基于级联H桥的STATCOM及其控制策略研究
发布时间：2018-08-07 08:18
【摘要】：近年来，配电网中迅速增多的非线性、冲击性及不平衡负荷，带来了很多电能质量问题。这些问题中尤以无功、谐波及三相不平衡问题最为突出。静止同步补偿器(static synchronous compensator，STATCOM)作为当前最先进的无功补偿装置，可以同时解决上述问题。H桥级联型STATCOM因具备诸多优点，在配电网中有广阔的应用前景。本文对H桥级联型STATCOM的一些关键问题进行了研究。 为使配电网STATCOM具备综合补偿能力，论文首先研究了适用于完全补偿的指令电流检测算法，对其中较常用的p q法、同步旋转坐标变换法及FBD法进行了分析比较，指出了各自的优缺点并给出了相应改进方法。详细的仿真实验验证了上述改进方法的有效性。为使STATCOM能够提供更加灵活的补偿功能，论文还研究了适用于选择性补偿的检测算法，在分析常用选择性指令电流检测算法优缺点的基础上，提出了一种同步旋转坐标变换及递归离散傅立叶变换相结合的检测算法，仿真实验证明该算法具有较高的检测精度及较好的动态性能。 STATCOM进行综合补偿时，传统的比例积分(PI)控制很难消除稳态误差。为此，论文采用谐振控制器来实现指令电流跟踪控制，为减少控制器数量，选择在同步旋转坐标系下应用谐振控制器，分别对基于传统谐振控制器的PI R控制器及基于矢量比例积分(vector proportion integral，VPI)控制器的PI VPI控制器进行了研究。通过详细的分析比较，论证了PI VPI控制器的优良性能。论文给出了相关参数设计方法，并对VPI控制器的离散化方法进行了详细分析，得出了最佳的离散化方法。 为了使控制器更加简化，论文还研究了基于重复控制器的指令电流跟踪控制策略。为了解决重复控制器动态响应慢的问题，提出了一种重复控制器与PI控制器串联的双闭环控制系统。为了解决重复控制器频率适应性差的问题，采用了一种基于固定采样点数的软件锁相环策略。仿真结果表明，使用该方法具有很好的补偿效果，且频率适应性很好。 讨论了PWM调制策略，通过对比多电平变换器常用的载波移相及载波层叠PWM方法，指出同向载波层叠PWM法具有较好的输出特性，且相对更加简单，更易于实际应用。在此基础上，采用了一种改进的同向载波层叠PWM方法，使用该方法时，载波数量可比采用普通方法减少一半，从而简化了设计。 针对级联型STATCOM直流侧电压的建立过程，论文提出一种软起控制策略，可使电容电压从零平稳上升到参考值，且整个过程中，装置都不会产生很大的冲击电流，从而确保了装置的安全启动。针对正常运行过程中的直流侧电容电压均衡控制问题，通过总体控制、相间均压和相内均压三种措施来平衡直流侧电容电压，可以很好地解决直流侧均压问题。论文采用零序电压注入法解决了相间均压问题。针对采用同向载波层叠PWM方法的STATCOM，本文根据直流侧电容电压的高低实时调整调制波分配规则，从而实现逆变桥自身能量平衡，，解决了直流侧电容相内均压问题，同时还解决了各功率单元开关频率不均的问题。最后通过仿真验证了本文所提方法的有效性。 论文以6kV±3MVar STATCOM为例，对H桥级联型STATCOM的软硬件设计进行了介绍。通过搭建实验平台，对装置的无功补偿及谐波补偿性能进行了测试，还测试了选择性补偿功能。最后给出了STATCOM装置投入实际工业应用的效果。实验及工程应用表明本文所设计的STATCOM装置可以取得很好的补偿效果，验证了本文所提控制策略的合理性及可行性。
[Abstract]:In recent years, the rapid increase of nonlinear, impact and unbalanced load in distribution network brings a lot of energy quality problems. Among these problems, the problems of reactive power, harmonic and three-phase unbalance are the most prominent. Static synchronous compensator (STATCOM), as the most advanced reactive power compensation device, can be solved simultaneously. In order to solve the above problems,.H bridge cascaded STATCOM has a wide application prospect in distribution network because of its many advantages. This paper has studied some key problems of cascaded STATCOM with H bridge.
In order to make the distribution network STATCOM have comprehensive compensation ability, this paper first studies the instruction current detection algorithm which is suitable for complete compensation. It compares the common p q method, synchronous rotation coordinate transformation method and FBD method, points out their advantages and disadvantages and gives the improved method. The detailed simulation experiment verifies the above. The effectiveness of the improved method. In order to provide more flexible compensation function for STATCOM, the paper also studies the detection algorithm suitable for selective compensation. On the basis of analyzing the advantages and disadvantages of the commonly used selective instruction current detection algorithm, a detection algorithm combining synchronous rotating coordinate transformation and recursive discrete Fu Liye transform is proposed. Simulation results show that the algorithm has higher detection accuracy and better dynamic performance.
When STATCOM is compensated, the traditional proportional integral (PI) control is difficult to eliminate the steady-state error. Therefore, this paper uses the resonant controller to realize the command current tracking control. In order to reduce the number of controllers, the resonant controller is applied in the synchronous rotating coordinate system, and the PI R controller based on the traditional resonant controller and the vector based on the vector are selected. The PI VPI controller of the proportional integral (vector proportion integral, VPI) controller is studied. Through the detailed analysis and comparison, the excellent performance of the PI VPI controller is demonstrated. The design method of the relevant parameters is given in this paper, and the discrete method of the VPI controller is analyzed in detail, and the best discretization method is obtained.
In order to make the controller more simplified, this paper also studies the command current tracking control strategy based on repetitive controller. In order to solve the problem of slow dynamic response of repetitive controller, a double closed loop control system with repeated controller and PI controller is proposed. In order to solve the problem of frequency adaptability of repetitive controller, a new control system is adopted. A software phase-locked loop (PLL) strategy based on fixed sampling points is proposed. Simulation results show that this method has good compensation effect and good frequency adaptability.
The PWM modulation strategy is discussed. By comparing the carrier phase shift and carrier layer PWM method commonly used in multilevel converters, it is pointed out that the same direction carrier layer PWM method has better output characteristics, and is relatively simpler and more practical. On this basis, an improved same direction carrier stack PWM method is adopted, and the number of carrier number is used when this method is used. The volume can be reduced by half by the common method, thus simplifying the design.
For the establishment of cascaded STATCOM DC side voltage, a soft start control strategy is proposed in this paper, which can make the capacitor voltage rise from zero to the reference value. In the whole process, the device will not produce a large impact current, thus ensuring the safe start of the device. The problem is to balance the DC side capacitance voltage by three measures, including overall control, phase mean pressure and phase mean pressure. The problem of DC side mean voltage can be solved well. The paper adopts zero sequence voltage injection method to solve the problem of interphase mean pressure. In this paper, the high and low voltage of DC side capacitance is based on the STATCOM of the same direction carrier cascading PWM method. The regulation of modulation wave distribution is adjusted to realize the energy balance of the inverter bridge, and the problem of the voltage equalizing in the capacitor phase of the DC side is solved. At the same time, the problem of the switching frequency of each power unit is solved. Finally, the effectiveness of the proposed method is verified by the simulation.
Taking 6kV + 3MVar STATCOM as an example, this paper introduces the hardware and software design of cascade STATCOM of H bridge. By building an experimental platform, the reactive power compensation and harmonic compensation performance of the device are tested, and the selective compensation function is tested. Finally, the effect of the application of the STATCOM device to the actual industrial application is given. The experimental and engineering application tables are given. It is shown that the STATCOM device designed in this paper can achieve good compensation effect, which verifies the rationality and feasibility of the control strategy proposed in this paper.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM761
本文编号：2169435
[Abstract]:In recent years, the rapid increase of nonlinear, impact and unbalanced load in distribution network brings a lot of energy quality problems. Among these problems, the problems of reactive power, harmonic and three-phase unbalance are the most prominent. Static synchronous compensator (STATCOM), as the most advanced reactive power compensation device, can be solved simultaneously. In order to solve the above problems,.H bridge cascaded STATCOM has a wide application prospect in distribution network because of its many advantages. This paper has studied some key problems of cascaded STATCOM with H bridge.
In order to make the distribution network STATCOM have comprehensive compensation ability, this paper first studies the instruction current detection algorithm which is suitable for complete compensation. It compares the common p q method, synchronous rotation coordinate transformation method and FBD method, points out their advantages and disadvantages and gives the improved method. The detailed simulation experiment verifies the above. The effectiveness of the improved method. In order to provide more flexible compensation function for STATCOM, the paper also studies the detection algorithm suitable for selective compensation. On the basis of analyzing the advantages and disadvantages of the commonly used selective instruction current detection algorithm, a detection algorithm combining synchronous rotating coordinate transformation and recursive discrete Fu Liye transform is proposed. Simulation results show that the algorithm has higher detection accuracy and better dynamic performance.
When STATCOM is compensated, the traditional proportional integral (PI) control is difficult to eliminate the steady-state error. Therefore, this paper uses the resonant controller to realize the command current tracking control. In order to reduce the number of controllers, the resonant controller is applied in the synchronous rotating coordinate system, and the PI R controller based on the traditional resonant controller and the vector based on the vector are selected. The PI VPI controller of the proportional integral (vector proportion integral, VPI) controller is studied. Through the detailed analysis and comparison, the excellent performance of the PI VPI controller is demonstrated. The design method of the relevant parameters is given in this paper, and the discrete method of the VPI controller is analyzed in detail, and the best discretization method is obtained.
In order to make the controller more simplified, this paper also studies the command current tracking control strategy based on repetitive controller. In order to solve the problem of slow dynamic response of repetitive controller, a double closed loop control system with repeated controller and PI controller is proposed. In order to solve the problem of frequency adaptability of repetitive controller, a new control system is adopted. A software phase-locked loop (PLL) strategy based on fixed sampling points is proposed. Simulation results show that this method has good compensation effect and good frequency adaptability.
The PWM modulation strategy is discussed. By comparing the carrier phase shift and carrier layer PWM method commonly used in multilevel converters, it is pointed out that the same direction carrier layer PWM method has better output characteristics, and is relatively simpler and more practical. On this basis, an improved same direction carrier stack PWM method is adopted, and the number of carrier number is used when this method is used. The volume can be reduced by half by the common method, thus simplifying the design.
For the establishment of cascaded STATCOM DC side voltage, a soft start control strategy is proposed in this paper, which can make the capacitor voltage rise from zero to the reference value. In the whole process, the device will not produce a large impact current, thus ensuring the safe start of the device. The problem is to balance the DC side capacitance voltage by three measures, including overall control, phase mean pressure and phase mean pressure. The problem of DC side mean voltage can be solved well. The paper adopts zero sequence voltage injection method to solve the problem of interphase mean pressure. In this paper, the high and low voltage of DC side capacitance is based on the STATCOM of the same direction carrier cascading PWM method. The regulation of modulation wave distribution is adjusted to realize the energy balance of the inverter bridge, and the problem of the voltage equalizing in the capacitor phase of the DC side is solved. At the same time, the problem of the switching frequency of each power unit is solved. Finally, the effectiveness of the proposed method is verified by the simulation.
Taking 6kV + 3MVar STATCOM as an example, this paper introduces the hardware and software design of cascade STATCOM of H bridge. By building an experimental platform, the reactive power compensation and harmonic compensation performance of the device are tested, and the selective compensation function is tested. Finally, the effect of the application of the STATCOM device to the actual industrial application is given. The experimental and engineering application tables are given. It is shown that the STATCOM device designed in this paper can achieve good compensation effect, which verifies the rationality and feasibility of the control strategy proposed in this paper.
【学位授予单位】：中国矿业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TM761
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