What is the difference between SVG and SVC?

1、 Basic working principle of SVG
SVG is also called static var generator. It is mainly produced by the converter which carries out the main power bridge between the self commutation semiconductors. In this process, it is divided into specific DC part and AC part by fully combining the main control device of reactive power. For the whole AC part, it is mainly connected with the whole power system. SVG can be divided into voltage type and current type. For its specific functions, it can not only provide relatively lagging reactive power, but also strengthen the provision of advanced power. For the whole power system, the AC power is converted by SVG converter, and finally it is directly stored in the specific memory. For DC itself. The main voltage and current are converted into AC voltage and current to the whole power system through the conversion of the main converter. It can be seen that the main working principle of SVG is to directly connect the self commutation phase-change current circuit through the power grid, and then adjust the measured current or relevant output voltage of the AC to meet the required reactive current or absorb the generated voltage, so as to achieve the purpose of dynamic control.

2、 Basic working principle of SVC
Compared with SVG, the working principle of SVC is relatively simple, and its main device has the function of rapid adjustment. By adjusting the reactive power, the voltage of the whole power system can be better maintained. It is mainly used in power devices with reactive power compensation. It makes full use of thyristor as a relatively solid state regulation, and then effectively controls the overall capacity of the main access system, which plays a very important role in changing the admittance of the whole transmission system. Due to the difference of controlled objects and modes, it can be divided into the comprehensive use of control reactor and switching capacitor, or the comprehensive use of mechanical switching capacitor, etc. SVC can be operated to control the voltage fluctuation with impulse effect, so as to reduce the influence of corresponding harmonics, and make full use of power factor to adjust the corresponding reactive power and make targeted compensation. Thus, the whole power system can be operated safely.
3、 Comparative advantages of SVG over SVC
In the whole power system, the choice and application of SVC or SVG mainly depends on the judgment of its performance. Compared with SVC, SVG has obvious advantages over SVC in the overall operating range and other aspects of performance. Its specific advantages are as follows:
1. Response speed
For SVG, its main response speed is fast, less than 5m / s, while compared with SVC, the specific response time without power compensation is more than 10m / s.
2. Controllability
Svg has strong ability to suppress flicker voltage. The voltage flicker suppression ability of SVG is more than 5:1. SVG is not very sensitive to the changes of the whole external system. In addition to good stability, it can also operate stably in relative interference environment. Due to its smaller capacity, it is not necessary to consider too many unidirectional low-frequency resonance in the integrated use of the whole power grid.
3. Operation range
Compared with SVC, SVG has a wider operating range. For SVG, its main operation scope can cover all aspects of daily life, but the specific application of SVC has certain limitations.
4. Compensation mode
Svg not only has fast power compensation to a certain extent, but also can carry out specific compensation in many aspects according to the specific actual needs. At the same time, it is easy to adopt a variety of compensation methods. For example: negative sequence current and harmonic current. The advantages of SVC in this respect are not very obvious.
5. Harmonic quantity
Svg adopts relative PWM technology, multiple technology and common three-level technology. For its own, because of its small harmonic content, it can carry out reactive power compensation for the harmonic of the load, and then realize its specific filtering function. For the main high-order harmonics, SVG can also reduce the frequency to a controllable range. In contrast, SVC in the overall device in a certain amount of reactive power compensation will produce a certain amount of harmonic. For the generated harmonics, although the generation of harmonics can be reduced by a certain filter processing, but it can not be ignored that the main filter processing, does not have the existing advantages, there are still large difficulties in the overall design and improvement.
6. Floor area
For the complete set of SVG, it mainly includes: starting device, main power, control system and other main aspects. In the main settings, according to different specific needs, targeted settings can be made. Compared with SVC, SVG has a smaller footprint, which is about 30% to 50% of SVC under the same capacity. Because it does not need to occupy a large area of capacitors and other components, thus reducing its relative floor area. The reactor of SVC has a very large volume. In order to strengthen the setting of the main insulation distance, the interval of different installation sections is taken into account, which increases the floor area as a whole. In addition, additional filter banks need to be considered, which undoubtedly increases the main floor area.

Post time: Aug-05-2020