31.5
過渡安定性とシステム制御
同期発電機や風力タービンの安定した運転には、発電機の電圧制御が重要です。旧モデルでは、ローターによって駆動される直流発電機がローターの界磁巻線に直流電力を供給し、電力はスリップリングとブラシを介して伝達されます。最新モデルでは、静的またはブラシレス励磁機が使用されます。静的励磁機は、発電機端子からの…
同期発電機では、励磁器は回転子の界磁巻線にDC電力を供給します。
古いモデルはローター駆動のDC発電機を励磁器として使用していますが、最近のモデルは静的またはブラシレスの励磁器を使用しています。
静的励磁器は、発電機の端子または母線からのAC電力を整流し、ローターに供給します。
ブラシレスエキサイターは、倒立同期発電機を使用し、アーマチュア巻線から界磁巻線へのAC電力を整流します。
タイプ1の励磁器には、シャフト駆動のDC発電機と、端子電圧に基づいて界磁電流を調整する電圧調整器があります。
風車では、励磁器の種類によって電圧制御が異なります。タイプ1には直接制御がありませんが、タイプ2は抵抗制御を使用して突風時に一定の出力を維持します。
タイプ3の励磁器は無効電力を制御し、無効電力を一定に保つか、実際の電力出力で変化させます。
ブロック図は、過渡安定性プログラムにおける発電機電圧制御を視覚化します。
高ゲインで高速応答の励磁器は、短絡時にフィールド電圧を増加させ、過渡安定性を向上させます。
ブロック線図の方程式は、過渡応答を計算します。
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Q1: What is the difference between static and brushless exciters in synchronous generators?
Static exciters rectify AC power from generator terminals or bus and supply DC power directly to the rotor field winding. Brushless exciters use an inverted synchronous generator, rectifying AC power from armature windings via diodes mounted on the rotor, eliminating slip rings and brushes. Both replace older rotor-driven DC generators, improving reliability and reducing maintenance.
Q2: How does a Type 1 exciter control generator terminal voltage?
A Type 1 exciter uses a shaft-driven DC generator with a voltage regulator that measures terminal voltage and compares it to a reference voltage. The voltage error is processed with a gain and time constant, producing a field voltage that adjusts the rotor field current. This feedback mechanism maintains stable terminal voltage output.
Q3: Why do high-gain, fast-responding exciters improve transient stability?
High-gain, fast-responding exciters rapidly increase field voltage during short circuits, strengthening the generator's ability to maintain synchronism. This quick response enhances the simplified synchronous machine model's transient performance by providing immediate reactive power support. Faster exciter response reduces voltage dips and improves overall system stability during disturbances.
Q4: What voltage control methods are used in different wind turbine types?
Type 1 wind turbines use squirrel cage induction machines without direct voltage regulation. Type 2 systems employ wound rotor machines with adjustable external resistance to maintain constant power during wind gusts. Type 3 and Type 4 configurations manage both real and reactive power, providing enhanced control over generator output.
Q5: How do block diagrams represent generator voltage control systems?
Block diagrams visualize the feedback control loop by showing terminal voltage measurement compared against reference voltage, with the error processed through a voltage regulator with gain and time constant parameters. These diagrams compute transient response equations and standardize the representation of exciter and generator dynamics for stability analysis and system design.
Q6: What role does the field winding play in synchronous generator voltage control?
The field winding receives DC power from the exciter, creating the magnetic field that generates terminal voltage. The voltage regulator adjusts field current based on terminal voltage feedback, allowing precise control of generator output. This excitation control is essential for maintaining stable voltage and improving transient stability during system disturbances.
Q7: How does Type 2 wind turbine resistance control maintain power output stability?
Type 2 wind turbines use adjustable external resistance in the rotor circuit of wound rotor induction machines to regulate slip and power output. During wind speed variations, the resistance adjustment maintains consistent power delivery despite changing wind conditions. This resistance control mechanism provides a cost-effective alternative to direct voltage regulation in variable-speed wind turbine systems.