JP2018107982A - Dc power transmission system, and, control device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a DC power transmission system which can continue to operate by avoiding operation stop of the DC power transmission system when the DC voltage of the DC power transmission system rises.SOLUTION: The DC power transmission system is provided that comprises: a power generation system for generating power; a first power converter for converting input power from the power generation system to DC power; a DC/AC power converter for converting the DC power input from the first power converter to AC power; a DC power transmission line connecting the first power converter to the DC/AC power converter; a DC voltage detector for detecting a DC voltage of the DC power transmission line; and a control device for controlling the power generation system on the basis of output of the DC voltage detector. The control device performs first protection control when a temporal change rate of DC voltage detected by the DC voltage detector exceeds a first threshold and performs second protection control when the DC voltage detected by the DC voltage detector exceeds a second threshold.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a DC power transmission system that links a power generation system such as a renewable energy power source via a power conversion station and a DC power transmission line, and a control device therefor.

  In recent years, an offshore direct current power transmission system that collects power generated by a plurality of windmills installed on the ocean at an offshore substation and transmits the power to land via a direct current power transmission system has attracted attention.

  In long-distance power transmission and submarine power transmission, a DC power transmission system is often used for higher efficiency, but a general power system such as a wind power generator is an AC system. In addition, it is necessary to transmit power after converting the power of the AC system to DC by a power converter (for example, abstract of Patent Document 1).

Japanese Patent Laying-Open No. 2015-80354

  In Patent Document 1, as shown in FIG. 1 of the same document, in a DC power transmission system in which at least one power generation system is connected to a forward converter and a power receiving system is connected to an inverse converter, When the DC voltage exceeds a certain threshold, the forward converter performs a protective operation to reduce the AC voltage on the forward converter side of the DC power transmission system, and in response, the amount of reactive power supplied from the power generation system is reduced. By causing the power generation system to perform an increasing stabilizing operation, the operation stop (also referred to as “trip”) of the power generation system due to the protective operation of the forward converter is avoided.

  However, when the DC voltage rise rate of the DC power transmission system is fast, even if the protection operation and the stabilization operation are executed after the threshold value is exceeded, the DC voltage rise cannot be suppressed due to communication or control delay of each device. There is a possibility that the DC power transmission system may be stopped before the power generation system is stopped, and the power transmission path from the power generation system to the power receiving system is cut off.

  In order to solve the above problems, the present invention provides a power generation system that generates electric power, a first power conversion device that converts input power from the power generation system into DC power, and the first power conversion device. DC / AC power converter for converting input DC power into AC power, DC power transmission line connecting the first power converter and DC / AC power converter, and detecting DC voltage of the DC power transmission line A direct-current power transmission system comprising: a direct-current voltage detection device that controls the power generation system based on an output of the direct-current voltage detection device, wherein the control device detects the direct-current voltage detected by the direct-current voltage detection device The first protection control is executed when the time change rate of the voltage exceeds the first threshold value, and the second protection control is executed when the DC voltage detected by the DC voltage detection device exceeds the second threshold value. Run.

  According to the present invention, even when the DC voltage of the DC power transmission system suddenly rises, protection control can be performed quickly, and the operation stop of the DC power transmission system can be avoided and the operation can be continued.

1 shows a conceptual system diagram of Embodiment 1. FIG. The conceptual diagram at the time of the DC voltage rise accompanying the power transmission capability fall to an electric power grid | system in Example 1 is shown. The operation characteristic figure of the AC / DC power converter device and power generation system of Example 1 is shown. The system conceptual diagram of Example 2 is shown. The system conceptual diagram of Example 3 is shown. The system conceptual diagram of Example 4 is shown.

  Embodiments of the present invention will be described below with reference to the drawings. The following examples show one form of the present invention, and the present invention includes other forms unless departing from the gist.

  First, the direct-current power transmission system 100 of Example 1 of this invention is demonstrated using FIGS. 1-3.

  The DC power transmission system 100 according to the present embodiment converts AC power generated by an AC power generation system 101 such as a wind power generation system installed on the ocean into an AC / DC power converter 103 (AC) installed in the vicinity of the AC power generation system 101. -DC power conversion device) is converted to direct current and then transmitted over long distances, and then converted from direct current to alternating current using DC / AC power conversion device 104 (DC-AC power conversion device) installed on land. Thus, when the DC voltage of the DC power transmission system 100 increases, the operation of the DC power transmission system 100 can be avoided and the operation can be continued.

  FIG. 1 is a conceptual diagram of a DC power transmission system 100, in which an electric circuit is indicated by a solid line and a communication path is indicated by a dotted line. As shown here, a DC power transmission system 100 includes an AC power generation system 101, an AC bus 102, an AC / DC power conversion device 103, a DC / AC power conversion device 104, a power system 105, a power generation system group control device 106, a DC power transmission. It comprises a protection control device 107, an AC voltage detection device 108, a power detection device 109, a DC voltage detection device 110, an AC power transmission line A111, an AC power transmission line B112, a DC power transmission line 113, and an AC power transmission line C114. Hereinafter, each configuration will be described in detail.

  Each of the plurality of AC power generation systems 101 is electrically connected to the AC bus 102 via the AC power transmission line A111. The AC bus 102 is electrically connected to the AC / DC power converter 103 via the AC power transmission line B112. Connected. The AC / DC power conversion device 103 is electrically connected to the DC / AC power conversion device 104 via the DC power transmission line 113, and the DC / AC power conversion device 104 is connected to the power system via the AC power transmission line C114. 105 is electrically connected.

The AC voltage detection device 108 detects the AC voltage V _ac of the AC bus 102 and transmits it to the DC power transmission protection control device 107. Further, the power detection device 109 detects the input power PG1 flowing through the AC power transmission line B112 and transmits it to the DC power transmission protection control device 107. Further, the DC voltage detection device 110 detects the DC voltage V _dc of the DC power transmission line 113 and transmits it to the DC power transmission protection control device 107.

  The AC / DC power converter 103 and the DC / AC power converter 104 are power converters generally referred to as self-excited AC / DC power converters such as a two-level converter and a modular multi-level converter configured using self-extinguishing elements. In addition to the equipment, it consists of electrical equipment such as transformers, circuit breakers, protective equipment, sensors, control devices, and communication equipment.

The power generation system group control device 106 is a control device that performs centralized control of the AC power generation system 101, and includes means for mutual communication with the AC power generation system 101, monitoring the operating state of the AC power generation system 101, and to the AC power generation system 101. The operation command and operation point of operation are transmitted. In addition, the DC power transmission protection control device 107 performs protection control of the entire DC power transmission system 100 based on signals from the AC voltage detection device 108, the power detection device 109, the DC voltage detection device 110, and the like in an emergency such as an accident. It is a control device to perform. The DC power transmission protection control device 107 detects three state quantities of the DC voltage V _dc , the input power PG 1, and the AC voltage V _ac and gives a command to the AC / DC power conversion device 103 and the power generation system group control device 106. However, it may be provided with means for detecting state quantities other than those described above and means for communicating with other control devices and devices.

Here, the steady-state power flow will be described with reference to FIG. In the steady state, AC power generated by the AC power generation system 101 is once converted into direct current by the AC / DC power converter 103 and transmitted to the DC power transmission line 113, and converted again to AC by the DC / AC power converter 104. Then, power is transmitted to the power system 105. If the loss of each device or transmission line is ignored, the magnitude of the input power PG1 before power conversion and the output power PG2 transmitted to the power system 105 after power conversion are substantially equal. The DC voltage V _{dc at} is maintained substantially constant.

On the other hand, the operation continuation control at the time when the DC voltage V _dc of the DC transmission line 113 is increased due to the voltage of the AC transmission line C114 being reduced to zero due to the influence of lightning or the like and the transmission capability to the power system 105 is reduced. Will be described with reference to FIGS.

FIG. 2 shows (a) the voltage of the AC transmission line C114, (b) the input power PG1 and the output power PG2, and (c) the DC transmission when the transmission capability to the power system 105 is reduced due to an accident such as a lightning strike. It is each conceptual diagram of the time change of DC voltage _Vdc of the electric wire 113, (d) AC voltage _Vac of the AC bus line 102, the vertical axis indicates the size of each element, and the horizontal axis indicates time. The vertical axis and the horizontal axis are both expressed in arbitrary units (hereinafter referred to as “au”).

  In FIG. 2, time T0 is the time when an accident such as a lightning strike has occurred, before this is a steady state and after this is an unsteady state. In this embodiment, in order to continue the operation of the AC power generation system 101 even in an unsteady state, two protection controls, a first protection control and a second protection control, which will be described later, are performed. Hereinafter, time T1 is a time when the first protection control is started, and time T2 is a time when the second protection control is started.

In the steady state before time T0, the voltage of the AC power transmission line C114, the input power PG1, the output power PG2, the DC voltage V _dc , and the AC voltage V _ac are all 1.0 [au].

In the unsteady state starting from time T0, as shown in FIG. 2A, the voltage of the AC power transmission line C114 decreases to 0.0 [au]. As shown in FIG. 2B, the input power PG1 does not change, but the output power PG2 decreases to 0.0 [au] as the voltage of the AC power transmission line C114 decreases. That is, the input power PG1 is larger than the output power PG2.
(First protection control)
Next, the first protection control performed at time T1 will be described. In the time zone from the time T0 to the time T1 before the first protection control starts, the input power PG1 is larger than the output power PG2, and thus the difference power is AC / DC power converter 103, DC / AC power converter 104. As a result, the DC voltage V _dc of the DC transmission line 113 rises as shown in FIG. 2C.

At this time, the DC power transmission protection control device 107 detects the DC voltage V _dc via the DC voltage detection device 110 and calculates the time change rate dV _dc of the DC voltage V _dc . This time change rate dV _dc is calculated by, for example, (Equation 1).

V _dc [T]: Detected value of DC voltage V _dc at time T V _dc [T−ΔT]: Detected value of DC voltage V _dc before ΔT from time T Note that ΔT in (Equation 1) It can be set arbitrarily within the range not departing from the gist of the invention, and if ΔT is shortened, there is a concern that the influence of noise included in the detection system of the DC voltage V _dc will increase. In this case, the DC voltage V _dc Instead of using the detected value in (Equation 1) as it is, it is possible to eliminate the influence by performing noise reduction processing such as a low-pass filter.

When the time rate of change dV _{dc at} times T0 to _T1 is greater than a predetermined threshold value dV _{dcth in} the DC power transmission protection control device 107, the DC power transmission protection control device 107 _{notifies the} power generation system group control device 106 of an accident occurrence flag. The power command value PG1 _ref during the accident used when it is desired to match Flg with the input power PG1 and the output power PG2. Hereinafter, the description will be continued by taking as an example the case where the power command value PG1 _ref during the accident is set to 0.2 [au].

When the time change rate dV _dc (inclination of the DC voltage V _dc ) at the times T0 to T1 shown in FIG. _2C is larger than the threshold value dV _{dcth, the} accident occurrence flag Flg and the power command value PG1 are _output from the DC power transmission protection control device 107. _The power generation system group control device 106 that has received _ref (0.2 [au]) calculates the operation command value of each AC power generation system 101 based on the operation state of the AC power generation system 101 in the steady state, and generates each AC power generation. Send to system 101. Thereby, normally, since the input power PG1 which is the sum total of the power generation of each AC power generation system 101 and the output power PG2 match, it is possible to avoid the operation stop of the AC power generation system 101.

Regarding the calculation method of the operation command value, for example, the AC power generation system 101 is ranked in advance based on the magnitude of the generated power of each AC power generation system 101 before the accident, and the input power PG1 = power command value PG1 _ref. In order to satisfy the above, a method of creating an operation command value so as to decrease the generated power in descending order of the generated power can be considered. Regarding the control of the generated power of the AC power generation system 101, it is effective to perform the emergency disconnection in addition to continuously controlling the generated power.

In the present embodiment, the generated power of each AC power generation system 101 may be controlled by the power generation system group control device 106 so as to satisfy the input power PG1 = power command value PG1 _ref, and a specific operation command value is calculated. The method is not limited to the above method.
(Second protection control)
As described above, since the input power PG1 and the output power PG2 coincide with each other and the DC voltage V _dc is kept constant by performing the first protection control as described above, the operation of the DC power transmission system 100 is performed. Stopping is avoided, but under certain conditions, even if control based on the power command value PG1 _ref is performed, the input power PG1 and the output power PG2 do not match, and if left as it is, the DC voltage V _dc of the DC power transmission line 113 increases. In some cases, the DC power transmission system 100 may stop operating. In order to avoid this, in this embodiment, the second protection control is executed after the first protection control is executed under a certain condition. Hereinafter, the second protection control will be described in detail.

As illustrated at times T1 to T2 in FIG. 2B, when the input power PG1 and the output power PG2 are not equal even by the first protection control, the influence of the capacitance component included in the DC power transmission line 113 or the like. Thus, the increase of the DC voltage V _dc continues. In the case of FIG. 2B, since the output power PG2 = 0.0 [au] with respect to the input power PG1 = 0.2 [au], the DC voltage V _dc increases as shown in FIG. If this is left unattended, the operation of the DC power transmission system 100 will be stopped.

Therefore, after starting the first protection control, the DC voltage V _dc is monitored, and if this becomes larger than the predetermined threshold value V _dcth , the second protection control is started. In this embodiment, the threshold value V _dcth = 1.1 [au] is set in advance, and at time T2 when the DC voltage V _dc reaches 1.1 [au], the second protection control, that is, FIG. Control for increasing the AC voltage _Vac input to the AC / DC power converter 103 in accordance with the range of increase from the reference value of the DC voltage V _dc shown in d) is started.

Here, the operation characteristics of the AC / DC power converter 103 and the AC power generation system 101 will be described with reference to FIG. 3 is an operating characteristic diagram of the AC / DC power converter 103, where the vertical axis indicates the change width ΔV _ac from the reference operating point of the AC voltage V _ac and the horizontal axis indicates the reference operating point of the DC voltage V _dc. The change width ΔV _dc from 3 is an operation characteristic diagram of the AC power generation system 101. The vertical axis represents the change width ΔV _ac from the reference operating point of the AC voltage V _ac and the horizontal axis from the reference operating point of the output power PG. The change width ΔPG is taken. By providing the AC / DC power converter 103 and the AC power generation system 101 with the operation characteristics shown here, each device operates independently according to the determined operation characteristics during the second protection control. It becomes possible to do. In FIG. 3, the case where the AC voltage V _ac , the DC voltage V _dc , and the power PG are all 1.0 [au] is exemplified as the reference operating point. In addition, any reference operating point can be set.

As shown in FIG. 2 (c), when the DC voltage V _dc reaches 1.1 [au] at time T2, and then the DC voltage V _dc further increases, according to the operating characteristic diagram in the left diagram of FIG. AC / DC power converter 103 raises AC voltage V _ac by a predetermined amount.

This will be described with reference to the left diagram of FIG. 3. When the change width ΔV _dc rises by 0.1 [au] (when the DC voltage V _dc rises to 1.1 [au]), the AC / DC power converter 103 is 3, the change width ΔV _ac is increased by 0.1 [au] (the AC voltage V _ac is increased to 1.1 [au]), as indicated by the operating characteristics in the left diagram of FIG.

Further, as shown in FIG. 3 the right figure, the variation width [Delta] V _ac is 0.1 [au] increases, according to the operation characteristic diagram of each alternator system 101 of FIG. 3 the right figure, the power PG, each of which power 0 Decrease by 2 [au]. As each power PG decreases, the input power PG1, which is the sum of them, also decreases by a predetermined amount. Since this second protection control is repeated while the DC voltage V _dc exceeds 1.1 [au], the input power PG1 gradually decreases, the difference between the input power PG1 and the output power PG2 approaches 0, and finally The DC voltage V _dc is constant at the operation equilibrium point where the input power PG1 = the output power PG2.

As described above, when the input power PG1 and the output power PG2 do not match even by the first protection control, the DC voltage V _dc can be kept constant by performing the second protection control. The operation stop of the DC power generation system 101 can be avoided.

  The above is the operation continuation control in the first embodiment, and when the power transmission capability to the power system 105 is recovered, the first protection control and the second protection control are stopped and returned to the state before time T0. What is necessary is just to control each apparatus in the DC power transmission system 100. FIG.

In the first embodiment, as shown in FIG. 3, the operation characteristics of the AC power generation system 101 are determined based on the AC voltage V _ac of the AC bus 102 as the second protection control. Instead of _ac , the voltage may be determined based on the voltage at the connection point between the AC power generation system 101 and the AC power transmission line A111.

  In the first embodiment, the first protection control is performed and then the second protection control is performed. However, the first protection control and the second protection control are performed simultaneously. There may be. In this case, when calculating the operation command value of the AC power generation system 101 in the first protection control, the calculation is performed in consideration of the operation characteristic diagram of FIG. 3, so that the first protection control and the second protection control are performed. Interference can be avoided.

  Next, the DC power transmission system 200 according to the second embodiment will be described with reference to FIG. The DC power transmission system 200 of the present embodiment is configured by connecting the power absorbing device 401 to the AC bus 102 of the first embodiment, and the other configuration is the same as that in FIG.

In the first embodiment, the DC power transmission system 100 is continuously operated when the DC voltage V _dc is increased by reducing the generated power of the AC power generation system 101. However, in the second embodiment, the power absorption device 401 uses the AC power generation. The input power PG1 from the system 101 is absorbed, and the operation of the DC power transmission system 200 is continued when the DC voltage V _dc rises. Hereinafter, the details of the operation continuation control at the time when the DC voltage rises due to the reduction in the transmission capability to the power system 105 in the second embodiment will be described.

  In the first embodiment, the operation command value is sent from the power generation system group control device 106 to the AC power generation system 101 in the first protection control. However, in the second embodiment, the operation command value is transmitted to the AC power generation system 101. Instead, by transmitting the absorbed power command value to the power absorbing device 401 and controlling the amount of absorbed power in the power absorbing device 401, it is possible to obtain the same effect as the first protection control in the first embodiment.

  Moreover, about 2nd protection control, it is equivalent to 2nd protection control in Example 1 by giving the electric power absorption apparatus 401 the characteristic similar to the driving | operation characteristic of the right of FIG. An effect can be obtained.

  As described above, even when the power absorbing device 401 is provided as in the second embodiment, the same effects as those in the first embodiment can be obtained.

  In FIG. 4, the power absorption device 401 is connected to only one place of the AC bus 102, but is connected to each AC power generation system 101 in a distributed manner, and the power generation system group control device 106 connects a plurality of storage batteries. A form of centralized control may be used.

  Next, the DC power transmission system 300 according to the third embodiment will be described with reference to FIG. The DC power transmission system 300 of this embodiment is provided with a system protection control device 501 that integrates these functions in place of the power generation system group control device 106 and the DC power transmission protection control device 107 of the first embodiment. Since the configuration other than that is the same as that in FIG.

In the third embodiment, compared with the first embodiment, the response delay of the protection control can be further improved by reducing the communication delay between the power generation system group control device 106 and the DC power transmission protection control device 107. That is, in the first embodiment, in the first protection control, the accident occurrence flag Flg and the power command value PG1 _ref are transmitted from the DC power transmission protection control device 107, and the power generation system group control device 106 that receives them transmits the AC power generation system 101. In the third embodiment, calculation of the accident occurrence flag Flg and the power command value PG1 _ref and calculation of the operation command value of the power generation system 101 are performed in the system protection control device 501. The communication delay can be reduced, and the same effect as that of the first embodiment can be obtained more quickly.

In the third embodiment, as in FIG. 3 of the first embodiment, the operation characteristics of the AC power generation system 101 are determined based on the AC voltage _Vac of the AC bus 102 as the second protection control. Instead of _ac , the voltage may be determined based on the voltage at the connection point between the AC power generation system 101 and the AC power transmission line A111.

  Also, in the third embodiment, as in the first embodiment, the first protection control is performed and then the second protection control is performed. However, the first protection control and the second protection control are performed. May be performed simultaneously.

  In this case, when calculating the operation command value of the AC power generation system 101 in the first protection control, the calculation is performed in consideration of the operation characteristic diagram of FIG. 3, so that the first protection control and the second protection control are performed. Interference can be avoided.

  Also in the third embodiment, as in the second embodiment, the power absorbing device 401 may be connected to the AC bus 102 or the AC power generation system 101.

  Next, a DC power transmission system 400 according to the fourth embodiment will be described with reference to FIG.

  The direct-current power transmission system according to the first to third embodiments converts alternating-current power generated by the alternating-current power generation system 101 such as a wind power generation system into direct current using the AC / DC power conversion device 103, and transmits power again. The direct current power transmission system 400 of the fourth embodiment converts the direct current power from the direct current power generated by the direct current power generation system 601 such as a solar power generation system into the DC / DC. The voltage is boosted by a power conversion device 603 (DC-DC power conversion) and then transmitted, and the DC / AC power conversion device 104 is again converted from DC to AC and transmitted to the power system 105. It will be described that even when the first and second protection controls are applied to the DC power transmission system 400, the same effects as those of the first to third embodiments can be obtained.

  6 is a system conceptual diagram of the DC power transmission system 400 of the fourth embodiment. The AC power generation system 101 in FIG. 1 is replaced with the DC power generation system 601, the AC bus 102 is replaced with the DC bus 602, and the AC / DC power conversion apparatus 103 is replaced. Is replaced with the DC / DC power converter 603, the AC power transmission line A111 is replaced with the DC power transmission line A604, the AC voltage detection device 108 is replaced with the DC voltage detection device 605, and the AC power transmission line B112 is replaced with the DC power transmission line B606. It is.

In the first protection control of the first embodiment, the generated power of the AC power generation system 101 is controlled based on the time rate of change dV _dc of the DC power transmission line 113. However, even with the configuration of the present embodiment, an equivalent first 1 can prevent the DC power generation system 601 from being stopped. In the second protection control of the first embodiment, the generated power of the AC power generation system 101 is controlled based on the magnitude of the DC power V _dc , but even with the configuration of the present embodiment, an equivalent second The protection control of the DC power generation system 601 can be prevented from being stopped.

As for the second protection control, in FIG. 3 of the first embodiment, the generated power can be controlled based on the AC voltage V _ac of the AC bus 102 as a characteristic of the AC power generation system 101. 4, as the characteristics of the DC power generation system 601, the generated power can be controlled based on the DC voltage V _dc2 of the DC bus 602 instead of the AC voltage V _ac , so that the same effect as in the first embodiment can be obtained. Can be obtained.

  Therefore, also in the fourth embodiment, the same effect as in the first embodiment can be obtained by performing the same protection control as in the first embodiment.

In the fourth embodiment, the operating characteristic of the DC power generation system 601 is determined based on the DC voltage V _dc2 of the DC bus 602 as the second protection control in accordance with FIG. 3 of the first embodiment, but the DC voltage V _dc2 Instead of this, it may be determined based on the voltage at the connection point between the DC power generation system 601 and the DC power transmission line A604.

  In the fourth embodiment, as in the first embodiment, the first protection control is performed and then the second protection control is performed. However, the first protection control and the second protection control are performed. It is also possible to adopt a form in which the above is performed in an overlapping manner.

  In this case, when calculating the operation command value of the DC power generation system 601 in the first protection control, the calculation is performed in consideration of the operation characteristic diagram of FIG. 3, so that the first protection control and the second protection control are performed. Interference can be avoided.

  Further, in the fourth embodiment, similarly to the second embodiment, the power absorption device 401 may be connected to the DC bus 602 or the DC power generation system 601. Further, in the fourth embodiment, similarly to the third embodiment, the delay of the signal between the two is suppressed by using the system protection control device 501 in which the functions of the power generation system group control device 106 and the DC power transmission protection control device 107 are integrated. It is good also as composition to do.

100, 200, 300, 400 DC power transmission system 101 AC power generation system 102 AC bus 103 AC / DC power conversion device 104 DC / AC power conversion device 105 Power system 106 Power generation system group control device 107 DC power transmission protection control device 108 AC voltage detection Device 109 Power detection device 110 DC voltage detection device 111 AC transmission line A
112 AC transmission line B
113 DC transmission line 114 AC transmission line C
401 Power absorber 501 System protection controller 601 DC power generation system 602 DC bus 603 DC / DC power converter 604 DC transmission line A
605 DC voltage detector 606 DC transmission line B
Flg Accident occurrence flag V _ac AC voltage V _dc , V _dc2 DC voltage dV _dc Time rate of change dV _dcth threshold PG1 Input power PG1 _ref power command value PG2 Output power T0, T1, T2 Time

Claims (11)

A power generation system for generating electric power;
A first power conversion device that converts input power from the power generation system into DC power;
A DC / AC power converter for converting DC power input from the first power converter to AC power;
A direct current transmission line connecting the first power converter and the DC / AC power converter;
A DC voltage detecting device for detecting a DC voltage of the DC transmission line;
A control device for controlling the power generation system based on the output of the DC voltage detection device;
A direct current power transmission system comprising:
The control device executes the first protection control when the time rate of change of the DC voltage detected by the DC voltage detection device exceeds a first threshold,
The DC power transmission system, wherein the second protection control is executed when the DC voltage detected by the DC voltage detector exceeds a second threshold value. The DC power transmission system according to claim 1,
The power generation system is an AC power generation system,
The first power conversion device is an AC / DC power conversion device that converts AC power input from the AC power generation system into DC power,
The first protection control is control for suppressing AC power generated by the AC power generation system,
The DC power transmission system, wherein the second protection control is control for increasing an AC voltage generated by the AC power generation system. The DC power transmission system according to claim 1,
The power generation system is a direct current power generation system,
The first power conversion device is a DC / DC power conversion device that converts DC power input from the DC power generation system into DC power,
The first protection control is control for suppressing DC power generated by the DC power generation system,
The DC power transmission system according to claim 2, wherein the second protection control is control for increasing a DC voltage generated by the DC power generation system. The DC power transmission system according to any one of claims 1 to 3,
The controller is
A protection device that generates a power command value for controlling the output of the first power converter based on the DC voltage of the DC power transmission line;
A power generation system group control device that calculates an operation command value for controlling each of the plurality of power generation systems based on the power command value;
DC power transmission system characterized by comprising. In the DC power transmission system according to any one of claims 1 to 4,
The DC power transmission system, wherein the second protection control is started after the first protection control is started. In the DC power transmission system according to any one of claims 1 to 4,
The direct current power transmission system, wherein the first protection control and the second protection control are executed simultaneously. In the DC power transmission system according to claim 4,
The protection device detects a DC voltage on the output side of the first power converter, and determines a voltage command for the power generation system based on predetermined operating characteristics of the DC voltage and a power transmission end voltage. DC power transmission system characterized by In the DC power transmission system according to claim 4,
The power generation system controls the generated power of the power generation system based on a predetermined voltage on the input side of the first power converter and operating characteristics of the generated power. In the direct-current power transmission system according to any one of claims 1 to 8,
A DC power transmission system, wherein a power absorption device is connected to an input side of the first power conversion device. In the direct-current power transmission system according to any one of claims 1 to 8,
The direct-current power transmission system, wherein the first power converter or the DC / AC power converter is a self-excited power converter configured using a self-extinguishing element. A control device for controlling a power generation system used in a DC power transmission system,
The DC power transmission system includes:
A power generation system for generating electric power;
A first power conversion device that converts input power from the power generation system into DC power;
A DC / AC power converter for converting DC power input from the first power converter to AC power;
A direct current transmission line connecting the first power converter and the DC / AC power converter;
A DC voltage detecting device for detecting a DC voltage of the DC transmission line;
A control device for controlling the power generation system based on the output of the DC voltage detection device;
Consists of
When the time rate of change of the DC voltage detected by the DC voltage detection device exceeds the first threshold value, the first protection control is performed.
A control device that performs second protection control when a DC voltage detected by the DC voltage detection device exceeds a second threshold value.

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