【作者】 赵志宏；

【导师】 赵剑锋；

【作者基本信息】 东南大学 ， 电气工程， 2017， 博士

【摘要】 储能既可作为发电单元又可作为负荷单元,对可再生能源发电消纳、电力"削峰填谷"、电动汽车以及微电网的建设等发挥举足轻重的作用,并构成未来智能电网的重要组成部分。本文以低压模块化PCS为研究对象,重点围绕多电平VSC的矢量调制与电压平衡、PCS并网模式电流环的控制以及PCS离网电压源输出系统控制展开研究,主要内容如下:1)介绍了全球可再生能源的发展现状,明确了我国新能源的现状以及对大规模储能的应用需求,分别从储能方式以及PCS拓扑两方面介绍了大规模储能的应用现状与发展趋势,并进一步总结了大容量PCS控制系统的难点与关键技术。2)鉴于多电平VSC在大功率模块化并联PCS应用存在的巨大优势,针对多电平VSC的SVM电压平衡展开研究,首先从两电平入手介绍了 SVM的基本原理与实现方法,并将该方法引入三电平VSC,介绍了冗余小矢量互补NTV-SVM与VSVM两种均压算法的原理与实现。进一步,拓展到5L-DCC并分析其SVM电压平衡,分别讨论了目标函数优化的NTV-SVM、VDSVM-H1、OVDSVM-H1以及IVDSVM电压平衡算法,实现了 5L-DCC在全功率因数范围的电压平衡,并且在过调制情况下系统依然稳定运行。3)针对电网电压平衡条件下PCS并网电流环的控制,首先分析了电流环PS-SRF交叉耦合项的影响,介绍了两种解耦方法并探讨了滤波器参数对解耦效果的影响。其次,讨论了数字控制一拍延时对电流环解耦效果与系统稳定性的影响,分别针对状态反馈解耦PI与cPI控制器分析了其延时补偿策略。再次,讨论了控制器参数设计方法,明确了临界阻尼控制器增益在调节时间与超调量方面的优势。此外,分析了状态反馈解耦PI与cPI控制器的电网电压扰动抑制能力,分析了电网电压前馈以及有源阻尼对提高系统抗扰动能力的有效性。4)针对电网不平衡与畸变条件下PCS并网电流环的控制,首先介绍了瞬时功率计算以及参考电流给定方法。其次,分析了基于状态反馈解耦PI与cPI控制器的DSRFC解耦有效性,以及两者对输出滤波器参数的敏感性。再次,讨论了 RCs与PS-SRF-PI/cPI控制器的暂态响应,进一步明确了两者的内在联系与区别。此外,分析了 RCs调节系统的最佳稳定判据,并分析了闭环奇异点产生的原因,讨论了基于RCs电流环的延时补偿策略及有效性。最后,介绍了离散域控制器的设计,分析了 PS-SRF-DcPI、DVPI控制器的优势,并讨论了延时补偿与闭环死区补偿方法。5)针对PCS工作于离网模式的输出电压源控制,首先建立了系统在离散域的矢量模型,并以输出电压有效值闭环控制方式入手,阐述了离网模式对PCS控制系统的要求。其次,详细讨论了电压瞬时值单闭环控制存在的局限性,明确了虚拟阻尼对抑制系统谐振的必要性。再次,探讨了双闭环控制结构电流内环最优增益设计准则,并以获得最大稳定性以及提高阻尼为目标,提出了内环最优增益设计方法。此外,以被控对象最优阻尼改造为考察对象,进一步明确了电流内环的本质及其与被控对象阻尼的内在联系。最后,详细讨论了离散域电压控制器的设计,以基波正序电压控制入手,介绍了 PS-SRF电压控制器的延时补偿与临界阻尼增益设计方法,并进一步得到静止坐标系DVPI-LC控制器,避免了坐标变换并通过将DVPI-LC推广都各次谐波分量,实现了对负序以及各频次电压的无静差调节。更多还原

【Abstract】 Energy storage system(ESS)can serve as both generation unit and load unit according to application demand.It plays an important role in renewable energy power generation,grid peak-load regulation,electric vehicles and micro-grid application,and it is also a great important part of the future smart grid.This paper focus on the control of modular paralleled power control system(PCS),with the space vector modulation(SVM)and dc-link capacitor voltage balancing,grid-connected current loop control,and off-grid voltage source control of the PCS as the main study topic,and the detailed contents are as follows:1)The current status of global renewable energy development is introduced first,followed by the renewable energy status of our country and the application demanding of large-scale ESS.Besides,the application status and development trend of large-scale ESS are introduced,from two the energy storage method and PCS topology are both introduced aspects.At last,this paper summarizes the difficulties and key points for the PCS control system.2)In view of the great advantage of multi-level VSC in application of the high-power multi-modular paralleled PCS,and the dc-link capacitor voltage of multi-level VSC based on SVM is analyzed.Firstly,the principle and implementation of SVM is introduced based on two-level VSC,and this method is introduced to the voltage balancing of three-level VSC,with the nearest three vector space vector modulation(NTV-S VM)based redundant space vector and virtual space vector modulation(VSVM)are analyzed.Furthermore,the voltage balancing of five-level diode clamped converter(5L-DCC)is studied,and the NTV-SVM based on objec-tive function optimization,vector decomposition space vector modulation based on hexagon one(VDSVM-Hl),the optimized vector decomposition space vector modulation based on hexagon one(OVDSVM-Hl),and the improved vector decomposition space vector modula-tion(IVDSVM)are analyzed for their voltage balancing capability.The voltage balancing is achieved with the three methods,irrespective of the power factor,and the converter can working stably even under over modulation.3)With respect of the current loop control of PCS with balanced grid voltage,the influ-ence of cross coupling of current loop in positive synchronous frame(PS-SRF)is analyzed,and two kinds of decoupling methods are introduced and the effect of filter parameters error on decoupling effect is discussed.Secondly,the effect of one-step delay of digital control on the decoupling of current loop is discussed,and the delay compensation method is analyzed for state feedback decoupling proportional-integral(PI)and complex-proportional-integral(cPl)controller respectively.In addition,the ability of gird voltage disturbance suppression for both state feedback decoupling PI and cPI controller are analyzed,and the effectiveness of grid volt-age feed-forward control and active damping to improve the system anti-disturbance ability is discussed.4)In order to effectively control the PCS current under unbalanced and distorted grid voltage,the instantaneous power calculation and reference current generation method are in-troduced.Secondly,the decoupling effectiveness of double synchronous reference frame con-trol(DSRFC)based on state feedback decoupling PI and cPI controller is analyzed,and the sensitivity to output filter parameters is analyzed.Thirdly,the transient response of RCs and PS-SRF-PI/cPI controller are discussed,and the relationship between RCs and PS-SRF-PI/cPI controller is clarified.In addition,the optimal stability criterion of RCs control system is an-alyzed,and the reason for closed-loop singularity generation is introduced.Besides,the delay compensating strategy of current loop based on RCs and its effectiveness are discussed.Finally,the controller design in discrete time domain is introduced,and the advantages of PS-SRF-DcPI and DVPI controller are analyzed,also the time delay compensation method and closed-loop dead-time compensation are introduced.5)For the output voltage source control of the PCS working in the off-grid mode,the vector model of the system in the discrete domain is deduced firstly.With the root-mean-square control of the output voltage is taken into account,the requirements of the PCS control system are a.Secondly,the limitation of single-loop instantaneous voltage control is discussed in detail,and the necessity of virtual damping to suppress the resonance of system is clarified.Thirdly,the optimal gain design criterion of the inner loop of the double closed-loop control structure is discussed.With the purpose of obtaining the maximum stability and improve the damping,an inner loop optimal gain design method is proposed.In addition,the optimal damping of the controlled object is taken into consideration,and the essence of the current inner loop is further clarified.Finally,the design of voltage controller in the discrete time domain is discussed in detail.Starting with positive-sequence voltage control of fundamental component,the delay compensation of PS-SRF voltage controller and the critical damping gain design method are introduced.Furthermore,the DVPI-LC controller is obtained,which is implemented in the stationary frame and avoiding the coordinate transformation.At last,the DVPI-LC controller is extended to the harmonic components,with the purpose of controlling the negative sequence and harmonic voltage.更多还原