Voltage In Electric Power Systems Research Articles

On Ensuring Dynamic Stability of Voltage in Electric Power Systems under Critical Loads

On Ensuring Dynamic Stability of Voltage in Electric Power Systems under Critical Loads

Comparison of Voltage Abnormality Detection Methods for Single-Phase Inverters to Meet the Requirements in IEEE Standard 1547-2018

This article compares the performance of different detection methods for a single-phase inverter interfacing a distributed energy resource during abnormal transients or failures of the utility electric power system voltage. The performance of the various methods is presented and compared to IEEE Standard 1547-2018 requirements using a physics-based model. Simulation scenarios are created to compare controller responses to intentional islanding and ride-through recommended timing specified in IEEE Standard 1547-2018. Additionally, four voltage abnormality detection methods were implemented in a Field Programmable Gate Array (FPGA)-based controller hardware-in-the-loop simulation and assessed for steady state and transient performance, and FPGA resource utilization. Finally, the physics-based model is validated by experimental measurements on a laboratory prototype with an FPGA-based controller.

Framework to Develop Time- and Voltage-Dependent Building Load Profiles Using Polynomial Load Models

The power consumption of buildings over the course of each minute, hour, day and season plays a major role in how this load influences the Electric Power System voltage and frequency, and vice versa. This consumption is based on the building’s load component types, efficiencies, and how they consume power and react to changes in real time. Due to this complexity, standard full-building load models are typically voltage-invariant. This paper proposes a novel framework to transform these voltage-invariant building load models into fully time- and voltage-dependent load profiles using available data on the voltage sensitivity of individual load components. While a voltage-dependent building model could theoretically be generated from static load models of every component in a building, this approach faces two challenges: first, load models representing all load components are impractical to develop for all possible load component types; second, building energy consumption is never measured or modeled at the individual component level. The proposed framework compiles available component data in the form of static ZIP load model parameters, and maps them into the end use categories utilized by standard building modeling programs. The voltage sensitivity of each end use category is then bounded by the extrema of the component models within it. This framework is applied to a load profile case study representing the aggregate U.S. residential building stock. In addition to the minimum/ maximum conditions, a load profile based on typical load composition and weighted ZIP parameters is generated for the same building stock. The results show that for a 10% drop in voltage, using the least sensitive ZIP parameters, active power is expected to be 3% to 14% lower than nominal, depending on the season and time of day. Using the most sensitive ZIP parameters, the active power is expected to be 9% to 20% lower than nominal, also depending on the season and time of day.

Введение понятия «низкоэнтропийный сигнал»

The article introduces the concept of a low-entropy signal as a time dependence that has a small variability coefficient. A high-entropy radio signal and a low-entropy electrical signal are compared. It is determined as a result of modeling that the variability coefficient of the electrical signal is 100 or more times smaller than the radio signal variability coefficient; therefore, this indicator is selected as a criterion for discrimination of electrical and radio signals. A conclusion is drawn about the need to improve the mathematical techniques for digital processing of signals for analyzing the currents and voltages in electric power systems. It is also shown that low entropy of an electrical signal can be used for improving the accuracy of instrumentation and control equipment. The effect of quantization noise degeneration into a set of harmonic components in modeling the analog-to-digital conversion of currents and voltages in measurement devices is considered. A procedure for compensating this effect by adding white Gaussian noise prior to carry out the quantization operation is proposed. A procedure that allows better accuracy of instrumentation and control equipment to be obtained by using the low entropy of an electric signal is presented. The analog-to-digital converter circuit diagram is given, and the gain in the conversion accuracy is estimated.

ON THE NORMALIZATION OF THE REACTIVE LOAD OF ELECTRIC TRANSMISSION OF INDUSTRIAL-LENNY AND ELECTRIC POWER CONSUMERS ELECTRICALLY CONSUMED

A new mathematical quantum physics-based approach to the process of power transmission to the industrial electricity consumers and the ones equated to them, which allows to improve the power supplying quality of the mentioned consumers and save electric power resources of a country is offered. Wherein electric power system voltage is considered as a potential form of electromagnetic energy and commercial product of electric power industry, which is a base one of any economy. The power transmission organizations, with the help of their and consumers’ networks, supply voltage to a receiving point in the power supplying system of specific consumers at the level of quality established by the state. It is known that the main voltage quality indicator is a level of its deviation from the nominal value. In the paper the voltage drops, linked with reactive consumer load, are proposed to be optional and completely dependent on its run mood.That is why it is offered to normalize (control) the reactive load coefficient value for each of the con-sumers in the way that the voltage deviation of the receiving point in the maximal load mood of power sup-plying system does not exceed 5 % of the nominal value. Taking into account that an integral part of any electric device is its electromagnetic field the one (field) of power supplying system can be presented in the form of a quanton, whose electrons of polarized molecules revolve in the two mutually perpendicular di-rections - lengthwise and crosswise the direction of electric transmission in the volume of solid angle 45 de-gree under the influence of geomagnetic field.

Efficient multiple-reference-frame controller for harmonic suppression in custom power devices

Abstract Tracking harmonic currents and voltages in electric power systems with custom power devices exceeds the capabilities of conventional Proportional+Integral controllers and more sophisticated algorithms are required, especially under grid-frequency variations. This paper presents a control method based on multiple reference frames for harmonic control in the context of a series active power filter. The proposed scheme allows recursive calculation when referring signals to reference frames rotating synchronously with harmonic equivalent space vectors whilst a minimum of trigonometric-function evaluations are required. Furthermore, the control of each harmonic can be dealt with using simple integral controllers applied to the transformed signals. The paper presents the closed-loop-stability analysis and experimental results of a series active power filter. A scenario with grid-frequency variations is considered to show the intrinsic adaptation capability of the proposed controller.

ANALIZA ZAKŁÓCEŃ W SIECIACH ELEKTROENERGETYCZNYCH WYWOŁANYCH WYŁADOWANIAMI PIORUNOWYMI

This paper deals with analyzing specific transient states of voltages in electric power systems of high voltages. The paper presents the results of the analysis of operational disturbances caused by lightning discharges in 110 kV power system. Furthermore, the analysis results of lightning surges as well as the optimization results of a surge protection system installed in a 110 kV substation are presented. A model of an electric power system (overhead lines and substation) and all simulations were performed using computer software Electromagnetic Transients Program-Alternative Transients Program (EMTP-ATP). This model is based on a set of appropriately connected elements (distributed and lumped parameter elements) taking wave effects and nonlinear effects into consideration.

A probabilistic nodal loading model and worst case solutions for electric power system voltage stability assessment

In this paper, a new nodal loading model for use in voltage stability assessment of electric power systems is proposed, and the formulation of worst cases based on this model, as well as related numerical methods, are described. In this nodal loading model, called the "hyper-cone" model, a set of future operating points in a load parameter space is modeled. That is, the "vertex" of the hyper-cone is taken to be the current operating point, and the "thickness" of the hyper-cone represents the uncertainty of future loading. The worst loading case is the point, among the set of transfer limit points on or within the hyper-cone, at which the total load is smallest. In other words, in terms of the uncertainty of future loading, the worst case corresponds to the most conservative transfer limit. Efficient numerical methods to compute this worst case are shown, and these methods are demonstrated on some sample power systems including IEEE 118-node system.

Synthesizing variant impedances in SPICE. A fast solution for power electronics and electric power systems simulations

The Simulation Program with Integrated Circuit Emphasis (SPICE) is a program widely used to simulate electric circuits. Characteristics such as versatility, large component libraries, integration of schematic edition, simulation and analyses have made it popular. As many students use this program early on, there is a natural tendency to continue using it in power electronics, electrical drives and electric power system courses. SPICE was initially developed to simulate integrated circuits. Therefore, sometimes the program parameters and components must be adapted to power circuits and systems. For example, the tolerances and component parameters have to be changed. Variant impedances frequently are present in electrical/electronic circuits. For example, an incandescent bulb is a power-variant resistance. A thermistor is a resistance that varies according to the temperature. An ideal thyristor controlled reactor (TCR), used to control voltage in electric power systems, is a variable inductance that changes its value depending on a control signal. A thyristor controlled series capacitor (TCSC) or a static reactive power compensator are ideally modeled as variable capacitances. Simulating such circuits requires defining the sub-circuits that, at their terminals, behave like the desired variant impedance.

A New Adaptive Active Filter for Harmonic Voltage Compensation in Electric Power Systems

This paper presents a new adaptive active filter for compensating harmonic voltages in electric power systems. In order to improve the control speed, the compensator provides a high-precision and high-speed compensation signal for eliminating the harmonic components. A new design method is proposed and various experimental results are presented. This method is based on a new principle using a high-speed DSP for the detection and prediction of the harmonic voltages. The adaptive compensation and the FFT processing are done in real time. The compensation has very good characteristics to instantaneous variations of load in the electric power system. Thus, it is possible to compensate such harmonic power as generated by flicker load. The control circuit is completely digitized using a DSP, and the interferences are suppressed at a high degree of precision. Therefore, it becomes possible to implement an economical high-precision adaptive active filter for electric power systems.

A hybrid nonlinear-least squares estimation of harmonic signal levels in power systems

It is expected that guides and recommended practices will be adopted in the United States for the limitation of harmonic currents and voltages in electric power systems. A method of using measurements and topological/mathematical methods to identify signal levels that do not comply with these guides and standards is described. The methodology is based on measurements, state estimators, and system modeling. An illustration of its application is given. A hybrid nonlinear-least-squares method is used for state estimation. This estimation theory is used to calculate (estimate) bus voltages and line currents which cannot be (or are not) measured directly. The basis for the least-squares estimator is the Kirchhoff current law, and the basis for the nonlinear technique is minimum mismatch power. >

(1) Arithmetic of Alternating Currents (2) Constant-voltage Transmission: a Discussion of the Use of Synchronous Motors for Eliminating Variation in Voltage in Electric Power Systems (3) Alternating-current Work: an Introductory Book for Engineers and Students (4) Experimental Electricity and Magnetism

(1) PROF. E. H. CRAPPER'S book can be recommended to all desiring to obtain a thorough working knowledge of the everyday calculations which have to be made by alternating-current engineers. The lengthy experience the author has had in training electrical engineers has convinced him that the only way to master the subject is to acquire facility in solving the types of numerical problems which occur in practice. There are 232 examples in the book. The answers to all of them are given, and fifty are worked out in full. They are arranged in order of difficulty, and none of them make excessive demands on the knowledge or ability of the student. We have tested the numerical accuracy of the answers given to several of the problems with satisfactory results. (1) Arithmetic of Alternating Currents. By E. H. Crapper. Pp. vii + 208. (London: Whittaker and Co., 1915.) Price 2s. 6d. net. (2) Constant-voltage Transmission: a Discussion of the Use of Synchronous Motors for Eliminating Variation in Voltage in Electric Power Systems. By H. B. Dwight. Pp. vii + 115. (New York: J. Wiley and Sons, Inc.; London: Chapman and Hall, Ltd., 1915.) Price 5s. 6d. net. (3) Alternating-current Work: an Introductory Book for Engineers and Students. By W. P. Maycock. Pp. xxiii + 415. (London: Whittaker and Co., 1915.) Price 6s. net. (4) Experimental Electricity and Magnetism. By M. Finn. Pp. x + 436. (London: G. Bell and Sons, Ltd., 1915.) Price 4s. 6d.