JP2014128159A - Power generation facility, operation method therefor, and control device for power generation facility - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generation facility capable of suppressing voltage rise of a DC transmission path while suppressing influence on a power generator, an operation method therefor and a control device for the power generation facility.SOLUTION: A power generation facility includes: at least one motor; at least one power generator configured to be driven by each of the motors; a local grid to which each of the power generators is connected; a DC transmission path provided between the local grid and a grid; an AC/DC converter for converting an AC power from the local grid into a DC power and supplying the same to the DC transmission path; a DC/AC converter for converting the DC power from the DC transmission path into an AC power and supplying the same to the grid; a first converter control unit for controlling the AC/DC converter so as to keep a voltage in the local grid at a set value or more when abnormal increase in the voltage occurs in the DC transmission path; and a motor control unit for controlling the motor so as to reduce a mechanical input from the motor to the power generator at the time of the abnormal increase in voltage in the DC transmission path.

Description

  The present disclosure relates to a power generation facility, an operation method thereof, and a control device for the power generation facility.

  As a power generation facility provided with a generator linked to an electric power system (grid), there is one provided at a place away from a grid connection point. For example, for renewable energy power generators such as wind power generators and tidal current power generators, the installation location is selected in consideration of the wind and tide conditions, so it is far away from the grid connection point, such as offshore or mountainous areas. Often provided. In particular, in an offshore wind power generation facility, installation may be planned in a place where the distance from the grid connection point exceeds 100 km.

  In a power generation facility provided at a location away from the grid connection point, it is considered advantageous to reduce power transmission loss by transmitting power to the grid by direct current power transmission without reactive power. In particular, when submarine cables are used to link power generation facilities to the grid, such as offshore wind power generation facilities, power transmission loss tends to increase in AC power transmission, and direct current power transmission is considered desirable. Note that transmission loss increases during AC power transmission using submarine cables because general submarine cables have a structure in which a conductor is surrounded by a relatively thin layer of an insulator and a conductor sheath, and have a high capacitance. Because.

As a power transmission facility of a direct current power transmission system, one that is connected to a grid via a high voltage direct current (HVDC) system is known.
The HVDC system has a sending converter (SEC) provided on the power generation facility side and a receiving converter (REC; receiving end converter) provided on the grid side. A direct current transmission line is provided between the sending converter and the receiving converter. The sending converter converts AC power from the power generation facility into DC power, and receives the DC power via the DC power transmission path and supplies the DC power to the converter. The receiving converter converts the DC power received from the sending converter through the DC power transmission path into AC power and supplies it to the grid.

  In DC power generation facilities, when an accident such as a short circuit, ground fault, or disconnection occurs in the power system or DC transmission path, the amount of power that can be transmitted from the power generation facility to the grid via the DC transmission path decreases instantaneously. The power supply-demand balance between the power generation facility and the grid is disrupted. That is, electric power exceeding the amount that can be transmitted from the power generation facility to the grid via the DC power transmission path is generated in the power generation facility. An imbalance (surplus power) between the amount of power generated at the power generation facility and the amount of power that can be transmitted to the grid causes an increase in the voltage of the DC transmission path. And if the voltage rise of a DC power transmission line exceeds a design withstand voltage, the apparatus containing a sending converter will be out of order.

  As a technique for preventing a failure of a device including a sending converter, there is known a method in which a DC chopper is provided in a DC transmission line and surplus power is dissipated by a braking resistance (Brake Resistor) of the DC chopper. However, since the power generation facilities connected to the grid are generally large in size, the DC chopper for dissipating the surplus power must be large in capacity, and there are problems in terms of cost, weight, and installation space. .

  Therefore, as a technique that does not depend on the DC chopper of the DC power transmission path, Patent Document 1 discloses a power adjustment method for a power generation facility in which a generator of a wind power generator is connected to a local grid via a converter. The method described in Patent Document 1 is based on the premise that the maximum value of the output current from the generator of the wind power generator is limited by the converter, and the voltage of the local grid is controlled by controlling the sending converter. To reduce the power flowing into the DC transmission line.

U.S. Pat. No. 8,305,778

By the way, because the converter is expensive and low in reliability, a power generation facility is proposed in which the generator is directly connected to the local grid without using the converter, and the local grid and the grid are connected via the HVDC system. Has been.
However, the method described in Patent Document 1 is based on the premise that the maximum value of the output current from the generator is limited by the converter, and the method is not limited to a power generation facility in which the generator is connected to the local grid without using the converter. It is unknown whether to apply it. If the method described in Patent Document 1 is applied to a power generation facility in which a generator is directly connected to a local grid, the voltage drop of the local grid affects the generator directly connected to the local grid. For example, if the generator connected to the local grid is a synchronous generator, the terminal voltage of the synchronous generator decreases as the voltage of the local grid decreases, and the synchronization power of the synchronous generator decreases. As a result, the rotating shaft of the synchronous generator is accelerated, and the synchronous generator may be stepped out.

  An object of at least one embodiment of the present invention is to provide a power generation facility, a power generation facility operation method, and a power generation facility control device capable of suppressing a voltage increase in a DC transmission line while suppressing an influence on a generator. is there.

A power generation facility according to at least one embodiment of the present invention,
At least one prime mover,
At least one generator configured to be driven by each said prime mover;
A local grid to which each said generator is connected;
A DC power transmission path provided between the local grid and the grid;
An AC / DC converter for converting AC power from the local grid to DC power and supplying the DC power to the DC power transmission path;
An orthogonal transformer for converting the DC power from the DC power transmission path into AC power and supplying the grid to the grid;
A first converter control unit for controlling the AC / DC converter so as to maintain a voltage in the local grid at or above a set value when an abnormal voltage rise in the DC power transmission path;
A prime mover control unit for controlling the prime mover so that mechanical input from the prime mover to the generator is reduced when the voltage of the DC power transmission line is abnormally increased.

According to the power generation facility, when the voltage of the DC transmission line abnormally rises, the AC / DC converter maintains the voltage of the local grid above the set value under the control of the first converter control unit. Even when is directly connected, the influence on the generator is suppressed. For example, when the generator is a synchronous generator, the voltage of the local grid is maintained at a set value or higher, so that the synchronization power of the synchronous generator is secured to some extent, and the synchronous generator is less likely to step out.
In addition, when the voltage of the DC transmission line rises abnormally, the prime mover control unit reduces the mechanical input from the prime mover to the generator, so the voltage of the local grid is controlled by the control of the AC / DC converter by the first converter control unit. Even if it maintains more than a set value, the electric power which flows into a DC power transmission line from a generator reduces, and the voltage rise of a DC power transmission line can be suppressed.
In this way, regardless of the generator-local grid connection method, it is possible to suppress an increase in the voltage of the DC transmission line while suppressing the influence on the generator.

In some embodiments, the at least one power generator includes a plurality of synchronous power generators directly connected to the local grid, and the power generation facility is configured so that each of the synchronous power generators is at the time of abnormal voltage rise in the direct current transmission line. A second converter control unit for controlling the AC / DC converter so as to suppress the vibration of the internal phase difference angle. Here, “directly connected” means that the synchronous generator is directly connected to the local grid without going through the converter.
The AC / DC converter suppresses the vibration of the internal phase difference angle of each synchronous generator under the control of the second converter control unit, so that the steady state stability after the second wave oscillation of the synchronous generator is improved.
In order to improve the transient stability by suppressing the first wave fluctuation of the synchronous generator using the super-fast response excitation control, and to increase the steady-state stability after the second wave oscillation that is reduced by the super-speed response excitation control. A technology for performing field control called PSS (Power System Stabilizer) has been established in large-scale power generation facilities using steam turbines and gas turbines. However, when a plurality of synchronous generators are connected to the local grid as described above, the capacity of individual synchronous generators that can be used for vibration attenuation is relatively small, so that the vibration attenuation effect by PSS control is sufficient. It may not be obtained. Further, since the response of the PSS control is relatively slow, this can also contribute to the fact that the fluctuation attenuation effect of the PSS control can be obtained only in a limited manner. In this regard, since the AC / DC converter between the local grid and the DC transmission line has a relatively large capacity and a relatively fast response, if the AC / DC converter is controlled by the second converter control unit as described above, the PSS Compared with the case where the field of the synchronous generator is controlled by the control, it is possible to enjoy a large improvement effect of the steady state stability.

In one embodiment, the second converter control unit controls the AC / DC converter so as to supply a current having a phase shifted from a current phase in the local grid to the local grid.
Thereby, a current having a phase shifted from the current phase in the local grid is supplied from the AC / DC converter to the local grid, and the vibration of the internal phase difference angle of the synchronous generator is effectively suppressed.

In some embodiments, the power generation facility further includes at least one active power consumption accumulating unit for consuming or accumulating active power when the voltage of the DC transmission line increases abnormally.
As a result, surplus power is consumed or accumulated by at least one active power consumption accumulating unit in addition to a decrease in surplus power due to a reduction in mechanical input from the prime mover to the generator. And the voltage increase of the DC transmission line can be more effectively suppressed.

In some embodiments, the power generation facility includes a third converter for tripping at least one of the AC / DC converter and the orthogonal converter when a voltage of the DC transmission line exceeds a first threshold V _th1 . And further comprising a control unit, wherein the prime mover control unit is configured such that when the voltage of the DC transmission line is equal to or lower than the first threshold value V _{th1 and} equal to or higher than a second threshold value V _th2 smaller than the first threshold value V _th1. The prime mover is configured to be controlled such that mechanical input is reduced.
Thereby, the frequency of trip of an AC / DC converter or an orthogonal converter becomes low, and the operation rate of a power generation facility improves.

  In some embodiments, the at least one prime mover includes a plurality of offshore wind turbines for driving each of the generators. That is, in some embodiments, the power generation facility includes a plurality of offshore wind turbines as prime movers.

An operation method of a power generation facility according to at least one embodiment of the present invention is as follows.
At least one prime mover, at least one generator configured to be driven by each prime mover, a local grid to which each of the generators is connected, and provided between the local grid and the grid A direct current transmission line, an AC / DC converter for converting alternating current power from the local grid into direct current power and supplying the direct current power line, and converting the direct current power from the direct current transmission line into alternating current power A method for operating a power generation facility including an orthogonal transformer for supplying to a grid,
A first converter control step of controlling the AC / DC converter so as to maintain a voltage in the local grid at a set value or higher when a voltage abnormality rises in the DC transmission line;
A prime mover control step for controlling the prime mover so that mechanical input from the prime mover to the generator is reduced when the voltage of the DC power transmission line increases abnormally.

In the above operation method, when the voltage of the DC transmission line rises abnormally, the voltage of the local grid is maintained above the set value by the control of the AC / DC converter, so the generator is directly connected to the local grid. Even if it exists, the influence on a generator is suppressed.
Also, when the voltage of the DC transmission line rises abnormally, the mechanical input from the prime mover to the generator is reduced by controlling the prime mover, so the voltage of the local grid is maintained above the set value by the control of the AC / DC converter. However, the electric power flowing into the DC transmission line from the generator is reduced, and the voltage increase in the DC transmission line can be suppressed.
In this way, regardless of the generator-local grid connection method, it is possible to suppress an increase in the voltage of the DC transmission line while suppressing the influence on the generator.

In some embodiments, the at least one power generator includes a plurality of synchronous power generators directly connected to the local grid, and the operation method of the power generation facility is configured such that each of the DC power transmission lines has an abnormal voltage increase. A second converter control step of controlling the AC / DC converter so as to suppress vibration of the internal phase difference angle of the synchronous generator is further provided.
In this way, by suppressing the oscillation of the internal phase difference angle of each synchronous generator by controlling the AC / DC converter, the steady state stability after the second wave oscillation of the synchronous generator is improved.

In one embodiment, in the second converter control step, the AC / DC converter is controlled so that a current having a phase shifted from a current phase in the local grid is supplied to the local grid.
Thereby, a current having a phase shifted from the current phase in the local grid is supplied from the AC / DC converter to the local grid, and the vibration of the internal phase difference angle of the synchronous generator is effectively suppressed.

In some embodiments, the operation method of the power generation facility further includes an active power consumption accumulation step of consuming or accumulating active power when the voltage of the DC power transmission line increases abnormally.
As a result, surplus power is reduced by reducing the mechanical input from the prime mover to the generator, and in addition, active power (surplus power) is consumed or accumulated, so that surplus power in the DC transmission path is reduced, and direct current is reduced. It is possible to more effectively suppress the voltage increase in the transmission line.

In some embodiments, the method for operating the power generation facility includes converter protection that trips at least one of the AC / DC converter and the orthogonal converter when the voltage of the DC transmission line exceeds a first threshold value V _th1. The motor control step, wherein the voltage of the DC transmission line is equal to or lower than the first threshold V _{th1 and} equal to or higher than a second threshold V _th2 smaller than the first threshold V _th1. The prime mover is controlled so that the target input is reduced.
Thereby, the frequency of trip of an AC / DC converter or an orthogonal converter becomes low, and the operation rate of a power generation facility improves.

A control device for a power generation facility according to at least one embodiment of the present invention,
At least one prime mover, at least one generator configured to be driven by each prime mover, a local grid to which each of the generators is connected, and provided between the local grid and the grid A direct current transmission line, an AC / DC converter for converting alternating current power from the local grid into direct current power and supplying the direct current power line, and converting the direct current power from the direct current transmission line into alternating current power A power generation facility control device including an orthogonal transformer for supplying to a grid,
A first converter control unit for controlling the AC / DC converter so as to maintain a voltage in the local grid at or above a set value when an abnormal voltage rise in the DC power transmission path;
A prime mover control unit for controlling the prime mover so that mechanical input from the prime mover to the generator is reduced when the voltage of the DC transmission line is abnormally increased.

In the above control device, when the voltage of the DC transmission line abnormally rises, the first converter control unit controls the AC / DC converter so that the voltage of the local grid is maintained at the set value or higher. Even when is directly connected, the influence on the generator is suppressed.
In addition, when the voltage of the DC transmission line increases abnormally, the prime mover control unit controls the prime mover so that the mechanical input from the prime mover to the generator is reduced. Therefore, the local converter is controlled by the AC / DC converter control by the first converter control unit. Even if the voltage of the grid is maintained at a set value or higher, the power flowing from the generator into the DC transmission line is reduced, and the voltage increase in the DC transmission line can be suppressed.
In this way, regardless of the generator-local grid connection method, it is possible to suppress an increase in the voltage of the DC transmission line while suppressing the influence on the generator.

  According to at least one embodiment of the present invention, it is possible to suppress a voltage increase in a DC power transmission line while suppressing an influence on the generator regardless of a connection method between the generator and the local grid.

It is a figure showing the whole power generation facility composition concerning one embodiment. It is a figure which shows the electric power generating apparatus which concerns on one Embodiment. It is a block diagram which shows the motor | power_engine control part which concerns on one Embodiment. It is a flowchart which shows the operating method of the electric power generating apparatus which concerns on one Embodiment. It is a graph which shows an example of a time-dependent change of each parameter before and behind generation | occurrence | production of the system fault in the electric power generation facility which concerns on embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

FIG. 1 is a diagram illustrating an overall configuration of a power generation facility according to an embodiment.
As shown in the figure, the power generation facility 1 includes at least one power generation device 10, a local grid 2 to which each power generation device 10 is connected, and an HVDC 20 provided between the local grid 2 and the grid 100. .

  In the exemplary embodiment shown in FIG. 1, the local grid 2 includes N cables 2 </ b> A connected to N (N is an integer of 1 or more) power generation apparatuses 10, and N cables 2 </ b> A via a bus 4. 1 cable 2B connected to the cable 2A. The local grid 2 includes a booster 3 connected to each of the N cables 2A and a substation transformer 6 connected to one cable 2B. Furthermore, the local grid 2 may be provided with a harmonic filter 7A and an interconnecting reactor 8A.

As shown in FIG. 1, the HVDC 20 includes a DC power transmission path 22 and a pair of VSC (Voltage Source Converter) provided on both sides of the DC power transmission path 22. The VSC on the local grid 2 side is an AC / DC converter (sending converter; SEC) 24 that converts AC power from the local grid 2 into DC power. On the other hand, the VSC on the grid 100 side is an orthogonal converter (reception converter; REC) 26 that converts DC power received from the SEC 24 side into AC power and supplies the AC power to the grid 100.
A harmonic filter 7B and an interconnecting reactor 8B may be provided between the REC 26 and the grid 100.

In the exemplary embodiment shown in FIG. 1, a cable 2 </ b> B obtained by consolidating N cables 2 </ b> A connected to N power generation apparatuses 10 into one by a bus 4 becomes one SEC (AC / DC converter) 24. Connected.
In this case, AC power from the N power generation devices 10 is supplied to one AC / DC converter 24 via the local grid 2 (cable 2A, bus 4 and cable 2B), and is supplied to one AC / DC converter 24. Converted to DC power. Then, DC power from one AC / DC converter 24 is supplied to one orthogonal transformer 26 via the DC transmission line 22, converted into AC power by one orthogonal converter 26, and sent to the grid 100. It is done.

In another embodiment, the local grid 2 is N cables connected to the N power generation devices 10, and each cable is connected to the DC power transmission path 22 via the AC / DC converter 24. That is, the N cables of the local grid 2 are not integrated into one cable by the hub, but are connected to the DC power transmission path 22 via the N AC / DC converters 24 provided for the N cables. Connected to.
In this case, AC power from the N power generation devices 10 is supplied to the N AC / DC converters 24 via the local grid 2 (N cables), and each of the N AC / DC converters 24 converts the AC power to DC power. Converted. Then, DC power from the N AC / DC converters 24 is supplied to one orthogonal transformer 26 via the DC power transmission path 22, converted into AC power by one orthogonal transformer 26, and sent to the grid 100. It is done.

  Each power generator 10 includes a prime mover 11 and a generator 12 driven by the prime mover 11. The prime mover 11 is, for example, an internal combustion engine such as a diesel engine that converts fuel combustion energy into output shaft rotational energy, a wind turbine rotor that converts wind energy into its own rotational energy, river current energy or tidal current energy into its own rotational energy. Includes a turbine wheel rotor to convert.

FIG. 2 is a diagram illustrating the power generation device 10 according to one embodiment.
As shown in the figure, in some embodiments, each power generator 10 includes a rotor 63 that rotates in response to wind energy, river energy, or tidal energy, a drive train 64 that is connected to the rotor 63, and a drive train. And the generator 12 that converts the rotational energy of the rotor 63 transmitted through the power 64 into electric power energy. In this case, the motor 11 is constituted by the rotor 63 and the drive train 64.

  In one embodiment, as shown in FIG. 2, the generator 12 of each power generator 10 is a synchronous generator connected to the local grid 2, and each synchronous generator 12 includes a converter such as an inverter or a converter. It is directly connected to the local grid 2 (specifically, the cable 2A) without being interposed.

In some embodiments, as shown in FIG. 2, the drive train 64 includes a hydraulic pump 64A that may be a variable displacement type driven by a rotor 63, and pressure oil generated by the hydraulic pump 64A. And a variable displacement hydraulic motor 64B to be driven. The displacements of the hydraulic pump 64A and the hydraulic motor 64B are controlled by the pump control unit 67A and the motor control unit 67B, respectively. The hydraulic pump 64A and the hydraulic motor 64B are connected to each other via a high pressure oil line 64C and a low pressure oil line 64D. Therefore, the hydraulic oil (high pressure oil) discharged from the hydraulic pump 64A is supplied to the hydraulic motor 64B via the high pressure oil line 64C, and the hydraulic oil (low pressure oil) after working in the hydraulic motor 64B is the low pressure oil line 64D. Is returned to the hydraulic pump 64A. Note that an oil tank in which hydraulic oil is stored may be connected to the low-pressure oil line 64D. In one embodiment, an accumulator 64E is connected to the high pressure oil line 64C. The accumulator 64E prevents pulsation in the high-pressure oil line 64C, accumulates high-pressure oil generated by the hydraulic pump 64A, and absorbs the difference between the discharge amount of the hydraulic pump 64A and the suction amount of the hydraulic motor 64B. Have a role.
The power generator 10 includes an exciter 66 for supplying a field current to the field winding of the synchronous generator 12, and the exciter 66 is configured to be controllable by an exciter controller 69. Good.

In another embodiment, the generator 12 of each power generator 10 is a synchronous generator (for example, a PMG synchronous generator), and the synchronous generator 12 is directly connected to the rotor 63 without the drive train 64. . In this case, the synchronous generator 12 may be connected to the local grid 2 via an AC-DC-AC link.
In yet another embodiment, the generator 12 of each generator 10 is a secondary winding induction generator, the stator winding of the generator 12 is directly connected to the local grid 2 and the rotor of the generator 12 is connected. The winding is connected to the local grid 2 through an AC-DC-AC converter. In this case, a drive train 64 including a gear type gearbox may be provided between the rotor 63 and the generator 12.

  The blades of the rotor 63 may be adjustable in pitch angle by a pitch control mechanism that operates under the control of the pitch control unit 68, as shown in FIG.

In some embodiments, the power generator 10 is an offshore wind power generator. That is, the prime mover 11 includes a wind turbine rotor 63 installed on the ocean.
In this case, the cables 2A and 2B provided between the wind power generator 10 and the transformer 3 installed on the ocean and the substation transformer 6 installed on the ocean substation may be configured by submarine cables. Further, the DC power transmission path 22 between the SEC 24 provided in the offshore substation and the REC 26 provided on land may also be configured with a submarine cable.

In the power generation facility 1, when an accident such as a short circuit, a ground fault, or a disconnection occurs in the grid 100 or the DC transmission path 22, the amount of power P _REC that can be transmitted from the _REC 26 to the grid 100 is instantaneously reduced. The power supply-demand balance between the two is disrupted. That is, power P _SEC exceeding the power P _REC that can be transmitted from the power generation facility 1 to the grid 100 via the DC power transmission path 22 is generated by the power generation device 10, and this power P _SEC flows into the DC power transmission path 22 via the _SEC 24. To do. The surplus power ΔP (= P _SEC −P _REC ) in the DC transmission path 22 thus generated causes a voltage increase in the DC transmission path 22.
FIG. 1 shows an example in which an accident 102 occurs on the grid 100 side.

Therefore, in some embodiments, the power generation facility 1 includes a control device 30 that functions to suppress a voltage increase in the DC power transmission path 22. The control device 30 includes a first converter control unit 40 and a prime mover control unit 50.
In addition, each element of the control apparatus 30 does not need to be provided in the same place, and some elements may be provided in the place different from another element. For example, each element of the control device 30 may be provided on the same control panel, or each element of the control device 30 may be provided in a distributed manner on a plurality of control panels. The prime mover control unit 50 may be provided on each of N control panels provided individually for each power generation apparatus 10. Furthermore, when the power generation facility 1 has a plurality of AC / DC converters (SEC) 24, the first converter control unit 40 is provided in each of a plurality of control panels provided individually for each AC / DC converter 24. May be.

First transducer control unit 40, so as to maintain the voltage (AC side voltage _{V SEC} of SEC24) in the local grid 2 more than the set value during the abnormal rise of the voltage _{V DC} of DC transmission path 22 SEC (AC-DC converter) 24 is controlled. For example, the voltage of the local grid 2 may be kept constant at the voltage value of the local grid 2 before the abnormal voltage rise of the DC power transmission path 22 is controlled by the control of the SEC 24 by the first converter control unit 40.

In one embodiment, the first converter control unit 40 starts control of the SEC 24 when the voltage _VDC of the DC power transmission path 22 directly measured by the voltage detector 34 exceeds a threshold value.
In another embodiment, the DC power transmission line 22 may be replaced with the voltage V _DC of the DC power transmission path 22 directly measured by the voltage detector 34 or in addition to the voltage V _DC of the DC power transmission path 22 directly measured by the voltage detector 34. The control of the SEC 24 by the first converter control unit 40 is started based on other information that is an indicator of 22 abnormal voltage rise.

In one embodiment, the first converter control unit 40 starts the control of the SEC 24 when a signal indicating the occurrence of an abnormal voltage rise in the DC power transmission path 22 is received from the abnormality determination unit 32.
The abnormality determination unit 32 may obtain voltage information acquired from the voltage detectors 34, 35, and 36 (voltage V _DC of the DC power transmission path 22, AC-side voltage V _{REC of the REC} 26, voltage V _{Grid of the} grid 100, etc.) Whether or not an abnormal voltage rise in the DC power transmission path 22 has occurred may be determined based on information about the accident including the switching state of the circuit breaker obtained from the power supply command station, the substation, the control station, and the like.
For example, normal ranges are set in advance for the voltage V _DC of the DC transmission path 22, the AC voltage V _{REC of the REC} 26, and the voltage V _{Grid of the} grid 100, and all voltage detection values V _DC , V _REC , and V _Grid are set. When it deviates from the normal range, it may be determined that an abnormal voltage rise of the DC transmission line 22 has occurred (AND condition), or when any voltage detection value deviates from the normal range, the voltage of the DC transmission line 22 It may be determined that an abnormal rise has occurred (OR condition). Alternatively, i values (i is the number of whether the voltage V _DC of the DC transmission line 22, the AC side voltage V _{REC of the REC} 26, the voltage V _Grid of the grid 100 deviates from the normal range, the circuit breaker open / closed state, etc.) It may be determined that an abnormal voltage increase in the DC transmission path 22 has occurred when j (where j <i) conditions are satisfied among the two or more conditions.

As described above, when the voltage of the DC power transmission line 22 rises abnormally, the SEC 24 maintains the voltage of the local grid 2 at a set value or higher under the control of the first converter control unit 40. Even when the generator 12 is directly connected to 2, the influence on the generator 12 is suppressed.
For example, when the generator 12 is a synchronous generator, lowering the voltage of the local grid 2 for the purpose of reducing the power P _REC in accordance with the decrease of the power P _REC, the risk of loss of synchronization of the synchronous generator Arise. On the other hand, in the above-described embodiment, the voltage of the local grid 2 is positively maintained above the set value by the control of the SEC 24, so that the synchronization power of the synchronous generator is secured to some extent, and the synchronous generator is out of step. Less likely to occur.

  Since the synchronizing power of the synchronous generator is secured to some extent by the control of the SEC 24 by the first converter control unit 40, the field control of the synchronous generator 12 (control of the exciter 66 by the exciter control unit 69) is usually performed. The same control as during operation (constant control of terminal voltage, power factor and reactive power) may be used. Alternatively, from the viewpoint of further enhancing the synchronization force of the synchronous generator 12 and improving the transient stability of the synchronous generator 12, the exciter control unit 69 controls the exciter 66 to control the field current of the synchronous generator 12. May be increased. Further, from the viewpoint of improving the steady state stability of the synchronous generator 12, PSS control may be performed by the exciter controller 69.

On the other hand, the prime mover control unit 50 controls the prime mover 11 so that the mechanical input from the prime mover 11 to the generator 12 is reduced when the voltage _VDC in the direct current transmission line 22 increases abnormally.

In one embodiment, the prime mover control unit 50 starts the reduction control of the mechanical input of the prime mover 11 when the voltage _VDC of the DC power transmission path 22 directly measured by the voltage detector 34 exceeds a threshold value.
In another embodiment, the DC power transmission line 22 may be replaced with the voltage V _DC of the DC power transmission path 22 directly measured by the voltage detector 34 or in addition to the voltage V _DC of the DC power transmission path 22 directly measured by the voltage detector 34. Based on the other information that is an indicator of the 22 abnormal voltage rise, reduction control of the mechanical input of the prime mover 11 by the prime mover control unit 50 is started.

  In one embodiment, the prime mover control unit 50 starts reduction control of the mechanical input of the prime mover 11 when a signal indicating the occurrence of an abnormal voltage rise in the DC power transmission path 22 is received from the abnormality determination unit 32. The specific configuration of the abnormality determination unit 32 is as described above.

In some embodiments, the prime mover control unit 50 operates the operation state (power generation amount, etc.) of each power generation apparatus 10, the voltage of the local grid 2 (AC side voltage V _{SEC of the SEC} 24), the degree of the accident 102 and its index ( The mechanical input by the prime mover 11 is adjusted to a target value determined based on at least one of the rising rate or absolute value of the DC voltage V _DC , the decrease amount of the AC voltages V _REC and V _Grid , and the change amount of the AC frequency. .
At this time, if the generator 12 is a synchronous generator, the prime mover 50 is finely controlled by the prime mover 50 in order to suppress the fluctuation of the synchronous generator 12, and the mechanical input by the prime mover 11 is increased or decreased at high speed. Good. That is, the target value of the mechanical input of the prime mover 11 may be raised and lowered, and the synchronous generator 12 may be positively suppressed by the control of the prime mover 11.

The control target of the prime mover control unit 50 is all or part of the prime mover 11, and when the power generation apparatus 10 has the configuration shown in FIG. 2, the direct control target of the prime mover control unit 50 may be the hydraulic motor 64B. . That is, as shown in FIG. 2, the prime mover 11 may be a rotor 63, a hydraulic pump 64A that may be a variable displacement type driven by the rotor 63, and a variable driven by pressure oil generated by the hydraulic pump 64A. When the displacement type hydraulic motor 64B is included, the prime mover control unit 50 may reduce the mechanical input to the generator 12 by adjusting the displacement volume of the hydraulic motor 64B. In this case, the motor control unit 67B may be configured to function as the prime mover control unit 50.
When the displacement of the hydraulic motor 64B is changed by the prime mover control unit 50, a difference occurs between the discharge amount of the hydraulic pump 64A and the suction amount of the hydraulic motor 64B, and the pressure of the hydraulic oil in the high pressure oil line 64C varies. Arise. Therefore, with the control of the hydraulic motor 64B by the prime mover control unit 50, the pump control unit 67A may control the hydraulic pump 64A so that the pressure of the hydraulic oil in the high pressure oil line 64C falls within an allowable range. The accumulator 64E absorbs the difference between the discharge amount of the hydraulic pump 64A and the suction amount of the hydraulic motor 64B, thereby contributing to the suppression of the pressure fluctuation of the hydraulic oil in the high pressure oil line 64C.
Further, when the displacement of the hydraulic pump 64A is changed by the pump control unit 67A, the rotational speed of the rotor 63 varies. Therefore, in accordance with the control of the hydraulic pump 64A by the pump control unit 64A, the pitch control unit 68 controls the pitch control mechanism so as to adjust the pitch angle of the blades of the rotor 63 so that the rotational speed of the rotor 63 falls within the allowable range. May be.

  FIG. 3 is a block diagram showing the prime mover control unit 50 according to one embodiment. In the exemplary embodiment shown in the figure, the prime mover control unit 50 includes a torque reduction logic 52 for determining a reduction amount (torque reduction amount) of the mechanical torque input from the prime mover 11 to the generator 12, and a torque. And a governor 54 that adjusts the output of the prime mover 11 based on the torque reduction amount determined by the reduction logic 52.

In some embodiments, the torque reduction amount determination unit 52 determines the torque reduction amount T _{m_red} based on accident information including the voltage and frequency of the DC power transmission path 22 or the grid 100. At this time, the torque reduction logic 52 estimates the power P _REC that can be sent from the SEC 24 to the grid 100 side from the accident information, so that power equivalent to the estimated power P _REC is generated in the entire power generation apparatus 10. The torque reduction amount T _{m_red} of each prime mover 11 may be determined.

In one embodiment, the governor 54 has a torque target value T _m ^* obtained by subtracting the torque reduction amount T _{m_red} from the normal torque request value T _{m_norm} determined by the logic for determining the torque request value during normal operation. The prime mover 11 is controlled to be realized. The torque target value T _m ^* can be calculated by the subtractor 56.
In this case, the mechanical input reduction control of the prime mover 11 in the abnormal voltage rise of the DC power transmission path 22 can be performed only by adding the torque reduction logic 52 to the logic for determining the torque request value during normal operation. .

  As described above, when the voltage of the DC power transmission line 22 increases abnormally, the prime mover control unit 50 reduces the mechanical input from the prime mover 11 to the generator 12, so that the first converter control unit 40 controls the SEC 24. Even if the voltage of the local grid 2 is maintained at a set value or higher, the power flowing from the power generation apparatus 10 to the DC power transmission path 22 is reduced, and the voltage increase of the DC power transmission path 22 can be suppressed.

Further, when the generator 12 is a synchronous generator, in some embodiments, the control device 30 causes the internal phase difference angle of each synchronous generator 12 when the voltage of the DC power transmission path 22 increases abnormally as shown in FIG. Is further provided with a second converter control unit 42 for controlling the SEC (AC / DC converter) 24 so as to suppress the vibration.
Under the control of the second converter control unit 42, the SEC 24 suppresses the vibration of the internal phase difference angle of the synchronous generator 12, so that the steady state stability after the second wave oscillation of the synchronous generator 12 is improved.

In addition, by controlling the exciter of the synchronous generator by super fast response excitation control using a thyristor, the first wave fluctuation of the synchronous generator is suppressed and the transient stability is improved. Technology for performing PSS (Power System Stabilizer) control in order to increase the steady state stability after the second wave oscillation has been established in large-scale power generation facilities using steam turbines and gas turbines.
However, when a plurality of synchronous generators 12 are connected to the local grid 2, the capacity of the individual synchronous generators 12 that can be used for vibration attenuation is relatively small. It may not be obtained. Further, since the response of the PSS control is relatively slow, this can also contribute to the fact that the fluctuation attenuation effect of the PSS control can be obtained only in a limited manner.
In this respect, since the AC / DC converter 24 between the local grid 2 and the DC power transmission path 22 has a relatively large capacity and a relatively fast response, the AC / DC converter 24 is controlled by the second converter control unit 42 as described above. If it controls, the improvement effect of a large steady state stability can be enjoyed compared with the case where the field of synchronous generator 12 is controlled by PSS control.

In one embodiment, the second converter control unit 42 controls the SEC (AC / DC converter) 24 so as to supply the local grid 2 with a current having a phase shifted from the current phase in the local grid 2. At this time, the second converter control unit 42 may control the _SEC 24 based on the current (AC-side current I _SEC ) in the local grid acquired from the current measuring device 37.
Thereby, a current having a phase shifted from the current phase in the local grid 2 is supplied from the SEC 24 to the local grid 2, and the vibration of the internal phase difference angle of the synchronous generator 12 is effectively suppressed.

  When the power generation facility 1 includes a plurality of AC / DC converters (SEC) 24, the second converter control unit 42 is provided in each of a plurality of control panels provided individually for each AC / DC converter 24. May be.

Furthermore, in some embodiments, the controller 30 causes the SEC 24 or the REC 26 to trip when the voltage V _DC of the DC transmission line 22 exceeds the first threshold V _th1, as shown in FIG. The third converter control unit 44 is provided. The prime mover control unit 50 performs mechanical input of the prime mover 11 when the voltage _VDC of the DC transmission line 22 is equal to or lower than the first threshold V _{th1 and} equal to or higher than the second threshold V _th2 that is smaller than the first threshold V _th1. Perform reduction control.
Thereby, the frequency of trip of SEC24 or REC26 becomes low, and the operation rate of the power generation facility 1 improves.

In some embodiments, as shown in FIG. 1, the power generation facility 1 further includes at least one active power consumption accumulating unit 70 for consuming or accumulating active power when the voltage of the DC power transmission line 22 increases abnormally. Prepare. The active power consumption accumulation unit 70 is, for example, a braking resistor, a marine organism adhesion prevention device, a storage battery, or the like.
Thereby, in addition to the surplus power being reduced due to the reduction of the mechanical input from the prime mover 11 to the generator 12, the surplus power is consumed or accumulated by the at least one active power consumption accumulating unit 70. The surplus electric power in 22 decreases, and the voltage rise of the DC power transmission path 22 can be suppressed more effectively.
When the power generation device 10 is a wind power generation device, a river flow power generation device, or a tidal current power generation device, a braking resistor using seawater or river water as a liquid resistance may be used as the active power consumption accumulation unit 70, or the effective power consumption. Seawater or river water may be used to cool the braking resistor as the storage unit 70.

  In one embodiment, the fluctuation of the electric power flowing into the DC power transmission path 22 is suppressed instead of the fluctuation attenuation control by the SEC 24 under the control of the second converter control unit 42 or in addition to the fluctuation attenuation control by the SEC 24. Thus, the amount of active power consumed or stored in the active power consumption accumulating unit 70 is adjusted.

  Next, an operation method of the power generation facility 1 will be described. FIG. 4 is a flowchart illustrating an operation method of the power generation device 1 according to an embodiment.

In one embodiment, as shown in FIG. 4, first, in step S _{<b> 2} , it is determined whether or not the voltage V _DC of the DC power transmission path 22 exceeds the first threshold value V _th1 . When the voltage _VDC of the DC power transmission path 22 exceeds the first threshold value V _th1 (YES determination in step S2), the process proceeds to step S4, and at least one of the SEC 24 and the REC 26 is tripped. On the other hand, when the voltage _VDC of the DC power transmission line 22 is equal to or lower than the first threshold value V _th1 (NO determination in step S2), the process proceeds to step S6.
In other embodiments, steps S2 and S4 are omitted, and steps S6 to S14 are performed.

In step S6, it is determined whether or not an abnormal voltage rise in the DC power transmission line 22 has occurred. When performing step S6 via step S2, it may be determined whether or not the second threshold value V _th2 is smaller than the first threshold value V _th1 .
In one embodiment, the voltage information obtained from the voltage detectors 34, 35, 36 (the voltage V _DC of the DC transmission line 22, the AC side voltage V _{REC of the REC} 26, the voltage V _{Grid of the} grid 100, etc.), or a converter station, The presence or absence of occurrence of abnormal voltage increase in the DC power transmission path 22 is determined based on the accident information including the switching state of the circuit breaker acquired from the power supply command station, the substation, the control station, and the like.
If an abnormal voltage rise in the DC transmission path 22 has not occurred (NO determination in step S6), the process returns to step S2, and it is determined again whether or not the voltage V _DC of the DC transmission path 22 has exceeded the first threshold value _Vth1. . On the other hand, if it is determined that an abnormal voltage rise in the DC power transmission path 22 has occurred (YES determination in step S6), the process proceeds to step S8.

In step S8, the _SEC 24 is controlled so that the voltage in the local grid 2 (AC side voltage V _{SEC of the SEC} 24) is maintained at a set value or more. For example, the voltage of the local grid 2 may be kept constant at the voltage value of the local grid 2 before the abnormal voltage rise of the DC power transmission path 22 occurs under the control of the SEC 24.

In step S10, the prime mover 11 is controlled to reduce mechanical input from the prime mover 11 to the generator 12.
In some embodiments, in step S10, the operating state (power generation amount, etc.) of each power generation device 10, the voltage of the local grid 2 (AC side voltage V _{SEC of} SEC24), the degree of the accident 102 and its index (DC voltage) The mechanical input by the prime mover 11 is adjusted to a target value determined based on at least one of the increase rate or absolute value of _VDC , the decrease amount of the AC voltages V _REC and V _Grid , and the change amount of the AC frequency.
When the power generation apparatus 10 has the configuration shown in FIG. 2, in step S10, the displacement of the hydraulic motor 64B configured to drive the generator 12 is adjusted, and mechanical input from the hydraulic motor 64B to the generator 12 is performed. May be reduced. Further, the hydraulic pump 64A may be controlled so that the hydraulic oil pressure in the high-pressure oil line 64C falls within an allowable range in conjunction with the adjustment of the displacement volume of the hydraulic motor 64B. Further, along with the adjustment of the displacement volume of the hydraulic pump 64A, the pitch angle of the blades of the rotor 63 may be adjusted by controlling the pitch control mechanism so that the rotational speed of the rotor 63 is within the allowable range.

In some embodiments, as shown in FIG. 2, the power generation apparatus 10 includes a plurality of synchronous generators 12 directly connected to the local grid 2, and each synchronous generator 12 is detected when the voltage of the DC transmission line 22 increases abnormally. The SEC 24 is controlled so that the vibration of the internal phase difference angle is suppressed (step S12 in FIG. 4).
In one embodiment, in step S <b> 12, the SEC 24 is controlled so that a current having a phase shifted from the current phase in the local grid 2 is supplied to the local grid 2.

In some embodiments, the power generation facility 1 has at least one active power consumption storage unit 70, and active power (surplus power) is consumed by the active power consumption storage unit 70 when the voltage of the DC transmission line 22 increases abnormally. Or it accumulate | stores (step S14).
In one embodiment, in place of the vibration attenuation control by SEC in step S12 or in addition to the vibration attenuation control by SEC 24, in step S14, the effective power is controlled so that the fluctuation of the power flowing into the DC power transmission path 22 is suppressed. The consumption or accumulation amount of active power in the consumption accumulation unit 70 is adjusted.

  In the exemplary embodiment shown in FIG. 4, steps S8, S10, S12, and S14 are sequentially performed. However, in other embodiments, at least some of these steps may be performed simultaneously. The order of these steps may be changed as appropriate.

FIG. 5 is a graph illustrating an example of a change with time of each parameter before and after the occurrence of the accident 102 in the power generation facility 1 according to the embodiment.
As shown in FIG. 5, in the case of the power generation facility 1 according to the embodiment, when a system fault occurs at time t _{0 and the} power P _REC that can be supplied from the _REC 26 to the grid 100 side suddenly decreases along with the grid voltage V _Grid , The surplus power is generated at 22 and the voltage _VDC in the DC transmission line 22 is abnormally increased. Control by the first converter control unit 40 and the prime mover control unit 50 of the control device 30 is started in response to an abnormal voltage rise in the DC power transmission path 22. That is, the voltage of the local grid 2 (AC side voltage V _{SEC of the SEC} 24) is maintained at a set value or more by the control of the _SEC 24 by the first converter control unit 40, and the generator is controlled by the control of the motor 11 by the motor control unit 50. mechanical torque T _m to be input is reduced to 12. In the example shown in FIG. 5, the voltage V _SEC is kept constant at a value before the occurrence of the accident 102 by the control of the _SEC 24 by the first converter control unit 40.
Thus, since the voltage of the local grid 2 is maintained at the set value or more when the voltage of the DC power transmission line 22 rises abnormally, the synchronization power of the synchronous generator 12 is secured to some extent. Therefore, although the fluctuation of the rotational speed ω of the synchronous generator 12 due to the vibration of the internal phase difference angle of the synchronous generator 12 slightly occurs, the step-out of the synchronous generator 12 is prevented.
Moreover, the mechanical torque T _m which is input to the synchronous generator 12 from the engine 11 when the voltage rises abnormally DC transmission line 22 is reduced, the voltage of the local grid 2 under the control of the SEC24 by the first transducer control unit 40 Is maintained at the set value or more, the power flowing from the synchronous generator 12 into the DC power transmission path 22 is reduced, and the voltage increase in the DC power transmission path 22 can be suppressed. Note that the fluctuation of the electromagnetic torque T _e of the originating the synchronous generator 12 to the vibration of the internal phase angle of the synchronous generator 12 occurs, variation occurs in the power P _SEC is supplied to the DC transmission line 22 via the SEC24 However, if the steady state stability of the synchronous generator 12 is improved by the control of the _SEC 24 by the second converter control unit 42, fluctuations in the power P _SEC can be suppressed.
In the example shown in FIG. 5, the mechanical torque T is not performed delicate adjustment of _m, the mechanical torque T by controlling the motor 11 by the engine control unit 50 in order to suppress the sway of the synchronous generator 12 _m may be finely adjusted.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to this, In the range which does not deviate from the summary of this invention, you may perform various improvement and deformation | transformation, Of the embodiment mentioned above A plurality may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Power generation facility 2 Local grid 3 Booster 4 Bus 6 Substation transformer 10 Power generation apparatus 11 Motor 12 Generator 20 HVDC (high voltage direct current system)
22 DC transmission line 24 SEC (AC / DC converter)
26 REC (Orthogonal Transformer)
DESCRIPTION OF SYMBOLS 30 Control apparatus 32 Abnormality determination part 40 1st converter control part 42 2nd converter control part 44 3rd converter control part 50 Motor | power_engine control part 52 Torque reduction logic 54 Governor 56 Subtractor 63 Rotor 64 Drive train 64A Hydraulic pump 64B Hydraulic motor 64C High pressure oil line 64D Low pressure oil line 64E Accumulator 66 Exciter 66A Pump controller 67B Motor controller 68 Pitch controller 69 Exciter controller

Claims (12)

At least one prime mover,
At least one generator configured to be driven by each said prime mover;
A local grid to which each said generator is connected;
A DC power transmission path provided between the local grid and the grid;
An AC / DC converter for converting AC power from the local grid to DC power and supplying the DC power to the DC power transmission path;
An orthogonal transformer for converting the DC power from the DC power transmission path into AC power and supplying the grid to the grid;
A first converter control unit for controlling the AC / DC converter so as to maintain a voltage in the local grid at or above a set value when an abnormal voltage rise in the DC power transmission path;
And a prime mover control unit for controlling the prime mover so that mechanical input from the prime mover to the generator is reduced when the voltage of the DC power transmission line is abnormally increased. The at least one generator includes a plurality of synchronous generators directly connected to the local grid,
The power converter further includes a second converter control unit for controlling the AC / DC converter so that vibration of an internal phase difference angle of each of the synchronous generators is suppressed when a voltage abnormality rises in the DC transmission line. The power generation facility according to claim 1.   3. The power generation facility according to claim 2, wherein the second converter control unit controls the AC / DC converter so as to supply a current having a phase shifted from a current phase in the local grid to the local grid. .   The power generation facility according to any one of claims 1 to 3, further comprising at least one active power consumption accumulating unit for consuming or accumulating active power when the voltage of the DC power transmission line abnormally increases. A third converter control unit for tripping at least one of the AC / DC converter and the orthogonal converter when the voltage of the DC transmission line exceeds a first threshold V _th1 ;
The prime mover control unit reduces the mechanical input when the voltage of the DC transmission line is equal to or lower than the first threshold V _{th1 and} equal to or higher than a second threshold V _th2 smaller than the first threshold V _th1. The power generation facility according to any one of claims 1 to 4, wherein the power generator is configured to control the motor.   The power generation facility according to any one of claims 1 to 5, wherein the at least one prime mover includes a plurality of offshore wind turbines for driving each of the power generators. At least one prime mover, at least one generator configured to be driven by each prime mover, a local grid to which each of the generators is connected, and provided between the local grid and the grid A direct current transmission line, an AC / DC converter for converting alternating current power from the local grid into direct current power and supplying the direct current power line, and converting the direct current power from the direct current transmission line into alternating current power A method for operating a power generation facility including an orthogonal transformer for supplying to a grid,
A first converter control step of controlling the AC / DC converter so as to maintain a voltage in the local grid at a set value or higher when a voltage abnormality rises in the DC transmission line;
And a prime mover control step for controlling the prime mover so that mechanical input from the prime mover to the generator is reduced when the voltage of the direct current transmission line is abnormally increased. The at least one generator includes a plurality of synchronous generators directly connected to the local grid,
2. A second converter control step of controlling the AC / DC converter so as to suppress vibration of an internal phase difference angle of each of the synchronous generators when an abnormal voltage rise of the DC transmission line is performed. 8. A method for operating the power generation facility according to 7.   9. The power generation facility according to claim 8, wherein, in the second converter control step, the AC / DC converter is controlled so as to supply a current having a phase shifted from a current phase in the local grid to the local grid. Driving method.   The method for operating a power generation facility according to any one of claims 7 to 9, further comprising an active power consumption accumulating step of consuming or accumulating active power when the voltage of the DC power transmission line abnormally increases. A converter protection step of tripping at least one of the AC / DC converter and the orthogonal converter when the voltage of the DC transmission line exceeds a first threshold V _th1 ,
In the prime mover control step, the mechanical input is reduced when the voltage of the DC transmission line is equal to or lower than the first threshold V _{th1 and} equal to or higher than a second threshold V _th2 smaller than the first threshold V _th1. The operation method of the power generation facility according to any one of claims 7 to 10, wherein the prime mover is controlled as described above. At least one prime mover, at least one generator configured to be driven by each prime mover, a local grid to which each of the generators is connected, and provided between the local grid and the grid A direct current transmission line, an AC / DC converter for converting alternating current power from the local grid into direct current power and supplying the direct current power line, and converting the direct current power from the direct current transmission line into alternating current power A power generation facility control device including an orthogonal transformer for supplying to a grid,
A first converter control unit for controlling the AC / DC converter so as to maintain a voltage in the local grid at or above a set value when an abnormal voltage rise in the DC power transmission path;
An apparatus for controlling a power generation facility, comprising: a motor controller for controlling the motor so that mechanical input from the motor to the generator is reduced when the voltage of the DC power transmission line increases abnormally.

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