Name: reducing reactive power in ac loads
Uploaded: 2024-07-08T13:19:54.000Z
Duration: 1 min 20 s
Channel: JoVE

공장으로의 전력 전송에는 유효 전력과 무효 전력의 전달이 포함됩니다. 총 전력에 대한 활성 전력의 비율은 역률을 정의합니다.
낮은 역률은 유도 전기 부하가 더 많은 무효 전력을 흡수하여 낮은 지연 역률을 유발한다는 것을 의미합니다. 이로 인해 부하 및 열 손실에서 전압 강하가 크게 발생하여 전기 비용이 증가하고 시스템 효율이 감소합니다.
역률은 부하에 병렬로 연결된 자체 튜닝 커패시터와 같은 보상 임피던스를 추가하여 개선할 수 있습니다. 이 접근 방식은 역률을 가능한 한 통일성에 가깝게 만듭니다.
커패시터를 추가하는 효과는 파워 트라이앵글을 사용하여 설명할 수 있습니다. 원래 회로의 파워 트라이앵글을 검사하여 실제 전력과 무효 전력을 결정할 수 있습니다.
용량성 부하를 추가하면 실제 전력을 변경하지 않고 역률 각도가 감소합니다. 새 삼각형에서 수정된 무효 전력의 값이 계산됩니다.
이러한 무효 전력의 감소는 션트 커패시턴스에서 비롯됩니다. 무효 전력의 표현을 다시 방문하여 션트 커패시터 값을 결정합니다.

 역률 보정

공장으로의 전력 전송에는 유효 전력과 무효 전력의 조합인 피상 전력의 전송이 포함됩니다. 역률은 전력이 얼마나 효과적으로 유용한 작업 출력으로 변환되는지를 측정합니다. 회로에 공급되는 피상 전력(KVA)에 대한 작업을 수행하는 실제 전력(KW)의 비율입니다.
<img alt="Equation 1" src="/files/ftp_upload/15123/15123_Equation_1.svg" style="height: 30px;">
역률이 낮다는 것은 유도성 전기 부하가 더 많은 무효 전력을 흡수하여 지연 역률이 낮다는 것을 의미합니다. 이로 인해 부하 및 열 손실 전반에 걸쳐 큰 전압 강하가 발생하여 전기 비용이 증가하고 시스템 효율성이 감소합니다. 역률 보정은 효율적인 시스템을 얻기 위해 역률을 1로 조정하여 수행됩니다. 부하에 병렬로 자체 조정 축전기와 같은 보상 온저항을 추가하면 역률을 향상시킬 수 있습니다. 전력 삼각형을 조사하면 실제 전력과 무효 전력을 분석할 수 있으므로 축전기 추가 효과를 전력 삼각형을 사용하여 설명할 수 있습니다.
<img alt="Equation 2" src="/files/ftp_upload/15123/15123_Figure_1.svg" style="height: 150px;">
용량성 부하가 직렬 또는 병렬로 추가되고 실제 전력을 변경하지 않고 역률 각도가 감소합니다. 역률의 값이 조정됩니다. 직렬 축전기는 긴 전송선의 역률 보정에 사용됩니다. 직렬 연결된 축전기는 지연 무효 전력의 일부를 중화할 수 있는 선행 전류를 제공하여 결과적으로 역률을 개선함으로써 라인의 유도 특성을 상쇄합니다. 션트 축전기는 역률 보정에 가장 널리 사용됩니다. 축전기는 부하에 병렬로 연결되며 유도성 부하로 인해 발생하는 지연 무효 전류를 상쇄하는 선행 전류를 제공합니다. 이는 전체 역률을 1에 더 가깝게 만듭니다. 유도 효과에 대응하여 션트 축전기는 공급 장치에서 끌어오는 무효 전력의 양을 줄여 시스템을 더욱 효율적으로 만들 수 있습니다.

공장으로의 전력 전송에는 유효 전력과 무효 전력의 전달이 포함됩니다. 총 전력에 대한 활성 전력의 비율은 역률을 정의합니다.
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Education

교육

JoVE Core

Electrical Engineering

전기공학

Unit 1

제1단원

AC Steady State Power

교류 정상 상태 전력

KEY TERMS AND CONCEPTS

주요 용어 및 개념

Power Factor Correction

reducing reactive power in ac loads

Power factor correction helps AC systems use electrical power more efficiently. In a factory circuit, transmitted power includes apparent power, which is made of active power and reactive power. Power factor is the ratio of real power, measured in kW, to apparent power, measured in kVA. It shows how much of the supplied power becomes useful work.

A low power factor often happens when an inductive load draws too much reactive power. This creates a lagging power factor. It can also cause large voltage drops across the load and thermal losses. As a result, electricity costs rise and system efficiency falls.

Power factor is improved by moving the value closer to unity. One way to do this is to add a compensating impedance, such as self-tuning capacitors, in parallel with the load. The change can be shown with the power triangle, where real power and reactive power are compared. A capacitive load can also be added in series or parallel, which lowers the power factor angle without changing the real power.

Series capacitors are used for power factor correction in long transmission lines. They counteract the inductive nature of the line by supplying a leading current that helps neutralize some of the lagging reactive power. Shunt capacitors are the most widely used option. They are connected in parallel with the load and provide a leading current that offsets the lagging reactive current from inductive loads. This brings the overall power factor closer to unity and reduces the reactive power drawn from the supply.

Reducing Reactive Power in AC Loads

instantaneous power

AC Power and Phase Shift

Instantaneous power in an electrical circuit comes from the voltage across an element and the current through it. It is written as p(t) and follows the passive sign convention. For sinusoidal input, this product helps show how power changes at each moment. When instantaneous power is expanded, it has two parts. One part is constant and depends on the phase difference between voltage and current. The other part is a sinusoidal term that varies at twice the frequency of the voltage or current. <br...

average power

Power Consumption in AC Circuits

Power consumption in AC circuits is often described with average power. In practical electrical work, the changing value of instantaneous power is less useful than the average over a time period. Average power is found by integrating instantaneous power over that time and then dividing by the duration. The time-domain expression for average power comes from simplifying the equation for instantaneous power. In that form, one cosine term averages to zero over a complete cycle. The result does...

effective value of a periodic waveform

RMS Value for AC Power Measurement

The RMS value, or effective value, helps measure how much power a periodic voltage or current can deliver. It is the direct current, or DC, value that gives the same average power to a resistor as the periodic signal does. This idea is especially important in AC circuits. To find the effective value of current, calculate the root mean square, or RMS, current. First square the instantaneous current values over one period. Then find the mean of those squared values and take the square root. The...

complex power

Power Triangle in AC Circuits

Power triangle and complex power help describe how an AC load uses energy. Engineers use complex power to capture the combined effect of parallel loads. It gives a full picture of the power consumed by a specific load. Complex power is found by multiplying voltage by the complex conjugate of current. Using rms values, it is written with the rms voltage phasor and the complex conjugate of the rms current phasor. It can also be written in terms of load impedance. The magnitude of complex power...

conservation of ac power

AC Power in Series and Parallel Circuits

AC power in series and parallel circuits follows a power preservation rule. In AC circuits, the complex power, real power, and reactive power produced by the source are equal to the total complex, real, and reactive powers absorbed by the loads. When two load impedances are connected in parallel to an AC source V, the source power can be written as the sum of the complex powers delivered to loads Z1 and Z2. If those same loads are connected in series with the voltage source, the complex power...

power factor

Power Factor and AC Load Behavior

Power factor describes how voltage and current behave in an AC load. It is the ratio of average, or active, power to apparent power. The power factor angle is the phase difference between voltage and current, and the cosine of that angle gives the power factor. It also matches the angle of the load impedance. Power factor shows how much apparent power becomes real, or average, power. Its value ranges from zero to one. When a load is purely resistive, voltage and current are in phase. In that...

power factor correction

Power factor correction helps AC systems use electrical power more efficiently. In a factory circuit, transmitted power includes apparent power, which is made of active power and reactive power. Power factor is the ratio of real power, measured in kW, to apparent power, measured in kVA. It shows how much of the supplied power becomes useful work. A low power factor often happens when an inductive load draws too much reactive power. This creates a lagging power factor. It can also cause large...

the power superposition principle

Power from Multiple AC Sources

Power from multiple AC sources is found by adding the effects of each source separately. In a circuit with two sinusoidal voltage sources, each source acts independently. The superposition principle says the total current is the sum of the currents produced by each source alone. If those currents are labeled i1 and i2, they combine to give the total current. Instantaneous power is the power at one moment in time. In this circuit, it equals the square of the instantaneous current times the...

the maximum power transfer theorem

Matching Load Impedance for Maximum Power

Maximum power transfer in an AC circuit depends on matching the load impedance to the Thevenin equivalent of the source network. The load draws current, and the circuit delivers power to that load. To analyze the current, the voltages, currents, network impedance, and load impedance are written in rectangular form. The average power delivered to the load comes from the square of the current multiplied by the load resistance. To find the condition for maximum power, the power is differentiated...

key terms and concepts

Learn how power factor correction improves AC efficiency by reducing reactive power, lowering voltage drops, and using series or shunt capacitors.

Reducing Reactive Power in AC Loads | JoVE K12

JoVE Core Electrical Engineering offers easy-to-understand animated videos that cover fundamental concepts of electric circuits along with circuit analysis techniques. It incorporates first-order and second-order circuits using operational amplifiers and circuit transformation concepts. The inclusion of practical design examples and real-world applications through scientist-in-action videos adds significant educational value, making complex concepts accessible.

electrical engineering

Reducing Reactive Power in AC Loads

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