Electric motor-driven generator

Abstract

An electric motor-driven power generating device capable of improving the stability of a power system while operating a rotating machine under torque control. [Solution] The motor-driven generator includes a storage device, a power conversion device that converts the DC voltage of the storage device into AC voltage, a rotating machine driven by the AC voltage of the power conversion device, a rotation detector that detects the rotational speed of the rotating machine, a synchronous generator whose shaft is directly connected to the rotating machine, a power system connected to the synchronous generator, and an external control device that outputs an external torque command value and the status of the power system to the power conversion device, and automatically switches between torque control and speed control in the power conversion device depending on the rotational speed of the rotating machine and a status signal of the power system.

Description

[Technical field]

[0001] The present invention relates to an electric motor-driven power generating device. [Background technology]

[0002] 2. Description of the Related Art In a power grid stabilization system using an electricity storage device, a motor-driven power generation device using a rotating machine and a generator is used.

[0003] Figure 4 shows an example of a motor-driven power generation device using a power storage device according to the prior art disclosed in Patent Document 1. In Figure 4, 1 is a synchronous generator, 2 is a rotating machine, 3 is a power storage device, 4 is a power conversion device, 5 is a rotation detector, and 6 is a power system.

[0004] In the motor-driven power generating device shown in FIG. 4, when the rotation speed of the rotating machine 2 detected by the rotation detector 5 is higher than the specified frequency of the power system 6, the power conversion device 4 performs speed control (deceleration operation) so that the rotation speed of the rotating machine 2 coincides with the specified frequency of the power system 6. At this time, the power storage device 3 performs charging operation. When the rotation speed of the rotating machine 2 detected by the rotation detector 5 is lower than the specified frequency of the power system 6, the power conversion device 4 performs speed control (acceleration operation) so that the rotation speed of the rotating machine 2 coincides with the specified frequency of the power system 6. At this time, the power storage device 3 performs discharging operation. The above-mentioned charging and discharging operation suppresses frequency fluctuations in the power system 6. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-61417 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional technology method is a mechanism for adjusting the active power by controlling the speed of the rotating machine 2 using the power conversion device 4. Therefore, in a system in which an active power command value is directly given to the power conversion device 4, it is necessary to convert the active power command value into a speed command value and indirectly control the active power, which poses the problem of a slower response to the active power command value compared to torque control.

[0007] On the other hand, although torque control responds faster to an active power command value than speed control, it does not directly contribute to suppressing frequency fluctuations, so there is a risk that the power system 6 may become unstable if an accident such as a short circuit or ground fault occurs in the power system 6.

[0008] Therefore, there is a demand for an electric motor-driven power generating device that can perform torque control with a fast response to an active power command value while improving the stability of the power system.

[0009] An object of the present invention is to provide a motor-driven power generating device that is capable of improving the stability of a power system while operating a rotating machine under torque control. [Means for solving the problem]

[0010] An electric motor-driven generator in an embodiment of the present invention comprises a power storage device, a power conversion device that converts a DC voltage of the power storage device into an AC voltage, a rotating machine driven by the AC voltage of the power conversion device, a rotation detector that detects the rotational speed of the rotating machine, a synchronous generator whose shaft is directly connected to the rotating machine, a power system connected to the synchronous generator, and an external control device that outputs an external torque command value and a status signal of the power system to the power conversion device, and is characterized in that torque control and speed control in the power conversion device are automatically switched depending on the rotational speed of the rotating machine and the status signal of the power system. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of the configuration of a motor-driven power generating device according to an embodiment of the present invention; [Diagram 2] 1 is a block diagram showing an example of the configuration of a power conversion device in a motor-driven power generating device according to an embodiment of the present invention; [Diagram 3] 5 is a flowchart showing an example of a mechanism of a torque command value switching unit in the power conversion device. [Figure 4] FIG. 1 is a diagram showing an example of the configuration of a motor-driven power generating device according to a conventional technique. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] FIG. 1 is a diagram showing an example of the configuration of a motor-driven power generating device according to an embodiment of the present invention.

[0013] In the motor-driven generator shown in FIG. 1, reference numeral 1 denotes a synchronous generator, 2 denotes a rotating machine, 3 denotes a power storage device, 4 denotes a power conversion device, 5 denotes a rotation detector, 6 denotes a power system, 7 denotes a capacitor, and 8 denotes an external control device.

[0014] First, the DC voltage of the power storage device 3 is smoothed by the capacitor 7, and the smoothed DC voltage is supplied to the power conversion device 4. Note that the capacitor 7 for smoothing may not be required in terms of configuration.

[0015] The power conversion device 4 converts the DC voltage smoothed by the capacitor 7 into an AC voltage and supplies it to the rotating machine 2. The power conversion device 4 receives an external torque command value T EXT * , the state signal of the power system 6, and the rotation speed ω of the rotating machine 2 detected by the rotation detector 5. m is input, and the state signal of power system 6 and the rotation speed ω m Based on this, the torque control and the speed control of the power conversion device 4 are switched.

[0016] The rotating machine 2 is driven by an AC voltage supplied by a power conversion device 4, and rotates a synchronous generator 1 whose shaft is directly connected.

[0017] The synchronous generator 1 is driven by a rotating machine 1 connected directly to its shaft, and supplies electric power to a power system 6. The power system 6 is generally composed of a diesel generator or an AC power source such as a commercial AC power source, and load equipment.

[0018] Here, the power conversion device 4 will be described in detail by taking as an example a case in which the rotating machine 2 is an induction motor.

[0019] FIG. 2 is a block diagram showing an example of the configuration of a power conversion device in a motor-driven power generating device according to an embodiment of the present invention.

[0020] The power conversion device 4 is composed of a speed control unit 4a, a torque command value switching unit 4b, a current command value conversion unit 4c, a slip frequency calculation unit 4d, an angle calculation unit 4e, a UVW-DQ conversion unit 4f, a current control unit 4g, a dq-UVW conversion unit 4h, and a gate signal conversion unit 4i.

[0021] The speed control unit 4a receives a rotation speed command value ω m * and rotation speed ω m Then, the speed control unit 4a receives the rotation speed command value ω m * and rotation speed ω m The internal torque command value T ASR * is calculated using PID control, etc.

[0022] The torque command value switching unit 4b receives the internal torque command value T ASR * , rotational speed ω m and the external torque command value T EXT * The state signal of the power system 6 is input. The torque command value switching unit 4b then receives the rotation speed ω m and the torque command value T m * The internal torque command value T ASR * (speed control) or external torque command value T EXT* (torque control), and the torque command value T m * Output.

[0023] The current command value conversion unit 4c converts the torque command value T m * The torque current command value I q * Convert to.

[0024] The slip frequency calculation unit 4d calculates the torque current command value I q * , excitation current command value I d * , and the equivalent circuit constant of the rotating machine 2, the torque command value T m * The slip angle frequency ω required to output slip Calculate the following.

[0025] The angle calculation unit 4e calculates the rotation speed ω m and slip angle frequency ω slip The rotation angle θ is calculated by integrating the angular velocity to which m+slip Calculate the following.

[0026] The uvw-dq conversion unit 4f converts the rotation angle θ m+slip By performing three-phase to two-phase conversion based on u , V phase current I v , and W-phase current I w , the torque current I q and the excitation current I d Convert to.

[0027] The current control unit 4g receives a torque current command value I q * , excitation current command value I d * , torque current I q , and the excitation current I d Then, the current control unit 4g receives the torque current command value I q * and torque current I qand the excitation current command value I d * and the excitation current I d The q-axis voltage command value V q * and the d-axis voltage command value V d * is calculated using PID control, etc.

[0028] The dq-uvw conversion unit 4h converts the rotation angle θ m+slip By performing two-phase to three-phase conversion based on q * and the d-axis voltage command value V d * and the U-phase voltage command value V u * , V-phase voltage command value V v * , and the W-phase voltage command value V w * Convert to.

[0029] The gate signal conversion unit 4i converts the U-phase voltage command value V u * , V-phase voltage command value V v * , and the W-phase voltage command value V w * is converted into a gate signal.

[0030] Here, as a detailed explanation of the torque command value switching unit, an example of the mechanism will be explained with reference to the flowchart of FIG.

[0031] First, in step S101, the torque command value switching unit 4b selects the upper frequency limit ω upper Set.

[0032] The torque command value switching unit 4b is responsible for the subsequent processing steps, and therefore, in the following description, it will be avoided to mention that the torque command value switching unit 4b is the main operator.

[0033] In step S102, the lower limit frequency ω lower Set.

[0034] In step S103, the rotation speed ω of the rotating machine 2 detected by the rotation detector 5 is m Get the.

[0035] In step S104, the rotation speed ω m is the upper frequency limit ω upper Is it greater than the lower frequency limit ω? lower If it is smaller than ω m is the upper frequency limit ω upper and the lower frequency limit ω lower If it is between, the process proceeds to step S106.

[0036] In process S105, the power electronics device 4 is switched to speed control, and the process returns to process S103.

[0037] In step S106, if the power electronics device 4 is in speed control and the power system is in a normal state, the process proceeds to step S107, and if not, the process returns to step S103.

[0038] In step S107, the power conversion device 4 is switched to the torque control, and the process returns to step S103.

[0039] With the above-described configuration, in the electric motor-driven generator according to an embodiment of the present invention, by automatically switching between torque control and speed control of the power conversion device in response to the rotational speed of the rotating machine and the status signal of the power system, it is possible to improve the stability of the power system while operating the rotating machine under torque control.

[0040] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0041] 1 Synchronous generator 2 Rotating Machines 3. Energy storage device 4. Power conversion device 4a Speed ​​control section 4b Torque command value switching section 4c Current command value conversion unit 4d Slip frequency calculation section 4e Angle calculation section 4f UVW-DQ conversion section 4g Current control section 4h dq-uvw converter 4i Gate signal conversion section 5 Rotation detector 6 Power system 7 Capacitor 8 External Control Device

Claims

[Claim 1] a power storage device, a power conversion device that converts a DC voltage of the power storage device into an AC voltage, a rotating machine driven by the AC voltage of the power conversion device, a rotation detector that detects the rotation speed of the rotating machine, a synchronous generator whose shaft is directly connected to the rotating machine, a power system connected to the synchronous generator, and an external control device that outputs an external torque command value based on an active power command value and a state signal of the power system to the power conversion device, the power conversion device further comprises a torque command value switching unit that sets an upper frequency limit value and a lower frequency limit value in the power system, performs speed control when the rotation speed of the rotating machine detected by the rotation detector is greater than the upper frequency limit value or smaller than the lower frequency limit value, and performs torque control only when the power system is in a normal state when the rotation speed is between the upper frequency limit value and the lower frequency limit value.

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