Longitudinal Compensation Research Articles

Reduction of Voltage Fluctuations in Electrical Networks Supplying Motors with a Rapidly Changing Load by Installing Longitudinal Compensation Batteries

The article deals with the reduction of voltage fluctuations in electrical networks of industrial enterprises with the help of longitudinal compensation batteries. The purpose of the article is to develop a method for calculating the optimal parameters of the longitudinal compensation installation, which makes it possible to perform calculations using numerical characteristics of the range of changes in the voltage and flicker dose. To achieve this goal, it is necessary to solve the following tasks: to develop a method for selecting the parameters of reducing voltage fluctuations, taking into account the random nature of the change in the parameters of network modes; using the proposed method, to develop a calculation method that allows choosing optimal parameters of capacitor units. The most significant result is the experimental and theoretical confirmation that the proposed method for selecting the parameters of longitudinal compensation batteries, taking into account the random nature of the change in the flicker dose, makes it possible to effectively apply longitudinal compensation to reduce voltage fluctuations in electrical networks of industrial enterprises with a rapidly changing load. The significance of the results is proved by the fact that the proposed method makes it possible to select a longitudinal compensation installation to limit voltage fluctuations at the design stage, thereby ensuring the quality of electric energy in networks with consumers having a rapidly changing load. The resulting calculation method is planned to be used in distribution electrical networks when performing technical measures to ensure the quality of electrical energy.

Closed-loop control of the longitudinal axis compensation point in the K-Rb-21Ne comagnetometer

Magnetic field drift is a significant factor that influences the long-term stability of the spin-exchange relaxation-free (SERF) comagnetometer. This work proposes a real-time closed-loop control method for the longitudinal compensation point of the comagnetometer. By developing a model of the transverse (x and y axes) oscillation magnetic field response of the K-Rb-21Ne comagnetometer, the relationship between the demodulation phase at a fixed driving frequency and the longitudinal (z-axis) remanence of the comagnetometer are provided in this paper. Based on this equation, a real-time closed-loop control system for the longitudinal axis compensation point is constructed, and the effectiveness of the closed-loop control method is verified by experiments. The experimental results show that the Allan variance at 100 s is reduced by 38.2% and the repeatability of the scale factor is improved by 83.3% in the closed-loop mode relative to the open-loop mode. The research work in this paper is crucial for advancing comagnetometer engineering applications.

“Neural dynamics supporting longitudinal plasticity of action naming across languages: MEG evidence from bilingual brain tumor patients”

Previous evidence suggests that distinct ventral and dorsal streams respectively underpin the semantic processing of object and action knowledge. Recently, we found that brain tumor patients with dorsal gliomas in frontoparietal hubs show a selective longitudinal compensation (post-vs. pre-surgery) during the retrieval of lexico-semantic information about actions (but not objects), indexed by power increases in beta rhythms (13–28 Hz). Here, we move one-step further and ask whether a similar organizational principle also stands across the different languages a bilingual speaks. To test this hypothesis, we combined a picture-naming task with MEG recordings and evaluated highly proficient Spanish-Basque bilinguals undergoing surgery for tumor resection in left frontoparietal regions. We assessed patients before and three months after surgery. At the behavioral level, we observed a similar performance across sessions irrespectively of the language at use, suggesting overall successful function preservation. At the oscillatory level, we found longitudinal selective power increases in beta for action naming in Spanish and Basque. Nevertheless, tumor resection triggered a differential reorganization of the L1 and the L2, with the latter one additionally recruiting the right hemisphere. Overall, our results provide evidence for (i) the specific involvement of frontoparietal regions in the semantic retrieval/representation of action knowledge across languages; (ii) a key role of beta oscillations as a signature of language compensation and (iii) the existence of divergent plasticity trajectories in L1 and L2 after surgery. By doing so, they provide new insights into the spectro-temporal dynamics supporting postoperative recovery in the bilingual brain.

Does equity-based compensation motivate executives to build strong brands?

ABSTRACT To defeat myopic brand management, we need to understand better what motivates executives to invest in brand building. Drawing from agency theory, we argue that a better alignment of executivesʻ and shareholdersʻ interests can help. Tests using longitudinal compensation data of chief executive officers (CEO) from 123 public firms suggest that decreasing the sensitivity of CEOʻs Equity-Based Compensation (EBC) to the firmʻs stock price and increasing its sensitivity to the firmʻs stock return volatility are associated with higher brand equity. Weak governance somewhat offsets these effects. Moreover, we find that the impact of EBC on brand equity is partially mediated through the firmʻs strategic emphasis. Our research highlights the importance of understanding managerial incentives as drivers of brand equity.

Data-driven trajectory-tracking in automated parking system via iterative learning compensation and model predictive control

Automated parking system (APS) that explicitly considers the time efficiency of the motion has received large amounts of attention in recent years. Trajectory planning module in these APS delivered parking trajectory, which was expected to be precisely tracked by tracking module. However, the reference points of frequently used trackers were selected in the spatial domain, resulting in significant trajectory tracking errors with temporal information. In this paper, a tracking control method called ILC-MPC, which combined model predictive control (MPC) and iterative learning control (ILC), was proposed to improve the spatiotemporal tracking accuracy of the autonomous vehicle. ILC was utilized for longitudinal compensation using the error signal between historical and expected speed. Accordingly, the error model in the longitudinal direction was simplified to decrease the number of decision variables in MPC. Simulation experiments using CarSim were carried out to compare the proposed method with open-loop control, linear quadratic regulator (LQR), and pure MPC that had a similar computing time with ILC-MPC. ILC-MPC converged in a few iterations of the learning process and achieved the highest tracking accuracy in spatiotemporal domain among the mentioned methods.

Distributed automated control and protection system for power lines with any degree of longitudinal compensation

With longitudinal compensation of the reactance of the line, the problem of its protection against overcurrents arises from the point of view of relay protection. The problem is relevant with a greater degree of compensation. When compensating more than 50% of the reactance of the line, the protection of the power transmission line becomes practically impossible due to the failure or false operation of all existing types and forms of protection [1, 2]. Therefore, at present, the compensation of the line reactance is, as a rule, no more than 50% [3, 4], which does not allow the full potential of the line in terms of its transmission capacity to be revealed. The purpose of this study was to develop and test a new relay protection algorithm to be able to solve the above problem. The studies were carried out using modeling techniques in the PS CAD package, where a power transmission line with longitudinal compensation and an algorithm to protect it from internal damage were built. When carrying out the research, the work was carried out on the protection algorithm of the power transmission line with longitudinal compensation in the static mode without transferring electricity between substations and without the transmission mode along the active power line in both directions. It is shown that in order to determine the location of the damage, it is possible to use the criterion of the angle of the active component of the short-circuit current, which depends exclusively on the voltage angle and does not depend on the reactive parameters of the electrical network. The simulation result showed correct operation in all investigated modes. The algorithm described in the article showed quite satisfactory results, which makes it possible to protect the power transmission line with any degree of longitudinal compensation.

Simulation of power lines with longitudinal compensation device

With series compensation of the line reactance, the problem of its protection against overcurrents arises regarding relay protection. The greater the degree of compensation, the greater the problem. When compensating for more than 50% of the reactance of the line, the protection of power transmission lines becomes practically impossible due to the failure or false operation of all existing kinds and types of protection [1, 2]. Therefore, as for now, the compensation of the line reactance usually is no more than 50% [3, 4], which does not allow to reveal the full potential of the line in terms of its transmission capacity. The goal of this research was to study the processes occurring in emergency modes on power lines equipped with a series capacitor bank, the understanding of which would help to produce algorithms that can protect power lines with SCB with a degree of the longitudinal resistance compensation of the line of more than 50%.

МОДЕЛИРОВАНИЕ РЕЖИМОВ ДАЛЬНИХ ЛЭП, ОСНАЩЕННЫХ УСТАНОВКАМИ ПРОДОЛЬНОЙ КОМПЕНСАЦИИ

The results of computer studies of long-distance transmission modes of 500 kV, equipped with a longitudinal compensation unit, shunt reactors and a controlled source of reactive power are presented. It is shown that in the presence of all of the above devices, the relative losses of active power at the main section of the power transmission line are reduced by half compared with situations of their absence.

ОЦЕНКА КАЧЕСТВА НАПРЯЖЕНИЯ НА ШИНАХ 27,5 кВ ТЯГОВОЙ ПОДСТАНЦИИ С УСТРОЙСТВОМ ПРОДОЛЬНОЙ ЕМКОСТНОЙ КОМПЕНСАЦИИ

The paper is dedicated to the investigation of electric energy quality in AC traction network. The object of investigations is voltage in the AC traction network on buses of 27.5 kV in the AC functioning substation. The probabilistic-statistical value of the voltage level and values of electric energy quality according to voltage non-sinusoidality is under fulfillment. 
 There are shown numerical characteristics and histograms of the distribution density of values under analysis for two operation modes of the AC traction substation – switching on and off of the longitudinal capacitive compensation device formed on the basis of natural measurements. The probabilistic-statistical processing of natural measurements results in power supply arms of the functioning traction substation located in the Far-East of the Russian Federation is carried out. 
 The analysis results are shown as distribution density histograms of random values according to the standard law and in a table form. The longitudinal compensation device impact upon quality values of electric power according to the voltage is under consideration. 
 The calculated indices of electric power quality at the traction substation are compared with the requirements of GOST 32144-2013 in force. It is mentioned that upon buses of 27.5 kV of the traction substation both in the mode of UPK switching on, and in the mode of its switching off the electric power quality by the factor of voltage harmonic components does not satisfy the requirements of GOST 32144-2013 in a number of harmonics. On the basis of the complex estimate of voltage parameters there is drawn a conclusion of the positive impact of longitudinal capacitive compensation devices upon voltage level and the absence of a distinct effect upon a harmonic structure of voltage in a traction network at longitudinal compensation switching on. The conclusion is drawn about filtration expediency of voltage highest harmonic components in power supply arms of the traction substation to bring quality indices on voltage non-sinusoidality to the requirements of the standard in force.

Research of Ferr-Resonance Oscillations at the Frequency of Subharmonics in Three-Phase Non-Linear Electric Circuits and Systems

It is known that the occurrence and existence of ferroresonant oscillations at the subharmonic frequency (SHC) in power transmission lines (TL) and in power supply systems is extremely undesirable, since they cause ferroresonant overvoltages at different frequencies. At the same time, there is a wide class of nonlinear electrical circuits, in which the excitation of autoparametric oscillations (AIC) at the frequency of the SHC forms the basis of frequency converting devices serving as secondary power sources. It is shown that three-phase nonlinear systems are in one way or another equivalent circuits for power transmission lines, the main elements of which are: longitudinal compensation capacitors, transverse compensation reactors, and transformers with a nonlinear characteristic. To study the regularities of the excitation and maintenance of SHC at a frequency in three-phase electro-ferromagnetic circuits (EFMC), theoretical and experimental studies of an equivalent model of a three-phase circuit with nonlinear inductance were carried out. For the analysis of the steady-state mode of the SHC at the frequency, the method of a small parameter (averaging) was applied. A shortened differential equation of motion for a three-phase nonlinear circuit is obtained. By solving them, the regions of existence of the SHC and the critical parameters of the chain were determined. The obtained results of theoretical research are confirmed by experimental studies.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ УРОВНЯ ПРОДОЛЬНОЙ КОМПЕНСАЦИИ НА ВОЗНИКНОВЕНИЕ И РАЗВИТИЕ ПОДСИНХРОННОГО РЕЗОНАНСА

ИССЛЕДОВАНИЕ ВЛИЯНИЯ УРОВНЯ ПРОДОЛЬНОЙ КОМПЕНСАЦИИ НА ВОЗНИКНОВЕНИЕ И РАЗВИТИЕ ПОДСИНХРОННОГО РЕЗОНАНСА

Self-oscillations at the frequency of subharmonics in nonlinear electric chains and systems

It is known that the occurrence and existence of autoparametric oscillations (AIC) at the subharmonic frequency (GHC) in power lines (power lines) and in power supply systems is extremely undesirable, since they cause ferroresonant overvoltages at different frequencies. At the same time, there is an extensive class of nonlinear electric circuits in which the excitation of the AIC at the frequency of the SGC forms the basis of frequency-converting devices serving as secondary power sources. It is shown that single-phase-three-phase nonlinear systems are, to one degree or another, equivalent circuits of power lines, the main elements of which are: longitudinal compensation capacitors, transverse compensation reactors, and transformers with non-linear characteristics. The regularities of the excitation of the GCC at the frequency (ω / 3) of the power lines were studied, theoretical and experimental studies of the equivalent model of single-phase-three-phase circuits with nonlinear inductance were carried out. For a theoretical analysis of the steady-state mode of SGK at a frequency (ω / 3) with inductive coupling, the frequency- energy approach is used. The conditions of existence and critical parameters of the circuit are determined, and the mechanism of the appearance of the SGC at the frequency (ω / 3) is also studied.

INVESTIGATION OF THE INFLUENCE OF THE TRANSFORMER OF A SERIES ACTIVE FILTER ON THE QUALITY OF VOLTAGE

Purpose. Investigate the features of using a series power transformer for the implementation of longitudinal compensation. Methodology. Methods of solving systems of differential equations of the first order, methods of matrix transformations, methods of numerical simulation, methods of calculating the active part of Frieze power, methods of the theory of transformation of coordinate systems. Findings. The functional scheme of the successive power active filter is realized in the implementation of longitudinal compensation, the connection of the parameters of the transformer with the parameters of the mode is investigated, the processes that take place in the transformer are considered, a method for determining the signal of the control of the successive filter is developed, in the visual programming environment a model of the simplified system of electricity consumption has been developed, researches, on the basis of which analysis, the efficiency of application of the proposed solution according to the level of voltage on the invoice is shown ancestry A series of experiments with a change in the active load power was carried out to assess the impact of the transformer on the load voltage. The conclusions of the influence of the parameters of the active filter transformers on the load voltage are formulated. Originality. Non-compliance with the quality of energy indicators leads to economic losses, reduced reliability of operation of electric networks and violation of technological processes, increase of additional losses in networks and elements of electrical equipment, shortening of service life of electrical power equipment of power systems. Longitudinal compensation is one of the solutions for ensuring the quality of electricity. Compensation provides for increasing the dynamic stability of the transmission line and the stability of the main network voltage. On the basis of the analysis of known works, it has been established that passive compensators with a permanent structure are less satisfied with the requirements for maintaining the quality of electricity. As a result, controlled filter compensating devices are developed and implemented - power active filters. The principle of the compensator - constantly creates harmonic voltages that exactly match the harmonic components generated by the load. The distortion is already compensated, already present in the power supply system. As a result, the voltage remains sinusoidal. The compensatory properties of the active filter depend on the algorithm for determining the control signal. With the use of the Frize power theory, a cer tain sequence of the synthesis of a control signal by a series active active filter is proposed. Practical value. A certain sequence of synthesizing the control signal of the compensator has been created, the effect of the power active filter transformers has been investigated for the realization of longitudinal compensation.

Testing a longitudinal compensation model in premanifest Huntington's disease.

The initial stages of neurodegeneration are commonly marked by normal levels of cognitive and motor performance despite the presence of structural brain pathology. Compensation is widely assumed to account for this preserved behaviour, but despite the apparent simplicity of such a concept, it has proven incredibly difficult to demonstrate such a phenomenon and distinguish it from disease-related pathology. Recently, we developed a model of compensation whereby brain activation, behaviour and pathology, components key to understanding compensation, have specific longitudinal trajectories over three phases of progression. Here, we empirically validate our explicit mathematical model by testing for the presence of compensation over time in neurodegeneration. Huntington's disease is an ideal model for examining longitudinal compensation in neurodegeneration as it is both monogenic and fully penetrant, so disease progression and potential compensation can be monitored many years prior to diagnosis. We defined our conditions for compensation as non-linear longitudinal trajectories of brain activity and performance in the presence of linear neuronal degeneration and applied our model of compensation to a large longitudinal cohort of premanifest and early-stage Huntington's disease patients from the multisite Track-On HD study. Focusing on cognitive and motor networks, we integrated progressive volume loss, task and resting state functional MRI and cognitive and motor behaviour across three sequential phases of neurodegenerative disease progression, adjusted for genetic disease load. Multivariate linear mixed models were fitted and trajectories for each variable tested. Our conceptualization of compensation was partially realized across certain motor and cognitive networks at differing levels. We found several significant network trends that were more complex than that hypothesized in our model. These trends suggest changes to our theoretical model where the network effects are delayed relative to performance effects. There was evidence of compensation primarily in the prefrontal component of the cognitive network, with increased effective connectivity between the left and right dorsolateral prefrontal cortex. Having developed an operational model for the explicit testing of longitudinal compensation in neurodegeneration, it appears that general patterns of our framework are consistent with the empirical data. With the proposed modifications, our operational model of compensation can be used to test for both cross-sectional and longitudinal compensation in neurodegenerative disease with similar patterns to Huntington's disease.

Electrodynamic tests of power transformers with reactive-power compensation

It is shown that electrodynamic tests of power transformers are accompanied by the predominant consumption of a reactive power that is many times higher than the active-power consumption. A scheme of electrodynamic tests with longitudinal compensation of the reactive power using a capacitor bank is proposed. It allows a considerable reduction of the power that is consumed from the power-supply system. The parameters of the capacitor bank and the preliminary-charging voltage levels were determined that provide various current regimes for conducting both adjusting and actual short-circuiting experiments. The possibility of performing electrodynamic tests of power transformers with nominal powers of up to 630 MV A under the conditions of factory test centers using a controlled alternating-voltage source with a regulation range of 1.5–7.5 kV and a power of 22 MW was substantiated. Short-circuiting tests have a negative effect on the power-supply system because they are able to initiate a voltage dip with a duration of up to 0.2 s and even a dynamic-stability loss. As a result, the quality and reliability of electric-power supply of other consumers of the power-supply system deteriorate. The above negative consequences can be avoided and the required testing short-circuit current simultaneously provided via reduction of the total power consumed from the powersuppl system. In this study, the problem of the electromagnetic compatibility of an electrodynamic-test bench and a power-supply system is solved by compensating the reactive power during short-circuiting experiments.

ON THE SIMULATION OF MODES ОF ELECTRIC POWER SYSTEMS WITH FACTS

Power flow control is an important task of development of electric power systems. It is necessary to reduce the power loss, improve the reliability and quality of power supply and increase the power transmission. Currently, on the basis of modern power electronics effective FАСТS devices for flexible control of power system operation modes have been developed. FАСТS devices are able to simultaneously influence the voltage, the reactance, the angle between the voltages. As it is known, the calculations of the established modes of electric systems are the most frequently performed tasks at all the territorial and time levels of control and planning operations. These calculations are significant by themselves, being also an integral part of software systems of calculation of losses of power and energy in electrical networks, calculation of optimal modes and also sustainability. The need for multiple mode calculation imposes high requirements to the methods of calculation of the established modes in real time in terms of performance and reliability of the results of the solution being obtained under operating conditions of electric power systems. In traditional calculations of the established modes of electrical networks, shunt reactors, current-limiting reactors, capacitor banks, longitudinal compensation devices were accounted in the simulation as passive elements. In regard with the introduction of FACTS devices in power systems, there is an arising need to develop appropriate algorithms and implement them in the form of software for analyzing and controlling the established modes of power systems. The methodology and software for calculation of the established modes of electric networks with consideration of FACTS devices have been developed. The software makes it possible to obtain practically acceptable solutions in three outer iterations. Based on the results of numerical simulation of modes of the power system of the “Azerenergy” JSC it was determined that the application of FACTS devices can significantly increase the transmission line active power, improve voltage levels and reduce losses of active power. The dependences of flows and power losses on the control parameter of FACTS devices have been derived.

Small devices for longitudinal compensation in overhead power lines

Distributed-series impedance (DSI) technology for overhead power lines is under active development in the United States and Russia. DSI can be used for a wide range of application, for example, for redistribution of power flows in parallel lines and cross sections; phase balancing; increasing the power-transfer capability, stability, and reliability of the functioning of an electric-power network; and reducing power losses. This article describes the principles of operation of the DSI and proposes a generalized analytical model, which illustrates the concept of controlling the reactance introduced by means of a device in a power line. The structure of an inductive-capacitive DSI with two capacitors made by OAO G.M. Krizhizhanovskii Energetics Institute in cooperation with AO NTTs FSK EES is described in detail. This work discusses general characteristics and parameters of the device. The main modes of operation of the developed DSI prototypes are presented. The feasibility of the devices has been confirmed during trial operation.

Inequities in Academic Compensation by Gender: A Follow-up to the National Faculty Survey Cohort Study.

Cross-sectional studies have demonstrated gender differences in salaries within academic medicine. No research has assessed longitudinal compensation patterns. This study sought to assess longitudinal patterns by gender in compensation, and to understand factors associated with these differences in a longitudinal cohort. A 17-year longitudinal follow-up of the National Faculty Survey was conducted with a random sample of faculty from 24 U.S. medical schools. Participants employed full-time at initial and follow-up time periods completed the survey. Annual pretax compensation during academic year 2012-2013 was compared by gender. Covariates assessed included race/ethnicity; years since first academic appointment; retention in academic career; academic rank; departmental affiliation; percent effort distribution across clinical, teaching, administrative, and research duties; marital and parental status; and any leave or part-time status in the years between surveys. In unadjusted analyses, women earned a mean of $20,520 less than men (P = .03); women made 90 cents for every dollar earned by their male counterparts. This difference was reduced to $16,982 (P = .04) after adjusting for covariates. The mean difference of $15,159 was no longer significant (P = .06) when adjusting covariates and for those who had ever taken a leave or worked part-time. The continued gender gap in compensation cannot be accounted for by metrics used to calculate salary. Institutional actions to address these disparities include both initial appointment and annual salary equity reviews, training of senior faculty and administrators to understand implicit bias, and training of women faculty in negotiating skills.

Corporate governance and CEO compensation in Indian firms

We examine the role of the board, ownership, and CEO characteristics in CEO compensation in Indian firms. Contrary to the evidence documented in prior studies, we find that CEO compensation is not associated with board characteristics. Instead, compensation is associated with firm's ownership attributes and its CEO's tenure. We also document that leaving out CEO fixed effects in a longitudinal compensation study can lead to potentially erroneous conclusions about the role of several governance attributes in CEO compensation contracting. Finally, we find that CEO compensation attributed to ownership characteristics in the private sector is positively related to future firm performance, whereas remuneration attributed to board and CEO characteristics in both private and public sectors are not. Our evidence is consistent with efficient CEO compensation contracting, rather than CEO rent extraction, in Indian firms.

PROVIDING QUALITY OF ELECTRIC POWER IN ELECTRIC POWER SYSTEM IN PARALLEL OPERATION WITH WIND TURBINE

The problem of providing electric power quality in the electric power systems (EPS) that are equipped with sufficiently long air or cable transmission lines is under consideration. This problem proved to be of particular relevance to the EPS in which a source of electrical energy is the generator of wind turbines since the wind itself is an instable primary energy source. Determination of the degree of automation of voltage regulation in the EPS is reduced to the choice of methods and means of regulation of power quality parameters. The concept of a voltage loss and the causes of the latter are explained by the simplest power system that is presented by a single-line diagram. It is suggested to regulate voltage by means of changing parameters of the network with the use of the method of reducing loss of line voltage by reducing its reactance. The latter is achieved by longitudinal capacitive compensation of the inductive reactance of the line. The effect is illustrated by vector diagrams of currents and voltages in the equivalent circuits of transmission lines with and without the use of longitudinal capacitive compensation. The analysis of adduced formulas demonstrated that the use of this method of regulation is useful only in the systems of power supply with a relatively low power factor (cosφ < 0.7 to 0.9). This power factor is typical for the situation of inclusion the wind turbine with asynchronous generator in the network since the speed of wind is instable. The voltage regulation fulfilled with the aid of the proposed method will make it possible to provide the required quality of the consumers’ busbars voltage in this situation. In is turn, it will make possible to create the necessary conditions for the economical transmission of electric power with the lowest outlay of reactive power and the lowest outlay of active power losses.