Досліджено роботу «динамічних конденсаторів» для компенсації реактивної потужності. Запропоновано оригінальну
систему управління «динамічним конденсатором», яка забезпечує споживання ним близького до синусоїдального вхідного
струму. Це дозволяє зменшити вплив «динамічного конденсатору» на амплітудно-частотну характеристику мережі,
підвищити надійність його роботи та покращити точність компенсації реактивної потужності.
Исследована работа «динамических конденсаторов» для компенсации реактивной мощности. Предложена оригинальная система управления «динамическим конденсатором», которая обеспечивает потребление им близкого к синусоидальному входного тока. Это позволяет уменьшить влияние «динамического конденсатора» на амплитудночастотную характеристику сети, повысить надежность его работы и улучшить точность компенсации реактивной мощности.
Purpose. Modern approaches of VAR compensation are: using
compensators with stepped regulation, STATCOMs, active power filters. Recently, more attention is paid to VAR compensator’s
design based on the direct AC / AC converters, which are called
dynamic capacitors. Methodology. The dynamic capacitor (DCAP) is the capacitor bank, which is connected to the mains
through direct AC / AC buck converter. By varying the duty
cycle of bidirectional switches, smooth control of reactive power
can be achieved. However, in case of distorted mains voltage,
D-CAP mains current will have a high THD. This is due to the
fact that the D-CAP affects the frequency response of electric
grid thus leading to the appearance of resonances. With nonsinusoidal mains voltage, capacitors are affected by harmonics.
This reduces the reliability of the D-CAP, increasing the probability of their failure. To eliminate these drawbacks it is suggested to improve the D-CAP control system so that the input
current of the dynamic capacitor is forced to be close to sinusoidal. This can be achieved if the duty cycle of the switching bidirectional switches is changed according to the proposed expression. Results. The research is done on a single-phase DCAP with the proposed control system, its input current diagrams are shown. In contrast to the D-CAP with a constant duty
cycle control, the resulting THD of its input current is much
lower. Thus, the control system provides a form of the input
current that is close to a sine wave. This reduces the influence of
mains voltage harmonics on the D-CAP operation, increases its
reliability and improves power quality. Originality. The proposed D-CAP control system ensures reliable operation with
non-sinusoidal mains voltage. Practical value. Application of DCAPs with the proposed control system allows for improved
energy efficiency of electrical mains by providing VAR compensation and improving power quality.
