Combined digital measuring current and voltage transformers (DCVTs), developed at Ivanovo State Power engineering University (ISPEU), are innovative products. The researchers have accumulated some operating experience...
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Electromagnetic current transformers, invented more than 100 years ago, are today the most widespread type of preliminary current converters, used in organizing metrological channels for commercial and technical elect...
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ISBN:
(纸本)9798331501105
Electromagnetic current transformers, invented more than 100 years ago, are today the most widespread type of preliminary current converters, used in organizing metrological channels for commercial and technical electricity metering, measuring and relay protection systems. Despite their relatively simple design and modest price, today the question of using unconventional preliminary current converters (Rogowski coils, optical transformers, galvanic-magnetic sensors) is being increasingly raised [1]. This situation is due to the shortcomings of electromagnetic current transformers (CT): large weight and dimensions), explosion and fire hazard, and also saturation of their magnetic conductor in transient modes with the presence of an aperiodic component in short circuiting (SC) current. The phenomenon of saturation leads to significant distortion of the transmitted secondary signal, which in turn may become the cause of overprotection with external SC or delayed protection with internal SC. Russian and international practice in coordinating CT characteristics and relay protection requirements presuppose ensuring correct operation of relay protection systems not only in steady, but also in transient modes with possible saturation of CT magnetic conductors [2]-[5]. At present, testing the correct operation of relay protection and automation devices (RPAD) in transient modes is carried out using the CT saturation time, which under the specific conditions of the location of the CT should be more than the exact current conversion time required for correct operation of the connected RPAD. This time is calculated by special approved methods [2]. Such use of two extreme CT magnetic conductor conditions (saturated/unsaturated), without regard to the current waveform itself may lead to significant inaccuracies in evaluating the correctness of RPAD operation. Fig 1 shows two instances of saturation in one and the same CT in different operating conditions and with the same time be
In the development of secondary systems of stations and substations, including relay protection, automation, control, electric power metering and other features, there have recently been qualitative changes related to...
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This study introduces a data-driven approach for state and output feedback control addressing the constrained output regulation problem in unknown linear discrete-time systems. Our method ensures effective tracking pe...
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This study introduces a data-driven approach for state and output feedback control addressing the constrained output regulation problem in unknown linear discrete-time systems. Our method ensures effective tracking performance while satisfying the state and input constraints, even when system matrices are not available. We first establish a sufficient condition necessary for the existence of a solution pair to the regulator equation and propose a data-based approach to obtain the feedforward and feedback control gains for state feedback control using linear programming. Furthermore, we design a refined Luenberger observer to accurately estimate the system state, while keeping the estimation error within a predefined set. By combining output regulation theory, we develop an output feedback control strategy. The stability of the closed-loop system is rigorously proved to be asymptotically stable by further leveraging the concept of λ-contractive sets.
A function of grid-connected VSGs is facilitating the recovery of sagging voltages to nominal levels, achieved by supplying reactive power (Q) to the grid. During normal operation, however, a VSG is required to supply...
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In laser powder bed fusion additive manufacturing, using fixed values for the process parameters (beam power, velocity, and other parameters) may not lead to homogeneously distributed heat in all locations in the buil...
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In recent years, wide bandgap semiconductor devices such as silicon carbide (SiC) and gallium nitride (GaN) have been increasingly applied in electric drive systems, effectively enhancing system power density. However...
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Power electronic switching devices and pulse width modulation (PWM) not only improves the performance of motor drive systems, but also brings about common-mode voltage (CMV) issues, that challenging the normal operati...
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The electromagnetic interference (EMI) problem caused by power electronic switching devices and pulse width modulation (PWM) affects the normal operation of the motor drive system. In this paper, a random PWM based on...
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The purpose of this article is to perform a comparison between two identification models: a nonlinear one referred to as HARMAX and a classical linear one, of Box-Jenkins (BJ) type. The first model modifies a classica...
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