Voltage Capacitor

Voltage Capacitor

STATCOM Whereas for the Promotion of the constant tension in the grid

1. INTRODUCTION

One of the most common power quality problems today voltage dips. A voltage dip is a short period of time (10 ms to 1 minute) cases which reduced the amplitude of RMS voltage occurs. Often be resolved only by two parameters, the depth and magnitude and duration. The voltage sag magnitude varies between 10% and 90% of the rated voltage (corresponding to 90% and 10% remaining voltage) and one-half cycle 1 min. In a dive in three-phase voltage system is by nature a phenomenon in three phases, affecting both the stage floor and stage phase voltages. A voltage dip is caused by a failure of system utilities not the customer premises or a substantial increase in load current, such as starting an engine or connect the transformer. Typical errors or multiple phases of elimination short-circuit, resulting in high currents. The results of a high intensity in a voltage drop across the impedance network. In the location of the fault voltage faulty phase drops to near zero, while the non-fault phase remains more or less unchanged.

Voltage dips are one of the problems occur as Food. Of course, for an industry with a blackout which is worse, a low voltage, voltage dips, but are more frequent and cause serious economic losses. Utilities often focus on the disruption of the end-user equipment such as problems of food quality. This is correct for many disturbances, flicker, harmonics, etc., but especially voltage dips are caused by the higher voltage levels. Faults due to lightning, is one of the most common causes of voltage dips in the airlines. If economic losses due to voltage drops are significant, mitigation measures can be profitable for the customer and, in some cases for the utility. Since there is no standard solution that works for each site, each mitigation action must be carefully planned and evaluated. It are different ways to mitigate voltage dips, swells and interruptions in transmission and distribution. Currently in a wide range of controllers very flexible, taking advantage of electronic components available on the power, are becoming power applications. Among them, the distribution static compensator and dynamic voltage restorer are most effective devices, both based on the principle of VSC. A new PWM control scheme has been implemented based a control valve in the VSC electronic two-level D-STATCOM and DVR.

2. VT SOURCE (VSC)

A voltage source converter is an electronic power device, which can generate a sinusoidal voltage with full scale necessary, the frequency and phase angle. voltage converters are widely used in source units adjustable-rate, but also can be used to reduce voltage drops. The VSC is used to replace either the voltage or the injection of "lack of tension. Tension "Lost" is the difference between real and nominal voltage. The converter is usually based on some form of energy storage, provide the converter with a voltage. The solid state electronics in the converter is then switched to obtain the desired output voltage. Normally, the VSC is used not only for mitigating voltage drop, but also for other issues like energy, for example, oscillations and harmonics.

3. AVR SERIES

Dynamic Voltage Restorer [(DVR)]

Voltage regulator in series is connected in series with the load protected, as shown in Figure 1. In general, the connection is via a transformer, but the parameters with direct connection via power electronics also exist. Tension resulting in the load bar is equal to the sum of the supply voltage and the voltage injected by the DVR. The converter generates power necessary reactive while the active power is drawn from storage.

Energy storage may be different depending on the need compensate. The DVR often has limitations in the depth and duration of voltage drop which can compensate.

Fig 1. standard configuration of a DVR.

Fig 2. Diagram of a DVR

The circuit on the left side of the DVR is the Thevenin equivalent circuit of the system. The impedance ZTH system depends on the level of guilt bus load. When the system voltage (V) falls, the DVR injects a series voltage VDVR through the injection transformer for the load voltage VL desired magnitude can be maintained.

Fig 3. Powerline

The target system control is to maintain constant voltage magnitude at the point where the load is sensitive, in case of disturbances of the system. The control system measures the voltage effective point of loading, ie no reactive power measurements are required. VSC switching strategy is based on a sinusoidal PWM technique offers the simplicity and good response. Since energy is a custom application of relatively low power PWM methods offer a more flexible option than the fundamental Frequency Switching (FFS) methods favored in FACTS applications. In addition, the high switching frequencies can be used to improve efficiency converter, without incurring switching losses.

The controller input is an error signal obtained from the reference voltage and the actual value of the voltage measured. This error is generated by a PI controller output is the angle?, Who provides the generator PWM signal. It is important to note that in this case, the converter indirectly controlled, there is an exchange of active power and reactive with the same network time: an error signal is obtained by comparing the reference voltage to the RMS value of the voltage measured at the loading point. The process generates PI the error signal to the angle required to drive the error to zero, ie the RMS load voltage is returned to power reference. The transmitting circuit is as shown in Figure 3.

 

 

Fig 4. Map PIC microcontroller

 

Fig 5. IGBT Driver Board

Although wind power is considered as a source of energy very prospective because of its characteristics and economic fluctuations in output because of the wind speed varies randomly remains a serious problem for manufacturers of wind turbines and grid companies, particularly in the case of fixed speed generators wind. Induction generators are used, in general, as required by the turbine, because of its superior features such as brushes and robust construction, maintenance and operational simplicity and low cost. Therefore, much research has been done over output generated by stationary sources soften the wind speed. In a storage system steering aims to mitigate the fluctuations of energy wind. Some authors have proposed superconducting magnetic energy storage (SMEs) for smoothing fluctuations in wind energy. In a system of capacitor energy (ECS), consisting of power electronics and a double layer capacitor (EDLC) is proposed to smooth the production of wind farms. But an inertial system, in general, the expected loss of up to about 5% of its rated power. In addition, the control system of inertia is relatively complex. Although SMEs and ECS systems are very good for power regulation because of its high speed response and high efficiency, high MW facility is doubtful practical applications because of high costs of installation maintenance. In addition, the BESS is a proven technology in power system applications due to its low cost, easy replacement technology, Despite some limitations because of its chemical process. Life BESS has been recently extended to innovation in the chemical industry. When the BESS is integrated STATCOM, it gives excellent ability to control both active power and reactive. Therefore, STATCOM / BESS topology is chosen in this study to an output smoothing and voltage at wind speed generator sets in terms of cost and efficiency performance. The microcontroller and the driver board as shown in Figure 4 and 5.

The STATCOM is a source of electronically generated phase voltage system is connected to AC transformer shunt. When STATCOM operates as an SME pure (without loss or attached) is exactly the voltage generated in phase with the voltage of the alternating current system. If the generated voltage exceeds the voltage across the device to provide VAR (ie, is capacitive) for the system. If the internal stress is lower than the voltage across the device VARS absorbed (ie inductive) system. Control system the STATCOM is extremely fast and can not quickly change the magnitude (and phase) of stress generated electronically. The magnitude of the AC voltage generated by the STATCOM is directly proportional to the DC bus voltage. Therefore, the voltage generated which VARS STATCOM control is controlled by changing the voltage of the DC bus. Changes in the DC bus voltage is effected by supply or absorb real power or the load or DC bus discharge capacitor DC. This is accomplished by advancing or retarding the voltage generated angle to the voltage AC.

In practice, the STATCOM has a small amount of losses (for example, resistance in the circuit, so the switching losses) and the angle to compensate the AC voltage is electronically generated a slight delay in terms of voltage conditioning system terminal. The angle difference (?) Between the voltage and the voltage generated system allows a real power flow and hence the losses in the STATCOM circuit. When the helicopter is used to transfer DC power to / from the coil and the DC bus voltage SMEs is loaded or unloaded. This change will be detected by the controller STATCOM, which automatically adjusts the angle of control (?) To maintain the voltage at the required level. In this way, of course, be adjusted to compensate for the implementation of the system energy SMEs. STATCOM control automatically adjusts the power of SMEs and the energy transfers to / from the mains.

4. CONCLUSIONS

One advantage of adding a PME system to STATCOM DC bus were taken into account. The power oscillation damping implementation of a STATCOM has been compared to a SME combination STATCOM +. A sign of the power line signal conditioned to provide an active auxiliary control voltage reference (in the If STATCOM) or small power rating (in the case of SMEs STATCOM + combination) was compared. The ability of both systems to absorb the machine oscillations Rotor 0.5 Hz oscillation has been demonstrated. The results reveal that only a STATCOM (ie, not POD) will regulate the tension in the heading period reserve, but does not add much, of course, the power oscillation damping. The STATCOM with the signal applied to the reference voltage POD swing oscillations can be wet after a disturbance, however, this is achieved at the expense of voltage regulation. The combination of STATCOM and SMEs POD output with modulation of SMEs to enable the system to regulate the voltage supply at a time and oscillation damping. The amount of power Actual requirements SMEs to moisture in the system oscillations is quite small (20 MW) under the symbol of STATCOM (160 MVAR). Controls were STATCOM not specially modified to accommodate the operation of SMEs coil.

About the Author

Assistant professor in lord venkateswara engineering college.I am doing phd in sathyabama university, Tamil Nadu,India.

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0.04uF 50V Low Voltage DIP Ceramic Disc Capacitors(Bag of 30) $2.83

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Russian Capacitors high-voltage ceramic K15-5 2200 pF 5kV 28 PS $4.00

1 X 200pF 7500V High Voltage HEC Trim Capacitor 7500 V $49.99

33pF 10kV High Voltage Doorknob Capacitors KVI-2 NOS IN BOX LOT OF 10 Pcs. $10.00

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Ceramic, high voltage capacitor K15U-2 (К15У-2) – 2 200 pF/6kV/35 kVAr. $27.99

CERAMIC, HIGH VOLTAGE CAPACITOR K15U-2 (К15У-2) – 1 000 pF/4kV/25 kVAr. $29.99

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100 Pcs 50V 680pF Low Voltage DIP Ceramic Disc Capacitor $5.45

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30 x 0.033uF 50V DIP Low Voltage Ceramic Disc Capacitors $3.73

50 x 10pF 50V Low Voltage DIP Ceramic Disc Capacitors $4.23

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