Static Phase Shifter Research Articles

Fault-Tolerant Quantum Computation with Static Linear Optics

The scalability of photonic implementations of fault-tolerant quantum computing based on Gottesman-Kitaev-Preskill (GKP) qubits is injured by the requirements of inline squeezing and reconfigurability of the linear optical network. In this work we propose a topologically error-corrected architecture that does away with these elements at no cost—in fact, at an advantage—to state preparation overheads. Our computer consists of three modules: a two-dimensional (2D) array of probabilistic sources of GKP states; a depth-four circuit of static beam splitters, phase shifters, and short delay lines; and a 2D array of homodyne detectors. The symmetry of our proposed circuit allows us to combine the effects of finite squeezing and uniform photon loss within the noise model, resulting in more comprehensive threshold estimates. These jumps over both architectural and analytical hurdles considerably expedite the construction of a photonic quantum computer.Received 9 April 2021Accepted 15 November 2021DOI:https://doi.org/10.1103/PRXQuantum.2.040353Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasMeasurement-based quantum computingOptical quantum information processingQuantum computationQuantum information architectures & platformsQuantum information processing with continuous variablesTopological quantum computingQuantum Information

Pure and Linear Frequency-Conversion Temporal Metasurface

Metasurfaces are ultrathin structures which are constituted by an array of subwavelength scatterers with designable scattering responses. They have opened up unprecedented exciting opportunities for extraordinary wave engineering processes. On the other hand, frequency converters have drawn wide attention due to their vital applications in telecommunication systems, health care devices, radio astronomy, military radars and biological sensing systems. Here, we show that a spurious-free and linear frequency converter metasurface can be realized by leveraging unique properties of engineered transmissive temporal supercells. Such a metasurface is formed by time-modulated supercells; themselves are composed of temporal and static patch resonators and phase shifters. This represents the first frequency converter metasurface possessing large frequency conversion ratio with controllable frequency bands and transmission magnitude. In contrast to conventional nonlinear mixers, the proposed temporal frequency converter offers a linear response. In addition, by taking advantage of the proposed surface-interconnector-phaser-surface (SIPS) architecture, a spurious-free and linear frequency conversion is achievable, where all undesired mixing products are strongly suppressed. The proposed metasurface may be digitally controlled and programmed through a field programmable gate array. This makes the spurious-free and linear frequency converter metasurface a prominent solution for wireless and satellite telecommunication systems, as well as invisibility cloaks and radars. This study opens a way to realize more complicated and enhanced-efficiency spectrum-changing metasurface.

Implementation and Experimental Verification of a Novel Control Strategy for a UPFC-Based Interphase Power Controller

Replacing the phase shifting transformers of interphase power controller with a reduced rating dual unified power flow controller (UPFC) results in a unified interphase power controller (UIPC) with potential for enhanced performance. However, in most cases, the UPFC is controlled as a static phase shifter (SPS), producing marginal improvements. A control approach that allows the minimization of the power ratings of the series voltage source converters (VSCs) of the UIPC was recently proposed. For that, one has to define four control parameters, as opposed to only two in the SPS-based UIPC. This can be done off-line, by means of an optimization procedure that splits the desired transmission line current among the capacitive and inductive branches of the UIPC. In this paper, a control scheme is presented for the implementation of the novel technique. The current sharing factors obtained from the optimization are stored in a lookup table. The gating signals for the VSCs are generated using Park's transformation so as to synthesize the optimal UIPC inductive and capacitive branch currents with proportional resonant controllers and sinusoidal pulse width modulation. The transmission line angle, as well as the magnitude and phase of the desired transmission line current with respect to the voltage at the receiving end voltage, is assumed to be provided by a transmission system operator. Experimental results that include steady state and transient conditions are provided to prove its feasibility.

Comparison of Static Phase Shifter and Unified Power Flow Controller-Based Interphase

The basic interphase power controller (IPC) presents the interesting features of simplicity and low cost but is less flexible than most flexible ac transmission system controllers. A compromise performance can be achieved by replacing the phase shifting transformers with a reduced rating dual unified power flow controller (UPFC) resulting in a unified IPC. The comparison of the basic, phase shifter-based, with a new UPFC-based, control logic is the main goal of this paper. The control variables of the dual UPFC are computed based on an optimization procedure to minimize a given cost function. The results show the higher capability of the proposed logic not only to control the current flow through the transmission line but also to achieve this task with lower branch currents that should lead to reduced power losses.

Multimode interference couplers as compact and robust static optical phase shifters

The ability to realise compact and wavelength insensitive static optical phase shifters is of great value for many photonic integrated circuits. The work in this paper presents a design for a compact static optical phase shifter based on 1×1 MMI couplers which has the potential to replace conventional tapered waveguide phase shifters. The operation of these phase shifters is described in detail and designs are presented for typical InP and Si based waveguide structures. For Si waveguides, a factor of 3 reduction in length is possible using the proposed 1×1 MMI phase shifter compared to using standard tapers. Such devices offer excellent performance over a wide operational wavelength range and are tolerant to fabrication errors. Although reflection and insertion losses in MMIs are higher than those found in adiabatic tapers, the overall reduction in length makes MMI based phase shifters an interesting choice for use in photonic integrated circuits where robust performance and compact size is required.

Power System Dynamic Stability Enhancement Using Optimum Design of PSS and Static Phase Shifter Based Stabilizer

Power system stability enhancement via individual and coordinated optimum design of power system stabilizer and static phase shifter based stabilizer is thoroughly investigated in this paper. The coordinated design problem of excitation and static phase shifter-based stabilizer at nominal loading condition over a wide range of uncertainties and system parameter variations is formulated as an optimization problem with an eigenvalue–based objective function. The reinforcement learning automata based optimization algorithm called Combinatorial Discrete and Continuous Action Reinforcement Learning Automata (CDCARLA) is employed to search for the optimal setting of the proposed controller parameters. The participation factors method is used to identify the poorly damped electromechanical mode which is used in the evaluation of the eigenvalue–based objective function. This study also presents a singular value decomposition–based approach to assess and measure the controllability of the identified electromechanical mode by different control inputs over a wide range of loading conditions. For evaluation of the effectiveness and the robustness of the proposed stabilizers, a weakly connected power system with different disturbances, loading conditions, and system parameter variations is considered. The nonlinear simulation results and the eigenvalues analysis indicate a high performance of the proposed stabilizers and their ability to provide efficient damping of the low frequency oscillations.

DAMPING OF SUBSYNCHRONOUS RESONANCE OSCILLATIONS USING THE VOLTAGE MAGNITUDE AND PHASE ANGLE CONTROL OF STATIC PHASE SHIFTER

The voltage magnitude and phase Angle control of static phase shifter (VMPA–SPS) to damp the subsynchronous resonance(SSR) oscillations is investigated. A linear mathematical model of seriescompensated transmission line power system with static phase shifter is developed .The input control signals to the simulated power system is the phase angle and voltage magnitude deviations of static phase shifter. A controllability measure based on singular value decomposition (SVD) is used to identify the effectiveness of each control input signal on the electromechanical modes. A state feedback supplementary controller based on the linear quadratic regulator principle with a full rank observer is used to modulate the voltage magnitude and phase angle deviations of SPS to stabilize the SSR modes under different operating conditions and compensation levels of the compensated transmission line. To validate the effectiveness of the proposed supplementary controller , the studied power system is subjected to different disturbances. The digital simulation results prove the powerful of the proposed static phase shifter supplementary controller in terms of the fast damping of the SSR oscillations with less overshoot/undershoot.

Nonlinear disturbance attenuation control of static phase shifter in sense of L2‐gain

AbstractStatic phase shifters (SPS) have the abilities to optimize power flow and to improve transient stability of power systems. In this paper, improving transient stability of the power system using the static phase shifter is considered. First, a nonlinear robust model of the power system including SPS is established. Then a Backstepping method is used to construct the storage function, and a disturbance attenuation controller in the sense of L2‐gain is achieved consequently. The controller reflects the nonlinearity of the system and attenuates disturbances explicitly. Simulations have proved the effectiveness of the nonlinear disturbance attenuation controller.

Improvement of power system dynamic performance with the magnitude and phase angle control of static phase shifter

Abstract Control strategies of static phase shifter (SPS) have been widely investigated to improve the stability of power systems. But the emphasis has been limited to the control of the phase angle of the SPS. However, much improvement in the system dynamic performance may be possible with the control of both the magnitude and the phase angle of the phase shifter. Installing such a phase shifter is equivalent to incorporating a general voltage source in series with transmission line. This will modify the system equations and therefore the power flows. Hence, the steady state and the dynamic performance of power system would depend on these modified equations. In this paper, we have derived the equations for a system incorporating SPS. We have also developed a control strategy considering control of both the magnitude and the phase angle of SPS. This may be one form of unified power flow controller (UPFC). Simulation results are presented to demonstrate the effectiveness of the developed control strategy.

00/00841 A tabu search based approach to power system stability enhancement via excitation and static phase shifter control

00/00841 A tabu search based approach to power system stability enhancement via excitation and static phase shifter control

A tabu search based approach to power system stability enhancement via excitation and static phase shifter control

Abstract Power system stability enhancement through control of excitation and static phase shifter (SPS) has been investigated. The design problem of excitation and SPS controllers is formulated as an optimization problem. An eigenvalue-based objective function to increase the system damping is proposed. Then, tabu search (TS) algorithm is proposed to search for optimal controller parameters. Different control schemes have been proposed and tested on a weakly connected power system with different disturbances, loading conditions, and parameter variations. It was observed that although excitation control enhances the power system stability, the SPS controller provides most of the damping and improves the voltage profile of the system. The nonlinear simulation results show the effectiveness and robustness of the proposed control schemes over a wide range of loading conditions and system parameter variations.

Coordinated Design of Power System Stabilizers and Static Phase Shifters Using Genetic Algorithm

Coordinated design of a power system stabilizer (PSS) and a static phase shifter (SPS) using genetic algorithm (GA) is investigated in this paper. The design problem of PSS and SPS controller is formulated as an optimization problem. An eigenvalue-based objective function to increase the system damping is proposed. Then, GA is employed to search for optimal controller parameters. Different control schemes have been proposed and tested on a weakly connected power system with different disturbances, loading conditions, and parameter variations. It was observed that although the PSS enhances the power system stability, the SPS controller provides most of the damping and improves the voltage profile of the system. The nonlinear simulation results show the effectiveness and robustness of the proposed control schemes over a wide range of loading conditions and system parameter variations.

A variable structure static phase shifting transformer for power system stabilization

Abstract A variable structure sliding mode control system for controlling a static phase shifter is developed. The static phase shifter aims at introducing voltage phase shift between the terminals of transmission line. The voltage phase shift is controlled by adding to the voltage of one end of transmission line a quadrature voltage component. The thyristor switches is used to regulate that quadrature component, whereupon, the phase shift is changed. A sample power system model used for digital simulation is linearzied to design the variable structure control algorithm. To validate the power and robustness of the proposed controller for enhancing power system stability, the studied power system is subjected to different disturbances such as tie line power, frequency or synchronous machine speed disturbances. The power system dynamic responses for the above disturbances prove the effectiveness and superiority of the variable structure control system in terms of fast damping response with less settling time.

Comparison Studies of Unified Power Flow Controllers with Static Var Compensators and Phase Shifters

This paper reports on the comparison of ratings and control flexibility of three major FACTS devices. The locations of UPFC installation is determined by 'contingency analysis.' After power flow modelling of SVC, PS, and UPFC is introduced, a new power flow control method for UPFC is described. Four practical indices are used to evaluate the behavior of power systems. The test results on a test network clearly illustrate the effectiveness of the proposed approach.

Application of static phase shifters on the damping of common‐mode torsional oscillations

AbstractA study on the application of thyristor‐controlled static phase shifters (SPS) to stabilize the common‐mode torsional oscillations occurring in a series‐capacitor compensated power system is presented in this paper. The IEEE Second Benchmark Model, system‐2, which has two non‐identical turbine‐generator sets connected to an infinite bus through a series‐capacitor compensated transmission line, is employed to investigate whether the possible unstable subsynchronous resonance (SSR) modal interactions can be suppressed by the proposed damping scheme. The torsional interactions due to one of the torsional oscillating frequencies in one machine is nearly the same as the one in another machine. In order to effectively suppress the unstable torsional modes in the studied system, a systematic approach based on modal control theory is proposed and a set of static phase‐shifter controllers (SPSC) is designed. The effectiveness of the proposed damping scheme is demonstrated by means of frequency‐domain approach based on eigenvalue analyses and time‐domain approach based on non‐linear model simulations. The simulations results show that the static phase shifters and the designed controllers can be applied to suppress common‐mode torsional interactions.

Optimal flexible AC transmission systems (FACTS) devices allocation

This paper presents the development of mathematical model representations of variable series capacitors and static phase shifters which are also known as Flexible AC Transmission Systems (FACTS) in power system economic dispatch. The objective of this research is to find the optimal locations of FACTS devices for improved economic dispatch. The proposed approach is based on the decomposition-coordination method and the network compensation technique. Taking advantage of accumulated experience in power system optimization and the existence of the Optimal Power Flow (OPF) software, the software development cost for implementing the proposed algorithm is reduced. In this paper, digital simulation studies on small power systems under different network parameters, with and without FACTS devices, were conducted. The purpose of the simulation studies was to assess the effectiveness of the proposed algorithm in minimizing the operating cost and enhancing the system performance. The results of the simulation studies and the proposed algorithm will be presented and discussed in detail in this paper.

Power system stability enhancement using static phase shifter

The role of static phase shifters in improving power system stability is investigated. A new technique, based on the nonlinear variable structure control principle, is used to formulate a control algorithm for the static phase shifter. Parameter uncertainty has been considered in the proposed scheme. Computer simulations show that a static phase shifter with the new control scheme has produced significant improvement in power system performance.

Design of series and shunt FACTS controller using adaptive nonlinear coordinated design techniques

A nonlinear coordinated generator excitation, static phase shifter (SPS) and static VAr compensator (SVC) controller is proposed to enhance the transient stability of a power system. The proposed controller is novel since it is able to control the three main parameters affecting AC power transmission-voltage, phase angle and reactance-in a coordinated manner. The SPS is located near the generator terminal and the SVCs are located at the midpoint of each transmission line in a power system. a nonlinear feedback control law is found which linearizes and decouples the power system. The coordinated controller consists of three separate controllers: an adaptive excitation and SPS controller; and two SVC controllers. These controllers are designed based on local measurements only. The results show that the proposed nonlinear coordinated series and shunt FACTS controller is able to enhance the transient stability of a single-machine-infinite-bus (SMIB) power system.

Nonlinear excitation and phase shifter controller for transient stability enhancement of power systems using adaptive control law

The highly nonlinear mature of the generator and system behaviour following a severe disturbance precludes the use of classical linear control techniques. In this paper, a nonlinear adaptive excitation and static phase shifter controller is proposed to enhance the transient stability of a power system. The phase shifter is located near the generator terminal in a power system. A third-order generator model is used, which is in the standard form of the nonlinear system representation. The phase shifter is represented by a first-order model. Nonlinear feedback control laws are found which linearize and decouple the power system. An adaptive control law is used to design the controller for the excitation and phase shifter. The design of the resulting controller is independent of the operating point. Our simulation results demonstrate that the proposed controller can ensure transient stability of the power system under a large sudden fault which may occur at the generator bus terminal.

Applications of static phase shifters in power systems

This paper examines various functions that can be assigned to a static phase shifter (SPS) to enhance the performance of a power system during steady-state conditions, small-signal dynamics, and large-signal dynamics. The investigations are conducted on four test systems which exhibit typical power system operational problems, e.g. torsional oscillations, inter-area oscillations, transient instability, transient mechanical torques and loop-flow phenomenon. An AC-DC power flow program, an eigenvalue analysis program, an AC-DC transient stability program, and the EMTP are used as the study tools. The investigations show that depending upon the type and the location of an SPS, it may be utilized for mitigation of small-signal oscillations and/or enhancement of transient stability, in addition to steady-state power flow regulation. The studies also reveal that most dynamic characteristics of an SPS can be achieved by augmenting an existing conventional (mechanical) phase-angle regulator with a relatively small size static power converter.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>