The intelligent reactive power compensation device is a universal device for compensating reactive power at present, which has good compensation effect and high safety performance and is an important component of the power grid transformation. What is the principle of the smart reactive power compensation device? Xiao Bian is the HDS type static var generator for an example today.
As early as the 1970s, Japan developed a 20MVA SVG with a forced-commutation thyristor bridge circuit. In 1980 and 1994, Japan and the United States respectively successfully developed 80VVA and 10OMVA SVGs using GTO thyristors. The earliest intelligent reactive power compensation device. Today, the HDS-type SVG from Henan Huide Electric Co., Ltd. has been upgraded several generations later, achieving modular production and at the same time realizing the effect of automatic intelligent control and compensation.
In a single-phase circuit, the energy associated with fundamental reactive power is back and forth between the power supply and the load. However, in a balanced three-phase circuit, the sum of three-phase instantaneous power is constant irrespective of the power factor of the load, and equal to the total active power of the three phases at any time. Therefore, as a whole, there is no non-functional back and forth between the power supply and the load of the three-phase circuit, and the no-function is to reciprocate back and forth between the three phases. Therefore, if a certain method can be used to treat all three-phase parts in a unified manner, because there is no non-functional transfer between the three-phase circuit power supply and the load in general, there is no need to set reactive energy storage on the total load side. element. The three-phase bridge-type converter circuit actually has such a feature that the three-phase parts are handled in a unified manner. Therefore, in theory, the DC side of the SVG's three-phase bridge-type converter circuit may not have an energy storage element. In reality, however, considering that the current drawn by the AC circuit does not only contain the fundamental wave, the presence of its harmonics will result in a little bit of non-functionality overall between the power supply and the SVG. Therefore, in order to maintain the normal operation of the bridge AC circuit, the DC side still needs a certain size of inductor or capacitor as the energy storage element, but the capacity of the required energy storage element is much smaller than the reactive capacity that the SVG can provide. According to different DC-side energy storage components, SVG is divided into two types: voltage-type bridge circuit and current-type bridge circuit. Two different types of energy storage elements, namely capacitance and inductance, are used. For a voltage bridge circuit, a reactor must be connected in series before it can be incorporated into the grid. For a current bridge circuit, a capacitor that absorbs the overvoltage in parallel must be connected in parallel on the AC side.
HDS static var generator (SVG) refers to a device that uses a bridge-type converter composed of fully-controlled power electronics to perform dynamic reactive power compensation. The basic principle is to connect the bridge-type inverter circuit in parallel with the reactor (or directly Parallel connection) On the power grid, the phase and amplitude of the output voltage of the AC side of the bridge converter circuit is appropriately adjusted or the AC side current is directly controlled so that the circuit absorbs or issues a reactive current meeting the requirements, thereby realizing dynamic reactive power compensation. purpose. The SVG has a faster adjustment speed, a wider operating range, and can greatly reduce the harmonic content of the compensation current after multiple measures or PWM techniques are taken. What's more, SVG uses less reactors and capacitive components than those used in SVC, which will greatly reduce the size and cost of the device.
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