CN-122001231-A - Full-control type static frequency converter for starting motor

CN122001231ACN 122001231 ACN122001231 ACN 122001231ACN-122001231-A

Abstract

The invention belongs to the field of frequency converter topologies for motor starting, and particularly relates to a full-control type static frequency converter for motor starting. Each bridge arm of at least one of the network bridge unit and the machine bridge unit adopts a fully-controlled power electronic device serial topology, and in the serial topology, the value of the number of the fully-controlled power electronic devices is determined according to the ratio of the product of the set safety coefficient 2 times of the root number and the voltage peak value of the power grid line to the rated voltage of the fully-controlled power electronic devices. The invention can adjust the number of the fully-controlled power electronic devices in each series topology according to actual requirements. Compared with a modularized multi-level topology, the invention can obviously reduce the number of the fully-controlled power electronic devices and the equipment cost and the size under the condition of meeting the actual requirements.

Inventors

LI JIKAI
LI GAOSHANG
FENG XINYANG
LIU ZONGSHENG
ZHANG ZHENXING
Deng Dieming
ZHANG ZILIANG
An Chuang
WU ZHUANG
YAN XIN
CHANG ZHONGTING
HE QINGLIAN
MENG XUELEI
DONG YIFENG
WANG SHAOBO
LIU CHANG

Assignees

许继电气股份有限公司
中国电气装备集团有限公司

Dates

Publication Date: 20260508
Application Date: 20241106

Claims (8)

1. The full-control type static frequency converter for starting the motor comprises a network bridge unit and a machine bridge unit, and is characterized in that all bridge arms of at least one of the network bridge unit and the machine bridge unit adopt a full-control type power electronic device serial topology, and in the serial topology, the value of the number of the full-control type power electronic devices is determined according to the ratio of the product of a set safety coefficient which is 2 times of the root number and a power grid line voltage peak value to the rated voltage of the full-control type power electronic devices.
2. The fully controlled stationary frequency converter for motor starting according to claim 1, wherein the means for determining the value of the number of fully controlled power electronics in each of said series topologies of bridge units and units from the ratio of the product of the set safety factor 2 times the root number and the peak grid line voltage to the rated voltage of the fully controlled power electronics comprises: n=n 0 +m Wherein n 0 is the number of fully-controlled power electronics required in each of the series topologies of bridge units and machine bridge units, n is the value of the number of fully-controlled power electronics in each of the series topologies of bridge units and machine bridge units determined, k is a set safety factor, U L is a grid line voltage rating; The method is characterized in that the method is a power grid line voltage peak value, U T is the rated voltage of a full-control type power electronic device, m is a set redundancy quantity value of the full-control type power electronic device, and m is more than or equal to 0.
3. The full-control type stationary frequency converter for motor starting according to claim 1, further comprising a soft start unit, a grid-side LC filter unit, a dc bus capacitor unit, a brake unit, and a motor-side LC filter unit.
4. The fully-controlled stationary frequency converter for motor starting according to claim 3, wherein the soft start unit is connected in series between the power grid and the LC filter unit on the power grid side, and the soft start unit comprises a soft start resistor and a bypass switch connected in parallel with the resistor, so as to perform current-limiting charging on the bus capacitor in the initial stage of system power-up.
5. A fully controlled stationary frequency converter for motor starting according to claim 3, wherein the grid-side LC filter unit is connected in series between the soft start unit and the bridge unit, and the grid-side LC filter unit is used for harmonic suppression of the bridge unit.
6. The fully-controlled stationary frequency converter for motor starting according to claim 3, wherein said dc bus capacitor unit and said brake unit are connected in parallel between said bridge unit and said bridge unit, said dc bus capacitor unit comprises respective series and parallel capacitors for smoothing and stabilizing dc bus voltage.
7. A fully controlled stationary frequency converter for motor starting according to claim 3, characterized in that the braking unit is mainly composed of a power electronic switch in series with a resistor, and the braking unit is adapted to discharge energy in case of failure.
8. The full-control type stationary frequency converter for motor starting according to claim 3, wherein the LC filter unit at the motor side is connected in series between the bridge unit and the motor, and the LC filter unit at the motor side is used for filtering the output waveform of the bridge unit to realize that the output waveform is a sine wave.

Description

Full-control type static frequency converter for starting motor Technical Field The invention belongs to the field of frequency converter topologies for motor starting, and particularly relates to a full-control type static frequency converter for motor starting. Background The pumped storage is taken as an important component of a novel power system, has three functions of guaranteeing safety of a large power grid, serving clean energy consumption and promoting optimal operation of the power system, is a flexible regulating power supply with the most mature technology, the most extensive application and the optimal economical efficiency at present, and plays an important role in the development process of clean low-carbon transformation of energy. The current pump storage power station set starts through a thyristor pump storage static Start Frequency Converter (SFC) device. However, since the thyristor is a semi-controlled device and is limited by the topological principle of the thyristor, the mode of using the thyristor as a frequency converter for starting a pumped storage power station motor is caused, and the harmonic wave generated in the starting operation process of the motor has great influence on a power grid, and meanwhile, the problems of low control precision, poor dynamic performance and the like exist. Therefore, the technology proposes a means of adopting a full-control type power electronic device as a static frequency converter started by a pumped storage power station motor, the on-off state of the full-control type power electronic device can be completely determined by a control signal, and a more complex control algorithm and higher control precision can be realized by adopting the full-control type static frequency converter. The full-control type static frequency converter topology for starting the pumped storage motor is usually a modularized multi-level topology, and the modularized multi-level topology structure is formed by connecting a plurality of sub-modules in series, wherein each sub-module comprises a full-control type power electronic device. However, in the case of using the modular multilevel topology, the number of fully-controlled power electronic devices is fixed (for example, the number of fully-controlled power electronic devices must be increased by integer multiples according to the number of the fully-controlled power electronic devices in the standardized sub-modules) due to the limitation of the standardized sub-modules, so that in practical applications, a situation that the actual number of the fully-controlled power electronic devices has larger redundancy often occurs, and equipment size is larger and cost is higher due to the redundancy. Disclosure of Invention The invention aims to provide a full-control type static frequency converter for starting a motor, which is used for solving the problems that in the prior art, the number of full-control type power electronic devices in the full-control type static frequency converter is fixed due to the limitation of a standardized sub-module, and larger redundancy is easy to exist. In order to achieve the aim, the invention provides a full-control type static frequency converter for starting a motor, which comprises a network bridge unit and a machine bridge unit, and is characterized in that each bridge arm of at least one of the network bridge unit and the machine bridge unit adopts a full-control type power electronic device serial topology, and in the serial topology, the value of the number of the full-control type power electronic devices is determined according to the ratio of the product of a set safety coefficient 2 times the root number and the voltage peak value of a power grid line to the rated voltage of the full-control type power electronic devices. Compared with the existing full-control type static frequency converter for motor starting, the full-control type static frequency converter has the advantages that the topology aspects of the bridge unit of the frequency converter and full-control power electronic devices in the bridge unit are improved. The topology of the existing full-control type static frequency converter for motor starting is modularized multi-level topology, and the number of the topology needs to meet the requirements on the basis of the standardized sub-modules, so that the situation of large redundancy is often caused. The invention can adjust the number of the fully-controlled power electronic devices in each series topology according to actual requirements on the basis of small redundancy by connecting the topology in series on the bridge arm of at least one of the network bridge unit and the machine bridge unit (the number of the series topology is determined by the ratio of the product of the set safety coefficient and the power grid line voltage which are 2 times the root number to the rated voltage of the fully-controlled power electronic devices). Compared with the m