Robust sparse network equivalent for large systems: part I-methodology

This paper deals with the calculation of a sparse network equivalent (SNE) for the analysis of electromagnetic transients in large systems. The main feature of the new approach is the enforcement of sparsity, stability, passivity, and accuracy at specific frequencies of the equivalent. The procedure is based on time-domain fitting with quadratic programming to enforce the constraints. The SNE can be interfaced with transient calculation programs directly in time domain. Results are presented in the companion paper.     

基于黑盒子方法的GIS内电压互感器高频电路模型的建立

为了研究气体绝缘变电站内的开关操作产生的陡波前过电压(VFTO)通过互感器对二次设备的影响,需要建立它们的高频电路模型。笔者提出了一种基于黑盒子方法的电压互感器(PT)高频电路模型的建立方法。该方法在应用矢量匹配法逼近PT导纳参数矩阵Y(s)的基础上建立了其π型等效电路,然后运用福斯特型RLC电路综合方法实现了该电路模型。为了保证电路模型仿真时的稳定性,对Y(s)的实部进行了无源性修正。由于该方法保证了所建模型的宏观无源性,所以建立的电路模型可以进行稳定、准确的数值仿真。对一个实际PT的测量和仿真计算验证了该方法的有效性。     

永磁同步发电机电磁暂态等效建模方法及稳定性分析

嵌套同时快速求解(nested fast and simultaneous solution, NFSS)算法通过消去电路节点可以显著提高仿真速度。然而,商业仿真软件提供的永磁同步发电机(permanent magnet synchronous generator, PMSG)模型无法获取等效电路,限制了该算法在海上风电中的应用。针对上述问题,提出了PMSG电磁暂态(electro-magnetic transient, EMT)等效建模方法,并分析了建模方法的稳定性。首先,将PMSG数学模型离散化,得到用三相受控电流源表示的等效电路及接口方法,给出PMSG的控制模式和等效模型求解流程。并结合实际PMSG参数取值,分析了等效建模方法的稳定性。最后,在PSCAD/EMTDC中搭建了PMSG详细模型和等效模型进行仿真精度对比及稳定性验证,结果表明,所提模型及稳定性分析具有较好的正确性,为NFSS算法在海上风电中的应用提供了模型基础,也为发电机参数的选取提供了约束条件。     

A semi‐analytic and cellular approach to rational system characterization through equivalent circuits

The partial fraction form of linear time‐invariant system transfer function is characterized through a cellular perspective, where each pole/residue fraction term is transformed into an equivalent circuit branch via an exact transformation. Minimal expressions for transformation of partial fraction form to/from equivalent circuit form are provided. The time‐domain and frequency‐domain impedance and admittance transfer function for resistor (R)–inductor (L), and resistance (R), inductance (L), capacitance (C), and conductance (G) equivalent circuit branches are presented in a form that is amenable to expedient inspection of cellular causality and stability and used to derive explicit expressions for the average power amenable to inspection of cellular passivity. The characteristics of passivity, causality, and stability at the cellular level are discussed to gain insight into the macro‐level network characteristics. Numerical examples are given to elucidate the aforementioned concepts and to provide insight into the behavior of linear time‐invariant systems. Copyright © 2015 John Wiley & Sons, Ltd.     

An algorithm for direct identification of passive transfer matrices with positive real fractions via convex programming

The paper presents a new algorithm for the identification of a positive real rational transfer matrix of a multi‐input–multi‐output system from frequency domain data samples. It is based on the combination of least‐squares pole identification by the Vector Fitting algorithm and residue identification based on frequency‐independent passivity constraints by convex programming. Such an approach enables the identification of a priori guaranteed passive lumped models, so avoids the passivity check and subsequent (perturbative) passivity enforcement as required by most of the other available algorithms. As a case study, the algorithm is successfully applied to the macro‐modeling of a twisted cable pair, and the results compared with a passive identification performed with an algorithm based on quadratic programming (QPpassive), highlighting the advantages of the proposed formulation. Copyright © 2010 John Wiley & Sons, Ltd.     

Multivariate theory‐based passivity criteria for linear fractional networks

In traditional linear network theory, the positive‐real (PR) criteria are widely used to judge the passivity of elements and networks in the light of the fact that there exists an equivalent relationship between the passivity and the PR property of their immittance functions (matrices). However, the equivalence will no longer hold when the fractional elements are introduced into the network, and the PR criteria are not suitable in complex frequency domain anymore. On the other hand, the rapid development of fractional‐order circuits and systems and the corresponding study in fractional circuit analysis and designs put forward an urgent requirement for the passivity criterion, which can tackle linear fractional networks. Hence, in this paper, we propose new passivity criteria for linear fractional networks by aid of generalized Tellegen's theorem and multivariable PR theory. By using the proposed criteria, the passivity of linear fractional networks can be judged, and the steps of the proposed criterion are illustrated by examples.     

A vectorized multiscale compressed decomposition‐based solver for partial element equivalent circuit method

The high level of integration has made the analysis and design of integrated circuits and packages increasingly challenging. Hence, there exists an urgent need to reduce the computational complexity of existing numerical methods. The integral equation‐based method known as the partial element equivalent circuit (PEEC) method naturally generates an equivalent circuit that can be analyzed in both the time and frequency domains. The enforcement of Kirchhoff laws to the equivalent circuit may easily result into a very large set of equations whose solution can be extremely time‐consuming. In this paper, we propose a vectorized version, over the frequency sweep, of the adaptive cross approximation algorithm. Furthermore, the multiscale block decomposition is applied to the PEEC method, powered by a vectorization strategy and an efficient management of the random access memory. It is found that the proposed use of vectorization and compression techniques in the framework of the multiscale block decomposition results in a significant computational speedup of the frequency‐domain analysis of PEEC models. The efficiency and accuracy of the proposed method are demonstrated through its application to two pertinent problems. Copyright © 2014 John Wiley & Sons, Ltd.     

三相电压型PWM整流器的无源性功率控制

根据电压型PWM整流器主电路结构,建立了整流器在两相同步旋转dq坐标系中的功率EL (Euler-Lagrange)数学模型。基于整流器的无源性,采用新的阻尼注入方法设计无源功率控制器。该无源功率控制器使整流器实现功率解耦控制,具有更好动静性能,优于现行的其它功率控制策略。特别是在负载扰动的情况下,应能保持功率快速响应、直流输出电压几乎不变的特性。仿真实验证明了新的整流器无源功率控制器设计方法的可行性。     

DC/DC变换器的一种无源化控制方案

针对DC/DC开关变换器的非线性控制问题,在电流连续型Buck变换器仿射非线性模型的基础上,通过非线性坐标变换,得到其标准链式结构,采用非线性系统无源化方法设计出系统的反馈镇定控制器,得到了一种无源化控制方案。仿真结果表明,所设计的控制器对负载扰动具有很强的鲁棒性,且控制器简单易实现,实现了对Buck变换器中电感电流和电容电压的有效控制。     

基于无源控制方法的TCSC控制器及其仿真研究

简要介绍了一类基于无源系统理论的最优控制方法－PBC方法，基于该方法设计了晶闸管控制的串联补偿器（TCSC）无源控制器，由于该控制器中的变量均可实现本地测量，故使其能有效地应用于实际电力系统中，针对川渝电力系统的仿真结果，证明了基于PBC控制器的TCSC可以有效地提高系统的暂态稳定性和传输功率。     

大功率链式STATCOM电磁暂态快速等效建模和误差评估

针对含有大量模块的大功率链式静止同步补偿器(STATCOM)存在的电磁暂态仿真速度缓慢的问题,提出一种链式STATCOM级联H桥拓扑的等效建模方法,以提高仿真效率。主要开展了以下的研究:对比分析了经典电磁暂态建模和快速等效建模的原理;推导出级联H桥换流链电压、电流之间的数学模型;结合换流链数学模型及其控制方法,设计出基于MATLAB/Simulink的仿真流程;分析主要电气量如功率模块直流电压、换流链电流和功率等的理论误差。比较精确模型和等效模型的仿真精度和仿真速度,结果表明所提的等效模型与精确模型的仿真误差小于1.2%,仿真时间缩短了80%。可见所提的大功率链式STATCOM电磁暂态快速等效建模和误差评估方法,可以在精度允许范围内大幅降低仿真时间并精确评估模型,具有较强的科学和工程应用价值。     

五电平MMC-UPQC的无源控制

分析五电平模块化多电平变换器-统一电能质量调节器(MMC-UPQC)的主电路拓扑和工作原理,建立其在dq0坐标系下的数学模型及EL模型。为加快误差能量收敛,采用阻尼注入方法设计电流内环无源控制器,确保MMC-UPQC的稳定性;通过电压外环PI控制器获得内环期望电流,消除静态误差。所提出的无源控制实现了对有功和无功的解耦控制,使系统具有良好的动静态性能。在负序二倍频坐标变换下采用相间解耦控制抑制环流,减少开关损耗;采用基于Park变换的电压电流补偿量提取方法,无需锁相环,提高补偿精度。最后在Matlab/Simulink搭建五电平MMC-UPQC仿真模型,仿真结果表明能够较准确地补偿不平衡、谐波电压以及无功、谐波电流,证明了无源控制的可行性。     

交流牵引电机温度场分析绕组气隙优化建模方法

针对交流牵引电机定子绕组间存在不规则气隙,而采用常规等效建模法所建模型准确性不高的问题,提出一种绕组气隙优化建模方法。确定了电机定子绕组等效模型的基本结构,提出了等效模型中绕组气隙最佳宽度确定方法,即根据所确定的等效气隙模型并采用有限元法对电机进行温度场分析以得到绕组模型表面某点对应的温度值。通过获取不同气隙宽度下模型表面某点对应的温度数据并采用数值拟合方法得到两者间的函数关系,根据所得函数关系并实测上述模型表面某点对应的实际温度,即可得到绕组等效气隙模型相应的最佳气隙宽度。该方法有效提高了交流牵引电机定子绕组建模的准确性,由此显著提升了其温度场分析结果的准确性,具有较好的应用价值。     

级联H桥型电力电子变压器的闭锁状态等效建模方法

电力电子变压器(power electronic transformer,PET)是未来交直流混合配电网的关键设备,对其进行多工况高效仿真的一个关键难点为闭锁等效建模。该文提出一种适用于级联H桥型PET(cascaded H-bridge based PET,CHB-PET)闭锁状态的等效建模方法。首先,以一个实际算例说明闭锁状态的电路特征;其次,经过合理简化后,推导部分闭锁和完全闭锁状态下的戴维南-诺顿等效参数;然后,分析闭锁等效模型的3种实施方式,提出一种与非闭锁模型共用状态变量存储单元的集成方法;最后,在PSCAD/EMTDC软件中搭建典型的10kV/3kV三相CHB-PET系统,并进行启动、电压暂降及直流故障闭锁工况仿真。结果表明,与详细模型相比,所提闭锁等效模型具有足够的仿真精度。     

Buck-Boost变换器的无源滑模控制研究

为解决无源性控制时Buck-Boost变换器电压与电流过冲的问题,在无源性控制的基础上加入滑模控制。通过建立Buck-Boost变换器的欧拉-拉格朗日(E-L)模型,可以得到Buck-Boost变换器的无源性控制规律。在此基础上,结合滑模控制原理,设计Buck-Boost变换器的无源滑模控制器。在Matlab环境下,进行Buck-Boost变换器无源滑模控制的动态仿真。仿真结果表明,Buck-Boost变换器的无源滑模控制对电源扰动、负载扰动具有很强的鲁棒性,且动态响应速度快,能够解决无源性控制电压与电流过冲的问题。     

BUCK-BOOST变换器的无源性电流控制方法

为了简化系统控制结构,提高Buck-Boost变换器的控制性能,本文提出了一种通过直接控制电感电流间接控制输出电压的Buck-Boost变换器无源性电流控制方法。首先根据无源性控制方法建立了系统的欧拉-拉格朗日能量模型,然后基于无源性理论和Layapunov稳定性理论,推导出了系统的无源性控制规律。实验结果表明,系统输出电压稳定,鲁棒性较强,动态响应良好。     

基于全景可观的深度聚合电网模型、求解方法及其应用

电力系统调度与控制正面临全局统筹、紧密协同的局面，而对外部电网的等值简化是该决策顺利实施的前提和关键。由于传统等值简化方法对等值电网“源”“网”“荷”的增加或删减操作改变了其结构和主动量、被动量，从而在电网全局统筹过程中，使调度与控制的精度面临挑战。对此，在电网全景可观环境下，提出了深度聚合电网模型及其求解方法和应用。首先，给出了发电厂、联络站的聚合方法，形成聚合电网模型。并在此基础上，将聚合厂站融合到输电线路，建立了深度聚合电网模型。然后，推导了深度聚合电网模型未知量与可调控量(发电机功率)之间的函数关系，并使用长短期记忆网络对其参数进行求解。最后，以经济调度应用为例进行仿真验证，证明了所提方法的有效性。     

Monitoring of flowing charges with an electrostatic voltmeter

This paper describes a simple method of monitoring the net electric charge of powders transported pneumatically through a dielectric pipe. An electrostatic voltmeter (ESVM) is used to measure the voltage induced on an isolated ring electrode placed on the outside surface of the pipe. An equivalent circuit model of the measurement system was constructed and experimentally verified using an electrophotographic toner and an aluminum oxide powder (Al/sub 2/O/sub 3/). Knowledge of the voltage induced by flowing charged particles on the electrode allows for the calculation of the total charge that flew through the pipe. However, in order to obtain an accurate voltage measurement, the input impedance of the instrument used for that purpose must be very high. The high impedance of an ESVM makes it uniquely suited for this application.     

改进的ASAP方法研究及应用

通过对ERP普遍实施方法 ASAP方法的研究,分析了在约束条件下实施方的不适应性,结合舟山电力局实施ERP系统的应用实例,提出了STIP方式,并详细阐述了STIP方式指标体系,为探索实施大型信息化系统开创了新的管理方式和绩效管理模式。