Name: load-frequency control in power grids
Uploaded: 2024-11-21T14:54:39.000Z
Duration: 1 min 28 s
Channel: JoVE

In sudden power surges, load-frequency control stabilizes the grid. LFC&#39;s goals are to nullify steady-state frequency error after load changes and maintain each area&#39;s scheduled tie-line power flow.
Area Control Error, combining tie-line power flow deviations and frequency error, guides adjustments to each turbine governor&#39;s reference power setting.
Commands to raise or lower these settings occur every few seconds, allowing new steady-state operations when all settings and ACE of all areas are zero.
Frequency bias should be high enough for area contribution to frequency control without causing instability through high integrator gain.
Additional LFC objectives include controlling 60-Hz motor-driven clocks&#39; timing and energy transfers by nullifying frequency and net tie-line errors.
During normal load and frequency changes, LFC maintains control.
Adjusting turbine governors&#39; reference power settings accomplishes LFC and economic dispatch objectives.
In a coordinated automatic generation control strategy, ACE is computed first, with a share allocated to each unit.
Then, deviations of total generation from the desired are computed and allocated, dictating each unit&#39;s raise or lower signals.

load-frequency control

Load-frequency control (LFC) is essentieel voor het handhaven van de stabiliteit van het elektriciteitsnet, en zorgt ervoor dat de frequentie en de stroom binnen acceptabele grenzen blijven tijdens belastingsveranderingen. Turbine-governor control elimineert rotorversnellingen en -vertragingen na belastingsveranderingen. Er blijft echter een steady-state frequentiefout zitten ​​wanneer de verandering in de turbine-governor referentie-instelling nul is. via transmissielijninterconnecties of tie-lines wordt in een elektriciteitsnet dat onderling verbonden is met elkaar afgestemd dat elk gebied een ​​geplande hoeveelheid stroom exporteert of importeert. Elk gebied absorbeert zijn eigen belastingsveranderingen om zo de geplande netto tie-line stroom (p_tie) te handhaven. De belangrijkste rollen van LFC zijn om de steady-state frequentiefout terug te brengen naar nul na een belastingsverandering en de netto tie-line stroom op de geplande waarde te handhaven.

De Area Control Error (ACE) wordt gedefinieerd als de netto tie-line power flow-afwijking van de geplande waarde plus een frequentiebias (B_f) term. De ACE voor elk gebied is een lineaire combinatie van de tie-line error en frequency error (Δ_f). De verandering in de referentie-vermogensinstelling (Δp_refi) van elke turbine-regelaar onder LFC is evenredig met de integraal van de ACE. Deze integrale actie zorgt ervoor dat zowel de frequentiefout als de tie-line power error naar nul worden gestuurd.

<img alt="Equation1" src="/files/ftp_upload/16174/16174_PT_Equation_1.svg" style="height: 14px;">
<img alt="Equation2" src="/files/ftp_upload/16174/16174_PT_Equation_2.svg" style="height: 30px;">

De frequentiebiasconstante en integratorversterking (K_i) beïnvloeden de transiënte respons op belastingsveranderingen. De frequentiebias moet hoog genoeg zijn voor adequate frequentieregeling. Bij Cohn's methode wordt de frequentiebias gelijkgesteld aan de frequentieresponskarakteristiek van het gebied voor bevredigende prestaties. De integratorversterking mag niet te hoog zijn om instabiliteit te voorkomen. Automatische generatiecontrolestrategieën coördineren LFC met economische dispatchdoelstellingen door de turbine-regelaarreferentievermogensinstellingen aan te passen. De gewenste outputs van elke generator, zoals bepaald door een economisch dispatchprogramma, worden met tussenpozen bijgewerkt, wat zorgt voor een efficiënte en stabiele werking van het elektriciteitssysteem.

Load-frequency control

In sudden power surges, load-frequency control stabilizes the grid. LFC&#39;s goals are to nullify steady-state frequency error after load changes and ...

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Electrical Engineering

Elektrotechniek

Unit 1

Transient Stability and System Controls

Transiënte stabiliteit en systeemregelingen

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load-frequency control in power grids

Load-frequency control keeps a power grid stable when electrical demand changes. It helps keep system frequency and power flow within acceptable limits. Turbine-governor control reduces rotor speed changes after a load shift, but a steady-state frequency error can still remain when the turbine-governor reference setting does not change.

In an interconnected power system, each area agrees to export or import a scheduled amount of power through tie-lines, which are the transmission lines that link areas together. Each area absorbs its own load changes so the scheduled net tie-line power flow stays on target. The two main goals of load-frequency control are to bring the steady-state frequency error back to zero and to keep the net tie-line power flow at its scheduled value.

The Area Control Error, or ACE, combines the tie-line power flow deviation from its scheduled value with a frequency bias term. In each area, ACE is a linear combination of tie-line error and frequency error. Under load-frequency control, the change in reference power setting for each turbine-governor is proportional to the integral of ACE. This integral action helps drive both the frequency error and the tie-line power error to zero.

The frequency bias constant and the integrator gain affect how the system responds after a load change. The frequency bias should be high enough to give good frequency control. Cohn's method suggests setting the frequency bias equal to the area frequency response characteristic for satisfactory performance. The integrator gain should not be too high, or the system can become unstable.

Automatic generation control works with load-frequency control to support economic dispatch goals. It adjusts turbine-governor reference power settings so each generator output matches the values chosen by the economic dispatch program. These output values are updated at intervals, which helps keep power system operation efficient and stable.

Load-frequency control in power grids

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Turbine-governor control helps keep generator frequency and rotor speed stable when electrical load changes. It does this by matching turbine mechanical power with the power demand on the system. In a power grid, that balance is important for steady operation. Turbine-generator units also store kinetic energy because their parts are rotating. When load increases, that stored energy is released to help meet the demand. At first, electrical torque rises while mechanical torque stays nearly...

Load-frequency control keeps a power grid stable when electrical demand changes. It helps keep system frequency and power flow within acceptable limits. Turbine-governor control reduces rotor speed changes after a load shift, but a steady-state frequency error can still remain when the turbine-governor reference setting does not change. In an interconnected power system, each area agrees to export or import a scheduled amount of power through tie-lines, which are the transmission lines that...

key terms and concepts

Explore how load-frequency control restores grid frequency, manages tie-line power flow, and uses ACE, frequency bias, and integral action to stabilize interconnected power systems.

Load-frequency control in power grids | 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

Load-frequency control in power grids

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