Name: voltage and reactive power control
Uploaded: 2024-11-21T14:54:26.000Z
Duration: 1 min 30 s
Channel: JoVE

O controle do fluxo de energia requer o gerenciamento de componentes como motor principal dos geradores e controle de excitação, bancos de capacitores de derivação, reatores, sistemas var estáticos e transformadores reguladores.
Um gerador em condições de estado estacionário é representado pelo equivalente de Thévenin, incluindo tensão terminal, tensão de excitação, ângulo de potência e reatância síncrona.
As potências atual, real e reativa do gerador são então calculadas.
Aumentar o ângulo de potência aumenta a potência real, mas diminui a potência reativa, enquanto aumentar a tensão de excitação aumenta a potência reativa e diminui ligeiramente o ângulo de potência.
Adicionar um banco de capacitores de derivação a um barramento aumenta sua tensão, enquanto um reator de derivação a diminui.
Os transformadores de comutação de derivação e reguladores de tensão controlam as tensões do barramento e os fluxos de potência reativa. Os transformadores reguladores de ângulo de fase controlam os ângulos do barramento e os fluxos de potência reais.
Alterações nas configurações de tap ou regulação de tensão alteram a relação de espiras do transformador calculada pelo programa de fluxo de potência.
O programa também avalia os efeitos de linhas de comutação, transformadores, cargas e geradores. Ele simula mudanças para atender ao crescimento futuro da carga.

controle do fluxo de energia

Existem vários métodos para controlar o fluxo de energia em sistemas de energia:

<ul style="padding-left: 35px; list-style-type: disc;">
	<li>Controle de excitação e motor primário de geradores</li>
	<li>Comutação de bancos de capacitores de derivação, reatores de derivação e sistemas var estáticos</li>
	<li>Controle de transformadores de comutação e regulação</li>
</ul>

Um gerador simples no sistema é representado por seu circuito equivalente de Thévenin, que representa seu modelo operando sob condições de estado estacionário balanceado. Os principais parâmetros incluem a tensão do terminal do gerador V_t, a tensão de excitação E_g, o ângulo de potência δ e a reatância síncrona de sequência positiva X_g.

<img alt="PT_Image1" src="/files/ftp_upload/16150/16150_PT_Image_1.svg" style="height: 36px;">

A corrente do gerador é:

<img alt="Equation1" src="/files/ftp_upload/16150/16150_PT_equation_1.svg" style="height: 160px;">

e a potência complexa fornecida é:

<img alt="Equation2" src="/files/ftp_upload/16150/16150_PT_equation_2.svg" style="height: 36px;">

Um banco de capacitores de derivação adicionado a um barramento do sistema de energia aumenta a magnitude da tensão do barramento e compensa a potência reativa. Este ajuste é modelado conectando um capacitor, que absorve potência reativa negativa, reduzindo assim a demanda geral de potência reativa do sistema. Além disso, transformadores de mudança de derivação são usados ​​para regular tensões de barramento e gerenciar fluxos de potência reativa ajustando a relação de voltas, influenciando assim o perfil de tensão e potência reativa na rede. Este ajuste ajuda a manter a estabilidade e eficiência do sistema, acomodando variações de carga e melhorando o fornecimento de energia.

Estudos de fluxo de energia geralmente usam tentativa e erro para ajustar níveis de geração e configurações de controle. Esses ajustes garantem que o sistema atenda às cargas de equipamento e perfis de tensão desejados, preparando a rede para crescimento de carga, novas transmissões, transformadores e geração. O controle do fluxo de energia é um processo dinâmico que envolve vários métodos e ajustes para manter a estabilidade, eficiência e confiabilidade do sistema.

Controle do Fluxo de Energia

O controle do fluxo de energia requer o gerenciamento de componentes como motor principal dos geradores e controle de excitação, bancos de capacitores de derivação, reatores, var estático ...

Education

JoVE Core

Electrical Engineering

Engenharia Elétrica

Unit 1

Unidade 1

Steady-State Transmission Lines and Power Flows

Linhas de Transmissão em Regime Permanente e Fluxos de Potência

steady-state-transmission-lines-and-power-flows

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

Control of Power Flow

voltage and reactive power control

Voltage and reactive power control help keep a power system stable and efficient. In this topic, generator settings, switched equipment, and transformer taps work together to guide how power moves through the network.

A generator can be modeled with a Thevenin equivalent circuit under balanced steady-state conditions. The main terms are terminal voltage Vt, excitation voltage Eg, power angle δ, and positive-sequence synchronous reactance Xg. From this model, the generator current and the complex power delivered can be determined.

One way to adjust power flow is through generator control. The prime mover and the excitation system can be changed to influence generation and voltage behavior. Power flow studies often use trial and error to set these values and other controls.

Shunt capacitor banks, shunt reactors, and static var systems are also used to manage reactive power. A shunt capacitor bank connected to a bus raises the bus voltage magnitude. It also compensates for reactive power by absorbing negative reactive power, which lowers the system’s overall reactive power demand.

Tap-changing and regulating transformers provide another way to control bus voltage and reactive power flow. By changing the turns ratio, these transformers alter the voltage profile across the network. This helps the system handle load changes and support efficient power delivery.

These control steps are used to meet equipment loading limits and desired voltage profiles. They also prepare the network for load growth, new transmission lines, transformers, and added generation. In this way, power flow control remains a dynamic process that supports stability, efficiency, and reliability.

Voltage and Reactive Power Control

transmission-line differential equations

Modeling Voltage and Current on Transmission Lines

Transmission lines carry electric power, and their resistance, inductance, and capacitance are spread out along the line. Because these properties are distributed per unit length, voltage and current change as they move from one end of the line to the other. Differential equations are used to describe that variation. A line-section model helps show how this works. In the model, a small length, Δx, is used to represent the line. Voltage V(x) and current i(x) are measured from the receiving end.

lossless lines

Lossless Lines and Voltage Behavior

Lossless transmission lines in electrical engineering are described by a purely imaginary propagation constant and a resistive characteristic impedance. Their ABCD parameters show an equivalent pi circuit with an imaginary series impedance and a shunt admittance. When the product of beta and line length is less than pi, the line has inductive series impedance and capacitive shunt admittance, which keeps it lossless. Wavelength is the physical length over which voltage or current phase changes...

maximum power flow and line loadability

Transmission Line Power Limits and Loadability

Transmission line power limits and loadability depend on voltage, angle, and line impedance. For lossy transmission lines, ABCD parameters in phasor form are used to relate sending-end and receiving-end voltages and currents. This matrix relation makes it possible to find the receiving-end current and then calculate the complex power delivered to the load. From the complex power, the real and reactive power components can be determined. For a lossless line, the equations become simpler, and...

the power flow problem and solution

Power Flow Analysis in Electric Networks

Power flow analysis helps determine how real and reactive power move through an electric network. It uses the system’s single-line diagram, which shows the buses, transmission lines, transformers, and loads. The analysis focuses on balanced three-phase steady-state operation. Each bus in the system has four key variables: voltage magnitude V k, phase angle δ k, real power P k, and reactive power Q k. Two of these four variables are treated as inputs. The power flow program solves for the...

control of power flow

Voltage and reactive power control help keep a power system stable and efficient. In this topic, generator settings, switched equipment, and transformer taps work together to guide how power moves through the network. A generator can be modeled with a Thevenin equivalent circuit under balanced steady-state conditions. The main terms are terminal voltage Vt, excitation voltage Eg, power angle δ, and positive-sequence synchronous reactance Xg. From this model, the generator current and the...

fast decoupled and dc powerflow

Power Flow Shortcuts for Grid Contingencies

Fast decoupled power flow and DC power flow give engineers faster ways to study a power system during contingencies such as generator outages or transmission line failures. These methods help operators get quick power flow solutions, which is important for real-time system adjustments. Fast decoupled power flow simplifies the Jacobian matrix, the set of equations used in power flow calculations, by neglecting some elements. The method drops J2 and J3 and assumes voltage magnitudes stay close...

key terms and concepts

Learn how generator settings, shunt capacitors, reactors, and tap-changing transformers help control voltage, reactive power, and power flow in power systems.

Voltage and Reactive Power Control | 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

Voltage and Reactive Power Control

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