ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED ...
ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED ... ÇUKUROVA UNIVERSITY INSTITUTE OF NATURAL AND APPLIED ...
3. FUNDAMENTALS OF DVR Mustafa İNCİ harmonic distortions on the load-side of the DVR can be reduced to a permissible level with a properly selected value of K (n) , where n=m(Choi, et al., 2002). 3.3. Control of DVR The main purpose of the control system is to maintain a constant voltage magnitude at the side where a sensitive load is connected, under sag/swell conditions. The control strategy is a fairly critical issue in DVR. All control strategies consist of five stages which are called as sag/swell detection, operation mode, voltage injection strategy, reference voltage generation and gate signal generation. 3.3.1. Sag/swell detection In control strategy, for the calculation of reference signals to achieve voltage sag/swell compensation, instantaneous voltage signals need to be measured. Instrumentation transformers and Hall-effect sensors are used to measure the voltage signals in system. Then, these measured signals are used to generate the reference signals for sag/swell compensation. 3.3.2. Operation Mode The phase angle and amplitude of the injected voltage are variable during sag. This will allow the control of active and reactive power exchange between the DVR and the distribution system. Generally , the operation of the DVR can be categorized into three operation mode: protection mode, standby mode (during steady state) and injection mode (during sag) (Teke, 2005). 31
3. FUNDAMENTALS OF DVR Mustafa İNCİ 3.3.2.1. Protection Mode If the current on the load side exceeds a permissible limit due to a short circuit on the load or large inrush current, the DVR will be isolated from the systems by using the bypass switches as shown in Figure 3.11, S2 and S3 will open and S1 will be closed to provide an alternative path for the load current (Shazly et al., 2013). Figure 3.11. Scheme of the protection mode 3.3.2.2. Standby Mode In the standby mode, the injection transformer’s secondary winding is shorted through the converter. The structure of standby mode is shown in Figure 3.12. This mode is preferred in steady-state conditions due to the voltage drops born of transformer reactance. Figure 3.12. Scheme of the standby mode 32
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- Page 3 and 4: ABSTRACT MSc THESIS MODELING AND AN
- Page 5 and 6: ACKNOWLEDGEMENTS First and foremost
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- Page 18 and 19: LIST OF ABBREVATIONS A AC APF ASD C
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3. FUNDAMENTALS <strong>OF</strong> DVR Mustafa İNCİ<br />
3.3.2.1. Protection Mode<br />
If the current on the load side exceeds a permissible limit due to a short<br />
circuit on the load or large inrush current, the DVR will be isolated from the systems<br />
by using the bypass switches as shown in Figure 3.11, S2 and S3 will open and S1<br />
will be closed to provide an alternative path for the load current (Shazly et al., 2013).<br />
Figure 3.11. Scheme of the protection mode<br />
3.3.2.2. Standby Mode<br />
In the standby mode, the injection transformer’s secondary winding is shorted<br />
through the converter. The structure of standby mode is shown in Figure 3.12. This<br />
mode is preferred in steady-state conditions due to the voltage drops born of<br />
transformer reactance.<br />
Figure 3.12. Scheme of the standby mode<br />
32
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