Analysis of complex microwave circuits using spice

This paper presents application of fuzzy set theory and interval arithmetic for computing the branch currents, node voltages. First load currents at every node are estimated based on hourly load pattern of different types of consumers using fuzzy set theory. Once the fuzzy load currents at each node are estimated, then by using forward path information matrix the branch currents are computed using the concepts of arithmetic operations on closed intervals. Node voltages are computed using the simple relationship of sending end and receiving end voltages and using the concept of arithmetic operations on closed intervals. The effectiveness of the proposed method is demonstrated through an example. It is also compared with the general load estimation process.

The partial element equivalent circuit (PEEC) method is a well-established technique for obtaining a circuit equivalent for an electromagnetic problem. The time domain solution of such models is usually performed using nodal voltages and branch currents, or sometimes charge and currents. The present paper describes a possible alternative approach, which can be obtained expressing and solving the problem in the waves domain. The digital wave theory is used to find an equivalent representation of the PEEC circuit in the wave domain. Through a pertinent continuous to discrete time transformation, the constitutive relations for partial inductances, capacitances, and resistances are translated in an explicit form. The combination of such equations with Kirchhoff laws allows to achieve a semiexplicit resolution scheme. Three different physical configurations are analyzed and their extracted digital wave PEEC models are simulated at growing sizes using the general-purpose digital wave simulator. The results are compared to those obtained by using standard SPICE simulators in both linear and nonlinear cases. When the size of the model is manageable by SPICE, an excellent accuracy and a speed-up factor of up to three orders of magnitude are observed with much lower memory requirements. A comparative analysis of results including the effect of parameters like the simulation time step choice is also presented.

This paper presents a new PMU-based Kalman Filter approach for Power System State Estimation, in which an estimator model is proposed to include the system frequency and exploit synchronized frequency measurements. The performance of this new estimator is evaluated in comparison to different state estimation methodologies, in order to assess the impact and potential benefits given by the integration of the frequency input. The improvement in the estimation accuracy achievable for the quantities of interest (node voltages and branch currents) thanks to the proposed approach is assessed under realistic operating conditions, taking into account, in particular, the possible occurrence of off-nominal frequency conditions. The main findings and results obtained by means of simulations performed on a standard IEEE network are presented and discussed.

The State Estimation (SE) is one of the key elements of the monitoring activity of an active distribution network and is the basis for every control and management application. Distribution networks present their own features, requiring specific estimation methodologies. The most widespread algorithms for Distribution System State Estimation (DSSE) are based on a weighted least squares (WLS) minimization of the residuals of the measurements and usually compute the state in terms ofeither node voltages or branch currents. The DSSE relies on real measurements collected by the distributed measurement system and on other available information, mainly obtained from historical data, that help obtaining observability. The prior information (the so called pseudo-measurements) derived from expected power profiles of both loads and generators is crucial for the accuracy of the estimation process and has to be fully exploited. A degree of correlation can often be assumed among power consumptions or generations of some particular nodes. The influence of the correlation on the quality of the estimation is investigated in this paper using a branch current DSSE algorithm. The importance of including correlation in the WLS is discussed using both traditional and synchronized measurements. Results obtained on a 95-bus distribution network are presented and analyzed.

This chapter introduces the analysis and design of linear circuits. It reviews basic direct‐current (DC) analysis using traditional circuits theorems with application to circuit analysis and design. Using node voltage instead of element voltages as circuit variables can greatly reduce the number of equations that must be treated simultaneously. The chapter treats the analysis and design of circuits containing active devices such as transistors or operational amplifiers (op amps). It also discusses alternating current (AC) circuits. Those ac circuits that are excited by a single frequency, for example, power systems, can be easily and effectively analyzed using sinusoidal steady‐state techniques. Linear circuits are often characterized by their behavior to sinusoids, in particular, how they process signals versus frequency. Audio, communication, instrumentation, and control systems all require signal processing that depends at least in part on their frequency response.

ABSTRACTCurriculum typically addresses classical electrodynamic field theory and circuit analysis (with resistors, capacitors, and inductors) separately. As such, there exists a gap relating the two. This work provides a strong tie between these two disciplines that is useful for bridging this gap. Prior work establishes a relationship between electrodynamic fields and circuit elements, but application to circuit analysis remains ambiguous because of the path-dependent node voltages formulated. This paper develops a model resulting in path-independent node voltages that are necessary for circuit analysis techniques. The model is based on the electric field and the magnetic vector potential. Both fields have components associated with the circuit elements as well as external or excitation sources. The model is applicable for determining the coupling of excitation electrodynamic fields to transmission lines. This paper provides a rigor and collective work not found elsewhere in electrodynamic or circuit theory literature.

This article presents an original application of the compression approach that combines two commercial simulators. A numerical calibration procedure is proposed in order to improve the interfacing between the two simulation environments using internal ports. The capabilities of the proposed method are demonstrated by studying simple passive and active packaged structures. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14: 525–534, 2004.

An efficient approach based on conventional techniques for transient analysis of transmission line circuit initially modelled as large number (N) of segments of lumped components is presented. This technique avoids the simultaneous solution of a large number of variables by computing an equivalent macromodel of each transmission line and splitting the analysis into two levels. The first level deals with a normal circuit analysis in which each transmission line is replaced by a simple lumped equivalent two port companion macromodel having only three resistors and two current sources. However, the initial N-segmented model of transmission line must be separately analyzed at the second level in order to update the transmission line companion macromodel at each timepoint. This latter analysis of the transmission line can be done efficiently using a set of recursive formulae whose complexities depend linearly on N. A simulation result of this technique is presented and compared with SPICE program.

Techniques for calculating average and variance of currents in various branches of power and ground buses are presented. These current estimates can be used to estimate mean time to failure due to electromigration in sections of the buses and to redesign them, if necessary, so that the electromigration failures over the estimated lifespan of the chip are minimized. The validity of the approach rests on the assumption that the bus can be modeled as a linear resistive network. The sparsity of this network is exploited to speed up the calculation of averages and variances. It is necessary to formulate and LU factorize the node admittance matrix only once. >

Although the modified nodal approach (MNA) has been widely used for formulating circuit equations, several limitations exist in this method including zero diagonal entries in its matrix and redundant variables like voltage source currents. Here, a new method of circuit equation formulation called Reduced Modified Nodal Approach (RMNA) is proposed, in which node voltages and controlling currents are adopted as the circuit variables. The circuit equations of the RMNA are formulated directly and systematically from a given circuit through three types of pivotings. In the RMNA matrix, its size is equal to the number of nodes in the circuit augmented by the short-circuit branches (SCB's) and zero diagonal entries are avoided.

The distribution of currents and voltages in a short ring transmission system

In order to explore the influence of multiple wind turbines with correlation on distribution network and reasonably evaluate the operation state of distribution network, a probabilistic load flow calculation method based on orthogonal transformation and cumulant method is proposed. Firstly, an appropriate Copula function is chosen to depict the correlation of wind turbines outputs using rank correlation coefficient and squared Euclidean distance. Secondly, orthogonal transformation is used to transform the correlated power outputs into uncorrelated variables. Finally, the cumulant method combined with Cornish-Fisher expansion is applied to calculate the probability distributions of node voltage and branch current, and the risk assessment of the operating state of distribution network is carried out. The accuracy and rapidity of proposed method are verified by comparison with Monte Carlo method on a typical 34-node system.

The performance of a medium ring transmission line at steady state

Comments on “A new heuristic approach for optimal reconfiguration in distribution systems” in 81 (2011) 282–289

A robust three phase power flow algorithm for radial distribution systems