Power Quality Improvement Using Dstatcom in Distribution Network

Gaurav Gangil

Power Quality Improvement Using Dstatcom in Distribution Network

Gaurav Gangil

2021 International Conference on Control, Automation, Power and Signal Processing (CAPS)

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Abstract

In the present scenario, power quality is an important element of power system. Different nonlinear devices like diodes, rectifiers, and furnaces are generating power fluctuation, voltage sag and swell concerns, load imbalance, voltage imbalance, and other power quality issues, which may be controlled by FACTS devices such as DVR, STATCOM, Active power filter, UPFC, and UPQC. In the present work, application of DSTATCOM in the distribution network to overcome power quality issues, meeting the reactive requirement of the load to raise power factor to unity are addressed. A novel Sinusoidal PWM (SPWM) control technique is employed to reduce the harmonics in the distribution network. It relies on weighted value convergence and is unaffected by carrier signal characteristics. In this paper, four different cases have been considered with varying supply voltages. The simulation results show that D-STATCOM works efficiently and offers very less THD for different power quality problem like voltage sag, swell, load imbalance, voltage fluctuation etc. The Voltage Source Converter is regulated using the Sinusoidal PWM method. The result indicates that the DSTATCOM and SPWM control technique is helpful for power quality improvement.

Figures (20)

Fig 3 Simulink Diagram of Distribution STATCOM in Distribution Network Fig. 2 Flowchart of Park’s transformation The main requirements of SPWM controller in DSTATCOM are to diagnose voltage imbalance activities in the distribution network [17-18]. To accurately measure the fixing voltage,

Fig. 1 Schematic diagram of DSTATCOM applied to distribution system

generate the pulses for the SPWM inverter, rectify a certain abnormality, and fired the gating pulses once the problem is resolved. In the absence of voltage sags/swells, the DSTATCOM controller may be utilized to switch the inverter to rectification mode and charging of the capacitors in the DC energy connection. DSTATCOM is controlled using the dgo or Park's transformation [19].

B. Simulink model: Fig. 5 Generation of gate pulses created in MATLAB Fig. 4 SPWM based control Algorithm created in MATLAB

TABLE 2 TEST CASES CONSIDERED FOR DESIGN

The performance of DSTATCOM under nonlinear load is analyzed to observe the impact of applied control approach on the value of voltage at PCC. Source voltage (Y), grid current (I,), load current (J,), compensator current (I-), DC bus voltage (Vpc), and voltage magnitude at the VSC and PCC are shown in Fig. 6(a) and Fig. 6(b).

Fig. 6(b) Load Voltage & current without Compensation Fig. 6(a) Source Voltage & current without Compensation

Fig 7(a) Grid voltage & current after using D-STATCOM In first case, initially balanced supply voltage is to be taken and type of load is linear. For linear load, inductive load is to be taken. In the distribution system shunt compensation is applied using D-STATCOM. Fig. 7(a) & 7(b) shows the waveforms of grid side & lode side. Fig. 7(c) depicts the shunt compensator current. The voltage and current waveforms are sinusoidal because the load is linear. When the load end becomes unbalanced at t=0.3s, the phase "c" of the load is instantaneously dropped out for a duration of | sec, resulting in load imbalance in the system. So, owing to DSTATCOM functioning, the grid currents are still precisely sinusoidal. Below are the simulated waveforms for the first example.

Fig 7(b) Load voltage & current after using D-STATCOM

Fig 8(a) Grid voltage & current after using D-STATCOM

In this case, initially balanced supply voltage is to be taken with volage sag is implemented for a duration of 0.1 to 0.15 sec. and type of load is nonlinear. For nonlinear load, Bridge rectifier with RL load is to be taken. In the distribution system shunt compensation is applied using D-STATCOM. Fig. 9(a) depicts a grid voltage and current waveform with a linear load. The load voltage and current waveforms are shown in Fig. 9(b). Fig. 9(c) illustrates the shunt compensator current. When the load end becomes unbalanced at t=0.3s, the phase "c" of the load is instantaneously dropped out for a duration of 1 sec, resulting in load imbalance in the system. So, owing to DSTATCOM functioning, the grid currents are still precisely sinusoidal. The waveforms of the simulation for the third scenario are displayed below. Fig 9(a) Grid voltage & current after using D-STATCOM

Fig 8(c) Compensator current for 3 Phase separately Fig 8(b) Load voltage & current after using D-STATCOM

Fig 10(b) Load voltage & current after using D-STATCOM Fig 10(a) Grid voltage & current after using D-STATCOM

In this case, initially balanced supply voltage is to be taken with volage swell is implemented for a duration of 0.1 to 0.15 sea. And type of load is nonlinear. For nonlinear load, Bridge rectifier with RL load is to be taken. In the distribution system shunt compensation is applied using D-STATCOM. Fig. 10(a) depicts the waveforms of grid voltage and current with a linear load. Fig. 10(b) illustrates the waveforms of the load side. Fig. 10(c) illustrates the shunt compensator current. When the load end becomes unbalanced at t=0.3s, the phase "c" of the load is instantaneously dropped out for a duration of 1 sec, resulting in load imbalance in the system. So, owing to DSTATCOM functioning, the grid currents are still precisely sinusoidal. Below are the simulated waveforms for the 4th example.

Fig 9(c) Compensator current for 3 Phase separately Fig 9(b) Load voltage & current after using D-STATCOM

Fig 10(c) Compensator current for 3 Phase separately A novel SPWM technique is applied in this paper, to the gating pulse of VSC which is connected to the DSTATCOM for PQ related issues. In this work four cases have been considered which has various supply voltage and varying type of load are taken. In first case, linear load is taken and for other cases nonlinear RL load is taken. In the distribution network shunt compensation is given using DSTATCOM. When the load end becomes unbalanced at t=0.3s, the phase "c" of the load is instantaneously dropped out for a duration of 1 sec, resulting in load imbalance in the system. So, owing to DSTATCOM functioning, the grid currents are still precisely sinusoidal on seeing the results of all the cases, it is observed that voltage sag, swell, or load unbalanced condition is well managed by DSTATCOM and offers satisfactory performance. The harmonics of load side is 27% which is reduced to minimum by the use of DSTATCOM. Due to harmonics, losses are reduced to minimum. In other words, power quality improvement is made by STATCOM in an efficient way and offer outstanding results.

Key takeaways

If the supply voltage reduced to 90% of the base value, voltage sag are recognized, while voltage swells are identified when the supply voltage rises to one fourth of the base value.
The scope is used in simulation model to show the behavior in source side and load side.
The input and load voltage and current waveforms in absence of compensation are illustrated in Fig. 6(a) and Fig. 6(b) respectively.
In this work four cases have been considered which has various supply voltage and varying type of load are taken.
It has been observed that the power factor is improved for sudden change in non-linear load, voltage profile is also improved in case of sudden voltage fluctuations and losses & harmonics are considerably reduced by applying DSTATCOM and SPWM control technique.

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