【作者】 杨达亮；

【导师】 杭乃善；

【作者基本信息】 广西大学 ， 电力系统及其自动化， 2014， 博士

【摘要】 随着能源压力加大和环保意识的提升,风力发电、光伏发电等可再生能源发电比重不断增加,高渗透率下新能源发电的不间断随机接入给配电网带来新的挑战。主动配电网是实现大规模间歇式新能源并网运行控制、电网与充放电设备互动、智能配用电等电网分析与运行关键技术的有效解决方案。然而,主动配电网还处在发展阶段,尚有许多亟待解决的理论问题和技术问题。如何研制相关智能电力设备并进行电压调节、无功补偿、谐波治理和可再生能源转换和接入成为电力电子设备层面的突出问题。本文针对主动配电网背景下电能质量和电能转换的共性关键技术问题进行研究,以脉冲宽度调制(pulse width modulation, PWM)变流器为研究对象,以实现动态和高品质控制效果为研究目的,进行了数学建模和功率分析、信号检测、控制方法研究、实验平台研制和数字信号处理器(digital signal processor, DSP)控制系统实现。完成从理论分析、仿真研究、实验验证到具体程序的代码实现,以便为主动配电网相关智能电力设备研制提供相应的理论保证和技术支撑。全文主要工作如下：1)建立数学模型和进行功率分析计算。采用开关函数描述法建立三相电压型PWM变流器在abc静止坐标系下的数学模型。由瞬时功率理论得到abc静止坐标系下功率计算公式；利用坐标变换方法,分析得到等量变换和等功率变换αβ止坐标系和dq同步旋转坐标系下的功率计算。2)针对单相系统电压暂降和电压定向信号的检测,提出一种新型检测方法。根据单相交流电压信号离散数据,利用相线电压相量关系,通过移相角度30°虚构出三相电压信号。本文提出的检测方法幅值变化延时仅为电网工频周期的1/12,理论延时为1.67ms,与目前延时3.33ms的瞬时电压dq分解法和延时5.Oms的αβ测法相比,实时性进一步提高。三相系统采用此方法,可减少交流电压检测的传感器数量,降低系统设计成本。给出了具体实现方法和仿真结果。3)提出一种新型准直接功率控制方法。从PWM控制的基本原理出发,对传统直接功率控制开关表调制机理进行深入分析,对其开关表调节有功功率和无功功率能力作出解释,分析选择不同零矢量的原因,并指出基于开关表结构的功率滞环控制的不足。针对PWM变流器主要实现整流和逆变功能,从电力系统瞬时有功功率和无功功率控制的角度,提出一种新型准直接功率控制策略。采用内环定频,外环功率的结构,满足功率流向控制的同时兼顾电流内环保护。同时给出控制器参数设计方法和控制仿真结果,仿真结果表明实现PWM变流器的动态高品质控制目标。4)提出基于abc坐标下的PWM变流器自然坐标控制方法,包括直接电流控制方法,无交流电压传感器控制方法和直接功率控制方法。由电压传感器采集交流侧三相电源经计算得到有功单位分量和无功单位分量实现矢量控制效果。对PWM变流器交流侧的相电压直接进行工程积分代替传统的微分方法,获得每相磁链的近似值,通过相电压估算和磁链估算模块实现无交流电压传感器控制。按照新型准直接功率控制策略的思想,采用功率外环电流内环的方法,完成基于自然坐标下的直接功率控制。本文提出的基于自然坐标的控制方法,不需要进行坐标变换和三角函数计算,物理概念清晰。给出PWM变流器基于自然坐标控制方法的稳态和动态仿真结果,仿真结果表明实现PWM变流器的动态高品质控制目标。5)为进行实验研究,按照V模式开发流程基于dSPACE核心平台研制了PWM变流器实时控制综合平台。设计了主电路、测量电路、驱动电路、故障检测和保护电路、电源电路等具体电路。进行了配电网静止同步补偿器(distribution static synchronous compensator, DSTATCOM)、动态电压恢复器(dynamic voltage restorer, DVR)、统一电能质量调节器(unified power quality conditioner, UPQC)等配电网电能质量控制实验和PWM变流器整流、逆变电能转换实验。给出相应的动静态实验测试结果,与仿真结果相符,算法比较实验表明本文提出的控制算法进一步提高了系统的动静态特性,实验结果表明实现PWM变流器的动态高品质控制目标。6)研制了基于DSP控制的PWM变流器控制系统。采用32位高性能处理器TMS320F2812,研制了50kvar容量的DSTATCOM实验样机,给出详细的实现过程、实验测试和实验结果。本文的仿真结果和实验结果表明,所提出的信号检测方法和PWM变流器控制方法,具有较好的实时检测性能和控制性能,对研究电能质量控制器和电能转换系统可起到一定的理论保证和技术支撑作用,系统设计也可为研制相关智能电力设备提供参考。更多还原

【Abstract】 Continuously increasing growth of renewable energy generation such as wind turbine(WT) and photovoltaic(PV) is posing new challenges to distribution network with increasing pressure on energy and environmental protection. The active distribution network(ADN) is an effective approach to solve the problems such as the high-penetration of intermittent renewable energy, interaction between grid and charge-discharge facilities, and also the analysis and operation of smart grid. However, the ADN is still in the development stage and there are many urgent theoretical and technical issues to be solved. A key issue of power electronic devices in distribution system is to develop the intelligent power devices in order to match the growing demand for different purposes, such as voltage regulation, reactive power compensation, harmonic suppression, energy conversion and the integration of renewable distributed generation(DG). In this dissertation, the key technologies of power quality and energy conversion in ADN are researched. The research subject is the control methods for pulse width modulation(PWM)converter with fast dynamic response and high quality of the current and voltage waveforms. The main contents include mathematical model and power analysis, voltage sag detection, control method, experimental platform development and digital signal processor(DSP) control system implementation. The process of theoretical analysis, simulation study, experimental verification and DSP code programming are proposed in order to provide appropriate assurance and technical support for development of intelligent power devices in AND system. The main contents of this dissertation are proposed as the following:1) The mathematical models, analysis and calculations of power for PWM converter are proposed. In abc stationary coordinate, the mathematical models of three-phase voltage-source PWM converter are presented using switching function description method and the calculation formulas of active power and reactive power are derived with the instantaneous power theory. Further, the power calculation equations under different coordinate systems such as αβ stationary frame and dq synchronous rotating frame are analyzed by Clarke transformation and Park transformation, respectively.2) A novel voltage sag detection method for single-phase voltage system is presented. With the sampling discrete data, a fictitious three-phase system is created from a reference single-phase voltage with30°phase angle shift according to phasor relationship phase voltage and line voltage. The delay time of proposed detection method is just1/12grid period and the theoretical delay time is1.67ms, which is faster than the instantaneous voltage dq conversion method with3.33ms delay and the αβ detection method with5.0ms delay, respectively. The sensor number and the design costs of three-phase system can be reduced using the proposed method. The implementation process and simulation results are presented.3) A novel quasi direct power control(DPC) method with fixed switching frequency is proposed. The principle of switching table modulation mechanism are discussed and the explanation of control effect to active and reactive power with different space vector from switching table is introduced in detail, respectively. The reasons for choosing different zero vectors are analyzed and the defects of power hysteresis control based on switching table are discussed. A novel quasi DPC method is proposed with the idea that PWM converter functions for rectifier and inverter, and power system control for instantaneous active and reactive power are considered simultaneously. The novel quasi DPC method with fixed switching frequency can not only control the instantaneous active and reactive power, but also give rapid regulation and protection for internal current loop. The design of controller parameters and simulation results are given and the results show the excellent performance of the proposed method for PWM converter control.4) Control methods for PWM converter based on abc coordinate, named natural coordinate in this dissertation, including direct current control(DCT), without line voltage sensors control and natural coordinate direct power control(NC-DPC), are presented. The unit vectors of active and reactive power in phase are derived using the three-phase voltages and a quadrature transformation. The total reference currents, which are equivalent to vector control, can be computed with the unit vectors. The sensorless control system is based on phase voltage estimation and virtual flux(VF) estimation. The VF are estimated using phase voltage of PWM converter with project integrator instead of traditional derivation. In NC-DPC, there are internal current loop and external power loop. Compared to the conventional control method, the natural coordinate control method has some advantages, such as no coordinate transformation, no trigonometric function and clear physical concept. The steady and transient simulation results are given and the results show the excellent performance of the proposed method for PWM converter control.5) A PWM converter integrated real-time control platform based on dSPACE is developed for experimental tests according to the V-cycle development process. The power circuit, voltage and current measurement circuit, PWM drive circuit, power supply circuit, fault diction and protection circuit are designed. The experimental tests for power quality and energy conversion are introduced including distribution static synchronous compensator(DSTATCOM), dynamic voltage restorer(DVR), unified power quality conditioner(UPQC), PWM rectifier/inverter and so on. The corresponding static and dynamic experimental results are given, and show the excellent performance of the proposed method for PWM converter control. The dynamic and static characteristics are improved compared to the method of DPC-SVM.6) A PWM converter control system is developed based on DSP. The development of50kvar DSTATCOM experimental prototype based on32-bit high-performance processor TMS320F2812is proposed. The implementation process, experimental tests and experimental results are introduced in detail.The simulation results and experimental results in this dissertation show that the proposed method of signal detection and control method for PWM converter has better detection performance and real-time control performance. The research can play a certain theory assurance and technical support for the study of power quality controller and power conversion systems and the system implementation can also provide a reference for the development of intelligent power equipments.更多还原