Abstract:Under electricity market environment,frequency regulation auxiliary service provided by the generator set needs to be evaluated reasonably,to ensure fair and equitable market.By analyzing the problems faced by assessment of primary frequency regulation and automatic generation control (AGC),an assessment system architecture and design ideas of online test of primary frequency regulation and AGC control performance are put forward.According to requirements of process data precision and timeliness,a PFR online test method based on remote terminal unit (RTU) and phasor measurement unit (PMU) data is proposed.In order to assess the unit's frequency regulation performance more accurately;this method improves the calculation of assessment results using multi-source data time scale calibration and statistical information screening.Meanwhile a regulation method of adjusting precision based on the regulation rate distribution is proposed,through adjusting the precision correction factor to establish the linkage mechanism of rate and precision to control the behavior of the unit and guide its behavior optimization.Finally,the effectiveness of the method is proved by case analysis.

Abstract:With the rapid development of HVDC (high voltage direct current) in Jiangsu Power Grid,large amount of electric power would be integrated through HVDC in the future.It is found that fault of the AC power grid would affect the operation of HVDC through the bus voltage of the converter station,which may lead to commutation failure.However,electromechanical simulations,which are used for power system stability analysis nowadays,may not be able to accurately reflect the dynamic process.In this paper,by using BPA and PSModel,electromechanical simulations as well as electromechanical and electromagnetic hybrid simulations are performed to study the impact of Jiangsu Power Grid fault on the operation of HVDC,and the conclusions are supposed to be helpful for power system analysis.

Abstract:With the rapid development of China's UHV power grid,the future development trend is the interconnection of the regional power grid.However,in the early stage of UHV power grid construction,the electrical connection of the interconnected system is weak,and the tie-line stochastic power fluctuation limits its transmission capacity.In this paper,a calculation method of the fluctuation amplitude of the tie-line considering the stochastic fluctuation characteristics of load and wind power is proposed,the power fluctuation mechanism of the tie-line based on the frequency response characteristic is introduced,the probability distribution of wind power and load fluctuation is studied,and the method of estimating power amplitude for tie-line based on improved Latin hypercube sampling is proposed.The accuracy and validity of the proposed algorithm are verified by the example of North China-Central China interconnection system.

Abstract:This paper mainly studies the hardware design and realization of excitation control system on the five-phase dual stator winding induction generator.This generator has basket winding and there are two types of five-phase winding on its stator:one type is control winding that is connected with excitation converter;the other is power winding which can provide direct electrical power after rectification.Excitation converter consists main circuit based on IGBT modular,drive circuit,digital signal calculation circuit,sampling conditioning circuit,protection circuit and so on.Excitation controller provides generator with changeable excitation reactive power to control the excitation of generator,realizing the control of output voltage.

Abstract:In order to give full play to the large capacity of SSTS and the rapid response of DVR,a single-phase voltage sag detection method based on single-phase dq transform and morphological filter is presented in this paper.The DVR and the SSTS coordinated control method are combined with the DVR and the SSTS to achieve the coordinated action of the DVR and the SSTS,thus ensuring the continuous high quality power supply of the sensitive load.The simulation model based on Matlab/Simulink verifies the correctness and validity of the proposed control strategy.

Abstract:Wind power and UHVDC (Ultra-High Voltage Direct Current Transmission) have been widely used in China.Safety and stability of the power system are threatened by uncontrollable power flow transferring,which is caused by the fluctuation of bulk wind power or UHVDC blocking.Hence,it is of great significance for improving the stable of the power system by developing efficient power flow control devices.To solve the uncontrollable power flow transferring problem,control strategy of SSSC (Static Synchronous Series Compensator) is deduced,and electromagnetic transient model of SSSC is constructed as well.Results of the simulations show that the designed control strategy regulates the DC voltage effectively,and can control the power flow accurately and rapidly.This study is supposed to be helpful for the controller design of SSSC,and to be useful for the operating and power flow control of the power system with bulk new energy or UHVDC integrated.

Abstract:A unit commitment optimization method based on affinely adjustable robust optimization is proposed for power system scheduling with uncertainty,especially when large-scale intermittent energy integrated.An affinely adjustable robust optimal model of uncertainty unit commitment is developed.The affine relationship between decision variables and uncertain parameters is established by linear decision rules.Therefore,the two-stage model can be reformulated into a single stage optimization problem.On this basis,the problem can be transformed to a standard mixed integer programming model through duality theory.Analysis of test system shows the effectiveness of the proposed algorithm.

Abstract:VSC-HVDC (voltage sourced converter based HVDC) transmission system has technical advantages in the AC and DC system interconnection,large-scale clean energy grid integration.With the application and promotion of the the high-voltage high-capacity multi-terminal VSC-HVDC transmission system,the master station monitoring function is hard to meet their development need.This paper analyzes the topology structure and key equipment features of ±500 kV/3000 MW four-terminal flexible DC power network.In the objective of unmanned converter stations,a monitoring functional framework based on existing monitoring functions of smart grid dispatching and control system (SGDCS) is proposed.Based on the most promising VSC-HVDC grid configuration of half bridge sub-module based modular multilevel converter (HB-MMC)+DC breaker,this paper presents the function schemes for 4 important monitoring modules,grid modeling,data acquisition,topology analysis and intelligent alarming.The proposed monitoring functions would be helpful for the project implementation in the future.

Abstract:With the emergence and development of the concept of energy Internet,the communication is playing an increasingly important role in the power system.It is necessary to study the synergy of communication system and power system.Based on the analysis of the demand of energy Internet communication,the general framework and key technologies of the simulation platform of power grid and communication network are put forward.The co-simulation platform of power grid and communication network is designed by using Matlab and OPNET to study the influence of communication on the operation of power system.Finally,a simulation example that distributed powers in energy Internet participate in the frequency modulation of power system is given to demonstrate the feasibility and effectiveness of the co-simulation platform.

Abstract:The optimal scheduling strategy of photovoltaic-energy storage hybrid system is an important guarantee for the economic and safe operation of photovoltaic-energy storage hybrid system,but the traditional economic dispatch models do not consider the effective management of the battery energy storage station (BESS)'s internal battery.An economic optimal scheduling strategy of photovoltaic-energy storage hybrid system is put forward,and a mathematics model of economic optimal scheduling is established by taken the lowest total cost a day as optimization objectives and using the power balancing,state of charge,power limit and scheduling cycle as constraint conditions,according to performance parameters and operating conditions of each battery pack.Improved particle swarm optimization (IPSO) algorithm is applied to solve the mathematics model.Finally,the simulation result proved that the improved particle swarm optimization algorithm is superior and the scheduling strategy is proper in the application of photovoltaic-energy storage hybrid system.

Abstract:Wind penetration limitation has great impact on power grid planning containing wind farm.In this paper,a traditional wind penetration limitation calculation model was built firstly,in which the constraints such as power flow,node voltage,and margin capacity were considered.The security constraints including frequency deviation and voltage deviation were considered based on the model.Frequency deviation based on central frequency and voltage deviation based on linear system theory were proposed with influencing factors of wind power access capacity considered from the viewpoint of safety.The research model was solved by GA method and it's validity was verified by calculation results of New England 39-bus system.

Abstract:The partial discharge of switchgear indicates the existence of insulation defects.Tthe location method of partial discharge in switchgear is studied.The corona discharge model was built in the laboratory,the ultrasonic signal is collected by the ultrasonic sensor and high frequency current sensor (HFCT) is used to collect high frequency current produced by coupling capacitance of partial discharge.Using delay time of ultrasonic relative high frequency current for positioning,data of discharge signal will be transferred from oscilloscope to PC communicated by USB.LabVIEW program is used to filter and analyze the waveform to obtain the exact position of the discharge location.Experiments show that the method has high accuracy.

Abstract:A high-speed acquisition and recording system for multi-channel traveling wave based on FPGA is designed,which can implement high speed acquisition,continuous transient recording and long process recording of multi-channel traveling wave signal for centralized traveling wave distance measuring devices,utilizing FPGA dual ports RAM and off-chip high capacity DDR to construct distributed two-stage recording buffers,combined with DSP embedded processors.The hierarchical caching mechanism adopted by the system decouples the"high rate"of signal acquisition and the"large capacity"application requirement of data caching.It realizes the real-time high-speed data acquisition of multi-channel traveling wave and high data throughput required by continuous transient recording.And it also has a large capacity cache space for fault location algorithm off-line analysis and recording data dump,which meet the technical specification requirements related to traveling wave fault location for transmission lines of power industry.

Abstract:When the power grid operation mode is changed,the relay operation mode should be adjusted synchronously,otherwise the relay may malfunction or reject action.The relay operation rule base design based on general protection model is proposed.The structure and function module of relay operation verification system are analyzed.The implementation of key modules such as equipment operation state identification and relay operation verification process is elaborated.The system test result is introduced.Using the power grid real-time operation status and relay operation information,the system verifies the relay operation results and determines whether the adjusted relay operation mode meets the requirements of power grid operation.

Abstract:The structure characteristics of the independent local power grid are summarized firstly.Then,the security and stability problem of the local power grid is analyzed,combined with the development trend of the state promoting sales side reform.Three lines of defense construction scheme are proposed taking an independent local power grid as an example.Some key technical problems related to the stability control system,low frequency and low voltage load shedding,high frequency cutting machine,out-of-step splitting solution are discussed.The applicability of the scheme is verified by RTDS and off-line simulation,the feasibility of on-line and real-time stability control system is demonstrated.Finally,the construction principles of the three lines of defense for the independent local power grid are summarized.

Abstract:Due to the dispatching and marketing load control method cannot satisfy the load emergency control and the power supply needs of large users and important loads when UHVDC block fault occur,a method is proposed to realize swift load control by improving specialty transformer user terminals in this paper.A common emergency load shedding control terminal is designed to meet the precise acquisition of interruptible load,real-time communication,and multi-master security fast control.A flexible configuration solution is designed for field load access,power calculation and tripping output.Finally,the terminal is applied at the user site.Actual load shedding test verified that the terminal fully meet the requirements of the precision load shedding system.

Abstract:This paper analyses the residential load characteristics by questionnaire survey and the relevant literatures,and introduces the economic mechanism of consumers'response on electricity price.Then this paper studies the load growth rate at the point of price changed according to the historical data of a typical residential neighborhood in Nanjing,and analyses the polymerization characteristics of residential electricity.This paper analyses the load growth rate of many areas and introduces the peak-to-valley ratio.Last,this paper concludes the residential load characteristics and influencial factors,and analyses the reasons and puts forward some suggestions.

Abstract:RTV is one of effective methods for power transmission equipment external insulation properties improving.However,the performance of RTV coating was affected by spraying operation,which was mainly artificial spraying on site.In this paper,an automatic spraying equipment was developed to deal with uneven coating thickness,flow and other phenomena of artificial spraying.The device can help the spraying gun achieve circular,up and down and swinging three-dimensional motion by setting up the gun's posture parameters.After spraying,spot detection found that artificial spraying thickness difference is quite large,while automatic spraying thickness is relatively uniform,and the automatic spraying equipment can effectively improve the RTV coating quality and efficiency.

Abstract:As a backup protection,distance protection is widely used as line and component protection for each voltage level.In order to ensure the direction,positive sequence voltage is used as the polarization voltage for distance protection.However,the positive sequence polarization voltage may not reflect the pre-fault voltage correetly when the system is in open-phase operating conditions.This paper introduced a mal-operation case of distance protection for a reverse fault,analyzed the disadvantages of using positive sequence polarization voltage,and proposed corresponding solutions.Finally,experiment results of RTDS validate the correctness of the scheme.

Abstract:The possible causes of the oil level abnormity were analyzed for the main transformer oil level abnormal defects,combined with the actual oil level,showed oil level and temperature-oil level curve.The length of pointer-type oil level swing-rod was calculated.The capacity of oil conservator was calculated and analyzed,and results show that it should be at least 10% of the body oil volume of main transformers.Defects and errors of existing main transformers were pointed out,and treatment measures and operational maintenance suggestions were put forward,which provides a reference for the main transformer acceptance and maintenance work.

Abstract:According to the abnormal voltage deviation of 110 kV section I and II bus in a power plant,the DCS system data,on-line examination,theoretical calculation and electrical test are comprehensive analyzed in this paper.Thinking that the 110 kV bus voltage anomaly is caused by some internal capacitor unit short circuit in the CVT.Then return the equipment to the factory,the result of the preliminary analysis is verified by the disassembly inspection,at the same time some capacitor unit quality defects are founded out,such as insulation material weakness and bad dipping property.Accordingly,require the manufacturer to replace all the products of this batch,then propose some treatment measures and suggestions for the same type equipment.

Abstract:The relationship between the constituents and the heating value of the coal is complicated.Currently there is no unified method in the energy loss analysis in coal-quality index for coal-fired boilers.The generally adopted method,of which the limitations are apparent,is to analyze the individual index of the coal quality.Study shows that the converted moisture,converted ash and the converted hydrogen are at once the quality index of the coal and the quantitative index of the combustion products which are closely related to the heat loss of the boiler.Starting from a formula for boiler heat loss,this article proposes a method for energy-loss analysis using the converted constituents of the coal with examples of calculation and analysis.Simple and practical as it is,this method can be an alternative for colleagues of other power plants in energy-loss analysis.

Abstract:In order to reduce NO_x emission,technical retrofit of low NO_x combustion had been carried out for opposed-firing supercritical boiler with swirl burner in a power plant.After retrofit the mass concentration of NO_x emission declined by more than 50% compared with the test results before retrofit.But the serious slagging was found and research was conducted to analyse the reason of the slagging based on testing and analysing the characteristics of the new burner.The serious slagging problem was solved by a series of experiments such as changing the swirl intensity of secondary air,fineness of pulverized coal,oxygen volumetric fraction and flow rate of over-fire air (OFA) etc.