CN219436881U - Energy storage converter based on frequency conversion soft start technology - Google Patents

Abstract

The utility model discloses an energy storage converter based on a variable frequency soft start technology, which comprises: three-phase asynchronous motor M, energy storage converter PCS, battery BAT, output contactor CB1, load circuit breaker CB2, thyristor switched module GTO, and grid circuit breaker CB3. The configuration power of the energy storage system provided by the utility model is reduced from 10 times of motor power to (50/30=1.6) 1.6 times of rated power of the motor, and the cost of the whole system is reduced to 1/6 of that of the traditional scheme. Due to the adoption of the variable frequency starting technology, the starting process is smoother, the impact on system machinery is greatly reduced, and the service life of mechanical equipment is prolonged. Meanwhile, the variable frequency starting technology is adopted, so that the starting current is greatly reduced, and the configuration capacity of the output contactor CB1 and the load breaker CB2 can be greatly reduced. And a thyristor switching component GTO is adopted, the off-grid switching time is less than 10ms, and the three-phase asynchronous motor M is ensured not to be powered off in the off-grid switching process.

Description

Energy storage converter based on frequency conversion soft start technology

Technical Field

The utility model relates to the technical field of energy storage converters, in particular to an energy storage converter based on a variable-frequency soft start technology.

Background

The direct starting current of the three-phase asynchronous motor M is 4-7 times of rated current, and the rated current of the three-phase 380V asynchronous motor is generally 2 times of power. Taking a 30kw three-phase asynchronous motor M as an example, the maximum direct starting current of the three-phase asynchronous motor M can reach 30 x2x7=420A, and if the energy storage converter PCS is selected to directly start the 30kw motor, the energy storage converter PCS above 300kw needs to be selected. Based on the reasoning, if the energy storage converter PCS is provided with the three-phase asynchronous motor M, the type of the energy storage converter PCS is more than 10 times of rated power of the motor. The PCS of the energy storage converter is relatively expensive, and if the type is selected and amplified by 10 times, the PCS is a motor driving scheme which is quite uneconomical.

The power of the power storage converter PCS needs to be amplified by 10 times when the power of the power storage converter PCS is amplified by 10 times, and in theory, the electric quantity of the battery BAT needs to be amplified by 10 times, because the charge-discharge multiplying power of the battery BAT is the inherent characteristic of the battery BAT. The solution of amplifying both the converter and the battery BAT by a factor of 10 is very expensive to manufacture, and causes great economic stress to the user.

If a frequency converter or a soft starter is added at the rear end of the energy storage current device, the system cost is increased, and the added equipment has power loss, so that the efficiency of the whole system is reduced.

Therefore, in an application occasion for a single large-sized motor, an energy storage converter PCS scheme based on a variable-frequency soft start technology is urgently needed to reduce the starting current of the motor.

Disclosure of Invention

The utility model aims to overcome the defects of the prior art and provides an energy storage converter based on a variable-frequency soft start technology.

The technical scheme of the utility model is as follows: the utility model provides an energy storage converter based on frequency conversion soft start technique, include: the three-phase asynchronous motor comprises a three-phase asynchronous motor M, an energy storage converter PCS, a battery BAT, an output contactor CB1, a load breaker CB2, a thyristor switching assembly GTO and a power grid breaker CB3, wherein the energy storage converter PCS is electrically connected with the battery BAT and the output contactor CB1, the load breaker CB2 and the thyristor switching assembly GTO are connected in parallel with the rear end of the output contactor CB1, the load breaker CB2 and the three-phase asynchronous motor M are connected in parallel to a load port, the rear end of the thyristor switching assembly GTO is electrically connected with the power grid breaker CB3, and the power grid breaker CB3 and the three-phase asynchronous motor M are connected in parallel to a power grid port.

Further, the energy storage converter PCS adopts a 50kw energy storage converter PCS.

Further, the battery BAT adopts a lithium iron phosphate battery BAT.

Further, the battery BAT is connected with a BMS.

Further, the rear end of the three-phase asynchronous motor M is connected with a maintenance bypass breaker CB4, one end of the maintenance bypass breaker CB4 is connected with the load breaker CB2 and the three-phase asynchronous motor M in parallel and is connected to a load port, and the other end of the maintenance bypass breaker CB4 is connected with the power grid breaker CB3 in parallel and is connected to a power grid port.

Further, the energy storage converter includes: IGBT switch T1, IGBT switch T2, IGBT switch T3, IGBT switch T4, IGBT switch T5, IGBT switch T6, isolation transformer and alternating current filter, IGBT switch T1's collecting electrode, IGBT switch T3's collecting electrode and IGBT switch T5's collecting electrode connect in parallel the positive pole DC+ of battery, IGBT switch T2's projecting pole, IGBT switch T4's projecting pole and IGBT switch T6's projecting pole connect in parallel the negative pole DC-of battery, IGBT switch T1's projecting pole and IGBT switch T2's collecting electrode connect in parallel the isolation transformer, IGBT switch T3's projecting pole and IGBT switch T4's collecting electrode connect in parallel the isolation transformer, IGBT switch T5's projecting pole and IGBT switch T6's collecting electrode connect in parallel the isolation transformer, isolation transformer's output and alternating current filter's input electric connection, alternating current filter's output and output contactor CB 1's one end electric connection.

By adopting the scheme, the configuration power of the energy storage system provided by the utility model is reduced from 10 times of motor power to (50/30=1.6) 1.6 times of rated power of the motor, and the cost of the whole system is reduced to 1/6 of that of the traditional scheme. Due to the adoption of the variable frequency starting technology, the starting process is smoother, the impact on system machinery is greatly reduced, and the service life of mechanical equipment is prolonged. Meanwhile, the variable frequency starting technology is adopted, so that the starting current is greatly reduced, and the configuration capacity of the output contactor CB1 and the load breaker CB2 can be greatly reduced. And a thyristor switching component GTO is adopted, the off-grid switching time is less than 10ms, and the three-phase asynchronous motor M is ensured not to be powered off in the off-grid switching process.

Drawings

Fig. 1 is a schematic diagram of a system circuit connection according to the present utility model.

Fig. 2 is a V/F graph of an energy storage converter starter motor.

Detailed Description

The utility model will be described in detail below with reference to the drawings and the specific embodiments.

Referring to fig. 1, the present utility model provides an energy storage converter based on a variable frequency soft start technology, comprising: three-phase asynchronous motor M, energy storage converter PCS, battery BAT, output contactor CB1, load circuit breaker CB2, thyristor switched module GTO, and grid circuit breaker CB3. The energy storage converter PCS is electrically connected with the battery BAT and the output contactor CB 1. The load circuit breaker CB2 and the thyristor switching assembly GTO are connected in parallel to the rear end of the output contactor CB 1. And the load circuit breaker CB2 is connected with the three-phase asynchronous motor M in parallel and connected to a load port. The rear end of the thyristor switching component GTO is electrically connected with the power grid breaker CB3. And the power grid breaker CB3 and the three-phase asynchronous motor M are connected in parallel to a power grid port.

The energy storage converter PCS adopts a 50kw energy storage converter PCS.

The battery BAT adopts a lithium iron phosphate battery BAT.

The battery BAT is connected with a BMS.

And the rear end of the three-phase asynchronous motor M is connected with a maintenance bypass breaker CB4. One end of the maintenance bypass breaker CB4 is connected with the load breaker CB2 and the three-phase asynchronous motor M in parallel and is connected to a load port. And the other end of the maintenance bypass breaker CB4 is connected with the power grid breaker CB3 in parallel to be connected to a power grid port.

The energy storage converter includes: IGBT switch T1, IGBT switch T2, IGBT switch T3, IGBT switch T4, IGBT switch T5, IGBT switch T6, isolation transformer and alternating current filter, IGBT switch T1's collecting electrode, IGBT switch T3's collecting electrode and IGBT switch T5's collecting electrode connect in parallel the positive pole DC+ of battery, IGBT switch T2's projecting pole, IGBT switch T4's projecting pole and IGBT switch T6's projecting pole connect in parallel the negative pole DC-of battery, IGBT switch T1's projecting pole and IGBT switch T2's collecting electrode connect in parallel the isolation transformer, IGBT switch T3's projecting pole and IGBT switch T4's collecting electrode connect in parallel the isolation transformer, IGBT switch T5's projecting pole and IGBT switch T6's collecting electrode connect in parallel the isolation transformer, isolation transformer's output and alternating current filter's input electric connection, alternating current filter's output and output contactor CB 1's one end electric connection.

Before starting the three-phase asynchronous motor M, it is ensured that the battery BAT has sufficient charge. If the battery BAT is deficient, the load breaker CB2 is firstly opened, the maintenance bypass breaker CB4 is opened, the power grid breaker CB3 is closed, and the PCS grid connection of the energy storage converter is started. When the grid connection of the energy storage converter PCS is successful, the power grid charges the battery BAT, and after the battery BATSOC is charged to be more than 60% (which can be set), the energy storage converter PCS stops running, the thyristor switching component GTO is disconnected, and the energy storage converter PCS is in an off-grid standby state.

Referring to fig. 2, the load circuit breaker CB2 is manually closed, and a soft start command (soft start switch is pressed) of the energy storage converter PCS is issued. The energy storage converter PCS starts the 30kw three-phase asynchronous motor M in a variable frequency starting mode, and keeps magnetic flux phi=V/F=380/50=190/25=38/5=19/2.5=constant in the starting process, so that the starting moment of the three-phase asynchronous motor M in the starting process is ensured to be constant. The control method for keeping the magnetic flux of the three-phase asynchronous motor M constant can ensure that the three-phase asynchronous motor M has constant starting torque,and the situation that the motor is burnt out by 'magnetic flux saturation' and cannot be started by 'weak magnetic' can be avoided. When the motor drives heavy load to start and larger starting torque is needed, the motor can stop at the frequency F _{Up to the point} The following step-up start-up voltage V _{Lifting up} When the three-phase asynchronous motor M drives the heavy load to start and larger starting torque is needed, the starting voltage V can be increased below the cut-off frequency F so as to improve the low-frequency-band-load starting capability of the energy storage converter PCS. The low-frequency torque is improved, and the low-frequency torque is generally not required to be too large, and is generally not more than 10% of rated voltage, so that the PCS low-frequency oscillation and overcurrent faults of the energy storage converter are easily caused by the too large torque. In the starting process of the energy storage converter PCS from 0 to 50Hz, the starting time can be set to be 0.1 to 200S, and the starting time can be set according to different application sites.

In the starting process of the 30kw three-phase asynchronous motor M, the starting time is set to be 10S, the running current of the PCS of the energy storage converter is not more than 72A, the running current is always controlled within the rated current of the PCS of the energy storage converter, and the starting process is stable. After the 30kw three-phase asynchronous motor is started, the running current of the energy storage converter PCS is maintained at about 58A. After the three-phase asynchronous motor M is started, the PCS of the energy storage converter can start a grid-connected function. And after the phase locking is successful, the PCS of the energy storage converter detects the phase of the power grid and controls the GTO of the thyristor switching component to carry out grid connection. After grid connection is successful, the power grid directly drives the three-phase asynchronous motor M, and meanwhile, the power grid can charge the battery BAT. When the power grid fails, the PCS of the energy storage converter is switched to off-grid operation, so that the three-phase asynchronous motor is ensured not to stop. The uninterrupted power supply of the three-phase asynchronous motor M is realized. Such applications are particularly suitable for: and the application occasions of medicines, steel and the like which do not allow power failure. When the power grid is powered on again, the PCS of the energy storage converter is connected again, the PCS of the energy storage converter detects the phase of the power grid, and after phase locking is successful, the GTO of the thyristor switching assembly is controlled to be connected. After grid connection is successful, the power grid directly drives the three-phase asynchronous motor M, and meanwhile, the power grid can charge the battery BAT.

In summary, the configuration power of the energy storage system provided by the utility model is reduced from 10 times of the motor power to (50/30=1.6) 1.6 times of the rated power of the motor, and the cost of the whole system is reduced to 1/6 of the traditional scheme. Due to the adoption of the variable frequency starting technology, the starting process is smoother, the impact on system machinery is greatly reduced, and the service life of mechanical equipment is prolonged. Meanwhile, the variable frequency starting technology is adopted, so that the starting current is greatly reduced, and the configuration capacity of the output contactor CB1 and the load breaker CB2 can be greatly reduced. And a thyristor switching component GTO is adopted, the off-grid switching time is less than 10ms, and the three-phase asynchronous motor M is ensured not to be powered off in the off-grid switching process.

The foregoing description of the preferred embodiment of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the utility model.

Claims (6)

1. An energy storage converter based on frequency conversion soft start technique, which is characterized by comprising: the three-phase asynchronous motor comprises a three-phase asynchronous motor M, an energy storage converter PCS, a battery BAT, an output contactor CB1, a load breaker CB2, a thyristor switching assembly GTO and a power grid breaker CB3, wherein the energy storage converter PCS is electrically connected with the battery BAT and the output contactor CB1, the load breaker CB2 and the thyristor switching assembly GTO are connected in parallel with the rear end of the output contactor CB1, the load breaker CB2 and the three-phase asynchronous motor M are connected in parallel to a load port, the rear end of the thyristor switching assembly GTO is electrically connected with the power grid breaker CB3, and the power grid breaker CB3 and the three-phase asynchronous motor M are connected in parallel to a power grid port.

2. The variable frequency soft start technology based energy storage converter of claim 1, wherein the energy storage converter PCS is a 50kw energy storage converter PCS.

3. The energy storage converter based on variable frequency soft start technology according to claim 1, wherein the battery BAT is a lithium iron phosphate battery BAT.

4. The energy storage converter based on variable frequency soft start technology according to claim 1, wherein the battery BAT is connected with a BMS.

5. The energy storage converter based on the variable frequency soft start technology according to claim 1, wherein a maintenance bypass circuit breaker CB4 is connected to the rear end of the three-phase asynchronous motor M, one end of the maintenance bypass circuit breaker CB4 is connected in parallel with the load circuit breaker CB2 and the three-phase asynchronous motor M and connected to a load port, and the other end of the maintenance bypass circuit breaker CB4 is connected in parallel with the grid circuit breaker CB3 and connected to a grid port.

6. The energy storage converter based on variable frequency soft start technology of claim 1, wherein the energy storage converter comprises: IGBT switch T1, IGBT switch T2, IGBT switch T3, IGBT switch T4, IGBT switch T5, IGBT switch T6, isolation transformer and alternating current filter, IGBT switch T1's collecting electrode, IGBT switch T3's collecting electrode and IGBT switch T5's collecting electrode connect in parallel the positive pole DC+ of battery, IGBT switch T2's projecting pole, IGBT switch T4's projecting pole and IGBT switch T6's projecting pole connect in parallel the negative pole DC-of battery, IGBT switch T1's projecting pole and IGBT switch T2's collecting electrode connect in parallel the isolation transformer, IGBT switch T3's projecting pole and IGBT switch T4's collecting electrode connect in parallel the isolation transformer, IGBT switch T5's projecting pole and IGBT switch T6's collecting electrode connect in parallel the isolation transformer, isolation transformer's output and alternating current filter's input electric connection, alternating current filter's output and output contactor CB 1's one end electric connection.