Large Units, Large Plants -Major Thermal Power Sources

China’s electric power industry as a basic industry, plays an important role in the longterm, sustained and healthy development of the whole national economy. China’s electric power industry attained great achievement in technology and economical results during the past eight years from 1987-1995. The total national installed generating capacity increased from 102.897 GW in 1987 to more than 200 GW in March, 1995.

Multi-model Predictive Control of Ultra-supercritical Coal-fired Power Unit

The control of ultra-supercritical(USC) power unit is a difficult issue for its characteristic of the nonlinearity, large dead time and coupling of the unit. In this paper, model predictive control(MPC) based on multi-model and double layered optimization is introduced for coordinated control of USC unit. The linear programming(LP) combined with quadratic programming(QP) is used in steady optimization for computation of the ideal value of dynamic optimization. Three inputs(i.e. valve opening, coal flow and feedwater flow) are employed to control three outputs(i.e. load, main steam temperature and main steam pressure). The step response models for the dynamic matrix control(DMC) are constructed using the three inputs and the three outputs. Piecewise models are built at selected operation points. Double-layered multi-model predictive controller is implemented in simulation with satisfactory performance.

Adaptive coordinated control of engine speed and battery charging voltage

In this paper, the control problem of auxiliary power unit （APU） for hybrid electric vehicles is investigated. An adaptive controller is provided to achieve the coordinated control between the engine speed and the battery charging voltage. The proposed adaptive coordinated control laws for the throttle angle of the engine and the voltage of the power-converter can guarantee not only the asymptotic tracking performance of the engine speed and the regulation of the battery charging voltage, but also the robust stability of the closed loop system under external load changes. Simulation results are given to verify the performance of the proposed adaptive controller.

Application of PID Controller Based on BP Neural Network in Export Steam’s Temperature Control System

By combining the Back-Propagation （BP） neural network with conventional proportional Integral Derivative （PID） controller, a new temperature control strategy of the export steam in supercritical electric power plant is put forward. This scheme can effectively overcome the large time delay, inertia of the export steam and the influencee of object in varying operational parameters. Thus excellent control quality is obtaitud. The present paper describes the development and application of neural network based controller to control the temperature of the boiler＇s export steam. Through simulation in various situations, it validates that the control quality of this control system is apparently superior to the conventional PID control system.

Coordinated control strategy for a PV-storage grid-connected system based on a virtual synchronous generator

Due to the characteristics of intermittent photovoltaic power generation and power fluctuations in distributed photovoltaic power generation,photovoltaic grid-connected systems are usually equipped with energy storage units.Most of the structures combined with energy storage are used as the DC side.At the same time,virtual synchronous generators have been widely used in distributed power generation due to their inertial damping and frequency and voltage regulation.For the PV-storage grid-connected system based on virtual synchronous generators,the existing control strategy has unclear function allocation,fluctuations in photovoltaic inverter output power,and high requirements for coordinated control of PV arrays,energy storage units,and photovoltaic inverters,which make the control strategy more complicated.In order to solve the above problems,a control strategy for PV-storage grid-connected system based on a virtual synchronous generator is proposed.In this strategy,the energy storage unit implements maximum power point tracking,and the photovoltaic inverter implements a virtual synchronous generator algorithm,so that the functions implemented by each part of the system are clear,which reduces the requirements for coordinated control.At the same time,the smooth power command is used to suppress the fluctuation of the output power of the photovoltaic inverter.The simulation validates the effectiveness of the proposed method from three aspects:grid-connected operating conditions,frequency-modulated operating conditions,and illumination sudden-drop operating condition.Compared with the existing control strategies,the proposed method simplifies the control strategies and stabilizes the photovoltaic inverter fluctuation in the output power of the inverter.

Control of Unit Power Factor PWM Rectifier

To solve the problem of harmonic pollution to the power grid that caused by traditional diode rectifier and phase controlled rectifier, the unit power factor PWM rectifier is designed. The topology structure of the rectifier circuit is introduced and the double closed-loop control strategy in three-phase stationary coordinate system is analyzed. For the deficiency of control strategy, the control strategy in two-phase synchronous rotating coordinate system is proposed. This makes the independent control of active current and reactive current to be realized. The simulation model of the PWM rectifier is built and the effectiveness of the control method proposed in this paper is verified by simulation.

An Improved Torque Sensorless Speed Control Method for Electric Assisted Bicycle With Consideration of Coordinate Conversion

In this paper,we propose an improved torque sensorless speed control method for electric assisted bicycle,this method considers the coordinate conversion.A low-pass filter is designed in disturbance observer to estimate and compensate the variable disturbance during cycling.A DC motor provides assisted power driving,the assistance method is based on the realtime wheel angular velocity and coordinate system transformation.The effect of observer is proved,and the proposed method guarantees stability under disturbances.It is also compared to the existing methods and their performances are illustrated through simulations.The proposed method improves the performance both in rapidity and stability.

Primary Frequency Control Ability Evaluation of Valve Opening in Thermal Power Units Based on Artificial Neural Network

With the development of new energy,the primary frequency control(PFC)is becoming more and more important and complicated.To improve the reliability of the PFC,an evaluation method of primary frequency control ability(PFCA)was proposed.First,based on the coupling model of the coordinated control system(CCS)and digital electro-hydraulic control system(DEH),principle and control mode of the PFC were introduced in detail.The simulation results showed that the PFC of the CCS and DEH was the most effective control mode.Then,the analysis of the CCS model and variable condition revealed the internal relationship among main steam pressure,valve opening and power.In term of this,the radial basis function(RBF)neural network was established to estimate the PFCA.Because the simulation curves fit well with the actual curves,the accuracy of the coupling model was verified.On this basis,simulation data was produced by coupling model to verify the proposed evaluation method.The low predication error of main steam pressure,power and the PFCA indicated that the method was effective.In addition,the actual data obtained from historical operation data were used to estimate the PFCA accurately,which was the strongest evidence for this method.

Profibus现场总线在大型火电机组控制系统中的应用

本文介绍了Profibus总线技术在火电厂机组控制中的应用情况,为后续工程项目的应用提供参考。

PJM电力市场风险管控措施及对南方区域的建议

电力市场改革的深化对电网运行风险管控提出了新的要求。通过总结PJM(Pennsylvania-New Jersey-Maryland)电力市场的风险管控策略,从两个方面分析其电力系统物理运行风险管控策略:包含长期、短期和实时的风险事故发生前措施,执行紧急中断与恢复的风险事故发生后措施;从日前的可靠性机组组合、与电能量市场联合优化的辅助服务市场、中长期的容量市场和输电权市场四个方面分析其基于电力市场的风险管控策略。并将其与南方电网现有风险管控措施相对比,提出了进行多时段风险评估、采取调度-市场相结合的管控风险手段、建设完备的市场体系、成立风险委员会等多方面建议。

飞轮储能辅助火电机组一次调频及其性能评价

为促进太阳能、风能等新能源消纳,进一步拓宽火电储能技术升级和灵活性改造渠道,助力双碳目标和新型电力系统建设,提出增设储能系统辅助火电机组调频以解决火电机组爬坡慢、机组振荡不稳定等问题。基于国内外研究现状,提出机组以及储能系统荷电状态出力控制策略模型,通过Matlab/Simulink搭建两区域电网进行模拟仿真。结果表明,在阶跃扰动下区域1机组耦合1 MW飞轮储能系统后,峰值降至1.93×10^(-3)pu,降低4×10^(-4) pu,占原频率波动率的9.39%,机组实际出力从2.45×10^(-2)pu降至1.61×10^(-2)pu,降低34%。结果表明,在外界相同扰动条件下,采用飞轮储能辅助火电机组调频可有效减小系统频率波动量,减少汽轮机输出功率波动,提升调频性能。

基于逐次变分模态分解的飞轮-火电一次调频控制策略

随着新型电力系统的大力建设与推广,火电机组面临的调频压力增大,提出一种逐次变分模态分解的飞轮-火电一次调频控制策略。首先,以飞轮储能和火电机组为研究对象,建立考虑新能源占比的飞轮-火电一次调频模型;其次,将一次调频功率指令利用逐次变分模态方法分解,由火电机组响应分解后的低频功率指令,同时设计飞轮储能下垂优化控制方法,实现飞轮储能与火电机组响应频率变化的协同控制;最后在不同工况下仿真验证,结果表明所提策略可有效避免火电机组一次调频时的频繁出力,减小火电机组响应频率变化时的调控要求,同时可最大限度地利用飞轮储能调频容量并保证飞轮储能调频期间的运行安全,进一步提升了系统的频率响应能力。

利用热网蓄能辅助供热机组调频的控制研究

随着如风电、太阳能等可再生能源的并网,使得火电机组需要进行深度调峰且快速响应调度指令。然而,传统的负荷调节控制方法难以使得机组应对调度指令的频繁变化。火电机组热网包含着大量的管道与热力设备,它们均具有很强的蓄热能力,合理利用其蓄热可在短时间内提升机组负荷响应速度。针对上述问题,对利用热网蓄能辅助供热机组负荷调节进行了研究,并设计了基于调度指令与负荷响应偏差的协调控制系统。仿真结果表明,所设计的协调控制系统能够提高机组负荷响应调度指令的能力,且保证供热压力的稳定。

火电机组大中径管道焊接施工工艺

介绍了某电厂2×66万千瓦机组焊接施工过程,严格执行DL/T 869-2021中国发电厂的焊接工艺规程以及电力建设工程施工及验收规范,阐述了千瓦机组大中径管道焊接施工的前期准备、施工工艺流程、焊接生产工艺和焊接质量控制措施,总结出合理的、保证质量的焊接施工经验,为广大电建企业焊接施工借鉴采用。

计及灵活经济环保运行的火电-飞轮储能系统容量配置与调频参数协同优化

提出了一种计及灵活经济环保运行的火储系统容量配置与调频参数协同优化方法。首先,设计了一种基于低通滤波自动分配火储功率和考虑储能荷电状态自恢复的火储联合一次调频协调控制策略;综合考虑系统调频性能、投入运行成本、污染物排放等,建立了火储容量配置与调频参数协同优化模型,并给出了基于粒子群算法的求解方法。最后,以某火储系统为例进行仿真验证。结果表明:协调控制策略和协同优化方法具有有效性。

基于三端柔性直流的光热储能站与新能源场站功率协同控制策略

新能源基地大多经传统交流方式接入高压交流或直流外送通道,为解决大规模新能源经交流接入方式下并网容量小、损耗大,以及功率波动对电网稳定性影响等问题,构建了一个基于柔性直流输电并网的风电和光伏、光热储能及电网三端柔性直流系统。基于直流电压-有功功率特性,提出一种适用于该系统的站间协调控制策略,根据柔性直流输电系统的直流电压波动情况,调整光热储能机组的出力,以平抑风、光功率波动,降低其对电网的影响。针对光热储能侧换流站,采用直流电压裕度下垂混合控制策略,通过控制器参数配置,抑制控制模式切换过程中的暂态过电压,提高系统响应速度。最后,在PSCAD/EMTDC中搭建三端柔性直流系统仿真模型,验证所提控制策略的有效性。

深度调峰工况下超临界机组的干湿态转换策略研究

为寻求深度调峰工况下合适的干湿态转换方式,在2台超临界机组上,采用2种不同的干湿态转换策略,对协调控制方式下的干湿态转换及其对系统稳定性的影响进行了研究。结果表明:2种策略均能够实现协调方式下的干湿态转换,可以通过转态进行进一步的深调工作;通过煤、水协同控制或给水流量控制均可实现干湿态转换,但水煤比变化情况不同;干转湿过程中,受到2种策略的影响,系统稳定性(主汽温度、主汽压力)区别明显;在湿转干过程中,2种策略下的系统都表现出良好的稳定性。

耦合相变储能的火电机组集成系统控制策略优化及效果分析

提升火电机组调峰调频能力是构建新型电力系统的重要举措。该文从锅炉-汽轮机能流解耦角度出发,设计抽取部分中压缸排汽进行储热的相变储能系统,与火电机组耦合后形成机-炉-储集成系统,提出重构机-炉-储三主体负荷指令的控制策略,并以某660 MW(P_(e0)=660 MW)超超临界机组为例进行效果评估。考虑中压缸排汽参数后,选取融化温度为117.7℃的赤藓糖醇为储能材料,研究抽汽比例对机组降负荷性能的影响。结果表明:当中压缸排汽的抽汽比例由0.00变为0.85时,机组等效降负荷速率由2.00%P_(e0)/min提升至5.13%P_(e0)/min,柔性明显增强;储能系统中储热量最大为118.73 GJ,储(火用)量最大为28.97 GJ;负荷指令重构后,系统瞬态过程中热效率增加,最大增加了1.85%,(火用)效率降低,最大降低了2.23%。

新型电力系统下火电机组灵活性运行技术发展及挑战

“双碳”背景下,新能源开始大规模并网发电,但新能源发电的随机性与波动性对电网造成一定冲击,亟需构建新型电力系统。在这一过程中,作为电力系统的基石,传统火电将向提供可靠容量、调峰调频等辅助服务的基础保障性和系统调节性电源转型,火电机组的灵活性改造成为必然选择。分析了构建新型电力系统的阶段性目标及面临的困难与挑战,探讨了现阶段火电机组灵活性改造遇到的问题,结合火电运行数据,分析火电机组配置储能设备的技术途径。研究认为:构建新型电力系统过程中存在着电力系统不稳定、传统火电转型困难、能耗大、环保压力大等问题;火电机组本体的灵活性改造面临调峰能力不足、运行成本较高、负荷响应慢、运行能耗大及安全性不高等问题;通过火电加储能的运行模式会带来较好的经济效益和环境效益。

考虑火电运行平稳性的飞轮储能辅助二次调频控制策略

为解决电网波动剧烈导致的火电机组运行平稳性问题,提出一种考虑火电运行平稳性的飞轮储能辅助二次调频控制策略。首先,建立了超超临界火电机组联合飞轮储能的二次调频控制模型;其次,提出了一种基于多层变增益速率限制的AGC指令非线性分解方法;最后,综合机组平稳性和系统AGC性能设计了适应度函数,借助鲸鱼优化算法(WOA)实现了最优化的速率限制算法参数获取。基于上述方法设计了火储协同二次调频控制策略。以某1000 MW火电机组-飞轮储能联合系统为例进行了仿真验证。结果表明:所提控制策略在不影响系统调频性能的前提下可以使联合系统有效响应系统高频指令,减小了火电机组的动作幅度,提升了机组运行的平稳性。