模块化多相永磁风力发电机串并联直流海上风电场电压协调控制

为满足高电压、大功率、高可靠性的风电场直流输电系统电能传输需求,该文提出基于模块化多相永磁风力发电机的新型串并联直流海上风电场拓扑,以及模块化多相永磁风力发电机串并联直流海上风电场电压协调控制方法。首先,建立基于模块化多相永磁风力发电机的直流风力发电系统数学模型,设计了模块化多相永磁风力发电机无差拍功率预测控制器,来提升dq轴电流跟踪精度和动态响应速度,并补偿无差拍预测控制器中的单拍延迟;然后,针对模块化多相永磁同步发电机串并联拓扑结构特点,提出一种考虑直流风电场潮流的功率-电压协调控制策略,通过实时调节风机的有功功率参考值,来抑制串并联直流风电场的风机过电压;最后,搭建了基于模块化多相永磁风力发电机的3×6×5 MW串并联直流海上风电场的模型,来验证所提无差拍功率预测控制和功率-电压协调控制的有效性。     

新型IGBT驱动器测试分析及其在同步发电机开关式励磁系统中的应用

介绍了IGBT驱动的要求，列举了目前广泛使用的IGBT驱动器的一些不足，提出了测试IGBT驱动器性能的几种方法，并对新型IGBT驱动TX—KA101进行了测试。测试结果表明，TX—KA101输出驱动电压合理，具有IGBT过流三段式保护，慢关断时间和过压保护阚值可调。最后将TX—KA101应用到同步发电机开关式励磁系统中，起励和士10％扰动试验表明TX—KA101满足该系统IGBT驱动的要求。     

NPC型三电平永磁同步风力发电并网逆变器模型预测控制满足低电压穿越要求研究

在风力发电中低电压穿越要求为:当电网电压降落的时候,风力发电机不脱网且能够稳定电网电压和频率。风力发电机需要较高的功率和电压等级。因此,多电平中中点箝位型三电平逆变器非常适合这种设备。和其它控制方法相比,模型预测控制具有动态响应快和跟踪性能好的优点,但是工作频率低。为了能够满足低电压穿越的要求,提出一种模型预测控制方法实现NPC三电平逆变器的风力转换。所提模型预测控制也能够实现NPC逆变器中点平衡控制,通过选择冗余小矢量实现。仿真和实验验证了所提算法正确性。     

IR推出三相逆变器驱动器集成电路

国际整流器公司(简称IR)最近推出IR2136三相逆变器驱动器集成电路系列，可简化变速电机驱动器设计。新器件集成了6个MOSFET或IGBT高电压栅驱动器，并融合多元化的保护功能，系统成本比光耦解决方案降低30％。     

永磁风力发电系统的变拓扑晶闸管整流器控制策略

为了克服电力电子器件尤其是绝缘栅双极晶体管(IGBT)对风电机组功率容量和电压等级的束缚,提出了一种适用于六相双Y永磁同步发电机的风力发电变流装置。该装置将变拓扑结构的晶闸管整流桥和三电平逆变器分别作为前端和后端。前端整流器中,2个三相晶闸管整流桥之间的串并联关系可通过二极管与开关组成的辅助电路在运行过程中进行动态切换。在低风速时,2个整流桥串联,提升输入电压;在高风速时,2个整流桥并联,扩大功率容量,以适应风力发电机输出电压的宽范围变化。新型电流峰值控制方法替代了传统比例积分(PI)控制方法,消除了变结构可能造成的电流突变,实现了动态运行中拓扑结构的无缝切换。三电平逆变器在发电机接近额定功率时根据风力机转速线性提高母线电压,使得整流器相位移因数保持稳定,提高功率因数。实验结果验证了原理的正确性和装置的可行性。     

对IGBT逆变器吸收电路的改进与仿真

本文在分析了传统IGBT逆变器吸收电路特点和工作原理的基础之上,结合IGBT在高频应用场合的开关特性,对传统IGBT逆变器吸收电路进行了改进.经过改进的IGBT逆变器吸收电路能够通过改变放电回路的放电电容,缩短吸收电容放电时间,在不降低吸收过电压效果的基础上,提高IGBT的工作频率,满足了IGBT逆变器在高频应用下的要求.最后,通过理论分析和电路仿真,验证了改进型吸收电路的有效性和适用性.     

变流器中IGBT驱动器的共模干扰影响因素研究

对逆变桥臂中IGBT的U_(ce)电压跳变所引起的共模干扰对驱动器的影响因素进行了分析和验证。建立了含有IGBT驱动器寄生电容的逆变侧共模回路等效模型,推导了流经IGBT驱动器中的共模电流与dU_(ce)/dt及驱动器原、副边寄生电容的影响关系方程。设计了一款寄生电容很小的驱动器进行了实验验证,结果与理论分析相吻合。提出的共模电流等效模型和实验结果对大功率变流器中IGBT驱动器的抗干扰及可靠性设计有一定的指导意义。     

外转子永磁同步风力发电机运行工作点的研究

随着高性能永磁材料的发展，永磁同步发电机在各类发电机中越来越具有竞争力。例如风力发电装置中对大功率风力发电机的需求越来越多。论文对外转子低速永磁同步风力发电机运行工作点进行了研究，并对其结构和优越性进行了分析。     

大功率永磁同步风力发电机电磁与温度特性分析

海上风电正在成为风力发电产业发展的主要方向,而随着装机容量的逐渐增加,大功率永磁风力发电机正成为国内外学者的研究热点。而目前对风力发电机的研究多集中在3MW以下的中等功率的样机,针对大功率的永磁风力发电机尚缺少相应的设计经验和参考。本文以7.6MW的永磁同步风力发电机为研究对象,对大功率永磁风力发电机的电磁特性进行了详细的分析,包括空载电磁特性、有无斜槽时的转矩波动与谐波分析、负载转矩波动等。同时对大功率的永磁风力发电机设计了冷却方案,基于3D有限元法对该电机的温度特性进行了详细的分析。在此基础上,加工了两台7.6MW样机,通过两台样机的对拖实验,验证了本文的理论分析。     

IGBT并联特性的研究与仿真

为满足大功率逆变器的设计需要,针对功率器件IGBT并联使用时的工作特性进行了研究.主要分析了驱动电路和器件各参数不理想时对IGBT并联工作产生的不利影响,重点研究了电流分配、安全工作范围、散热以及寄生振荡等关键问题.最后结合仿真结果,提出保证多个IGBT并联工作的合理建议.     

分布式电源接入的配电系统多类型无功源出力优化方法

同时考虑光伏发电系统、风电机组、静止无功发生器、并联电容器等多类型无功源的协同运行问题,建立多类型无功源协同运行的优化模型,增强了无功协调能力和优化效果。研究了光伏逆变器无功的调节原理和双馈电机风力发电系统无功调节能力。考虑光伏发电系统和风电机组的无功特性,构建向分布式电源和静止无功发生器的输出或吸收无功功率的约束条件函数。采用潮流雅可比矩阵直接变换求取灵敏度系数,构建基于线性规划的分布式电源、并联电容器和静止无功发生器输出无功功率的约束域及其罚函数。通过潮流雅可比矩阵进行矩阵变换,构建考虑有功网损最小化的目标函数灵敏度系数的线性化模型。采用两阶段单纯形法对优化问题进行求解,获得了好的效果。     

Characteristics of Parallel Operation of Inverter‐Type Distributed Generators Operated by a Virtual Synchronous Generator

The capacity of distributed generators (DGs) connected to a grid by inverters is growing. The inverters are generally controlled by a phase locked loop (PLL) in order to achieve synchronization with the power system frequency. They cannot have synchronous power. Power systems become unstable if the capacity of the inverter‐type DGs is increased. The concept of controlling inverters to behave like a synchronous generator is studied in this paper. The result is referred to as a “virtual synchronous generator” (VSG). The VSG has synchronous power. Power systems become stable as a result of using the VSG. The VSG is useful in the parallel operation of DGs. The VSG can synchronize with other VSGs, synchronous generators, or the grid. In this paper, a method for the synchronous operation of a VSG is studied, and experimental results on a VSG running in parallel with a synchronous generator and other VSGs are presented.     

鼠笼异步风机和双馈风机低电压渡过能力对电网电压影响的研究

为了电力系统的安全稳定运行,电网安全运行准则要求风力发电机组在电网故障引起电压跌落时具有一定的低电压运行能力。文章通过一个实例,研究鼠笼异步风机和双馈风机在电网发生故障后风机并网运行与否对电网电压的影响,发现在电压恢复过程中,双馈风机由于具有无功调节能力可向电网发出无功功率,而鼠笼异步风机则吸收无功功率,对电网电压的恢复起负面作用。这就要求电网规划设计中应减少鼠笼异步风机装机容量的比例,同时采取动态无功补偿的措施,以降低鼠笼异步风机在电网发生故障后恢复过程中并网运行对电网电压的负面影响,满足电网对于风力发电系统的要求。     

Stabilization of a Power System Including Inverter‐Type Distributed Generators by a Virtual Synchronous Generator

The capacity of distributed generators (DGs) connected to the grid by inverters is growing year after year. The inverters are generally controlled by a phase locked loop (PLL) in order to achieve synchronization with the power system frequency. Power systems may become unstable as the capacity of the inverter‐type DGs continues to increase, because the inverter frequency is controlled just to follow the frequency determined by other synchronous generators. It has been suggested that inverters be controlled to behave like a synchronous generator. This concept is referred to as the virtual synchronous generator (VSG). In this paper, a control scheme for a VSG is presented, and the design method for the required energy storage and the capacity for grid stabilization control by a VSG is investigated by computer simulations.     

基于模式切换的逆变器与发电机并联控制策略

随着新能源技术的发展,偏远山区、海岛等独立电力系统越来越多地采用新能源发电设备与柴油发电机混合供电方式。针对这类系统中新能源逆变器单独供电、与柴油发电机并联供电的功能需求,以逆变器单独供电时采用电压源控制、与柴油发电机并联时采用电流源控制为基础,提出基于逆变器控制模式切换和柴油发电机准同期并联相结合的控制策略,解决逆变器与柴油发电机并联过程的控制问题,电磁暂态时域仿真和1∶1样机物理实验验证了该控制策略的有效性。     

高频条件下对IGBT逆变器缓冲电路的改进

绝缘栅双极晶体管（IGBT）逆变器多应用在变频器、开关电源和分布式发电系统等工作频率较高的场合。逆变器工作频率越高,缓冲电路吸收的过电压能量在开关器件下一次关断动作前放电完毕的时间就越短。提出了一种改进型IGBT逆变器缓冲电路,通过改变放电回路的放电电容,可以满足IGBT逆变器在高频应用下的要求。通过理论分析和电路仿真,证明了该改进型缓冲电路的有效性和适用性。     

SUPERCONDUCTING LOW VOLTAGE DC TRANSMISSION NETWORKS

ABSTRACT

A new paradigm for electric power transmission based on high temperature superconducting dc. networks is studied as a feasible alternative to ac power transmission systems. The dc network operates at generation voltages allowing for direct connection of the generators to the rectifiers, eliminating the need for high voltage insulation and transformers. The overall system consists of a mesh connected, low voltage, high current dc superconducting transmission system, supplied by unit connected generators and feeding many small inverters to pass controlled levels of real and reactive power to ac loads. This paper introduces the concept of a superconducting dc mesh. Inverter topologies and control strategies required for interfacing the ac distribution systems to the dc mesh. The paper presents a conceptual overview of the operation of the system based on simulation studies.     

Iron Loss Characteristics of Electrical Steel Sheet under Inverter Excitation by Power Semiconductor with Extremely Low On‐Voltage Property

In this study, it is demonstrated that the iron loss from the SiC‐MOSFET, which represents a new power semiconductor with an extremely low on‐voltage for electric machine drives, is almost the same as that from an Si‐IGBT, which is a conventional power semiconductor. In order to evaluate the iron loss characteristics when an SiC device is used, two single‐phase pulse width modulation inverters were built and used for the excitation of a ring made up of electrical steel sheet. One of the inverter employed an SiC‐MOSFET, and the other inverter employed an Si‐IGBT. The iron losses for the two inverters are compared.     

New control for HVDC system connected to large windfarm

HVDC consisting of self‐commutated inverters is able to be applied for power transmission connecting from a remote large windfarm to a weak AC system. Most self‐commutated HVDC is applied for connection between two AC systems that have synchronous power sources, but it is not suitable for a windfarm that consists of induction generators without synchronous power source. This paper presents new control for the self‐commutated HVDC system connected to a large windfarm of induction generators. The effect of the proposed control is shown by EMTP simulation. ©2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 31–39, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20539     

一种新型的UPFC拓扑

提出了统一潮流控制器的一种新型拓扑,它包含两个交流侧面对面连接,而不是通过公共直流环节背对背连接的逆变器.该新型结构具有以下优点:1)两个逆变器间没有有功功率交换,两个逆变器仅提供或吸收无功功率;2)级联式逆变器可以用于这种结构,因而取消了传统的磁接口--曲折变压器,大幅度减少了功率损耗;3)在许多负载情况下,所需要的逆变器容量可以大大减少;4)模块化的级联式逆变器和它的冗余性使得这种新型结构更具设计的灵活性和实现的可靠性.仿真结果清楚表明:在所需的容量方面,新型拓扑比传统拓扑更具优势,实用,实现更容易.