ANALISIS RANGKAIAN AC, KONSEP DAYA - SISTEM TENAGA LISTRIK

Introduction

This tutorial covers the analysis of AC circuits, focusing on phasors and power concepts as demonstrated in the video by TEORI & PRAKTEK ELEKTRO. Understanding these concepts is crucial for anyone working with electrical engineering, as they form the foundation for analyzing and designing electrical systems.

Step 1: Understanding AC Circuit Basics

• Define Alternating Current (AC): AC is an electric current that periodically reverses direction, unlike direct current (DC). Familiarize yourself with the key characteristics:

  • Voltage and current vary sinusoidally over time.
  • Commonly used in power systems and household electricity.

• Phasors Explained: A phasor is a complex number representing the amplitude and phase of sinusoidal functions.

  • Magnitude: Represents the peak value of voltage or current.
  • Phase Angle: Indicates the shift in time between the voltage and current waveforms.

Step 2: Analyzing AC Circuits with Phasors

• Convert Time Domain to Frequency Domain:

  • Use phasors to simplify calculations involving AC circuits.
  • Convert sinusoidal functions into phasor form:
    • ( V(t) = V_m \sin(\omega t + \phi) ) converts to ( V = V_m \angle \phi ).

• Kirchhoff’s Laws in AC Circuits:

  • Apply Kirchhoff’s Voltage Law (KVL) and Kirchhoff’s Current Law (KCL) using phasors.
  • For KVL, the sum of the voltage drops in a closed loop must equal the sum of the voltage sources.

Step 3: Calculating Power in AC Circuits

• Types of Power:

  • Real Power (P): The actual power consumed by the circuit, measured in watts (W).
  • Reactive Power (Q): Power stored and released by reactive components like inductors and capacitors, measured in volt-amperes reactive (VAR).
  • Apparent Power (S): The total power in an AC circuit, calculated using the formula ( S = V_{rms} \times I_{rms} ).

• Power Factor: Understand the significance of the power factor, which is the ratio of real power to apparent power.

  • A power factor of 1 indicates all power is being effectively used.
  • Formula: ( \text{Power Factor} = \frac{P}{S} )

Step 4: MATLAB Simulation

• Setting Up MATLAB: Use MATLAB to simulate AC circuits and visualize phasors and power calculations.

  • Start by defining the circuit parameters (resistances, inductances, capacitances).
  • Use built-in functions for phasor analysis and power computations.

• Sample MATLAB Code:

% Define circuit parameters
R = 10; % resistance in ohms
L = 0.1; % inductance in henries
C = 0.01; % capacitance in farads
f = 50; % frequency in hertz
omega = 2 * pi * f;

% Calculate impedances
Z_R = R; 
Z_L = 1j * omega * L; 
Z_C = -1j / (omega * C);
Z_total = Z_R + Z_L + Z_C;

% Calculate current and power
V_s = 230; % source voltage
I = V_s / Z_total; % current
P = real(V_s * conj(I)); % real power
Q = imag(V_s * conj(I)); % reactive power

• This code snippet helps you analyze the circuit and calculate the power values.

Conclusion

In this tutorial, we explored the fundamentals of AC circuit analysis, focusing on phasors and power calculations. You have learned how to convert time-domain functions to phasors, apply Kirchhoff’s laws in AC circuits, and calculate different types of power. Additionally, you gained insights on simulating these concepts using MATLAB, enhancing your practical skills in electrical engineering.

Next steps may include experimenting with your own circuit designs in MATLAB or delving deeper into advanced topics such as resonance and power quality analysis.