【作者】 陈忠；

【导师】 丁明； 苏建徽；

【作者基本信息】 合肥工业大学 ， 电气工程， 2014， 博士

【摘要】 储能既可作为发电单元又可作为负荷单元,独特的双向调节性能将使其在可再生能源发电消纳中发挥重要作用。本文以电池储能为研究对象,基于现阶段电池系统的构建技术水平,采用VSC模块并联型功率调节系统作为电池储能系统并网接口,重点研究功率调节系统的拓扑控制及储能运行策略,主要内容如下：(1)广泛收集整理了国内外有代表性的储能技术文献,归纳了典型储能技术的基本原理、发展现状和需要突破的关键技术等。总结了储能技术在传统电力系统和新能源发电集成中的应用模式。结合电池储能系统的配置方式、电池系统、功率调节系统和系统集成等关键技术,探讨了面向可再生能源发电的大容量电池储能系统构建方案。(2)考虑并网隔离变压器影响,建立了功率调节系统在两相坐标系下的线性动态模型,揭示了变压器对并网功率调节系统性能的影响。重点对比分析了3种典型坐标系下的线性电流控制策略,揭示了dq坐标系PI控制的本质及其与αβ坐标系PR控制的关联；基于传递函数模型对3种坐标系下控制的稳态误差、动态响应、抗扰动性能进行了详细分析。给出了PR调节器具有频率适应性的数字化实现方案,提高了调节器对电网频率变化的适应性。(3)通过建立不同坐标系下模块间环流的线性动态模型,揭示了环流产生的机理。基于双傅里叶分析建立了变流器模块PWM调制输出电压、电流的频谱模型,通过建立的频谱模型研究了模块间载波交错运行对功率调节系统共模电压、并联电流和模块间环流的影响,揭示了载波交错运行能够消除并网电流谐波,提高等效开关频率的本质原因。推导论证了环流分布式控制规律和结构的可行性,提出了一种基于分布式结构的高低频复合环流抑制策略。(4)采用阻抗建模技术和电路网络分析方法建立了功率调节系统的集中等效电路模型,引入互联阻抗比概念,从等效开环传递函数角度借助奈奎斯特判据研究了功率调节系统和电网互联系统的交互稳定性问题。在功率调节系统和电网互联系统交互稳定性分析的基础上,进一步借助电路串并联谐振概念分析了多VSC模块间、VSC模块和电网间的谐波交互作用,揭示了模块间形成谐波交互的潜在原因。从输入导纳的角度对并网VSC控制策略进行设计,提出采用多陷波器组的电网电压前馈方案,提高了功率调节系统和电网互联系统的交互稳定性和稳态性能。(5)以配合可再生能源发电的储能应用为背景,给出了电池储能PCS平滑出力波动的控制策略。分析了电网电压不对称对功率调节系统并网控制策略相关环节的影响,提出采用线电压检测的对称分量提取与锁相环技术,以对称电流控制作为并网控制目标,增强了功率调节系统在电网电压弱不对称条件下的运行能力。提出了电网电压对称/不对称跌落条件下储能功率调节系统的统一电压支撑策略,兼顾正序、负序无功补偿；通过限流环节的设计,实现正负序电流的合理分配,避免了功率调节系统过流而触发保护停机,优化了功率调节系统无功容量利用率。(6)搭建了配合可再生能源发电的电池储能系统实验平台。设计了基于以太网为主干的系统网络结构,采用套接字Socket开发了相关通讯软件,实现了设备间的信息交互。研制了基于两VSC模块并联的功率调节系统实验样机,编写了硬件底层驱动程序和控制策略软件,对PCS相关控制策略的有效性进行了实验测试。更多还原

【Abstract】 Energy storage system(ESS) can serve as both generation unit and load unit according to different application. For its unique bidirectional properties, it will play an important role in the solutions to integrate renewable energy generation into grid. In this paper, battery energy storage is selected as the researched objective. According to the technical level of battery system construction nowadays, the power conditioning system(PCS) based on parallel converter modules is proposed to be as the interface of grid-connected battery energy storage system(BESS). The study is focused on the control schemes of PCS and operation strategies of BESS, the main contents are as follows:(1)The existing typical energy storage technologies are reviewed in a wide range of domestic and foreign representative literature, the basic principles,current status and to-be-solved key technologies of some popular technologies are generalized. The application modes of energy storage technologies in the traditional power system and renewable energy generation integration are summarized. In particular, the key technologies of large capacity BESS for renewable energy generation are analyzed, from the aspect of configuration mode, the battery system, PCS and system integration.(2)The linear dynamic models in two-phase coordinates of PCS,including grid-connected isolation transformer, are established.The models reveal the effect of the transformer on the performance of PCS.Three typical linear current control strategies for grid-connected converter are compared.The essential of the PI controller in dq coordinates and its relationship with PR controller in ap coordinates is reyealed.Based on transfer function model, concern on steady error, dynamical response and grid disturbance rejection, the performance of three different linear current schemes are compared theoretically.The digital implementation of the resonant regulator is investigated, which improves the adaptation of the regulator on the variable grid frequency.(3)The dynamic circulating current models in different coordinates are established respectively, which reveals the generation mechanism of circulating current. Based on double Fourier analysis, the spectrum models of PWM converter module output voltage and current are established. Through the established spectrum models, the effection of inter-module interleaved carrier on common-mode voltage, parallel current and circulating current of the PCS is studied, revealing the essence that interleaved carrier can eliminate grid-connected current harmonics, while increase the equivalent switching frequency. The distributed control laws and structures for circulating control are analyzed, and a composite circulating current suppressing scheme based on distributed structure is designed for low frequency and high frequency component respectively.(4)Using impedance modeling techniques and the analysis method of circuit network, the centralized equivalent circuit model of PCS is derived.The concept of interconnected impedance ratio is introduced, and the interaction stability issues of interconnected system between PCS and grid is studied from the aspect of equivalent open loop transfer function, using the Nyquist criterion. Furthermore, the harmonic interaction issues among the converter modules, between the inverter module and the grid is analyzed with the principle of circuit series parallel resonance. As a result, the potential reason for harmonic interaction is revealed.The design of grid-connected control scheme, from the perspective of the input admittance,is proposed. As an example, a design method of grid voltage feedforward with notch filters is given, which can improve system stability and steady-state performance.(5)Considering the application of energy storage coordinated with renewable energy generation, the smoothing scheme of PCS for battery energy storage is given. The impact of asymmetry grid voltage on major aspects of traditional grid-connected control scheme is focused, then an improved control scheme is given, using line voltage for symmetrical components extraction and phase-locked loop and setting symmetric current as grid-connected current control objectives, which enhances its adaptability to the non-ideal grid. The operation strategy of PCS under serious voltage drop is explored, a unified voltage support scheme of BESS under both symmetrical and asymmetrical grid voltage drop is proposed,both positive and negative sequence reactive power compensation can be achieved.Furthermore,a method of current limiting is designed, achieving a reasonable distribution of positive and negative sequence current,as a result,the overcurrent protection and shutdown of PCS can be avoided, and the reactive power capacity utilization of PCS is optimized.(6) The BESS experimental platform coordinated with renewable energy generation is established. The communication network structure based on Ethernet is designed, and related communications software is developed with Socket in the PC Windows platform, achieving the critical information exchange between key devices. Based on two parallel converter modules the PCS prototype is established, the software of PCS prototype is developed,including the hardware driver code and main control schemes, the effectiveness of the related control schemes for PCS is validated initially.更多还原