Sensitivity-based Approach Research Articles

A sensitivity-based approach to analyzing signal delay uncertainty of coupled interconnects

Performance optimization is a critical step in the design of integrated circuits. Rapid advances in very large scale integration (VLSI) technology have enabled shrinking feature sizes, wire widths, and wire spacings, making the effects of coupling capacitance more apparent. As signals switch faster, noise due to coupling between neighboring wires becomes more pronounced. Changing the relative signal arrival times (RSATs) alters the victim line delay due to the varying coupling noise on the victim line. The authors propose a sensitivity-based method to analyze delay uncertainties of coupled interconnects due to uncertain signal arrival times at its inputs. Compared to existing methods of analyzing delay uncertainties of coupled interconnects, the simulation results show that the proposed method strikes a good balance between model accuracy and complexity compared to the existing approaches.

SBT soft fault diagnosis in analog electronic circuits: a sensitivity-based approach by randomized algorithms

This paper addresses the fault diagnosis issue based on a simulation before test philosophy in analog electronic circuits. Diagnosis, obtained by comparing signatures measured at the test nodes with those contained in a fault dictionary, allows for sub-systems testing and fault isolation within the circuit. A novel method for constructing the fault dictionary under the single faulty component/unit hypothesis is proposed. The method, based on a harmonic analysis, allows for selecting the most suitable test input stimuli and nodes by means of a global sensitivity approach efficiently carried out by randomized algorithms. Applicability of the method to a wide class of circuits and its integration in diagnosis tools are granted since randomized algorithms assure that the selection problem can be effectively carried out with a poly-time algorithm independently from the fault space, structure, and complexity of the circuit.

Preventive control of voltage security margins: a multicontingency sensitivity-based approach

Summary form only given, as follows. This paper addresses the problem of changing the operating point of a power system in order to keep voltage security margins with respect to contingencies above some minimal value. Margins take on the form of maximum pre-contingency power transfers either between a generation and a load area or between two generation areas. They are determined by means of a fast time-domain method. The paper first discusses the use of a general optimal power flow, in which linear voltage security constraints are added. The simultaneous control of several (possibly conflicting) contingencies is considered. Then, the paper focuses on the minimal control change objective. Among the possible controls, emphasis is put on generation rescheduling and load curtailment. Examples are presented on an 80-bus test system as well as on a real system.

Preventive Control of Voltage Security Margins: A Multi-Contingency Sensitivity-Based Approach

This paper addresses the problem of changing the operating point of a power system in order to keep voltage security margins with respect to contingencies above some minimal value. Margins take on the form of maximum precontingency power transfers either between a generation and a load area or between two generation areas. They are determined by means of a fast time-domain method. The paper first discusses the use of a general optimal power flow, in which linear voltage security constraints are added. The simultaneous control of several (possibly conflicting) contingencies is considered. Then, the paper focuses on the minimal control change objective. Among the possible controls, emphasis is put on generation rescheduling and load curtailment. Examples are presented on an 80-bus test system as well as on a real system.

On bilevel programming, Part I: General nonlinear cases

This paper is concerned with general nonlinear nonconvex bilevel programming problems (BLPP). We derive necessary and sufficient conditions at a local solution and investigate the stability and sensitivity analysis at a local solution in the BLPP. We then explore an approach in which a bundle method is used in the upper-level problem with subgradient information from the lower-level problem. Two algorithms are proposed to solve the general nonlinear BLPP and are shown to converge to regular points of the BLPP under appropriate conditions. The theoretical analysis conducted in this paper seems to indicate that a sensitivity-based approach is rather promising for solving general nonlinear BLPP.

Structural control of electric power networks for transient stability

This paper presents a sensitivity-based approach for structural control of electric power networks using FACTS (flexible AC transmission system) devices in order to improve the transient stability margin for one controlling unstable equilibrium point (u.e.p). It is comprised of the sensitivity analysis of critical energy of the TEF (transient energy function), network control strategy and evaluation. A related practical application to a 39-bus test system follows and shows that the structural control of power networks is effective for the enhancement of power system transient stability. >

Sensitivity-based characterization and optimization of viscoelastically damped honeycomb structures

Control of dynamic vibrations is critical to the operational success of many aerospace systems. Large space structures, for practical reasons, are lightweight and hence highly flexible. This paper addresses the problem of vibration control of such structures through passive damping, using viscoelastic materials. A new sensitivitybased approach to characterize viscoelastic material property variation with frequency is outlined. It is demonstrated that, using structural optimization techniques, viscoelastically damped honeycomb structures can be tailored to provide weight-effective vibration damping. A spacecraft payload mounting platform is used as the demonstration structure.

Voltage problems on transmission networks subject to unusual power flow patterns

Conditions for the existence of a physically acceptable voltage solution in power transmission networks are given, and a sensitivity-based approach for their real-time evaluation is outlined. Theoretical results are illustrated on a simplified Pennsylvania-New Jersey-Maryland model, on which reactive power/voltage problems were reported to exist. On the same system a comparison of the most typical voltage controls is made. Different corrective control actions are compared in the context of their role within a multiple-utility power wheeling operating mode. The study represents an overall attempt to link existing operating voltage problems (frequently economics driven) to the theoretical results necessary for their fundamental understanding and for designing efficient real time system monitoring and control techniques. >

Steady-state security control using a sensitivity-based approach

Real time security assessment is gaining more and more attention with the increasing complexity of electrical power systems. Steady-state security control is made to keep the system in a state without violating any constraints. In this paper, an algorithm based on the first-order sensitivities is presented both for real power and for reactive power security control. Relations between uncompensated sensitivity factors used for corrective control and compensated sensitivity factors used for preventive control have been derived theoretically. It is found that the combined effects of a line outage and a line switching cannot be summed directly, because of inherent nonlinearity. The effectiveness of the proposed method is investigated by studying the Taiwan power system.

Transmission System Expansion Planning by Interactive Methods

The objective of any electric utility is to ensure that within a planning horizon, the future load demand is satisfied at a reliable level of performance. A sensitivity-based approach is used to determine the locations of network additions comprising new generation lines and the possibility of a phase-shifter to reinforce a heavily loaded a.c. system. The security of the new system is evaluated using qualitative and quantitative methods with further line additions if necessary. Tests carried out on the IEEE 24-bus reliability system are presented.

A sensitivity-based approach to tolerance assignment

A new and efficient algorithm is described for selecting the most economic set of component tolerances for a mass-produced electronic circuit, and is illustrated by application to two filter circuits. The algorithm is based on a statistical sampling of component space, and its efficiency is a consequence of using inexpensive sensitivity information to calculate response from a truncated Taylor-series approximation. The algorithm extends, to tolerance space, the familiar concept of undertaking exploratory random perturbations in order to seek an optimum design. The computational cost of the algorithm is shown to be reasonable: moreover, theoretical considerations and experimental evidence indicate the likelihood of further considerable reduction in the computational cost of tolerance assignment.