【作者】 茅靖峰；

【导师】 孙玉坤；

【作者基本信息】 江苏大学 ， 农业电气化与自动化， 2008， 博士

【摘要】 静止同步补偿器(STATCOM)是柔性交流输电系统(FACTS)的重要组成部件,它以电力电子变流器为装置核心,通过向电力系统注入方向与幅值均可连续动态调节的无功补偿电流,以维持装置接入点母线电压的稳定,同时阻尼功率振荡,提高暂稳极限。与传统的静止无功补偿器(SVC)相比,STATCOM具有无功调节连续、响应快、运行范围宽、体积小、产生谐波和损耗低等明显优势。因此,STATCOM装置的研究和设计受到了国内外电力界的广泛关注。考虑到电力系统强非线性、变结构、变参数的特点,应用非线性控制理论来进行STATCOM控制器设计,以充分挖掘STATCOM的工作潜能,始终是STATCOM技术研究领域的热点问题。本文在详细分析了当前STATCOM非线性控制研究现状的基础上,应用模糊控制、滑模变结构控制、直接反馈线性化技术以及相关非线性控制方法,对电力系统STATCOM无功补偿内、外环控制器进行了较深入的研究,同时理论联系实际,完成了一台配电端无功补偿应用的STATCOM数字系统设计方案。全文的主要内容如下:1.深入分析了STATCOM装置的组成结构与工作原理。利用输入输出建模方法和能量方程,建立了STATCOM装置时域数学模型和稳态数学模型;运用数学模型,对STATCOM装置主电路的基本工作特性进行了分析;针对大容量补偿应用,讨论了STATCOM多重化主电路结构的设计方法及其电路控制参数,并利用Matlab/Simulink平台对相关电路设计内容进行了数字仿真验证。2.提出电力系统STATCOM控制器的两层模型。推导出直接相角控制和有功-无功电流解耦控制这两种基本无功电流内环控制方法,利用STATCOM装置级的控制系统数字建模与仿真,完成了装置动态工作特性的深入分析;讨论了系统级外环控制的功能、结构原理、纯电压控制对电力系统阻尼的影响和提升系统暂稳特性的补偿方法;它们为STATCOM控制器的具体参数设计提供理论依据。3.应用电力系统暂态稳定分析的李雅普诺夫直接法(暂态能量函数法)对含STATCOM的单机-无穷大系统(SMIB)稳定域进行了分析,在考虑系统阻尼效应的前提下,运用首次积分法建立了系统能量函数,并进行了实例估算,得出系统稳定域随着STATCOM等效无功电流的增加而扩大的趋势。4.针对STATCOM无功电流内环控制系统,提出了一种无功电流滑模变结构控制策略。根据STATCOM的装置级非线性数学模型,应用极点配置法设计出滑动模态超平面,在考虑外界扰动因素的条件下,完成了变结构控制规律的设计。数字仿真结果表明,设计的无功电流滑模变结构控制器较传统的PID控制器,在无功电流的追踪能力上具有更快的响应速度,对系统摄动和外加干扰具有较强的鲁棒性。5.针对STATCOM电力系统无功补偿需求,提出了一种自治型STATCOM外环模糊滑模控制器(FSMC)。根据含STATCOM的单机-无穷大系统三阶非线性数学模型,应用M型模糊控制方法设计了滑模控制律,为了消除模糊控制死区,保证电压控制精度,将传统PI控制器串入系统。数字仿真实验验证了该FSMC在电力系统大参数变动条件下的算法有效性和鲁棒性。6.对发电机附加励磁与STATCOM协调非线性控制器设计进行了研究。提出了基于T-S型模糊滑模控制方法的发电机附加励磁控制器和基于T-S型模糊的非线性变增益STATCOM控制器。协调控制器以满足发电机功角稳定和STATCOM接入节点电压稳定为目标,其控制增益能够根掘电力系统当前状态依据规则产生大范围的非线性平滑调整,在较大的系统工作空间内均可有效提高电力系统电压调节能力和暂态稳定性能。协调控制器实现了本地量输入,在单机-无穷大系统的仿真中,展示了良好的性能。7.立足于配电端小容量无功补偿场合的STATCOM应用,完成了一台±50KVar配电端小容量无功补偿的STATCOM整体方案设计。分析了配电端STATCOM逆变器主电路的拓扑结构及其工作原理,给出了主电路各参数的设计依据;研究了基于瞬时无功功率理论的ip-iq方法的电网谐波和无功电流实时检测算法:阐述了电流跟踪型SVPWM控制方法;在此基础上,对DSP+CPLD复合功能结构的数字控制器相关硬件及关键软件流程进行了详细叙述。最后完成了系统的动模实验。更多还原

【Abstract】 Voltage-sources-converter-based Flexible AC Transmission System(FACTS)plays an important role in modern high voltage transmission system.Static synchronous compensator (STATCOM)is classified as second generation FACTS.The fundamental principle of STATCOM is the generation of a controllable ac voltage source by voltage source inverters connected to adc capacitor.In this way,STATCOM can provide smooth and rapid reactive power compensation to power system.It has been reported that STATCOM can offer a number of performance advantages for reactive power control applications over the conventional static VAR compensator(SVC)because of its greater reactive current output capability at depressed voltage,faster response,better control stability,lower harmonics,and smaller size,etc.Up to now,a great many successful applications of STATCOM equipment for voltage control and transient stability improvement have been reported in the literature.Conventionally,the STATCOM regulator is designed from a small-signal model at a given operating point.But the traditional controller suffers from the inadequacies of providing suitable control and transient stability enhancement over a wide range of power system operation conditions.The power system is a typical nonlinear system.Thus,it is reasonable to design the controller for STATCOM using nonlinear control theory.After having investigated the present research situation of STATCOM nonlinear controller,this dissertation studies on a series of effective nonlinear coordinated regulators for STATCOM inner-loop and outer-loop controllers by using fuzzy control(FC),sliding mode control(SMC), direct feedback linearization(DFL),etc.Besides,a DSP-based lab prototype model is built to validate the concepts of three-phase distribution level small capacity STATCOM and the control scheme proposed in this dissertation.The main content of this dissertation falls into the following seven parts:1.The system structure and operation principle of STATCOM are thoroughly investigated.Using in-out modeling and energy equations,a time domain and a steady state mathematical model of a STATCOM are developed.Based on the mathematical model,the fundamental running characteristic of STATCOM main circuit is analyzed.Aim at large capacity compensation situation,the design method of STATCOM multiple main circuit configuration and its control parameters are discussed.The results of simulative experiment are given to verify the feasibility of the main circuit scheme.2.Two-level structure control model of power system STATCOM controller is proposed. Firstly,two basic reactive current inner-loop control laws are derived.Based on Matlab/Simulink tools,a STATCOM device level control system is modeled.Then the digital simulation is carried out,the results illustrate that the model is correct and these control laws are effectiveness.Finally,concerning power system stability control,the outer-loop control system structure and voltage type control characteristics of STATCOM are comprehensively analyzed.These conclusions are necessary to the future study in the following sections.3.The stable region of one-machine infinite-bus power system with STATCOM is studied.According to the power system mathematic model,a damping-reflected energy function is derived with first integral.Based on the energy function,the system stable region is estimated,and some simulation results are given.The simulation results show the changing tendency of the system stable region is equivalent to reactive current capacity of STATCOM, which indicates STATCOM is beneficial for the system stable operation and efficiently expand the power system asymptotic stable region.4.A sliding mode controller(SMC)for STATCOM reactive current inner-loop control system is designed.Firstly,the reactive current control model is built up based on STATCOM device level nonlinear.mathematical model.The model is transformed into a linear system using direct feedback linearization(DFL)technique.Then a pole-placement method is employed to select a suitable sliding mode hyper plane,from which the variable structure control scheme considering disturbance is constructed.The chattering in the control signal is suppressed by replacing the sign function with a smoothing function in the control function. Finally,the control logic is evaluated in Matlab/Simulink,and the simulation results are compared with the traditional PID control design.It is shown that the proposed approach is superior to the traditional PID method in response performance,has stronger robustness against external disturbance.5.According to the nonlinear model of the power system including STATCOM,the paper presents the design of a nonlinear fuzzy sliding mode controller(FSMC)for STATCOM to enhance the transient stability performance of power system.For the three-order nonlinear system model,it is be transformed into a linear system by use of the DFL technique.Based on the linear sliding mode hyper plane designed by means of pole-placement method,a Mamdani-type fuzzy sliding mode control scheme is carried out. The parameters of the fuzzy controller can be varied widely by a suitable choice of membership functions and parameters in the rule base.In order to eliminate the control dead-zone of FSMC signal and improve voltage regulation accuracy,a proportional-integral (PI)regulator is implemented into the control system.The simulation results show the effectiveness and robustness of the proposed approach over a wide range of operating condition changes.6.A coordinated nonlinear controller of STATCOM and generator excitation is designed according to the DFL technique and the T-S type FSMC theory.The proposed coordinated controller can improve both the power angle stability of generator and the voltage behavior at the STATCOM location.The characteristics of the gain variation are parameterized and governed by the rule proportionality.The controller can provide suitable voltage control and transient stability enhancement over a wide rang of power system operating conditions.It is designed based on local measurements and possess good robustness.The simulating studies indicate the proposed coordinated controller can improve the accuracy of voltage control and strengthen the stability of power system.7.The algorithm of harmonic and reactive current detection by ip-iq method based on instantaneous reactive power theory is analyzed.Voltage Source Inverter(VSI)main circuit of small capacity STATCOM is introduced and its operational principles are deduced.The main circuit parameters design method and the current-track-method’s SVPWM control algorithm are presented.In order to meet the real time requirement of STATCOM with direct current control strategy to reference current acquisition,a hard circuit based on Digital Signal Processor(DSP)TMS320F2812 and Complex Programmable Logic Device(CPLD) EPM7128SLC is designed.The key hardware and software of system are presented.The algorithm simulation on three-phase ac circuit is done.Experimental results confirm the validity and feasibility of the proposed method.更多还原