To ensure frequency stability in power systems with high wind penetration,the doubly-fed induction generator(DFIG)is often used with the frequency fast response control(FFRC)to participate in frequency response.Howeve...To ensure frequency stability in power systems with high wind penetration,the doubly-fed induction generator(DFIG)is often used with the frequency fast response control(FFRC)to participate in frequency response.However,a certain output power suppression amount(OPSA)is generated during frequency support,resulting in the frequency modulation(FM)capability of DFIG not being fully utilised,and the system’s unbalanced power will be increased during speed recovery,resulting in a second frequency drop(SFD)in the system.Firstly,the frequency response characteristics of the power system with DFIG containing FFRC are analysed.Then,based on the analysis of the generation mechanism of OPSA and SFD,a combined wind-storage FM control strategy is proposed to improve the system’s frequency response characteristics.This strategy reduces the effect of OPSA and improves the FM capability of DFIG by designing the fuzzy logic of the coefficients of FFRC according to the system frequency index in the frequency support stage.During the speed recovery stage,the energy storage(ES)active power reference value is calculated according to the change of DFIG rotor speed,and the ES output power is dynamically adjusted to reduce the SFD.Finally,taking the IEEE 39-bus test system as an example,real-time digital simulation verification was conducted based on the RTLAB OP5707 simulation platform.The simulation results showthat theproposedmethodcan improve theFMcapabilityofDFIG,reduce the SFDunder thepremise of guaranteeing the rapid rotor speed recovery,and avoid the overshooting phenomenon so that the systemfrequency can be quickly restored to a stable state.展开更多
含光储充的主动配电网作为一种灵活的新型调节资源,可通过聚合其内部的多类分布式电源组成配网虚拟电厂(distribution-level virtual power plant,DVPP)进而整体参与系统二次调频,具有广阔的发展前景。但实际配电网内部情况复杂,存在储...含光储充的主动配电网作为一种灵活的新型调节资源,可通过聚合其内部的多类分布式电源组成配网虚拟电厂(distribution-level virtual power plant,DVPP)进而整体参与系统二次调频,具有广阔的发展前景。但实际配电网内部情况复杂,存在储能配置有限导致可调容量不足、光伏短时出力难以预测导致控制不精确、功率分配不合理导致内部电压越限的问题,传统虚拟电厂调频策略难以适用。针对上述问题,提出了一种基于随机模型预测控制(stochastic model predictive control,SMPC)的DVPP二次调频策略,通过聚合模型设计、光伏不确定功率的场景树模型搭建、SMPC策略设计的方式实现了分布式电源出力扰动情况下DVPP快速、准确响应自动发电控制(automatic generation control,AGC)指令的目标,并有效降低了功率调节对系统内部电压的影响,为DVPP参与系统二次调频提供了理论基础。展开更多
Variable-speed wind power generation system usually adopts maximum power point tracking(MPPT)below the rated wind speed or constant power control above the rated wind speed.However,single objective control has large d...Variable-speed wind power generation system usually adopts maximum power point tracking(MPPT)below the rated wind speed or constant power control above the rated wind speed.However,single objective control has large dynamic loads on transmission systems.This paper presents a multi-objective control scheme for wind turbine in low wind speed,which achieves not only high power capture efficiency but also low fatigue load on mechanical parts.Input wind speed is separated into two components:a slowly varying seasonal component and a rapidly varying turbulent component.Correspondingly,the machine-side converter controller is divided into low frequency loop and high frequency loops.The low frequency loop implements MPPT control,the high frequency loop reduces the fluctuations of torque,and both loops together suppress the variations of output power.Simulation was conducted in Matlab/Simulink and FAST code was used to further verify the correctness of the multi-objective control strategy.展开更多
光伏电网频率调整过程中,依靠常规Smith预估控制器实现电网调频控制,对模型精度具有较强的依赖性,控制策略实施后最大频率变化率(rate of change of frequency,RoCoF)较大。因此,提出基于改进型Smith预估计器与大数据的光伏电网调频逐...光伏电网频率调整过程中,依靠常规Smith预估控制器实现电网调频控制,对模型精度具有较强的依赖性,控制策略实施后最大频率变化率(rate of change of frequency,RoCoF)较大。因此,提出基于改进型Smith预估计器与大数据的光伏电网调频逐步惯性控制方法。首先,采集历史气象数据和光伏电网运行数据,应用大数据分析领域的密度峰值聚类算法进行划分处理,再筛选相似日数据输入长短期记忆网络中,预测出未来光伏发电的功率变化;然后,依托逐步惯性控制思想,设计包含短时超发、转速恢复等多个阶段的电网调频控制策略,将模糊自适应比例-积分-微分(proportion-integration-differentiation,PID)控制器融入常规Smith预估计器,从而升级得到优化版的Smith预估计器;最后,在不受被控模型变化影响的情况下,依据预估补偿原理完成逐步惯性调频控制,并应用麻雀搜索算法求解出最优控制参数。实验结果表明:该控制方法实施后,光伏电网运行过程中最大RoCoF仅为0.086 Hz/s,有效降低了对模型精度的依赖性,保证了电力系统的稳定运行。展开更多
基金funded by Jilin Province Science and Technology Development Plan Projects(20230508157RC)the National Natural Science Foundation of China(U2066208).
文摘To ensure frequency stability in power systems with high wind penetration,the doubly-fed induction generator(DFIG)is often used with the frequency fast response control(FFRC)to participate in frequency response.However,a certain output power suppression amount(OPSA)is generated during frequency support,resulting in the frequency modulation(FM)capability of DFIG not being fully utilised,and the system’s unbalanced power will be increased during speed recovery,resulting in a second frequency drop(SFD)in the system.Firstly,the frequency response characteristics of the power system with DFIG containing FFRC are analysed.Then,based on the analysis of the generation mechanism of OPSA and SFD,a combined wind-storage FM control strategy is proposed to improve the system’s frequency response characteristics.This strategy reduces the effect of OPSA and improves the FM capability of DFIG by designing the fuzzy logic of the coefficients of FFRC according to the system frequency index in the frequency support stage.During the speed recovery stage,the energy storage(ES)active power reference value is calculated according to the change of DFIG rotor speed,and the ES output power is dynamically adjusted to reduce the SFD.Finally,taking the IEEE 39-bus test system as an example,real-time digital simulation verification was conducted based on the RTLAB OP5707 simulation platform.The simulation results showthat theproposedmethodcan improve theFMcapabilityofDFIG,reduce the SFDunder thepremise of guaranteeing the rapid rotor speed recovery,and avoid the overshooting phenomenon so that the systemfrequency can be quickly restored to a stable state.
文摘含光储充的主动配电网作为一种灵活的新型调节资源,可通过聚合其内部的多类分布式电源组成配网虚拟电厂(distribution-level virtual power plant,DVPP)进而整体参与系统二次调频,具有广阔的发展前景。但实际配电网内部情况复杂,存在储能配置有限导致可调容量不足、光伏短时出力难以预测导致控制不精确、功率分配不合理导致内部电压越限的问题,传统虚拟电厂调频策略难以适用。针对上述问题,提出了一种基于随机模型预测控制(stochastic model predictive control,SMPC)的DVPP二次调频策略,通过聚合模型设计、光伏不确定功率的场景树模型搭建、SMPC策略设计的方式实现了分布式电源出力扰动情况下DVPP快速、准确响应自动发电控制(automatic generation control,AGC)指令的目标,并有效降低了功率调节对系统内部电压的影响,为DVPP参与系统二次调频提供了理论基础。
基金Supported by the National Natural Science Foundation of China under Grants 51320105002 and 51577025.
文摘Variable-speed wind power generation system usually adopts maximum power point tracking(MPPT)below the rated wind speed or constant power control above the rated wind speed.However,single objective control has large dynamic loads on transmission systems.This paper presents a multi-objective control scheme for wind turbine in low wind speed,which achieves not only high power capture efficiency but also low fatigue load on mechanical parts.Input wind speed is separated into two components:a slowly varying seasonal component and a rapidly varying turbulent component.Correspondingly,the machine-side converter controller is divided into low frequency loop and high frequency loops.The low frequency loop implements MPPT control,the high frequency loop reduces the fluctuations of torque,and both loops together suppress the variations of output power.Simulation was conducted in Matlab/Simulink and FAST code was used to further verify the correctness of the multi-objective control strategy.
文摘光伏电网频率调整过程中,依靠常规Smith预估控制器实现电网调频控制,对模型精度具有较强的依赖性,控制策略实施后最大频率变化率(rate of change of frequency,RoCoF)较大。因此,提出基于改进型Smith预估计器与大数据的光伏电网调频逐步惯性控制方法。首先,采集历史气象数据和光伏电网运行数据,应用大数据分析领域的密度峰值聚类算法进行划分处理,再筛选相似日数据输入长短期记忆网络中,预测出未来光伏发电的功率变化;然后,依托逐步惯性控制思想,设计包含短时超发、转速恢复等多个阶段的电网调频控制策略,将模糊自适应比例-积分-微分(proportion-integration-differentiation,PID)控制器融入常规Smith预估计器,从而升级得到优化版的Smith预估计器;最后,在不受被控模型变化影响的情况下,依据预估补偿原理完成逐步惯性调频控制,并应用麻雀搜索算法求解出最优控制参数。实验结果表明:该控制方法实施后,光伏电网运行过程中最大RoCoF仅为0.086 Hz/s,有效降低了对模型精度的依赖性,保证了电力系统的稳定运行。
文摘多微源独立微网中,传统下垂控制的输出频率动态响应速度快,虚拟同步发电机(virtual synchronous generator,VSG)控制可改善频率响应特性,但无法兼顾功率和频率的动态调节性能。针对此问题,提出一种改进的转动惯量自适应控制(improved adaptive control of inertia,IACI)。首先,在同步旋转坐标系下建立VSG数学模型,并分析转动惯量对VSG输出特性的影响;其次,在VSG控制的基础上通过在转动惯量控制中引入频率变化量形成VSG转动惯量自适应控制,并给出频率跟踪系数、转动惯量和阻尼系数等参量的整定方法;最后利用Matlab/Simulink对比VSG控制和IACI控制在VSG并入微网和负载扰动条件下的有功和频率响应曲线,在由两台1k W的VSG组成的独立微网实验平台上进行实验验证,结果表明所提控制策略可避免VSG并入微网过程中的有功振荡,且可以有效优化频率响应曲线。
