be cut off. The system that has been hit loses more active and reactive power support, and the power system's performance deteriorates. Therefore, it is necessary to study the evaluation indexes of the protection and control of the near area generator set of UHV DC project and the cooperation performance of the grid.

With the rapid development of renewable energy, the demand for frequency regulation and peak shaving of coal-fired power plants is increasing. As the utilization hours of coal-fired power plants are gradually reduced, the economy of coal-fired power plants is gradually reduced. In order to improve the economic benefits of thermal power plants, thermal power plants are changing from the income model dominated by power generation to the income model of “cogeneration of power generation and auxiliary power service”. Among them, the energy storage system of Lingwu power plant of Ningxia electric power company of Guoneng group belongs to the first large-scale thermal power plant large-capacity solar thermal energy storage (flywheel) project at home and abroad. While ensuring the functions of conventional power supply, heating and cogeneration, the system can also provide auxiliary power services, support the safe and stable operation of a large power grid, and improve the flexibility and economic benefits of traditional thermal power plants. With the application of new technologies in coal-fired power plants, improving the economy of coal-fired generating units and power auxiliary services will be the main direction of power generation groups. At the same time, it also puts forward new requirements for power grid operation.

Due to the integration of renewable energy, the maximum output of conventional power plants is reduced, and the change of peak valley difference is no longer periodic. In order to cope with the fluctuation of renewable energy, the system needs to increase the rotating reserve capacity. At present, power supply is mainly thermal power in China. The inflexibility of thermal power switch and the existence of minimum technical output increase the volatility of start-up response to renewable energy, and limit the output of renewable energy in the period of low load and renewable energy. Predicting the output power of renewable energy and reducing the uncertainty of renewable energy fluctuation is one of the effective means to reduce the redundant standby capacity of the system. The increase of reserve capacity is related to the prediction accuracy of output power of renewable energy stations. Therefore, renewable energy power prediction is of great significance to the safe and economic operation of power system. According to the requirements of relevant documents and regulations of the national energy administration, all grid connected renewable energy stations need to establish a renewable energy power prediction system. In this paper, hundreds of renewable energy power forecasting service providers has emerged. However, the performance and prediction accuracy of renewable energy power prediction results are uneven, there is a lack of unified test standards and test platform, and an effective integration mechanism and identification method have not been established. Therefore, it is necessary to establish relevant evaluation mechanisms and provide third-party evaluation services, so as to provide a fair reference for selecting strong renewable energy production scheduling support services. However, different from conventional power supply, renewable energy has random volatility, and large-scale renewable energy grid connection brings challenges to the security, stability and economic operation of power grid.

During the Francis Hydro-generators across the vibration zone, it may cause power oscillation due to its inherent characteristics, although it rarely occurs, it is still one of the important issues that endanger the stability of the power grid. In this paper, the Prony method is used to analyze the actual power oscillation data of the hydropower station in Southwest Power Grid, determined it as the forced power oscillation across the vibration zone. And through simulation analysis to study the impact of Excitation System on generator damping, optimize the excitation control system PID parameters, and field tests verify that optimizing the excitation control system parameters to increase generator damping is the effective way to reduce the amplitude of the forced power oscillation.

In order to obtain the low voltage ride through (LVRT) and high voltage ride through (HVRT) control model parameters of static var generator (SVG) with wide adaptability and high accuracy. A parameter testing and identification method of SVG fault model based on full fault set is proposed. Firstly, the electromechanical simulation model structure of SVG is analyzed, and the parameters to be identified are defined. Then, according to the voltage disturbances of various types and amplitudes that may occur in the operation of SVG, the test fault set is designed, and a comprehensive test is carried out for the package electromagnetic calculation given by the manufacturer. Finally, the fault control model of the manufacturer is obtained according to the test results, and the least square method is identified according to the parameters of PSASP model. The correctness of the test and identification results is verified by time-domain simulation.

The moment of inertia is the basic parameter of the generator and also the basic data of PSS parameter tuning. The parameter setting of PSS will increase the damping of the unit and improve the small disturbance stability of the system. When the rotational inertia parameter is not consistent with the real rotational inertia of the unit, the PSS parameter setting will not increase the damping of the unit, but sometimes it will cause the oscillation of the unit. Here, the correlation analysis is carried out with the small signal stability analysis program, and the field test is carried out in Qinghai Kang Yang power plant. The influence of moment of inertia on PSS is analysed by small disturbance analysis and field test.

Due to the increase of the proportion of nuclear power unit capacity in the power grid, the simulation analysis of the PWR nuclear power unit is increasingly important for power grid stability analysis, which is regarded as one of the important parts of China's nuclear power unit. The original mathematical model of the PWR nuclear power unit is very complex and not suitable for the stable calculation and actual measurement modeling of the power grid. Based on the actual modeling of conventional islands, a simplified simulation model of the nuclear island is proposed in this paper and is conducted the actual modeling test of nuclear islands and conventional islands at the NINGDE Nuclear Power Station and FUQING Nuclear Power Station in Fujian Province. In the load test, the models and parameters of the nuclear reactor control system, temperature control circuit, steam generator, speed control system, actuator, and steam turbine were measured. The nuclear island uses the mathematical model built by MATLAB in conjunction with PSD-BPA software for simulation verification. The simulation results can truly reflect the dynamic characteristics of the nuclear islands and conventional islands of PWR nuclear power units, providing mathematical models and parameters for grid stability calculations, which can be used for dispatching safety and stability calculations.

<正>8月5日,省人大常委会副主任林志慧赴孝感市调研保障性住房建设情况。林志慧一行先后到孝感市红光花园、西城嘉园、沙沟廉租房住宅小区、三军帅府等一个建成和三个在建的保障性住房建设项目现场实地考察,重点就工程建设质量方面问题同当地领导、项目负责人和工程技术人员进行探讨,深入保障房入住户进行

随着建筑和装饰等行业对石材产品要求的提高,石材加工装备和工艺也要相应地得到较快发展。本文介绍了一种新型切石机的部分创新设计之处,包括摆动机构总成、带锯切割力监控部件及前、后吸盘机构等的结构设计。该新型数控大板切石机可以克服现有切石机的传动系统复杂、振动大、噪声大、不易切割大型薄石板、平整度、厚薄度不理想等缺陷。