scholarly journals A definition of the "reactive power" concept

2021 ◽  
pp. 47-51
Author(s):  
Yevgen Honcharov ◽  
Nataliya Kruykova ◽  
Vladyslav Markov ◽  
Igor Polyakov
Keyword(s):  
Electric Fields ◽  
Physical Meaning ◽  
Reactive Power ◽  
Electrical Energy ◽  
Alternating Current ◽  
Active Power ◽  
Electrostatic Fields ◽  
Definition Of ◽  
The Magnetic Field ◽  
Power Concept

A definition of the "reactive power" concept needs to be clarified, since in the literature it is often given extremely vaguely, which causes difficulties in students' perception and is not entirely clear to the general public. Analysis of numerous sources shows that the physical meaning of this concept almost escapes the definitions given in these sources. Moreover, the formula by which the reactive power is calculated raises no objections. However, it does not explain the physical meaning of the concept. The need for a capacious definition that reflects the physical meaning is long overdue. Analysis of literature sources allows us to conclude that reactive power corresponds to the energy that goes from the source to the consumer and returns back, moreover, the process of circulation of this energy proceeds without dissipation. This energy is stored in inductors, keeping the current constant, and in capacitors, because they charge and discharge, keeping the voltage constant. The inductance and capacitance of the circuit consume and return reactive power. The power transferred to the inductor is stored in the magnetic field when the field expands and returns to the source when the field collapses. The power supplied to the capacitor is stored in an electrostatic field when the capacitor is charged and returned to the source when the capacitor is discharged. This power supplied to the circuit by the source is not consumed. It all returns to the source. Thus, the active power, which is the consumed power, is zero. We know that alternating current is constantly changing; thus, cycles of expansion and collapse of magnetic and electrostatic fields constantly occur. The following definition is proposed: non-dissipated electrical energy of alternating current, which excites the magnetic or electric fields, respectively, in inductive and capacitive elements and, coming from them back to the network, is called reactive power.

Study on Dispersed Wind Power Connected to Power Grid

2014 ◽  
Vol 672-674 ◽  
pp. 262-268
Author(s):  
Wei Xu ◽  
Xiang Ning Xiao ◽  
Zhi Chao Zhou
Keyword(s):  
Wind Power ◽  
Reactive Power ◽  
Frequency Control ◽  
Power Grid ◽  
Active Power ◽  
Fault Ride Through ◽  
Power Frequency ◽  
Grid Codes ◽  
Definition Of ◽  
Technology Indicators

The necessity for grid codes of the dispersed wind power connected to power grid is described briefly and the definition of the dispersed wind power is discussed compared with the distributed wind power in China. Aimed at the dispersed wind power, the main technology indicators of wind power grid codes between Denmark (below 100kV), Germany (below 60kV) and China in aspects of access principle, connection mode, active power / frequency control, reactive power / voltage control, fault ride through and power quality are compared to provide reference for the modification and completion of the dispersed wind power grid code in China.

scholarly journals Time development of electric fields and currents in space plasmas

2006 ◽  
Vol 24 (3) ◽  
pp. 1137-1143
Author(s):  
A. T. Y. Lui
Keyword(s):  
Magnetic Field ◽  
Electric Current ◽  
Electric Fields ◽  
Time Development ◽  
Space Plasmas ◽  
Simplifying Assumptions ◽  
Electric Fields And Currents ◽  
Definition Of ◽  
The Magnetic Field ◽  
Made In

Abstract. Two different approaches, referred to as Bu and Ej, can be used to examine the time development of electric fields and currents in space plasmas based on the fundamental laws of physics. From the Bu approach, the required equation involves the generalized Ohm's law with some simplifying assumptions. From the Ej approach, the required equation can be derived from the equation of particle motion, coupled self-consistently with Maxwell's equation, and the definition of electric current density. Recently, some strong statements against the Ej approach have been made. In this paper, we evaluate these statements by discussing (1) some limitations of the Bu approach in solving the time development of electric fields and currents, (2) the procedure in calculating self-consistently the time development of the electric current in space plasmas without taking the curl of the magnetic field in some cases, and (3) the dependency of the time development of magnetic field on electric current. It is concluded that the Ej approach can be useful to understand some magnetospheric problems. In particular, statements about the change of electric current are valid theoretical explanations of change in magnetic field during substorms.

scholarly journals Voltage stability in low voltage microgrids in aspects of active and reactive power demand

2016 ◽  
Vol 65 (1) ◽  
pp. 19-32 ◽  
Author(s):  
Mirosław Parol ◽  
Łukasz Rokicki
Keyword(s):  
Voltage Stability ◽  
Reactive Power ◽  
Low Voltage ◽  
Stability Margin ◽  
Electrical Energy ◽  
Active And Reactive Power ◽  
Voltage Stability Margin ◽  
Stability Issue ◽  
Node Voltage ◽  
Definition Of

Abstract Low voltage microgrids are autonomous subsystems, in which generation, storage and power and electrical energy consumption appear. In the paper the main attention has been paid to the voltage stability issue in low voltage microgrid for different variants of its operation. In the introduction a notion of microgrid has been presented, and also the issue of influence of active and reactive power balance on node voltage level has been described. Then description of voltage stability issue has been presented. The conditions of voltage stability and indicators used to determine voltage stability margin in the microgrid have been described. Description of the low voltage test microgrid, as well as research methodology along with definition of considered variants of its operation have been presented further. The results of exemplary calculations carried out for the daily changes in node load of the active and reactive power, i.e. the voltage and the voltage stability margin indexes in nodes have been presented. Furthermore, the changes of voltage stability margin indexes depending on the variant of the microgrid operation have been presented. Summary and formulation of conclusions related to the issue of voltage stability in microgrids have been included at the end of the paper.

scholarly journals On alternating current electrolysis

1920 ◽  
Vol 97 (682) ◽  
pp. 124-144 ◽  
Keyword(s):  
Electric Current ◽  
Electric Fields ◽  
Alternating Current ◽  
Detailed Examination ◽  
Field Of View ◽  
Electrostatic Fields ◽  
Alternating Electric Current ◽  
Small Bubbles

In the summer of 1915, Mr. E. Meigh, M. Sc., and the author, were engaged in some research dealing with the behaviour of bacteria under the action of electric fields. No definite conclusions were formed concerning the action of alternating electrostatic fields, and it was decided, therefore, to examine the effect of an alternating electric current on bacteria. It was noticed, however, that small bubbles of gas were formed at the electrodes, and, although these bubbles were not in the field of view of the microscope, nevertheless, they gave rise to a displacement of the volume of liquid under examination, this displacement masking completely any changes that might have occurred in the movement of the bacteria. This led to an investigation of the conditions under which such bubbles were formed, and, in the end, to a detailed examination by the author of some of the phenomena of alternating current electrolysis.

Improving the efficiency of oilfield electric power distribution

2019 ◽  
pp. 79-87
Author(s):  
Yu. F. Yu. F. Romaniuk ◽  
О. V. Solomchak ◽  
М. V. Hlozhyk
Keyword(s):  
Power Distribution ◽  
Reactive Power ◽  
Power Transmission ◽  
Transmission Efficiency ◽  
Active Power ◽  
Oil Field ◽  
Total Power ◽  
Simultaneous Increase ◽  
Active Load ◽  
Step Down

The issues of increasing the efficiency of electricity transmission to consumers with different nature of their load are considered. The dependence of the efficiency of the electric network of the oil field, consisting of a power line and a step-down transformer, on the total load power at various ratios between the active and reactive components of the power is analyzed, and the conditions under which the maximum transmission efficiency can be ensured are determined. It is shown by examples that the power transmission efficiency depends not only on the active load, but also largely on its reactive load. In the presence of a constant reactive load and an increase in active load, the total power increases and the power transmission efficiency decreases. In the low-load mode, the schedule for changing the power transmission efficiency approaches a parabolic form, since the influence of the active load on the amount of active power loss decreases, and their value will mainly depend on reactive load, which remains unchanged. The efficiency reaches its maximum value provided that the active and reactive components of the power are equal. In the case of a different ratio between them, the efficiency decreases. With a simultaneous increase in active and reactive loads and a constant value of the power factor, the power transmission efficiency is significantly reduced due to an increase in losses. With a constant active load and an increase in reactive load, efficiency of power transmission decreases, since with an increase in reactive load, losses of active power increase, while the active power remains unchanged. The second condition, under which the line efficiency will be maximum, is full compensation of reactive power.  Therefore, in order to increase the efficiency of power transmission, it is necessary to compensate for the reactive load, which can reduce the loss of electricity and the cost of its payment and improve the quality of electricity. Other methods are also proposed to increase the efficiency of power transmission by regulating the voltage level in the power center, reducing the equivalent resistance of the line wires, optimizing the loading of the transformers of the step-down substations and ensuring the economic modes of their operation.

Mutagenic Potential of Alternating Current Electric Fields.

1997 ◽  
Author(s):  
John Obringer ◽  
Brandon Horne ◽  
Brian Kelchner
Keyword(s):  
Electric Fields ◽  
Alternating Current ◽  
Mutagenic Potential

scholarly journals Optimal Sizing and Placement of Capacitor Banks in Distribution Networks Using a Genetic Algorithm

Electricity ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 187-204
Author(s):  
Gian Giuseppe Soma
Keyword(s):  
Genetic Algorithm ◽  
Electricity Market ◽  
Distribution Systems ◽  
Reactive Power ◽  
Electricity Consumption ◽  
Distribution Networks ◽  
Optimal Placement ◽  
Capacitor Banks ◽  
Control Pattern ◽  
Definition Of

Nowadays, response to electricity consumption growth is mainly supported by efficiency; therefore, this is the new main goal in the development of electric distribution networks, which must fully comply with the system’s constraints. In recent decades, the issue of independent reactive power services, including the optimal placement of capacitors in the grid due to the restructuring of the electricity industry and the creation of a competitive electricity market, has received attention from related companies. In this context, a genetic algorithm is proposed for optimal planning of capacitor banks. A case study derived from a real network, considering the application of suitable daily profiles for loads and generators, to obtain a better representation of the electrical conditions, is discussed in the present paper. The results confirmed that some placement solutions can be obtained with a good compromise between costs and benefits; the adopted benefits are energy losses and power factor infringements, taking into account the network technical limits. The feasibility and effectiveness of the proposed algorithm for optimal placement and sizing of capacitor banks in distribution systems, with the definition of a suitable control pattern, have been proved.

scholarly journals Real Fault Location in a Distribution Network Using Smart Feeder Meter Data

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3242
Author(s):  
Hamid Mirshekali ◽  
Rahman Dashti ◽  
Karsten Handrup ◽  
Hamid Reza Shaker
Keyword(s):  
Fault Location ◽  
Network Reliability ◽  
Distribution Network ◽  
Estimation Method ◽  
Electrical Energy ◽  
Distribution Networks ◽  
Active Power ◽  
Financial Loss ◽  
Smart Meters ◽  
The Real

Distribution networks transmit electrical energy from an upstream network to customers. Undesirable circumstances such as faults in the distribution networks can cause hazardous conditions, equipment failure, and power outages. Therefore, to avoid financial loss, to maintain customer satisfaction, and network reliability, it is vital to restore the network as fast as possible. In this paper, a new fault location (FL) algorithm that uses the recorded data of smart meters (SMs) and smart feeder meters (SFMs) to locate the actual point of fault, is introduced. The method does not require high-resolution measurements, which is among the main advantages of the method. An impedance-based technique is utilized to detect all possible FL candidates in the distribution network. After the fault occurrence, the protection relay sends a signal to all SFMs, to collect the recorded active power of all connected lines after the fault. The higher value of active power represents the real faulty section due to the high-fault current. The effectiveness of the proposed method was investigated on an IEEE 11-node test feeder in MATLAB SIMULINK 2020b, under several situations, such as different fault resistances, distances, inception angles, and types. In some cases, the algorithm found two or three candidates for FL. In these cases, the section estimation helped to identify the real fault among all candidates. Section estimation method performs well for all simulated cases. The results showed that the proposed method was accurate and was able to precisely detect the real faulty section. To experimentally evaluate the proposed method’s powerfulness, a laboratory test and its simulation were carried out. The algorithm was precisely able to distinguish the real faulty section among all candidates in the experiment. The results revealed the robustness and effectiveness of the proposed method.

scholarly journals Effect of Symmetrically Switched Rectifier Topologies on the Frequency Regulation of Standalone Micro-Hydro Power Plants

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3201
Author(s):  
Henry Bory ◽  
Jose L. Martin ◽  
Iñigo Martinez de Alegria ◽  
Luis Vazquez
Keyword(s):  
Power Factor ◽  
Power Plants ◽  
Reactive Power ◽  
Alternating Current ◽  
Frequency Regulation ◽  
Hydro Power ◽  
Major Energy Source ◽  
Hydro Power Plants ◽  
Electronic Load ◽  
Ac Converters

Micro-hydro power plants (μHPPs) are a major energy source in grid-isolated zones because they do not require reservoirs and dams to be built. μHPPs operate in a standalone mode, but a continuously varying load generates voltage unbalances and frequency fluctuations which can cause long-term damage to plant components. One method of frequency regulation is the use of alternating current-alternating current (AC-AC) converters as an electronic load controller (ELC). The disadvantage of AC-AC converters is reactive power consumption with the associated decrease in both the power factor and the capacity of the alternator to deliver current. To avoid this disadvantage, we proposed two rectifier topologies combined with symmetrical switching. However, the performance of the frequency regulation loop with each topology remains unknown. Therefore, the objective of this work was to evaluate the performance of the frequency regulation loop when each topology, with a symmetrical switching form, was inserted. A MATLAB® model was implemented to simulate the frequency loop. The results from a μHPP case study in a small Cuban rural community called ‘Los Gallegos’ showed that the performance of the frequency regulation loop using the proposed topologies satisfied the standard frequency regulation and increased both the power factor and current delivery capabilities of the alternator.

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