多电平大功率逆变电源的研制

分析了多电平大功率逆变电源的控制原理,提出一种新型的适用于大功率逆变电源的控制方案。该方案将单个功率单元的二重化SPWM技术与功率单元多重叠加技术相结合,可减少开关损耗,改善输出波形,降低输出电压的谐波畸变率;对所研究的控制方法进行了仿真,通过硬件实验进一步验证了控制原理及仿真结果的正确性。     

A novel step-up topology for multilevel power conversion

Renewable energy sources employ a power conditioning unit for injecting power into the grid. Such resources of small capacity are characterized by low generated voltage and thus require a high voltage boost at the inversion stage. This paper proposes a novel transformer-less, single-phase grid-connected, 13-level inverter to yield the voltage boost. The presented topology is realized through 12 unidirectional switches, 2 diodes, and 3 capacitors. A single-stage circuit synthesizes 13 levels with a single input source and yielding an overall voltage gain of six. The adapted modulation technique is robust enough to keep the capacitors self-balanced for all values of the modulation index. The proposed topology is modular and cost-effective in comparison to other similar typologies due to reduced device count and space requirement. The presented topology is validated experimentally with satisfactory operation in yielding input voltage boost by a factor of six.     

基于单级多电平开关变流的超大容量海上风电变流器

海上风机正向超大容量方向发展,基于较低电平数目变流技术的风电变流器在电压、容量等级的提升方面受到限制。提出了基于单级多电平开关变流的超大容量海上风电变流器方案,采用直流电压可大范围调节的宽直流电压模块化多电平变流器(MMC),在单级多电平变流器中实现DC/DC和DC/AC两级变换功能。基于风电变流器的单向功率传输特性,采用单向电流型宽直流电压MMC优化开关器件用量,并基于负电平利用优化调制比大幅降低MMC的子模块电容用量。所提出的方案不仅具有电压与容量等级高、功率损耗低、谐波含量低的优势,还能最大限度降低开关器件和电容的用量。与现有风电变流器方案进行对比,结果表明所提方案在经济性、运行性能等方面具有显著优势。通过仿真验证了所提方案拓扑结构和控制策略的可行性和有效性。     

Improved multilevel bipartitioning for controlled power system islanding

Nowadays interconnected power systems work close to their limits because of increased economic benefits. If a severe disturbance occurs in any part of the interconnected power system, it can be propagated through it. If no intelligent supervisory action is taken, a power system may be driven into an emergency state which could either cause system collapse by natural islanding or total system blackout. One possible measure to be put in effect in an emergency state is controlled power system islanding. In this paper, our previously proposed multilevel approach for controlled islanding is improved by using slow coherency grouping of generators in the aggregation phase. The approach has been applied to the IEEE 118 bus power system. The results indicate that the best partitioning of the power system is obtained with minimum generation/load imbalance in the islands, and with the coherent groups of generators maintained in each island making the restoration easy. A comparison of the computational complexities involved in the spectral, multilevel kernel k‐means and the improved multilevel approaches is made by applying these methods to the IEEE 9 bus, the IEEE 30 bus, the IEEE 39 bus, the IEEE 57 bus, the IEEE 118 bus, the IEEE 300 bus, the 2383 bus Polish and the 2746 bus Polish power systems to show the suitability of the proposed approach for controlled islanding of large‐scale power systems. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

高轨大功率卫星电源系统的MPPT技术

针对高轨大功率卫星的环境特点,对空间电源系统设计开展研究。高轨大功率卫星通常采用直接能量传输(DET)方式的电源系统,为保证卫星寿命末期电源系统的功率输出,通常把太阳电池方阵寿命末期的最大功率点设在母线电压附近,这就导致卫星寿命初期太阳能的利用率较低,提出了一种控制方法,保持DET电源系统的高传输效率优势的同时,采用分段固定电压最大功率跟踪(MPPT)技术,实现太阳电池方阵始终接近最大功率输出,从而寿命初期的能源利用率远高于其他形式的电源系统。     

日本电力市场的新竞争机制及绿色电力制度

1　电力市场的竞争机制日本国内电力需求以 2 %左右的速度逐年增加 ,政府每年投入电力生产的设备费用约为 4兆日元 ,并作为电力生产成本计入基本电价。日本国内现有东京电力、关西电力、中部电力、中国电力、东北电力、四国电力、北陆电力、九州电力、冲绳电力和北海道电力 1 0     

基于Web的电力系统数据模型转换

为提高不同厂商提供的电力系统规划软件包的使用效率,实现电力企业的电网模型数据共享,设计了基于Web的电力系统数据转换应用(WebCPS)。分析了WebCPS的技术途径,系统建立在客户端、Web服务器、数据库服务器3层结构上,其中数据库根据银河科技调度自动化系统YH-9000系列数据模型(YH-DM)构造,软件采用组件技术实现;分析了用户接口组件和数据转换组件的构成,当公共信息模型(CIM)的数据文件上载后,系统将调用网络拓扑处理(NTP)组件分析电网模型,创建拓扑岛,网络拓扑处理结果将映射到相应的计算模型;讨论了系统的性能,即系统响应时间和最大文件大小;指出可通过增加数据模型调整、数据模型归并等方式提升系统性能。     

Evaluation of alternatives for power system coordination andpooling in a competitive environment

The paper defines and classifies essential issues that relate the need for electric power system coordination with the increasing development of competition. Principles are formulated and a coordination model and a market structure are proposed, emphasizing the need for economic dispatch in the wholesale market. A detailed comparison is made of the market and pooling implementations developed in Argentina and Chile, countries that have pioneered the creation of competitive markets in the electric energy sector. An evaluation of strengths and weaknesses of those two implementations is included     

Imperialist competitive algorithm for optimal STATCOM design in a multimachine power system

A new optimization technique, Imperialist Competitive Algorithm (ICA), which is inspired from socio-political phenomenon of imperialistic competition, is proposed in this paper for optimal design of static synchronous compensator (STATCOM) in a multimachine environment. PV curves are illustrated to deduce the best location of STATCOM. The STATCOM parameter tuning problem is converted to an optimization problem which is solved by ICA. The performance of the proposed ICA based STATCOM (ICASTATCOM) is compared with Genetic Algorithm (GA) based STATCOM (GASTATCOM) and open loop STATCOM under various operating conditions and disturbances. The superiority of the proposed technique in damping oscillations and enhancing voltage profiles over a wide range of operating conditions and system configurations is confirmed through eigenvalues and time domain simulation results.     

Direct power control of a multilevel inverter based active power filter

A cascaded H-bridge multilevel inverter based active power filter with a novel direct power control is proposed in this paper. It can be directly connected to medium/high voltage power line without using the bulky transformer or passive filter. Due to the limited switching frequency (typically below 1 kHz) of high-power solid-state devices (GTO/IGCT), multiple synchronous/stationary reference frame current controllers are reviewed and derived. Based on this, a novel current controller is proposed for harmonic current elimination and system power factor compensation. Furthermore, a synchronous/stationary hybrid structure can be derived with fundamental de-coupling control. The instantaneous reactive power theory and synchronous reference frame based control are compared based on mathematical models. A direct power control concept is then derived and proposed. It is equivalent as the hybrid synchronous/stationary frame current controller, but has a simpler implementation. It has clear physical meaning and can be considered as a simplified version of the hybrid frame current controller. Simulations on a 4160 V/1.2 MVA system and experimental results on a 208 V/6 kVA laboratory prototype are presented to validate the proposed active power filter design.     

基于LCL滤波器的双向储能变流器研究

为了在中/大型功率并网系统中引入更具优势的LCL滤波器,必须采用特殊的控制策略对LCL滤波器引入的谐振峰加以抑制。从节省双向储能变流器系统成本的角度,提出了一种基于滤波电容电流内环、并网电流外环的双环控制策略。从主电路的参数设计、控制器的参数设计、控制器的性能分析3个方面对策略进行了详细的阐述,并给出了先内环后外环的参数设计方法。搭建了一台50 kW的双向储能变流器作为试验样机,通过实验证明了所提控制策略不仅可以保证LCL滤波器稳定工作,而且可以减小并网电流谐波。     

电力系统静态安全混合控制方法

提出一种将预防控制和校正控制相协调的电力系统静态安全混合控制方法。预防控制模块中,利用风险指标确定进入预防控制模块的预想故障集,该风险指标考虑了预想故障发生的概率及其严重性,采用连续线性规划技术求解考虑多预想故障的静态安全预防控制策略。校正控制模块中,首先判断系统静态安全裕度是否满足要求,并考虑风电/光伏的随机波动特性,针对不安全故障分别制定校正控制策略。所提方法通过系统风险指标协调预防控制和校正控制中考虑的预想故障集,从而将预防控制和校正控制相互协调,以获得安全性和经济性均满足系统需求的静态安全控制策略。以我国某682节点系统的算例验证了所提方法的有效性。     

板级电源系统ADM1166的电源管理应用研究

电源是影响电子产品可靠性和耐用度的重要指标。产品性能的提升在很大程度上依赖于电源管理技术,因此需要从系统上对电源进行综合管理。基于电源管理芯片ADM1166,研究了电源管理的基本功能,包括多电源上电时序控制、电源电压异常监控功能,并研究了电源电压在线调节功能。结合实际的应用案例,对上述功能进行了测试和验证。     

Transfer function identification in power system applications

The authors present an introduction to concepts and applications of transfer function identification in power systems. They begin with a brief introduction to transfer function identification methods using least-squares approaches and then discuss applications which include static VAR compensators, model validation applications, and software validation. A comparison is also made between eigenvalues obtained from transfer function identification and small signal analysis. Methods for testing the validity of identified transfer functions are also discussed     

Wavelet transform applications in power system dynamics

This paper proposes the use of the discrete wavelet transform (DWT) to analyze and locate the low frequency oscillations of power systems, which can result in a loss of stability or in a black-out. The proposed DWT applied to active power signal is tested and compared with more conventional approaches of Prony and Eigenvalue analyses. The DWT also enables estimation of the total active power imbalance of a system. Estimation performances of different wavelet families are tested. Based on the proposed DWT of electromechanical transient oscillations, the DWT is also applied to identify the network nodes in the neighbourhood of the original disturbance. The performance of the proposed DWT is evaluated on the New England (NE) 39-bus test system.     

基于双星型多电平潮流控制器与YNvd变压器的同相供电系统

针对高速电气化铁路领域中存在的负序、谐波与电分相问题,提出了一种基于双星型多电平潮流控制器与YNvd平衡变压器的新型铁路同相供电系统。该双星型多电平潮流控制器为交交变换结构,由四个多电平级联型H桥子模块链节组成,无需直流母线电容。与潮流控制器两端均通过降压隔离变压器连接于变压器二次侧的传统作法不同,该系统将双星型多电平潮流控制器的一侧连接于YNvd平衡变压器二次侧?相分接头,减少了一个降压隔离变压器的成本。分析了该同相供电系统的拓扑结构与工作原理,提出了一种综合控制策略,最后通过仿真验证了所提方案的可行性与有效性。     

Bulk power system reliability concepts and applications

While it is pointed out that probabilistic methods for the reliability assessment of composite generation and bulk transmission in electric power systems are still under development, an overview is given of the purposes and uses of power systems reliability studies. Probabilistic indices and reliability criteria are discussed. The features of a comprehensive reliability program to compute these indices are listed, and of these features, those required in selected applications are examined. Modeling and computational difficulties are discussed, and the necessity of balancing program accuracy and computing effort is stressed     

Control of a hybrid asymmetric multilevel inverter for competitive medium-voltage industrial drives

In symmetric multilevel inverters, there is a tradeoff between the output quality and the reliability and efficiency of the converter. New asymmetric and hybrid solutions, using different voltages and devices in various parts of the inverter, promise significant improvements for medium-voltage industrial drives. This paper investigates such a hybrid asymmetric nine-level inverter. It consists of a three-phase three-level integrated gate-commutated thyristor inverter (main inverter), with a two-level insulated-gate bipolar transistor H-bridge (subinverter) in series with each phase. To keep the power part simple and the efficiency high, the subinverters have no feeding from the net and can only supply reactive power. This is a very interesting solution in terms of power quality, efficiency, reliability, and cost. But the nonsupplied intermediate-circuit capacitors form an unstable system. This paper proposes a control method to stabilize their voltages. Power balancing is guaranteed by varying the common-mode voltage, using an online nonlinear model-predictive controller. The controller predicts the system evolution as a function of the control inputs. A cost function of system and control quantities is iteratively minimized in real time, to find the optimal control to apply to the system. Simulations and measurements demonstrate stable behavior in steady state and during transients. Precharging of the nonsupplied capacitors is also an issue to consider. This paper proposes a startup method that charges them in parallel with the supplied ones, without any additional equipment. Measurements show its successful application in the proposed drive system.     

多逆变器模块并联驱动的大功率无线电能传输系统研究

针对传统单个逆变器驱动的无线电能传输系统（WPT）输出功率有限的问题,提出了一种多逆变器模块并联驱动的大功率无线电能传输系统,并对多逆变器模块并联的拓扑结构和各模块间的环流进行了分析。为了解决逆变器并联时产生的环流问题,提出了基于主从策略的相位同步控制方法,通过从逆变器输出电压和发送端电流相位差同步于主逆变器输出电压和发送端电流相位差实现逆变器模块间的相位差补偿。研制了三个逆变器模块并联驱动的无线电能传输系统样机,实验结果表明,在500V直流输入时,负载端获得功率约为20kW,传输效率达94%,且各逆变器输出电压相位实现同步,证明了相位同步控制方法的有效性。