Hydroelectric generating unit and flexible direct current system island starting method and device

Abstract

The application discloses a method and device for island startup of a hydroelectric generating set and a flexible direct current system, which responds to an input calling instruction, calls a black start service of the flexible direct current system, constructs an initial alternating current line voltage, calls a black start service of the hydroelectric generating set, constructs a terminal voltage of the hydroelectric generating set, calculates a synchronization closing difference value between the initial alternating current line voltage and the terminal voltage, sends a closing command to an alternating current circuit breaker if the synchronization closing difference value meets a synchronization operation condition, so that the hydroelectric generating set and the flexible direct current system are synchronously operated, and the output of the hydroelectric generating set is adjusted according to a preset gradient until the power of the hydroelectric generating set is increased to a preset threshold. In the case of not relying on an external alternating current power grid, the hydroelectric generating set and the flexible direct current system respectively take black start, an alternating current circuit breaker arranged on the hydroelectric generating set constructs an alternating current line connecting the hydroelectric generating set and the flexible direct current system, the hydroelectric generating set and the flexible direct current system are synchronously operated, and the impact in the synchronous operation process is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power transmission engineering, and in particular to a method and device for island startup of a hydroelectric generating set and a flexible direct current system. BACKGROUND

[0002] China will continue to promote the adjustment of industrial structure and energy structure, and vigorously develop clean energy. Clean hydropower will be transmitted to various load centers for consumption through long-distance large-capacity flexible direct current transmission technology.

[0003] Due to the fact that there is no load around some areas to consume large-scale hydropower, and the AC grid is weak, large-scale hydropower is usually transmitted in a point-to-point manner, and a pure hydropower island system is connected to a flexible direct current system, and energy is transmitted to the receiving end grid through a long-distance direct current line for consumption. Since the sending end converter station of the flexible direct current system has no AC grid to provide voltage support during the startup process, it brings challenges to the island startup of the pure hydropower island system connected to the flexible direct current system.

[0004] The existing large-scale hydropower transmission for consumption adopts a conventional direct current transmission system, but the conventional direct current does not have self-black-start capability and needs to rely on external AC grid for startup. The usual startup method is to switch from networking to islanding. In the networking mode, the hydropower generating set is first unlocked and operated to establish output by the sending end AC grid, and the conventional direct current is normally unlocked and operated. Then, the active power of the hydropower output and the conventional direct current is adjusted to reduce the power of the AC tie line, and finally the AC circuit breaker switch on the AC tie line is disconnected, switching the hydropower and the conventional direct current to island operation mode. The reason for adopting the island operation of the hydropower and the conventional direct current instead of always operating in the networking mode is that the sending end AC grid can provide startup support, but it is relatively weak overall. If the networking mode is adopted, when a large power is transferred to the sending end AC grid through the AC tie line, the sending end AC grid will be greatly impacted, thereby affecting the safe and stable operation of the sending end AC grid. SUMMARY

[0005] The present application provides a method and device for island startup of a hydropower generating set and a flexible direct current system, which fully utilizes the self-black-start capability of the flexible direct current and the hydropower generating set to solve the problem that the existing large-scale hydropower transmission through a conventional direct current needs to rely on an AC grid for startup.

[0006] The first aspect of the present application provides a method for island startup of a hydropower generating set and a flexible direct current system, the hydropower generating set being a pure island operation system, an AC circuit breaker being connected between the hydropower generating set and the flexible direct current system, and the method comprising:

[0007] in response to an input call instruction, calling a black-start service of the flexible direct current system to build an initial AC line voltage;

[0008] calling a black start service of the hydroelectric generating set to build a terminal voltage of the hydroelectric generating set;

[0009] calculating a synchronization closing difference between the initial AC line voltage and the terminal voltage of the hydroelectric generating set;

[0010] if the synchronization closing difference meets a synchronization operation condition, sending a closing command to the AC circuit breaker to make the hydroelectric generating set and the flexible system run synchronously;

[0011] adjusting an output of the hydroelectric generating set according to a preset gradient until the power of the hydroelectric generating set is raised to a preset threshold.

[0012] Optionally, the step of calling the black start service of the hydroelectric generating set to build the terminal voltage of the hydroelectric generating set comprises:

[0013] in response to an input calling instruction, calling a sending-end converter station in the flexible system to receive DC power transmitted by a receiving-end converter station, converting the DC power into AC power, and building an AC voltage on an AC side of the sending-end converter station;

[0014] real-time detecting an AC voltage and a first frequency corresponding to the AC side of the sending-end converter station, and controlling the AC voltage and the first frequency on the AC side of the sending-end converter station to be preset AC voltage reference values and first frequency reference values;

[0015] connecting the flexible system and the AC line through the AC circuit breaker to build an initial AC line voltage.

[0016] Optionally, the step of calling the black start service of the hydroelectric generating set to build the terminal voltage of the hydroelectric generating set comprises:

[0017] in response to an input calling instruction, calling the black start service of the hydroelectric generating set to start the hydroelectric generating set in an idle running state;

[0018] real-time detecting a terminal voltage and a second frequency corresponding to the hydroelectric generating set, and controlling the terminal voltage and the second frequency of the hydroelectric generating set to be preset terminal voltage reference values and second frequency reference values;

[0019] building the terminal voltage of the hydroelectric generating set.

[0020] Optionally, the synchronization closing difference comprises a phase angle difference, a frequency difference, and an amplitude difference, and the step of if the synchronization closing difference meets a synchronization operation condition, sending a closing command to the AC circuit breaker to make the hydroelectric generating set and the flexible system run synchronously comprises:

[0021] compare the phase angle difference value, the frequency difference value and the amplitude difference value with preset setting values;

[0022] if the phase angle difference value, the frequency difference value and the amplitude difference value are all less than the preset setting values, it is determined that the synchronization operation condition is met;

[0023] send a closing command to the AC circuit breaker, so that the hydroelectric generating set and the flexible system are synchronously operated.

[0024] Optionally, the method further comprises:

[0025] if the synchronization closing difference value does not meet the synchronization operation condition, adjusting the voltage reference value and the frequency reference value corresponding to the hydroelectric generating set and the flexible system respectively in response to an input reference value adjustment instruction;

[0026] jump to execute the step of calculating the synchronization closing difference value between the initial AC line voltage and the machine terminal voltage.

[0027] The second aspect of the present application provides a hydroelectric generating set and flexible system island startup device, the hydroelectric generating set is a pure island operation system, the hydroelectric generating set and the flexible system are connected with an AC circuit breaker, and the device comprises:

[0028] an initial AC line voltage construction module, configured to call the black start service of the flexible system in response to an input call instruction, and construct an initial AC line voltage;

[0029] a hydroelectric generating set machine terminal voltage construction module, configured to call the black start service of the hydroelectric generating set, and construct a machine terminal voltage of the hydroelectric generating set;

[0030] a synchronization closing difference value calculation module, configured to calculate a synchronization closing difference value between the initial AC line voltage and the machine terminal voltage;

[0031] a first information processing module, configured to send a closing command to the AC circuit breaker so that the hydroelectric generating set and the flexible system are synchronously operated if the synchronization closing difference value meets a synchronization operation condition;

[0032] a power adjustment module, configured to adjust the output of the hydroelectric generating set according to a preset gradient until the power of the hydroelectric generating set is increased to a preset threshold.

[0033] Optionally, the initial AC line voltage construction module comprises:

[0034] a first call sub-module, configured to call the sending end converter station in the flexible system to receive the DC power transmitted by the receiving end converter station in response to an input call instruction, convert the DC power into AC power, and construct the AC voltage on the AC side of the sending end converter station;

[0035] The first control submodule is configured to detect the AC voltage and the first frequency corresponding to the AC side of the sending end converter station in real time, and control the AC voltage and the first frequency of the AC side of the sending end converter station to be preset AC voltage reference value and first frequency reference value.

[0036] The first construction submodule is configured to electrically connect the HVDC system and the AC line through the AC circuit breaker to be closed, and construct an initial AC line voltage.

[0037] Optionally, the hydropower unit terminal voltage construction module comprises:

[0038] The second calling submodule is configured to call the black start service of the hydropower unit in response to an input calling instruction, and start the hydropower unit in an idle load state.

[0039] The second control submodule is configured to detect the terminal voltage and the second frequency corresponding to the hydropower unit in real time, and control the terminal voltage and the second frequency of the hydropower unit to be preset terminal voltage reference value and second frequency reference value.

[0040] The second construction submodule is configured to construct the terminal voltage of the hydropower unit.

[0041] Optionally, the synchronization closing difference value comprises a phase angle difference value, a frequency difference value and an amplitude difference value, and the first information processing module comprises:

[0042] The comparison submodule is configured to compare the phase angle difference value, the frequency difference value and the amplitude difference value with a preset setting value.

[0043] The judgment submodule is configured to determine that the synchronization operation condition is met if the phase angle difference value, the frequency difference value and the amplitude difference value are all less than the preset setting value.

[0044] The execution submodule is configured to send a closing command to the AC circuit breaker, so that the hydropower unit and the HVDC system are synchronously operated.

[0045] Optionally, the device further comprises:

[0046] The second information processing module is configured to adjust the voltage reference value and the frequency reference value corresponding to the hydropower unit and the HVDC system, respectively, in response to an input reference value adjustment instruction if the synchronization closing difference value does not meet the synchronization operation condition.

[0047] The jump module is configured to jump to execute the step of calculating the synchronization closing difference value between the initial AC line voltage and the terminal voltage.

[0048] From the above technical solutions, the present application has the following advantages:

[0049] The application, when responding to the input call instruction, constructs an initial AC line voltage by calling the black start service of the flexible system, constructs a machine terminal voltage on the machine terminal side of the hydroelectric generating set by calling the black start service of the hydroelectric generating set when responding to the input call instruction, calculates the phase angle difference, frequency difference and amplitude difference between the two sides of the voltage by obtaining the initial AC line voltage and the machine terminal voltage, sends a closing command to the AC circuit breaker if the synchronization closing difference meets the synchronization operation condition, that is, the synchronization closing difference meets the preset setting value of the synchronization operation, so that the hydroelectric generating set and the flexible system are synchronized to run, the output of the hydroelectric generating set is adjusted according to the preset gradient, the preset gradient is set according to the needs of people, and the power of the AC interconnection line is increased to the preset threshold value, and the output of the hydroelectric generating set is adjusted; thereby solving the technical problem of relying on the AC power grid in the starting process when large-scale hydropower is sent for consumption; therefore, the application fully utilizes the self-black start capability of the flexible and hydroelectric generating set, constructs the AC line connecting the hydroelectric generating set and the flexible system by setting the AC circuit breaker of the hydroelectric generating set, realizes the synchronous operation of the hydroelectric generating set and the flexible system, and reduces the impact in the synchronous operation process. BRIEF DESCRIPTION OF DRAWINGS

[0050] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor.

[0051] Figure 1 A step flow chart of a hydroelectric generating set and flexible system island start method provided for the first embodiment of the present application;

[0052] Figure 2 A step flow chart of a hydroelectric generating set and flexible system island start method provided for the second embodiment of the present application;

[0053] Figure 3 A schematic diagram of a hydroelectric power station and a flexible system provided for the embodiment of the present application;

[0054] Figure 4 A structural block diagram of a hydroelectric generating set and flexible system island start device provided for the third embodiment of the present application. DETAILED DESCRIPTION

[0055] The embodiment of the present application provides a method and device for island startup of a hydroelectric generating set and a flexible direct current system, fully utilizes the self-black-start capability of the flexible direct current and the hydroelectric generating set, and is used for solving the problem that a large-scale hydroelectric power needs to be started by relying on an alternating current power grid in advance when being transmitted through a conventional direct current.

[0056] In order to make the invention purposes, features and advantages of the present application more obvious and easy to understand, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the following described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0057] Please refer to Figure 1 , Figure 1 A step flow chart of a method for island startup of a hydroelectric generating set and a flexible direct current system is provided for the first embodiment of the present application.

[0058] The present application provides a method for island startup of a hydroelectric generating set and a flexible direct current system, the hydroelectric generating set is a pure island operation system, an alternating current circuit breaker is connected between the hydroelectric generating set and the flexible direct current system, and the method comprises the following steps.

[0059] Step 101, in response to an input calling instruction, a black start service of the flexible direct current system is called to construct an initial alternating current line voltage.

[0060] The calling instruction is an instruction for calling the black start service of the flexible direct current system and the hydroelectric generating set.

[0061] The black start service refers to that after a system is shut down due to a fault, the system is completely powered off and is in a full "black" state, does not rely on help from other networks, and is started by a generator set with a self-starting capability to drive a generator set without a self-starting capability, gradually expands the system recovery range, and finally realizes the recovery of the whole system.

[0062] In the embodiment of the present application, when responding to the input calling instruction, the black start service of the flexible direct current system is called to construct the initial alternating current line voltage.

[0063] Step 102, a black start service of the hydroelectric generating set is called to construct a generator terminal voltage of the hydroelectric generating set.

[0064] In the embodiment of the present application, when responding to the input calling instruction, the black start service of the hydroelectric generating set is called to construct the generator terminal voltage on the generator terminal side of the hydroelectric generating set.

[0065] Step 103, a synchronization closing difference between the initial alternating current line voltage and the generator terminal voltage is calculated.

[0066] The synchronization closing difference value refers to the phase angle difference value, the frequency difference value and the amplitude difference value between the initial AC line voltage and the generator terminal voltage, and is a judgment condition for judging whether to perform synchronization operation.

[0067] In the embodiment of the present application, the phase angle difference value, the frequency difference value and the amplitude difference value between the two sides of the voltage are calculated by acquiring the initial AC line voltage and the generator terminal voltage.

[0068] If the synchronization closing difference value meets the synchronization operation condition, a closing command is sent to the AC circuit breaker to make the hydroelectric generating set and the flexible system run synchronously.

[0069] The synchronization operation condition refers to the satisfaction condition for judging whether to perform synchronization operation, and is a preset setting value for synchronization operation.

[0070] The AC circuit breaker is arranged in the hydropower station, and the AC circuit breaker is connected between the hydroelectric generating set and the flexible system to detect the synchronization closing difference value between the initial AC line voltage and the generator terminal voltage, that is, to detect the synchronization closing difference value of the voltage on both sides of the AC circuit breaker.

[0071] In the embodiment of the present application, if the synchronization closing difference value meets the synchronization operation condition, that is, the synchronization closing difference value meets the preset setting value for synchronization operation, a closing command is sent to the AC circuit breaker, the AC circuit breaker receives the closing command to close, so that the hydroelectric generating set and the flexible system run synchronously.

[0072] Step 105: The output of the hydroelectric generating set is adjusted according to a preset gradient until the power of the hydroelectric generating set is increased to a preset threshold value.

[0073] The output of the hydroelectric generating set refers to the energy output by the hydropower station in a unit of time, also known as the output power of the hydropower station.

[0074] In the embodiment of the present application, the output of the hydroelectric generating set is adjusted according to a preset gradient, the preset gradient is set according to the needs of people, and the power of the AC interconnection line is increased to a preset threshold value, and then the output of the hydroelectric generating set is adjusted.

[0075] In the embodiment, the application, in response to the input call instruction, calls the black start service of the flexible system to build the initial AC line voltage, in response to the input call instruction, calls the black start service of the hydroelectric generator set to build the terminal voltage at the terminal side of the hydroelectric generator set, obtains the initial AC line voltage and the terminal voltage, calculates the phase angle difference, the frequency difference and the amplitude difference between the two sides, if the synchronization closing difference meets the synchronization operation condition, that is, the synchronization closing difference meets the preset setting value of the synchronization operation, sends the closing command to the AC circuit breaker, the AC circuit breaker receives the closing command to close, so that the hydroelectric generator set and the flexible system run synchronously, adjusts the output of the hydroelectric generator set according to the preset gradient, the preset gradient is set according to the demand of people, until the power of the AC interconnection line is increased to the preset threshold, the output of the hydroelectric generator set is adjusted; Thus, the technical problem of relying on the AC power grid in the starting process when large-scale hydropower is sent out for consumption is solved; Therefore, the application fully utilizes the self-black start capability of the flexible and hydroelectric generator set, builds the AC line connecting the hydroelectric generator set and the flexible system through the AC circuit breaker arranged in the hydroelectric generator set, realizes the synchronous operation of the hydroelectric generator set and the flexible system, and reduces the impact in the synchronous operation process.

[0076] Please refer to Figure 2 , Figure 2 The application provides a water and electricity generator set and a flexible system island starting method.

[0077] The application provides a water and electricity generator set and a flexible system island starting method, the water and electricity generator set is a pure island operation system, an AC circuit breaker is connected between the water and electricity generator set and the flexible system, and the method comprises the following steps.

[0078] Step 201, in response to the input call instruction, calling the black start service of the flexible system to build the initial AC line voltage.

[0079] Further, step 201 can comprise the following sub-steps S11-S13:

[0080] Step S11, in response to the input call instruction, calling the sending end converter station in the flexible system to receive the direct current transmitted by the receiving end converter station, converting the direct current into alternating current, and building the alternating voltage of the alternating side of the sending end converter station.

[0081] The flexible system has the characteristics of bidirectional power transmission, in the starting process of calling the black start service, the power is sent back to the passive sending end converter station in the flexible system through the active receiving end AC power grid, the alternating voltage of the alternating side of the sending end converter station is built through the AC power grid, and the connection with the AC power grid is realized.

[0082] In the embodiment of the present application, in response to the input call instruction, the black start service of the flexible HVDC system is called, and in the process of starting, the active receiving converter station transmits DC power to the sending converter station in the flexible HVDC system, and converts the DC power into AC power to build AC voltage on the AC side of the sending converter station.

[0083] In step S12, the AC voltage and the first frequency corresponding to the AC side of the sending converter station are detected in real time, and the AC voltage and the first frequency of the AC side of the sending converter station are controlled to be the preset AC voltage reference value and the first frequency reference value.

[0084] After the AC voltage built on the AC side of the sending converter station, the 500kv AC line can be started, and the AC voltage and the first frequency are built on the flexible HVDC system side of the AC circuit breaker.

[0085] In the embodiment of the present application, the AC voltage and the first frequency corresponding to the AC side of the sending converter station are detected in real time, and the AC voltage and the first frequency are adjusted according to the preset AC voltage reference value and the first frequency reference value.

[0086] In step S13, the flexible HVDC system is electrically connected with the AC line through the closing of the AC circuit breaker to build an initial AC line voltage.

[0087] In the embodiment of the present application, the flexible HVDC system is electrically connected with the AC line through the closing of the AC circuit breaker to build an initial AC line voltage.

[0088] In step 202, the black start service of the hydroelectric generating set is called to build the terminal voltage of the hydroelectric generating set.

[0089] Further, step 202 can include the following sub-steps S21-S23:

[0090] In step S21, in response to the input call instruction, the black start service of the hydroelectric generating set is called to start the hydroelectric generating set in the no-load operation state.

[0091] The generator with the self-starting function in the hydroelectric generating set has the black start capability, and if the station power is needed, it can be provided by the diesel generator or the flexible HVDC system.

[0092] In the embodiment of the present application, when the black start service of the hydroelectric generating set is called in response to the input call instruction, the generator with the self-starting function in the hydroelectric generating set starts to operate.

[0093] In step S22, the terminal voltage and the second frequency corresponding to the hydroelectric generating set are detected in real time, and the terminal voltage and the second frequency of the hydroelectric generating set are controlled to be the preset terminal voltage reference value and the second frequency reference value.

[0094] In the embodiment of the present application, the terminal voltage of the hydroelectric generating set and the second frequency are detected in real time, and the terminal voltage and the second frequency are adjusted according to the preset terminal voltage reference value and the second frequency reference value.

[0095] In step S23, the terminal voltage of the hydroelectric generating set is constructed.

[0096] In the embodiment of the present application, the terminal voltage of the hydroelectric generating set is constructed according to the adjusted terminal voltage and the second frequency.

[0097] In step 203, the synchronization closing difference between the initial AC line voltage and the terminal voltage is calculated.

[0098] In the embodiment of the present application, the specific implementation process of step 203 is similar to that of step 103, which will not be described here.

[0099] In step 204, if the synchronization closing difference meets the synchronization operation condition, a closing command is sent to the AC circuit breaker to make the hydroelectric generating set and the flexible system run synchronously.

[0100] Further, the synchronization closing difference includes the phase angle difference, the frequency difference and the amplitude difference, and step 204 can include the following sub-steps S31-S33:

[0101] In step S31, the phase angle difference, the frequency difference and the amplitude difference are compared with the preset setting value.

[0102] The preset setting value refers to a value set in the hydroelectric generating set, and when the value is reached, a certain action will occur.

[0103] In the embodiment of the present application, the phase angle difference, the frequency difference and the amplitude difference are compared with the preset setting value, and in the embodiment, the preset setting value is 1% of the rated value.

[0104] Synchronization operation refers to putting the generator into parallel operation of the power system, which needs a series of operations, called parallel operation or synchronization operation. The running state of the generator is called synchronous operation.

[0105] In order to reduce the impact in the process of synchronous operation of the engine, therefore, in the embodiment, the preset setting value can be 1% of the rated value.

[0106] In step S32, if the phase angle difference, the frequency difference and the amplitude difference are all less than the preset setting value, it is determined that the synchronization operation condition is met.

[0107] In the embodiment of the present application, the phase angle difference, the frequency difference and the amplitude difference are obtained, and when the above differences are all less than the preset setting value, the synchronization operation condition is met, and the synchronization operation is performed.

[0108] In step S33, a closing command is sent to the AC circuit breaker to make the hydroelectric generating set and the flexible system run synchronously.

[0109] By adopting the closing AC circuit breaker in the synchronous operation mode, the hydroelectric generating set and the flexible system are enabled to realize synchronous operation.

[0110] In the embodiment of the present application, when the AC circuit breaker receives the closing command, the AC circuit breaker is closed to enable the hydroelectric generating set and the flexible system to realize synchronous operation and complete the synchronous operation.

[0111] Step 205: The output of the hydroelectric generating set is adjusted according to the preset gradient until the power of the hydroelectric generating set is increased to the preset threshold.

[0112] In the embodiment of the present application, the specific implementation process of step 205 is similar to that of step 105, which is not described herein again.

[0113] In another example of the present application, the output of the hydroelectric generating set can also be adjusted according to the real-time output information of the hydroelectric generating set and the preset gradient. In the embodiment, the hydroelectric generating set is adjusted, that is, the gradient method is used to adjust the hydroelectric generating set, so that the power of the hydroelectric generating set through the AC tie line is increased to the preset threshold.

[0114] In another example of the present application, the difference between the real-time power of the hydroelectric generating set through the AC line and the preset threshold can also be calculated according to the real-time output information of the hydroelectric generating set, and the output of the hydroelectric generating set is directly adjusted according to the difference result.

[0115] Further, the method further comprises:

[0116] Step 206: If the synchronous closing difference does not satisfy the synchronous operation condition, the voltage reference value and the frequency reference value corresponding to the hydroelectric generating set and the flexible system are adjusted in response to the input reference value adjustment instruction.

[0117] In the embodiment of the present application, the phase angle difference, the frequency difference and the amplitude difference are obtained, and when any of the above differences is not less than the preset setting value, the synchronous operation condition is not satisfied, and the voltage reference value and the frequency reference value corresponding to the hydroelectric generating set and the flexible system are adjusted in response to the input reference value adjustment instruction, that is, the AC voltage and the first frequency of the hydroelectric generating set and the generator terminal voltage and the second frequency of the flexible system are synchronously adjusted.

[0118] In the embodiment of the present application, the phase angle difference, the frequency difference and the amplitude difference are obtained, and when any of the above differences is not less than the preset setting value, the synchronous operation condition is not satisfied, and the voltage reference value and the frequency reference value corresponding to the hydroelectric generating set and the flexible system are adjusted in response to the input reference value adjustment instruction.

[0119] Step 207: The step of calculating the synchronous closing difference between the initial AC line voltage and the generator terminal voltage is executed.

[0120] In the embodiment of the present application, after the AC voltage and the first frequency of the hydroelectric generating set and the machine terminal voltage and the second frequency of the flexible direct current system are adjusted, the difference between the initial AC line voltage and the machine terminal voltage is calculated again, and then it is judged whether the synchronization closing difference meets the synchronization operation condition, and if not, the adjustment is performed again until the synchronization operation condition is met.

[0121] As shown in Figure 3 , the hydropower station comprises a hydroelectric generating set and an AC circuit breaker, the hydroelectric generating set further comprises a booster transformer, the flexible direct current system comprises a sending end converter station, and the sending end converter station further comprises a booster transformer; the hydroelectric generating set in the hydropower station is connected with the sending end converter station in the flexible direct current system through the AC circuit breaker, and when the AC circuit breaker is closed, an AC line is built between the hydroelectric generating set and the sending end converter station, and the hydroelectric generating set and the flexible direct current system are realized to be synchronously operated.

[0122] In the embodiment of the present application, when the calling instruction is input, the initial AC line voltage is built by calling the black start service of the flexible direct current system, when the calling instruction is input, the machine terminal voltage is built at the machine terminal side of the hydroelectric generating set by calling the black start service of the hydroelectric generating set, the phase angle difference, the frequency difference and the amplitude difference between the two sides are calculated by acquiring the initial AC line voltage and the machine terminal voltage, if the synchronization closing difference meets the synchronization operation condition, that is, the synchronization closing difference meets the preset setting value of the synchronization operation, the closing command is sent to the AC circuit breaker, the AC circuit breaker receives the closing command to close, so that the hydroelectric generating set and the flexible direct current system are synchronously operated, the output of the hydroelectric generating set is adjusted according to the preset gradient, the preset gradient is set according to the demand of people, and the output of the hydroelectric generating set is adjusted until the power of the AC line is increased to the preset threshold value, and the adjustment of the output of the hydroelectric generating set is completed; thereby the technical problem that in the starting process, the large-scale hydropower is sent out for consumption and relies on the AC power grid is solved; therefore, without relying on the external AC power grid, the self-black start capability of the flexible direct current and the hydroelectric generating set is fully utilized, the AC line connecting the hydroelectric generating set and the flexible direct current system is built through the AC circuit breaker arranged in the hydroelectric generating set, the hydroelectric generating set and the flexible direct current system are realized to be synchronously operated, and the impact in the synchronous operation process is reduced.

[0123] Please refer to Figure 4 , Figure 4 , a structural block diagram of a hydroelectric generating set and a flexible direct current system island starting device provided in the third embodiment of the present application.

[0124] The embodiment of the present application provides a hydroelectric generating set and a flexible direct current system island starting device, the hydroelectric generating set is a pure island operation system, an AC circuit breaker is connected between the hydroelectric generating set and the flexible direct current system, and the device comprises:

[0125] An initial AC line voltage construction module 301 is configured to invoke a black start service of the HVDC system to construct an initial AC line voltage in response to an input invocation instruction.

[0126] A hydro-generator terminal voltage construction module 302 is configured to invoke a black start service of the hydro-generator to construct a terminal voltage of the hydro-generator.

[0127] A synchronization closing difference calculation module 303 is configured to calculate a synchronization closing difference between the initial AC line voltage and the terminal voltage.

[0128] A first information processing module 304 is configured to send a closing command to the AC circuit breaker to synchronize the hydro-generator with the HVDC system for operation if the synchronization closing difference satisfies a synchronization operation condition.

[0129] A power adjustment module 305 is configured to adjust an output of the hydro-generator according to a preset gradient until the power of the hydro-generator is increased to a preset threshold.

[0130] Further, the initial AC line voltage construction module 301 comprises:

[0131] A first invocation submodule is configured to invoke a sending converter station in the HVDC system to receive DC power transmitted by a receiving converter station, convert the DC power into AC power, and construct an AC voltage on an AC side of the sending converter station in response to an input invocation instruction.

[0132] A first control submodule is configured to detect the AC voltage and a first frequency corresponding to the AC side of the sending converter station in real time, and control the AC voltage and the first frequency on the AC side of the sending converter station to be preset AC voltage reference values and first frequency reference values.

[0133] A first construction submodule is configured to connect the HVDC system and the AC line through the AC circuit breaker to construct the initial AC line voltage.

[0134] Further, the hydro-generator terminal voltage construction module 302 comprises:

[0135] A second invocation submodule is configured to invoke a black start service of the hydro-generator to start the hydro-generator in an idle state in response to an input invocation instruction.

[0136] A second control submodule is configured to detect a terminal voltage and a second frequency corresponding to the hydro-generator in real time, and control the terminal voltage and the second frequency of the hydro-generator to be preset terminal voltage reference values and second frequency reference values.

[0137] A second construction submodule is configured to construct the terminal voltage of the hydro-generator.

[0138] Further, the synchronization closing difference includes a phase angle difference, a frequency difference and an amplitude difference, and the first information processing module 304 includes:

[0139] a comparison submodule, configured to compare the phase angle difference, the frequency difference and the amplitude difference with preset setting values.

[0140] a judgment submodule, configured to determine that the synchronization operation condition is met if the phase angle difference, the frequency difference and the amplitude difference are all less than the preset setting values.

[0141] an execution submodule, configured to send a closing command to the AC circuit breaker to enable the hydroelectric generating set and the flexible system to run synchronously.

[0142] Further, the device further includes:

[0143] a second information processing module, configured to adjust voltage reference values and frequency reference values corresponding to the hydroelectric generating set and the flexible system respectively in response to an input reference value adjustment instruction if the synchronization closing difference does not meet the synchronization operation condition.

[0144] a jump module, configured to jump to a step of calculating a synchronization closing difference between an initial AC line voltage and a machine terminal voltage.

[0145] In the embodiments, when the black start service of the flexible system is called in response to an input call instruction, the initial AC line voltage is constructed, when the black start service of the hydroelectric generating set is called in response to an input call instruction, the machine terminal voltage is constructed at the machine terminal side of the hydroelectric generating set, the phase angle difference, the frequency difference and the amplitude difference between the two sides of the voltage are calculated by acquiring the initial AC line voltage and the machine terminal voltage, if the synchronization closing difference meets the synchronization operation condition, that is, the synchronization closing difference meets the preset setting value of the synchronization operation, a closing command is sent to the AC circuit breaker, the AC circuit breaker receives the closing command to close, so that the hydroelectric generating set and the flexible system run synchronously, the output of the hydroelectric generating set is adjusted according to a preset gradient, the preset gradient is set according to the needs of people, and the power of the AC interconnection line is increased to a preset threshold value, and the output of the hydroelectric generating set is adjusted; thereby solving the technical problem that the starting process depends on the AC power grid when large-scale hydroelectric power is sent for consumption; therefore, without relying on external AC power grids, the self-black start capability of the flexible and hydroelectric generating set is fully utilized, the AC circuit breaker provided on the hydroelectric generating set is used to construct the AC line connecting the hydroelectric generating set and the flexible system, the hydroelectric generating set and the flexible system run synchronously, and the impact in the synchronous running process is reduced.

[0146] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described system, device and unit can refer to the corresponding processes in the foregoing method embodiments, which will not be described herein.

[0147] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other manners. For example, the division of the above-described device embodiments is only a logical function division, and there can be another division manner for actual implementation, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual couplings or direct couplings or communication connections between different units, or the among different units, can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0148] The units described as separated components can or can not be physically separated, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purposes of the embodiments of the present application.

[0149] In addition, each functional unit in the various embodiments of the present application can be integrated in one processing unit, or each unit can exist physically as a separate unit, or two or more units can be integrated in one unit. The integrated unit can be implemented in the form of hardware, or in the form of a software functional unit.

[0150] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for islanded start-up of a hydroelectric generating unit with a flexible direct current system, the method comprising: starting the hydroelectric generating unit; and starting the flexible direct current system after the hydroelectric generating unit has started. The water turbine generator is a pure island operation system, an alternating current circuit breaker is connected between the water turbine generator and the flexible direct current system, and the method comprises: In response to an input call instruction, a black start service of the flexible direct current system is called to build an initial alternating current line voltage; A black start service of the water turbine generator is called to build a terminal voltage of the water turbine generator; A synchronization closing difference value between the initial alternating current line voltage and the terminal voltage of the water turbine generator is calculated; If the synchronization closing difference value meets a synchronization operation condition, a closing command is sent to the alternating current circuit breaker to make the water turbine generator and the flexible direct current system run synchronously; The output of the water turbine generator is adjusted according to a preset gradient until the power of the water turbine generator is increased to a preset threshold value; The method further comprises: If the synchronization closing difference value does not meet the synchronization operation condition, in response to an input reference value adjustment instruction, voltage reference values and frequency reference values corresponding to the water turbine generator and the flexible direct current system are adjusted respectively; The step of calculating the synchronization closing difference value between the initial alternating current line voltage and the terminal voltage of the water turbine generator is jumped to execute.

2. The method of claim 1, wherein the method further comprises: The step of calling the black start service of the flexible direct current system to build the initial alternating current line voltage in response to the input call instruction comprises: In response to an input call instruction, a sending end converter station in the flexible direct current system receives direct current transmitted by a receiving end converter station to convert the direct current into alternating current to build an alternating current voltage on an alternating current side of the sending end converter station; The alternating current voltage and a first frequency corresponding to the alternating current side of the sending end converter station are detected in real time, and the alternating current voltage and the first frequency of the alternating current side of the sending end converter station are controlled to be preset alternating current voltage reference values and first frequency reference values; The flexible direct current system and the alternating current line are electrically connected by closing the alternating current circuit breaker to build the initial alternating current line voltage.

3. The method of claim 1, wherein the method further comprises: The step of calling the black start service of the water turbine generator to build the terminal voltage of the water turbine generator comprises: In response to an input call instruction, a black start service of the water turbine generator is called to start the water turbine generator in an idle running state; The terminal voltage and a second frequency corresponding to the water turbine generator are detected in real time, and the terminal voltage and the second frequency of the water turbine generator are controlled to be preset terminal voltage reference values and second frequency reference values; The terminal voltage of the water turbine generator is built.

4. The method of claim 1, wherein, The synchronization closing difference value comprises a phase angle difference value, a frequency difference value and an amplitude difference value, and the step of sending a closing command to the alternating current circuit breaker to make the water turbine generator and the flexible direct current system run synchronously if the synchronization closing difference value meets a synchronization operation condition comprises: The phase angle difference value, the frequency difference value and the amplitude difference value are compared with preset setting values; If the phase angle difference value, the frequency difference value and the amplitude difference value are all less than the preset setting values, it is determined that the synchronization operation condition is met; The closing command is sent to the alternating current circuit breaker to make the water turbine generator and the flexible direct current system run synchronously.

5. A hydroelectric generating unit and flexible direct system islanding start-up apparatus, characterized by, The water turbine generator is a pure island operation system, an alternating current circuit breaker is connected between the water turbine generator and the flexible direct current system, and the device comprises: An initial AC line voltage construction module is configured to invoke a black start service of the HVDC system to construct an initial AC line voltage in response to an input invocation instruction; A hydroelectric generator set terminal voltage construction module is configured to invoke a black start service of the hydroelectric generator set to construct a terminal voltage of the hydroelectric generator set; A synchronous closing difference calculation module is configured to calculate a synchronous closing difference between the initial AC line voltage and the terminal voltage of the hydroelectric generator set; A first information processing module is configured to send a closing command to the AC circuit breaker to synchronize the hydroelectric generator set and the HVDC system for operation if the synchronous closing difference satisfies a synchronous operation condition; A power adjustment module is configured to adjust an output of the hydroelectric generator set according to a preset gradient until the power of the hydroelectric generator set is increased to a preset threshold value; The device further comprises: A second information processing module is configured to adjust voltage reference values and frequency reference values corresponding to the hydroelectric generator set and the HVDC system, respectively, in response to an input reference value adjustment instruction if the synchronous closing difference does not satisfy the synchronous operation condition; A jump module is configured to jump to execute the step of calculating the synchronous closing difference between the initial AC line voltage and the terminal voltage of the hydroelectric generator set.

6. The hydroelectric generating unit and HVDC system islanding start-up apparatus according to claim 5, characterized in that, The initial AC line voltage construction module comprises: A first invocation submodule is configured to invoke a sending-end converter station in the HVDC system to receive DC power transmitted by a receiving-end converter station, convert the DC power into AC power, and construct an AC voltage on an AC side of the sending-end converter station in response to an input invocation instruction; A first control submodule is configured to detect an AC voltage and a first frequency corresponding to the AC side of the sending-end converter station in real time, and control the AC voltage and the first frequency on the AC side of the sending-end converter station to be preset AC voltage reference values and first frequency reference values; A first construction submodule is configured to electrically connect the HVDC system and an AC line through an AC circuit breaker to construct an initial AC line voltage.

7. The hydroelectric generating unit and HVDC system islanding start-up apparatus according to claim 5, characterized in that, The hydroelectric generator set terminal voltage construction module comprises: A second invocation submodule is configured to invoke a black start service of the hydroelectric generator set to start the hydroelectric generator set in an idle state in response to an input invocation instruction; A second control submodule is configured to detect a terminal voltage and a second frequency corresponding to the hydroelectric generator set in real time, and control the terminal voltage and the second frequency of the hydroelectric generator set to be preset terminal voltage reference values and second frequency reference values; A second construction submodule is configured to construct a terminal voltage of the hydroelectric generator set.

8. The hydroelectric generating unit and HVDC system islanding start-up apparatus according to claim 5, characterized in that, The synchronous closing difference comprises a phase angle difference, a frequency difference, and an amplitude difference, and the first information processing module comprises: A comparison submodule is configured to compare the phase angle difference, the frequency difference, and the amplitude difference with preset setting values; A judgment submodule is configured to determine that a synchronous operation condition is satisfied if the phase angle difference, the frequency difference, and the amplitude difference are all less than the preset setting values; An execution submodule is configured to send a closing command to the AC circuit breaker to synchronize the hydroelectric generator set and the HVDC system for operation.

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