New energy power generation transmission system and control method based on high voltage direct current series tapping

Abstract

The present disclosure relates to the technical field of renewable energy power generation and direct current transmission, and in particular to a renewable energy power generation and transmission system and control method based on high-voltage direct current series tapping. The system comprises: a thyristor rectifier converts the sending-end alternating current power inputted from the sending-end alternating current grid into a first direct current power, and inputs the first direct current power into a thyristor inverter; a series tapping hybrid converter converts the alternating current power inputted from the wind power generation and photovoltaic power generation field into a second direct current power, and inputs the second direct current power into a thyristor inverter, wherein the series tapping hybrid converter is a DC voltage variable modular multi-level converter; a thyristor inverter converts the third direct current power into the receiving-end alternating current power, and inputs the receiving-end alternating current power into the receiving-end alternating current grid, wherein the third direct current power is the sum of the first direct current power and the second direct current power. The present disclosure can economically, efficiently and reliably transmit the power of wind power generation and photovoltaic power generation field to the load center over long distances.

Description

Technical Field

[0001] The present disclosure relates to the technical field of renewable energy power generation and direct current transmission, and in particular to a renewable energy power generation and transmission system based on high voltage direct current series tapping and a control method. Background Art

[0002] Wind power generation and photovoltaic power generation are widely used new energy power generation forms with large-scale development prospects. In related technologies, wind power and photovoltaic power generation bases are mainly located in deserts, Gobi and wasteland areas, far away from load centers. Therefore, how to economically, efficiently and reliably transport the electricity from wind power and photovoltaic power generation bases to load centers over long distances has become a focus of attention. Summary of the invention

[0003] The present disclosure provides a new energy power generation and transmission system based on high-voltage direct current series tapping and a control method, the main purpose of which is to economically, efficiently and reliably transmit the power of wind power and photovoltaic power generation bases to load centers over long distances. The technical solution of the present disclosure is as follows:

[0004] According to a first aspect of an embodiment of the present disclosure, a new energy power generation and transmission system based on high-voltage direct current series tapping is provided, characterized in that it comprises: a thyristor rectifier, a thyristor inverter, a series tapping hybrid converter, a first high-voltage direct current transmission line, a second high-voltage direct current transmission line and a third high-voltage direct current transmission line; the DC positive end of the thyristor rectifier is connected to the DC negative end of the series tapping hybrid converter through the first high-voltage direct current transmission line, the DC positive end of the series tapping hybrid converter is connected to the DC positive end of the thyristor inverter through the second high-voltage direct current transmission line, and the DC negative end of the thyristor rectifier is connected to the DC negative end of the thyristor inverter through the third high-voltage direct current transmission line; wherein,

[0005] The thyristor rectifier is used to convert the sending-end AC power input from the sending-end AC power grid into the first DC power, and input the first DC power to the thyristor inverter;

[0006] The series-tapped hybrid converter is used to convert the AC power input from the wind power generation and photovoltaic power generation field into a second DC power, and input the second DC power into the thyristor inverter, wherein the series-tapped hybrid converter is a DC voltage variable modular multi-level converter;

[0007] The thyristor inverter is used to convert the third DC power into receiving-end AC power, and input the receiving-end AC power into the receiving-end AC power grid, wherein the third DC power is the sum of the first DC power and the second DC power.

[0008] Optionally, in an embodiment of the present disclosure, the thyristor rectifier is further used to control the current size corresponding to the third DC power by triggering a delay angle;

[0009] The thyristor inverter is further used to control the voltage corresponding to the third DC power by triggering a delay angle.

[0010] Optionally, in one embodiment of the present disclosure, the series-tapped hybrid converter comprises: a twelve-pulse diode rectifier, a connecting transformer, and a full-bridge modular multilevel converter; wherein,

[0011] The AC side of the twelve-pulse diode rectifier is connected to the wind power generation and photovoltaic power plant, the AC side of the full-bridge modular multilevel converter is connected to the wind power generation and photovoltaic power plant through the connecting transformer, and the DC negative end of the twelve-pulse diode rectifier is connected to the DC positive end of the full-bridge modular multilevel converter;

[0012] The DC positive terminal of the twelve-pulse diode rectifier is the DC positive terminal of the series-tapped hybrid converter, and the DC negative terminal of the full-bridge modular multi-level converter is the DC negative terminal of the series-tapped hybrid converter.

[0013] According to a second aspect of an embodiment of the present disclosure, a control method for a new energy power generation and transmission system based on high voltage direct current series tapping is provided, comprising:

[0014] Acquire an AC voltage frequency target value, a three-phase AC voltage instantaneous value, and an AC voltage target value, and determine a three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value, the three-phase AC voltage instantaneous value, and the AC voltage target value;

[0015] Obtaining a submodule capacitor voltage value and a submodule capacitor voltage average value corresponding to a full-bridge modular multilevel converter in a new energy power generation transmission system, and determining a DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value;

[0016] According to the instantaneous value reference value of the three-phase AC output voltage and the DC voltage target value, a bridge arm reference voltage set corresponding to the full-bridge modular multi-level converter is determined to control the renewable energy power generation and transmission system.

[0017] Optionally, in one embodiment of the present disclosure, determining a three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value, the three-phase AC voltage instantaneous value and the AC voltage target value includes:

[0018] The AC voltage frequency target value is sent to an integrator to obtain an AC voltage synchronization angle;

[0019] Determining an AC output voltage amplitude reference value according to the three-phase AC voltage instantaneous value and the AC voltage target value;

[0020] A three-phase AC output voltage instantaneous value reference value is determined according to the AC voltage synchronization angle and the AC output voltage amplitude reference value.

[0021] Optionally, in an embodiment of the present disclosure, determining the AC output voltage amplitude reference value according to the three-phase AC voltage instantaneous value and the AC voltage target value includes:

[0022] Determining an effective value of an AC voltage according to the instantaneous value of the three-phase AC voltage;

[0023] Determine an AC voltage deviation signal according to the AC voltage effective value and the AC voltage target value;

[0024] The AC voltage deviation signal is passed through a proportional controller to obtain an AC output voltage amplitude reference value.

[0025] Optionally, in one embodiment of the present disclosure, the obtaining of the submodule capacitor voltage value and the submodule capacitor voltage average value corresponding to the full-bridge modular multilevel converter in the renewable energy power generation transmission system includes:

[0026] Obtaining a submodule capacitor voltage acquisition value corresponding to each submodule in the full-bridge modular multi-level converter to obtain a submodule capacitor voltage acquisition value set;

[0027] The average value of the submodule capacitor voltage is determined according to the average value of the submodule capacitor voltage collection value set.

[0028] Optionally, in an embodiment of the present disclosure, determining a DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value includes:

[0029] Determining a submodule capacitor voltage deviation signal according to the submodule capacitor voltage value and the submodule capacitor voltage average value;

[0030] The submodule capacitor voltage deviation signal is passed through a proportional sub-controller to obtain a DC voltage target value.

[0031] Optionally, in an embodiment of the present disclosure, after determining the arm reference voltage set corresponding to the full-bridge modular multi-level converter, the method further includes:

[0032] Sending the bridge arm reference voltage set to a pulse width modulation unit to obtain a control pulse signal corresponding to the full-bridge modular multi-level converter;

[0033] The full-bridge modular multi-level converter is controlled according to the control pulse signal to control the new energy power generation and transmission system.

[0034] According to a third aspect of an embodiment of the present disclosure, a control device for a new energy power generation and transmission system based on high voltage direct current series tapping is provided, comprising:

[0035] A reference value determination module, used to obtain an AC voltage frequency target value, a three-phase AC voltage instantaneous value and an AC voltage target value, and determine a three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value, the three-phase AC voltage instantaneous value and the AC voltage target value;

[0036] A target value determination module is used to obtain a submodule capacitor voltage value and a submodule capacitor voltage average value corresponding to a full-bridge modular multilevel converter in a new energy power generation transmission system, and determine a DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value;

[0037] The system control module is used to determine the bridge arm reference voltage set corresponding to the full-bridge modular multi-level converter according to the three-phase AC output voltage instantaneous value reference value and the DC voltage target value, so as to control the new energy power generation and transmission system.

[0038] According to a fourth aspect of an embodiment of the present disclosure, a terminal is provided, including:

[0039] at least one processor; and

[0040] a memory communicatively connected to the at least one processor; wherein,

[0041] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform any one of the methods described in the above aspect.

[0042] According to a fifth aspect of an embodiment of the present disclosure, a non-transitory computer-readable storage medium storing computer instructions is provided, wherein the computer instructions are used to enable the computer to execute any one of the methods described in the preceding aspects.

[0043] According to a sixth aspect of an embodiment of the present disclosure, a computer program product is provided, including a computer program, wherein the computer program implements any one of the methods described in the preceding aspects when executed by a processor.

[0044] In summary, in some or related embodiments, a new energy power generation and transmission system based on high-voltage direct current series tapping includes: a thyristor rectifier, a thyristor inverter, a series tapping hybrid converter, a first high-voltage direct current transmission line, a second high-voltage direct current transmission line, and a third high-voltage direct current transmission line; the DC positive end of the thyristor rectifier is connected to the DC negative end of the series tapping hybrid converter through the first high-voltage direct current transmission line, the DC positive end of the series tapping hybrid converter is connected to the DC positive end of the thyristor inverter through the second high-voltage direct current transmission line, and the DC negative end of the thyristor rectifier is connected to the DC negative end of the thyristor inverter through the third high-voltage direct current transmission line; wherein , the thyristor rectifier is used to convert the sending-end AC power input from the sending-end AC grid into the first DC power, and input the first DC power into the thyristor inverter; the series-tapped hybrid converter is used to convert the AC power input from the wind power generation and the photovoltaic power plant into the second DC power, and input the second DC power into the thyristor inverter, wherein the series-tapped hybrid converter is a DC voltage variable modular multi-level converter; the thyristor inverter is used to convert the third DC power into the receiving-end AC power, and input the receiving-end AC power into the receiving-end AC grid, wherein the third DC power is the sum of the first DC power and the second DC power. Therefore, by connecting the wind power generation and the photovoltaic power plant in series to the existing high-voltage DC transmission line through the series-tapped hybrid converter, the existing high-voltage DC transmission line can be used to transmit new energy power to the remote load center, which can avoid the investment and land occupation required for the construction of new transmission lines for the new energy power generation base, thereby bringing significant economic benefits. At the same time, by adopting the series-tap method, the DC voltage required for the series-tap hybrid converter can be reduced, which can greatly reduce the cost and space occupied by the tap converter, so that the electricity from wind power and photovoltaic power generation bases can be economically, efficiently and reliably transmitted to the load center over long distances.

[0045] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description or learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The above and / or additional aspects and advantages of the present disclosure will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0047] Figure 1 A schematic diagram of the structure of a new energy power generation and transmission system based on high voltage direct current series tapping provided by an embodiment of the present disclosure;

[0048] Figure 2 A schematic diagram of the structure of a series-tap hybrid converter provided by an embodiment of the present disclosure;

[0049] Figure 3 A schematic diagram of the structure of a full-bridge modular multi-level converter provided in an embodiment of the present disclosure;

[0050] Figure 4 A schematic diagram of the structure of a full-bridge submodule provided in an embodiment of the present disclosure;

[0051] Figure 5 A schematic diagram of the structure of a twelve-pulse diode rectifier provided in an embodiment of the present disclosure;

[0052] Figure 6 A flow chart of a control method for a new energy power generation and transmission system based on high voltage direct current series tapping provided by an embodiment of the present disclosure;

[0053] Figure 7 A schematic diagram of a control flow of a series-tap hybrid converter provided by an embodiment of the present disclosure;

[0054] Figure 8 A schematic diagram of the structure of a control device for a new energy power generation and transmission system based on high voltage direct current series tapping provided by an embodiment of the present disclosure;

[0055] Fig. 9 It is a block diagram of a terminal used to implement the control method of the new energy power generation and transmission system based on high-voltage direct current series tapping according to the embodiment of the present disclosure. DETAILED DESCRIPTION

[0056] Embodiments of the present disclosure are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present disclosure, and are not to be construed as limitations of the present disclosure. On the contrary, the embodiments of the present disclosure include all changes, modifications, and equivalents that fall within the spirit and connotation of the appended claims.

[0057] It is easy to understand that DC transmission has better technical and economic benefits in long-distance power transmission. Among them, high-voltage DC transmission lines are an important way to achieve large-scale long-distance power transmission from energy centers to load centers. If wind power and photovoltaic power generation bases can be connected to existing high-voltage DC transmission main lines in a tapping manner, it will be possible to avoid the construction of new long-distance high-voltage DC transmission lines specifically for wind power and photovoltaic power generation bases, which will have better technical and economic benefits and better realize the transmission of renewable energy electricity from wind power and photovoltaic power generation bases in remote areas to load centers.

[0058] Among the relevant long-distance and large-capacity DC transmission systems, the high-voltage DC transmission system using thyristor technology uses a thyristor rectifier at the sending end of the high-voltage DC transmission system to convert the sending-end AC power input from the sending-end AC grid into DC power, which is then transmitted to the receiving end of the high-voltage DC transmission system through a high-voltage DC transmission line. At the receiving end of the high-voltage DC transmission system, a thyristor inverter is used to convert the DC power into receiving-end AC power and then input it into the receiving-end AC grid.

[0059] According to some embodiments, if there are wind power and photovoltaic power generation bases along the high-voltage direct current transmission line, the AC power generated by the wind power and photovoltaic power generation bases can be converted into DC power and connected to the high-voltage direct current transmission line nearby through tapping.

[0060] In some embodiments, the AC power generated by the wind power and photovoltaic power generation bases is converted into DC power and connected to the high-voltage DC transmission line in a nearby tapping manner, which specifically includes the following two tapping methods:

[0061] The first tapping method: adopting the parallel access method, the AC power generated by wind power and photovoltaic power generation sites is converted into DC power through the tap converter and then connected to the high-voltage DC transmission line. However, the capacity of the high-voltage DC transmission line is greater than the capacity of wind power and photovoltaic power generation sites. Therefore, the DC voltage level required by the tap converter under the first method is higher, which brings greater cost and space issues.

[0062] The second tapping method: using the series tapping method, the AC power generated by wind power and photovoltaic power plants is converted into DC power through the tap converter and then connected in series to the high-voltage DC transmission line. At this time, the DC side of the tap converter bears the rated line current, but the DC voltage level required by the tap converter is relatively low, which can greatly reduce the cost and footprint of the tap converter.

[0063] Among them, the series tapping method specifically includes the following two series tapping methods:

[0064] The first series tapping method: using diode rectifiers to implement tapped converters. However, the DC voltage of the diode rectifier cannot be adjusted, and it cannot provide AC synchronous grid-connected voltage for wind power and photovoltaic power plants. At the same time, there are also large harmonic and reactive power problems.

[0065] The second series tapping method: using modular multilevel converters to implement tap converters. However, when using the series tapping method, since the line current of the HVDC transmission line is determined by the thyristor converters at the sending and receiving ends of the HVDC transmission system, that is, the transmission power of the thyristor rectifier and thyristor inverter, when the line current of the HVDC transmission line is constant, in order to make the DC side power of the tap converter adapt to the changes in the power of wind power and photovoltaic power plants, the tap converter needs to have the function of continuously adjusting the DC voltage within a preset range. Among them, the DC voltage of the conventional modular multilevel converter based on the half-bridge submodule can only operate near the rated value, and cannot meet the needs of continuous adjustment of the DC voltage within a preset range.

[0066] The present disclosure is described in detail below with reference to specific embodiments.

[0067] Figure 1 A schematic diagram of the structure of a new energy power generation and transmission system based on high voltage direct current series tapping provided in an embodiment of the present disclosure.

[0068] like Figure 1 As shown, an embodiment of the present disclosure provides a new energy power generation and transmission system based on high-voltage direct current series tapping, including: a thyristor rectifier, a thyristor inverter, a series tapping hybrid converter, a first high-voltage direct current transmission line, a second high-voltage direct current transmission line and a third high-voltage direct current transmission line; the DC positive terminal DC1+ of the thyristor rectifier is connected to the DC negative terminal DC2- of the series tapping hybrid converter through the first high-voltage direct current transmission line, the DC positive terminal DC2+ of the series tapping hybrid converter is connected to the DC positive terminal DC3+ of the thyristor inverter through the second high-voltage direct current transmission line, and the DC negative terminal DC1- of the thyristor rectifier is connected to the DC negative terminal DC3- of the thyristor inverter through the third high-voltage direct current transmission line; wherein,

[0069] A thyristor rectifier, used for converting the sending-end AC power energy input from the sending-end AC power grid into a first DC power energy, and inputting the first DC power energy into the thyristor inverter;

[0070] A series-tapped hybrid converter is used to convert the AC power input from the wind power generation and photovoltaic power generation field into a second DC power, and input the second DC power into the thyristor inverter, wherein the series-tapped hybrid converter is a DC voltage variable modular multi-level converter;

[0071] The thyristor inverter is used to convert the third DC power into receiving-end AC power and input the receiving-end AC power into the receiving-end AC power grid, wherein the third DC power is the sum of the first DC power and the second DC power.

[0072] According to some embodiments, the AC power grids corresponding to the sending-end AC power grid and the receiving-end AC power grid do not specifically refer to a fixed power grid. For example, the sending-end AC power grid and the receiving-end AC power grid may both be three-phase AC power grids, such as Figure 1 shown.

[0073] According to some embodiments, the AC side of the series-tapped hybrid converter is connected to the wind power generation and photovoltaic power generation field, so that the AC power input from the wind power generation and photovoltaic power generation field can be received. The DC side of the series-tapped hybrid converter is connected in series with the high-voltage direct current transmission line, so that the AC power input from the wind power generation and photovoltaic power generation field received by the AC side can be transmitted to the high-voltage direct current transmission line.

[0074] In the disclosed embodiment, the thyristor rectifier is further used to control the current magnitude corresponding to the third DC power by triggering a delay angle;

[0075] The thyristor inverter is also used to control the voltage corresponding to the third direct current energy by triggering a delay angle.

[0076] In the disclosed embodiment, Figure 2 This is a schematic diagram of the structure of a series-tap hybrid converter provided by an embodiment of the present disclosure. Figure 2 As shown, the series-tapped hybrid converter includes: a twelve-pulse diode rectifier, a connecting transformer, and a full-bridge modular multilevel converter; wherein,

[0077] The AC side of the twelve-pulse diode rectifier is connected to the wind power generation and photovoltaic power generation field, the AC side of the full-bridge modular multilevel converter is connected to the wind power generation and photovoltaic power generation field through a connecting transformer, and the DC negative end of the twelve-pulse diode rectifier is connected to the DC positive end of the full-bridge modular multilevel converter;

[0078] The DC positive end of the twelve-pulse diode rectifier is the DC positive end DC2+ of the series-tapped hybrid converter, and the DC negative end of the full-bridge modular multilevel converter is the DC negative end DC2- of the series-tapped hybrid converter.

[0079] According to some embodiments, if the DC rated voltage of the series-tap hybrid converter is U dcN , then the DC rated voltage of the twelve-pulse diode rectifier and the full-bridge modular multilevel converter is U dcN / 2. Since the DC voltage of the full-bridge modular multilevel converter can be dcN / 2~U dcN The DC output voltage of the series-tapped hybrid converter composed of a twelve-pulse diode rectifier and a full-bridge modular multilevel converter can be continuously adjustable between 0 and U / 2. dcNThe transmission power of the series-tap hybrid converter can be continuously adjusted between 0 and the rated capacity (rated power) by adjusting the DC output voltage.

[0080] In some embodiments, the full-bridge modular multilevel converter can also compensate for harmonics generated by the twelve-pulse diode rectifier and provide a dynamic reactive power compensation function.

[0081] According to some embodiments, Figure 3 Schematic diagram of the structure of a full-bridge modular multi-level converter provided by an embodiment of the present disclosure. Figure 3 As shown, the full-bridge modular multi-level converter includes: a first phase unit, a second phase unit and a third phase unit. Each phase unit includes an upper bridge arm and a lower bridge arm, the upper bridge arm includes an upper bridge arm submodule string connected in series and an upper bridge arm inductor, and the lower bridge arm includes a lower bridge arm submodule string connected in series and a lower bridge arm inductor;

[0082] Wherein, the positive electrode of the upper bridge arm submodule string is connected to the DC positive bus, the first end of the upper bridge arm inductor is connected to the negative electrode of the upper bridge arm submodule string, the negative electrode of the lower bridge arm submodule string is connected to the DC negative bus, the first end of the lower bridge arm inductor is connected to the positive electrode of the lower bridge arm submodule string, and the second end of the upper bridge arm inductor and the second end of the lower bridge arm inductor are connected to the AC neutral point;

[0083] The upper bridge arm submodule string and the lower bridge arm submodule string both include N cascaded full-bridge submodules, where N≥2.

[0084] The first phase unit is connected to the AC neutral point A. The second phase unit is connected to the AC neutral point B. The third phase unit is connected to the AC neutral point C. The DC positive bus is the DC positive terminal DC4+ of the full-bridge modular multilevel converter. The DC negative bus is the DC negative terminal DC4- of the full-bridge modular multilevel converter.

[0085] In some embodiments, Figure 4 Schematic diagram of the structure of a full-bridge submodule provided by an embodiment of the present disclosure. Figure 4 As shown, the full-bridge submodule includes: a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4 and a DC capacitor C1.

[0086] The collector of the second switch S2 and the emitter of the first switch S1 are the input terminal T1 of the full-bridge submodule, and the collector of the fourth switch S4 and the emitter of the third switch S3 are the output terminal T2 of the full-bridge submodule.

[0087] Among them, the positive electrode of the DC capacitor C1 is connected to the collector of the third switch S3 and the collector of the first switch S1, and the negative electrode of the DC capacitor C1 is connected to the emitter of the second switch S2 and the emitter of the fourth switch S4. The positive electrode of the first diode D1 is connected to the emitter of the first switch S1, and the negative electrode of the first diode D1 is connected to the collector of the first switch S1. The positive electrode of the second diode D2 is connected to the emitter of the second switch S2, and the negative electrode of the second diode D2 is connected to the collector of the second switch S2. The positive electrode of the third diode D3 is connected to the emitter of the third switch S3, and the negative electrode of the third diode D3 is connected to the collector of the third switch S3. The positive electrode of the fourth diode D4 is connected to the emitter of the fourth switch S4, and the negative electrode of the fourth diode D4 is connected to the collector of the fourth switch S4.

[0088] In some embodiments, the switches provided in the embodiments of the present disclosure, for example, the first switch S1, the second switch S2, the third switch S3, and the fourth switch S4, do not specifically refer to a fixed type of switch. The types of switches include, but are not limited to, bipolar junction transistors (Bipolar Junction Transistor, BJT), gate turn-off thyristors (GTO), insulated gate bipolar transistors (Insulated Gate Bipolar Transistor, IGBT), integrated gate commutated thyristors (Integrated Gate Commuted Transistor, IGCT) and metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET), etc.

[0089] According to some embodiments, Figure 5 The structure diagram of a twelve-pulse diode rectifier provided by the embodiment of the present disclosure is shown in FIG. Figure 5 As shown, the twelve-pulse diode rectifier includes: a first rectifier transformer, a second rectifier transformer, a first six-pulse diode converter and a second six-pulse diode converter;

[0090] The six-pulse diode converter provided by the embodiment of the present disclosure, that is, the first six-pulse diode converter and the second six-pulse diode converter, includes a first bridge arm, a second bridge arm and a third bridge arm, each of which includes an upper bridge arm diode and a lower bridge arm diode connected in series. The cathode of the upper bridge arm diode and the anode of the lower bridge arm diode are the midpoints of the bridge arms, the anode of the upper bridge arm diode is the anode of the bridge arm, and the cathode of the lower bridge arm diode is the cathode of the bridge arm.

[0091] Among them, Figure 5As shown, in the first six-pulse diode converter, the first bridge arm includes a fifth diode D5 and a sixth diode D6 connected in series, the second bridge arm includes a seventh diode D7 and an eighth diode D8 connected in series, and the third bridge arm includes a ninth diode D9 and a tenth diode D10 connected in series.

[0092] Among them, Figure 5 As shown, in the second six-pulse diode converter, the first bridge arm includes an eleventh diode D11 and a twelfth diode D12 connected in series, the second bridge arm includes a thirteenth diode D13 and a fourteenth diode D14 connected in series, and the third bridge arm includes a fifteenth diode D15 and a sixteenth diode D16 connected in series.

[0093] The positive electrode of the first bridge arm, the positive electrode of the second bridge arm and the positive electrode of the third bridge arm are connected together to form a DC positive terminal of the six-pulse diode converter. The negative electrode of the first bridge arm, the negative electrode of the second bridge arm and the negative electrode of the third bridge arm are connected together to form a DC negative terminal of the six-pulse diode converter.

[0094] Among them, the DC positive end of the first six-pulse diode converter is the DC positive end DC5+ of the twelve-pulse diode rectifier, and the DC negative end of the second six-pulse diode converter is the DC negative end DC5- of the twelve-pulse diode rectifier. The DC negative end of the first six-pulse diode converter is connected to the DC negative end of the second six-pulse diode converter. The three output ends of the first rectifier transformer are connected to the midpoint of the bridge arm of the first six-pulse diode converter, and the output ends of the first rectifier transformer correspond one-to-one to the midpoint of the bridge arm of the first six-pulse diode converter. The three output ends of the second rectifier transformer are connected to the midpoint of the bridge arm of the second six-pulse diode converter, and the output ends of the second rectifier transformer correspond one-to-one to the midpoint of the bridge arm of the second six-pulse diode converter.

[0095] The voltages of the auxiliary transformer windings of the first rectifier transformer and the second rectifier transformer differ by 30 degrees, and the input ends of the first rectifier transformer and the second rectifier transformer are both connected to the wind power generation and photovoltaic power generation fields.

[0096] According to some embodiments, the rated voltage of the twelve-pulse diode rectifier can be set to half of the DC rated voltage of the series hybrid tap converter, that is, U dcN / 2.

[0097] It is easy to understand that although the DC voltage of a full-bridge modular multilevel converter or a hybrid modular multilevel converter based on a full-bridge submodule can be adjusted within a preset range, the adjustable range is related to the proportion of the full-bridge submodule in the bridge arm of the converter. Since the amount of switching devices used in the full-bridge submodule is twice that of the half-bridge submodule, the cost and volume of the tap converter are relatively large. Therefore, the embodiment of the present disclosure can reduce the number of full-bridge submodules in the full-bridge modular multilevel converter by adopting a series-tapped hybrid converter composed of a twelve-pulse diode rectifier and a full-bridge modular multilevel converter, thereby reducing the amount of switching devices, and further reducing the cost and volume of the series-tapped hybrid converter while enabling the series-tapped hybrid converter to have a function of continuously adjustable DC voltage within a preset range.

[0098] In summary, the system proposed in the embodiment of the present disclosure includes: a thyristor rectifier, a thyristor inverter, a series-tapped hybrid converter, a first high-voltage direct current transmission line, a second high-voltage direct current transmission line, and a third high-voltage direct current transmission line; the DC positive end of the thyristor rectifier is connected to the DC negative end of the series-tapped hybrid converter through the first high-voltage direct current transmission line, the DC positive end of the series-tapped hybrid converter is connected to the DC positive end of the thyristor inverter through the second high-voltage direct current transmission line, and the DC negative end of the thyristor rectifier is connected to the DC negative end of the thyristor inverter through the third high-voltage direct current transmission line; wherein, the thyristor rectifier , used to convert the sending-end AC power input from the sending-end AC grid into the first DC power, and input the first DC power into the thyristor inverter; the series-tapped hybrid converter, used to convert the AC power input from the wind power generation and the photovoltaic power plant into the second DC power, and input the second DC power into the thyristor inverter, wherein the series-tapped hybrid converter is a DC voltage variable modular multi-level converter; the thyristor inverter, used to convert the third DC power into the receiving-end AC power, and input the receiving-end AC power into the receiving-end AC grid, wherein the third DC power is the sum of the first DC power and the second DC power. Therefore, by connecting the wind power generation and the photovoltaic power plant in series to the existing high-voltage DC transmission line through the series-tapped hybrid converter, the existing high-voltage DC transmission line can be used to transmit new energy power to the remote load center, which can avoid the investment and land occupation required for the construction of new transmission lines for the new energy power generation base, thereby bringing significant economic benefits. At the same time, by adopting the series-tap method, the DC voltage required for the series-tap hybrid converter can be reduced, which can greatly reduce the cost and space occupied by the tap converter, so that the electricity from wind power and photovoltaic power generation bases can be economically, efficiently and reliably transmitted to the load center over long distances.

[0099] In order to implement the above embodiments, the present disclosure also proposes a control method for a new energy power generation and transmission system based on high voltage direct current series tapping.

[0100] Figure 6 The present invention provides a flow chart of a control method for a new energy power generation and transmission system based on high voltage direct current series tapping provided in an embodiment of the present invention.

[0101] like Figure 6 As shown, a control method for a new energy power generation and transmission system based on high voltage direct current series tapping includes:

[0102] Step 610: Obtain AC voltage frequency target value ω ref , three-phase AC voltage instantaneous value and AC voltage target value U s_ref , and according to the AC voltage frequency target value ω ref , three-phase AC voltage instantaneous value and AC voltage target value U s_ref Determine the instantaneous value reference value of the three-phase AC output voltage;

[0103] Step 620: Obtain the submodule capacitor voltage value U corresponding to the full-bridge modular multi-level converter in the renewable energy power generation transmission system cap_ref and the average value of the submodule capacitor voltage u cap , and according to the submodule capacitor voltage value U cap_ref and the average value of the submodule capacitor voltage u cap Determine the DC voltage target value E dc_ref ;

[0104] Step 630: According to the three-phase AC output voltage instantaneous value reference value and the DC voltage target value E dc_ref , determine the bridge arm reference voltage set corresponding to the full-bridge modular multi-level converter to control the renewable energy power generation transmission system.

[0105] According to some embodiments, when controlling a new energy generation and transmission system based on high-voltage direct current series tapping, the key is to control the series tapping hybrid converter. When controlling the series tapping hybrid converter, the key is to control the full-bridge modular multi-level converter to provide synchronous AC grid-connected voltage for wind power generation and photovoltaic power generation, and to send the AC power input from the wind power generation and photovoltaic power generation into the DC line.

[0106] In some embodiments, when the full-bridge modular multilevel converter is controlled to provide a synchronous AC grid-connected voltage for wind power generation and photovoltaic power generation, the AC output voltage of the full-bridge modular multilevel converter can be controlled to be the synchronous AC grid-connected voltage provided by the wind power generation and photovoltaic power generation.

[0107] In some embodiments, when controlling a full-bridge modular multilevel converter to provide synchronous AC grid-connected voltage for wind power generation and photovoltaic power generation, a frequency control method may be used to control the full-bridge modular multilevel converter.

[0108] According to some embodiments, when the full-bridge modular multilevel converter sends the AC power energy received from the wind power generation and photovoltaic power plant input into the DC line, it can be achieved by adjusting the DC voltage of the full-bridge modular multilevel converter.

[0109] In some embodiments, when the DC voltage of the full-bridge modular multilevel converter is regulated, since the sub-module capacitor voltage marks the balance of the AC and DC side power of the full-bridge modular multilevel converter, the DC voltage required to be output by the full-bridge modular multilevel converter can be obtained with the goal of stable control of the sub-module capacitor voltage, thereby achieving the balance of the AC and DC side power.

[0110] According to some embodiments, the instantaneous value of the three-phase AC voltage does not specifically refer to a fixed value. The instantaneous value of the three-phase AC voltage includes the instantaneous value of the A-phase AC voltage u sa , instantaneous value of phase B AC voltage u sb and the instantaneous value of phase C AC voltage u sc .

[0111] In some embodiments, the three-phase AC output voltage instantaneous value reference value does not specifically refer to a fixed value. The three-phase AC output voltage instantaneous value includes the A-phase AC output voltage instantaneous value reference value u a_ref , B phase AC output voltage instantaneous value reference value u b_ref And the instantaneous value reference value of phase C AC output voltage u b_ref .

[0112] According to some embodiments, the bridge arm reference voltage set includes a first upper bridge arm reference voltage u ap_ref , the first lower bridge arm reference voltage u an_ref , the second upper bridge arm reference voltage u bp_ref , the second lower bridge arm reference voltage u bn_ref , the third upper bridge arm reference voltage u cp_ref and the third lower bridge arm reference voltage u cn_ref .

[0113] In some embodiments, according to the three-phase AC output voltage instantaneous value reference value and the DC voltage target value E dc_ref , when determining the arm reference voltage set corresponding to the full-bridge modular multilevel converter, each arm reference voltage in the arm reference voltage set can be determined according to the following formula:

[0114]

[0115] In the embodiment of the present disclosure, according to the AC voltage frequency target value ω ref , three-phase AC voltage instantaneous value and AC voltage target value U s_refDetermine the instantaneous reference value of the three-phase AC output voltage, including:

[0116] Set the AC voltage frequency target value ω ref It is sent to the integrator to obtain the AC voltage synchronization angle θ;

[0117] According to the instantaneous value of the three-phase AC voltage and the AC voltage target value U s_ref Determine the AC output voltage amplitude reference value E ac_ref ;

[0118] According to the AC voltage synchronization angle θ and the AC output voltage amplitude reference value E ac_ref Determine the instantaneous reference value of the three-phase AC output voltage.

[0119] According to some embodiments, according to the AC voltage synchronization angle θ and the AC output voltage amplitude reference value E ac_ref When determining the instantaneous reference value of the three-phase AC output voltage, the instantaneous reference value of the three-phase AC output voltage can be determined according to the following formula:

[0120]

[0121] In the embodiment of the present disclosure, according to the instantaneous value of the three-phase AC voltage and the AC voltage target value U s_ref Determine the AC output voltage amplitude reference value E ac_ref ,include:

[0122] Determine the effective value of the AC voltage U according to the instantaneous value of the three-phase AC voltage s ;

[0123] According to the AC voltage effective value U s and AC voltage target value U s_ref Determine the AC voltage deviation signal Δu s ;

[0124] The AC voltage deviation signal Δu s Through the proportional controller, the AC output voltage amplitude reference value E is obtained. ac_ref .

[0125] According to some embodiments, according to the AC voltage effective value U s and AC voltage target value U s_ref Determine the AC voltage deviation signal Δu s When , the AC voltage deviation signal can be determined according to the following formula:

[0126] Δu s =U s_ref -U s .

[0127] It is easy to understand that the AC voltage effective value is determined according to the instantaneous value of the three-phase AC voltage, and then the AC voltage deviation signal is determined according to the AC voltage effective value and the AC voltage target value, and finally the AC voltage deviation signal is passed through the proportional controller to obtain the AC output voltage amplitude reference value. This can improve the stability of the AC voltage effective value.

[0128] In the embodiment of the present disclosure, the submodule capacitor voltage value U corresponding to the full-bridge modular multi-level converter in the renewable energy power generation transmission system is obtained. cap_ref and the average value of the submodule capacitor voltage u cap ,include:

[0129] Obtaining a submodule capacitor voltage acquisition value corresponding to each submodule in the full-bridge modular multilevel converter to obtain a submodule capacitor voltage acquisition value set;

[0130] According to the average value of the submodule capacitor voltage collection value set, determine the submodule capacitor voltage average value u cap .

[0131] In the embodiment of the present disclosure, according to the submodule capacitor voltage value U cap_ref and the average value of the submodule capacitor voltage u cap Determine the DC voltage target value E dc_ref ,include:

[0132] According to the submodule capacitor voltage value U cap_ref and the average value of the submodule capacitor voltage u cap , determine the submodule capacitor voltage deviation signal Δu cap ;

[0133] The submodule capacitor voltage deviation signal Δu cap Through the proportional controller, the DC voltage target value E is obtained. dc_ref .

[0134] According to some embodiments, according to the submodule capacitor voltage value U cap_ref and the average value of the submodule capacitor voltage u cap , determine the submodule capacitor voltage deviation signal Δu cap When , the submodule capacitor voltage deviation signal can be determined according to the following formula:

[0135] Δu cap =u cap -U cap_ref

[0136] In the embodiment of the present disclosure, after determining the arm reference voltage set corresponding to the full-bridge modular multi-level converter, the method further includes:

[0137] The bridge arm reference voltage set is sent to the pulse width modulation unit to obtain a control pulse signal corresponding to the full-bridge modular multi-level converter;

[0138] The full-bridge modular multi-level converter is controlled according to the control pulse signal to control the renewable energy power generation transmission system.

[0139] According to some embodiments, Figure 7 This is a control flow diagram of a series-tap hybrid converter provided by an embodiment of the present disclosure. Figure 7 As shown, first, by calculating the instantaneous value of the A phase AC voltage u sa , instantaneous value of phase B AC voltage u sb and the instantaneous value of phase C AC voltage u sc Perform three-phase voltage effective value detection to determine the AC voltage effective value U s Next, by calculating the effective value of the AC voltage U s and AC voltage target value U s_ref The difference is calculated and the AC voltage deviation signal Δu is obtained. s Through the proportional controller PI, the AC output voltage amplitude reference value E is obtained ac_ref In addition, by changing the AC voltage frequency target value ω ref The AC voltage synchronization angle θ is then sent to the integrator 1 / S to obtain the AC voltage synchronization angle θ. Then, the AC output voltage amplitude reference value E is used to calculate the AC voltage synchronization angle θ and the AC output voltage amplitude reference value E. ac_ref Determine the instantaneous reference value u of the A phase AC output voltage a_ref , B phase AC output voltage instantaneous value reference value u b_ref And the instantaneous value reference value of phase C AC output voltage u b_ref Secondly, by calculating the average value of the submodule capacitor voltage u cap and submodule capacitor voltage value U cap_ref The difference is calculated and the submodule capacitor voltage deviation signal Δu is obtained after the difference is calculated. cap Through the proportional controller PI, the DC voltage target value E is obtained dc_ref Next, according to the DC voltage target value E dc_ref , A phase AC output voltage instantaneous value reference value u a_ref , B phase AC output voltage instantaneous value reference value u b_ref And the instantaneous value reference value of phase C AC output voltage u b_ref , determine the first upper bridge arm reference voltage u ap_ref , the first lower bridge arm reference voltage u an_ref , the second upper bridge arm reference voltage u bp_ref , the second lower bridge arm reference voltage u bn_ref , the third upper bridge arm reference voltage u cp_ref and the third lower bridge arm reference voltage ucn_ref Finally, the first upper bridge arm reference voltage u ap_ref , the first lower bridge arm reference voltage u an_ref , the second upper bridge arm reference voltage u bp_ref , the second lower bridge arm reference voltage u bn_ref , the third upper bridge arm reference voltage u cp_ref and the third lower bridge arm reference voltage u cn_ref The pulse width modulation unit is input to obtain a control pulse signal, so as to control the series-tap hybrid converter according to the control pulse signal.

[0140] In summary, the method proposed in the embodiment of the present disclosure obtains the AC voltage frequency target value and the AC voltage target value, and determines the three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value and the AC voltage target value; obtains the submodule capacitor voltage value and the submodule capacitor voltage average value corresponding to the full-bridge modular multilevel converter in the new energy power generation and delivery system, and determines the DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value; determines the bridge arm reference voltage set corresponding to the full-bridge modular multilevel converter according to the three-phase AC output voltage instantaneous value reference value and the DC voltage target value, so as to control the new energy power generation and delivery system. Therefore, by determining the three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value and the AC voltage target value, a stable AC synchronous grid-connected voltage can be provided for wind power generation and photovoltaic power generation. By determining the arm reference voltage set corresponding to the full-bridge modular multilevel converter, the full-bridge modular multilevel converter can be controlled according to the arm reference voltage set, so that the AC power received by the wind power generation and the AC power input by the photovoltaic power plant on the AC side of the series-tap hybrid converter can be transmitted to the DC line, thereby achieving the balance of power on the AC and DC sides of the series-tap hybrid converter.

[0141] In order to implement the above-mentioned embodiments, the present disclosure also proposes a control device for a new energy power generation and transmission system based on high voltage direct current series tapping.

[0142] Figure 8 A schematic diagram of the structure of a control device for a new energy power generation and transmission system based on high voltage direct current series tapping provided in an embodiment of the present disclosure.

[0143] like Figure 8 As shown, a control device 800 of a new energy power generation and transmission system based on high voltage direct current series tapping includes:

[0144] A reference value determination module 810 is used to obtain an AC voltage frequency target value and an AC voltage target value, and determine a three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value and the AC voltage target value;

[0145] The target value determination module 820 is used to obtain the submodule capacitor voltage value and the submodule capacitor voltage average value corresponding to the full-bridge modular multi-level converter in the new energy power generation transmission system, and determine the DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value;

[0146] The system control module 830 is used to determine the arm reference voltage set corresponding to the full-bridge modular multi-level converter according to the three-phase AC output voltage instantaneous value reference value and the DC voltage target value, so as to control the renewable energy power generation and transmission system.

[0147] In summary, the device proposed in the embodiment of the present disclosure obtains the AC voltage frequency target value and the AC voltage target value through the reference value determination module, and determines the three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value and the AC voltage target value; the target value determination module obtains the submodule capacitor voltage value and the submodule capacitor voltage average value corresponding to the full-bridge modular multilevel converter in the new energy power generation and delivery system, and determines the DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value; the system control module determines the bridge arm reference voltage set corresponding to the full-bridge modular multilevel converter according to the three-phase AC output voltage instantaneous value reference value and the DC voltage target value, so as to control the new energy power generation and delivery system. Therefore, by determining the three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value and the AC voltage target value, a stable AC synchronous grid-connected voltage can be provided for wind power generation and photovoltaic power generation. By determining the arm reference voltage set corresponding to the full-bridge modular multilevel converter, the full-bridge modular multilevel converter can be controlled according to the arm reference voltage set, so that the AC power received by the wind power generation and the AC power input by the photovoltaic power plant on the AC side of the series-tap hybrid converter can be transmitted to the DC line, thereby achieving the balance of power on the AC and DC sides of the series-tap hybrid converter.

[0148] According to an embodiment of the present disclosure, the present disclosure also provides a terminal, a readable storage medium and a computer program product.

[0149] Fig. 9 A schematic block diagram of an example terminal 900 that can be used to implement embodiments of the present disclosure is shown. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit implementations of the present disclosure described and / or claimed herein.

[0150] like Fig. 9As shown, the terminal 900 includes a computing unit 901, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 902 or a computer program loaded from a storage unit 908 into a random access memory (RAM) 903. In the RAM 903, various programs and data required for the operation of the terminal 900 can also be stored. The computing unit 901, the ROM 902, and the RAM 903 are connected to each other via a bus 904. An input / output (I / O) interface 905 is also connected to the bus 904.

[0151] A number of components in the terminal 900 are connected to the I / O interface 905, including: an input unit 906, such as a keyboard, a mouse, etc.; an output unit 907, such as various types of displays, speakers, etc.; a storage unit 908, such as a disk, an optical disk, etc.; and a communication unit 909, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 909 allows the terminal 900 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0152] The computing unit 901 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the computing unit 901 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The computing unit 901 performs the various methods and processes described above, such as a control method for a new energy power generation and transmission system based on high-voltage direct current series tapping. For example, in some embodiments, the control method for a new energy power generation and transmission system based on high-voltage direct current series tapping may be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit 908. In some embodiments, part or all of the computer program may be loaded and / or installed on the terminal 900 via the ROM 902 and / or the communication unit 909. When the computer program is loaded into the RAM 903 and executed by the computing unit 901, one or more steps of the control method for a new energy power generation and transmission system based on high-voltage direct current series tapping described above may be executed. Alternatively, in other embodiments, the computing unit 901 may be configured in any other appropriate manner (for example, by means of firmware) to execute a control method for a new energy power generation and transmission system based on high voltage direct current series tapping.

[0153] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0154] The program code for implementing the method of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that the program code, when executed by the processor or controller, enables the functions / operations specified in the flow chart and / or block diagram to be implemented. The program code may be executed entirely on the machine, partially on the machine, partially on the machine as a stand-alone software package and partially on a remote machine, or entirely on a remote machine or terminal.

[0155] In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0156] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0157] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data terminal), or a computing system that includes middleware components (e.g., an application terminal), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), the Internet, and a blockchain network.

[0158] A computer system may include a client and a terminal. The client and the terminal are generally remote from each other and usually interact through a communication network. The relationship between the client and the terminal is generated by computer programs running on the corresponding computers and having a client-terminal relationship with each other. The terminal may be a cloud terminal, also known as a cloud computing terminal or a cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services ("Virtual Private Server", or "VPS" for short). The terminal may also be a terminal of a distributed system, or a terminal combined with a blockchain.

[0159] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0160] The above specific implementations do not constitute a limitation on the protection scope of the present disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A new energy power generation and transmission system based on high voltage direct current series tapping, It is characterized in that include: a thyristor rectifier, a thyristor inverter, a series-tap hybrid converter, a first high-voltage direct current transmission line, a second high-voltage direct current transmission line, and a third high-voltage direct current transmission line; The DC positive end of the thyristor rectifier is connected to the DC negative end of the series-tapped hybrid converter through the first high-voltage DC transmission line, the DC positive end of the series-tapped hybrid converter is connected to the DC positive end of the thyristor inverter through the second high-voltage DC transmission line, and the DC negative end of the thyristor rectifier is connected to the DC negative end of the thyristor inverter through the third high-voltage DC transmission line; wherein, The thyristor rectifier is used to convert the sending-end AC power input from the sending-end AC power grid into the first DC power, and input the first DC power to the thyristor inverter; The series-tapped hybrid converter is used to convert the AC power input from the wind power generation and photovoltaic power generation field into a second DC power, and input the second DC power into the thyristor inverter, wherein the series-tapped hybrid converter is a DC voltage variable modular multi-level converter; The thyristor inverter is used to convert the third DC power into receiving-end AC power, and input the receiving-end AC power into the receiving-end AC power grid, wherein the third DC power is the sum of the first DC power and the second DC power; The series-tap hybrid converter comprises: a twelve-pulse diode rectifier, a connecting transformer, and a full-bridge modular multi-level converter; wherein, The AC side of the twelve-pulse diode rectifier is connected to the wind power generation and photovoltaic power plant, the AC side of the full-bridge modular multilevel converter is connected to the wind power generation and photovoltaic power plant through the connecting transformer, and the DC negative end of the twelve-pulse diode rectifier is connected to the DC positive end of the full-bridge modular multilevel converter; The DC positive terminal of the twelve-pulse diode rectifier is the DC positive terminal of the series-tapped hybrid converter, and the DC negative terminal of the full-bridge modular multi-level converter is the DC negative terminal of the series-tapped hybrid converter.

2. The system according to claim 1, It is characterized in that The thyristor rectifier is further used to control the current corresponding to the third DC power by triggering a delay angle; The thyristor inverter is further used to control the voltage corresponding to the third DC power by triggering a delay angle.

3. A control method for a new energy power generation and transmission system based on high voltage direct current series tapping according to any one of claims 1 to 2, It is characterized in that include: Acquire an AC voltage frequency target value, a three-phase AC voltage instantaneous value, and an AC voltage target value, and determine a three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value, the three-phase AC voltage instantaneous value, and the AC voltage target value; Obtaining a submodule capacitor voltage value and a submodule capacitor voltage average value corresponding to a full-bridge modular multilevel converter in a new energy power generation transmission system, and determining a DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value; According to the instantaneous value reference value of the three-phase AC output voltage and the DC voltage target value, a bridge arm reference voltage set corresponding to the full-bridge modular multi-level converter is determined to control the renewable energy power generation and transmission system.

4. The method according to claim 3, It is characterized in that The step of determining a three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value, the three-phase AC voltage instantaneous value and the AC voltage target value comprises: The AC voltage frequency target value is sent to an integrator to obtain an AC voltage synchronization angle; Determining an AC output voltage amplitude reference value according to the three-phase AC voltage instantaneous value and the AC voltage target value; A three-phase AC output voltage instantaneous value reference value is determined according to the AC voltage synchronization angle and the AC output voltage amplitude reference value.

5. The method according to claim 4, It is characterized in that The step of determining the AC output voltage amplitude reference value according to the three-phase AC voltage instantaneous value and the AC voltage target value comprises: Determining an effective value of an AC voltage according to the instantaneous value of the three-phase AC voltage; Determine an AC voltage deviation signal according to the AC voltage effective value and the AC voltage target value; The AC voltage deviation signal is passed through a proportional controller to obtain an AC output voltage amplitude reference value.

6. The method according to claim 3, It is characterized in that The obtaining of the submodule capacitor voltage value and the submodule capacitor voltage average value corresponding to the full-bridge modular multi-level converter in the new energy power generation transmission system includes: Obtaining a submodule capacitor voltage acquisition value corresponding to each submodule in the full-bridge modular multi-level converter to obtain a submodule capacitor voltage acquisition value set; The average value of the submodule capacitor voltage is determined according to the average value of the submodule capacitor voltage collection value set.

7. The method according to claim 3, It is characterized in that The step of determining a DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value includes: Determining a submodule capacitor voltage deviation signal according to the submodule capacitor voltage value and the submodule capacitor voltage average value; The submodule capacitor voltage deviation signal is passed through a proportional sub-controller to obtain a DC voltage target value.

8. The method according to claim 3, It is characterized in that After determining the arm reference voltage set corresponding to the full-bridge modular multi-level converter, the method further includes: Sending the bridge arm reference voltage set to a pulse width modulation unit to obtain a control pulse signal corresponding to the full-bridge modular multi-level converter; The full-bridge modular multi-level converter is controlled according to the control pulse signal to control the new energy power generation and transmission system.

9. A control device for a new energy power generation and transmission system based on high voltage direct current series tapping according to any one of claims 1 to 2, It is characterized in that include: A reference value determination module, used to obtain an AC voltage frequency target value, a three-phase AC voltage instantaneous value and an AC voltage target value, and determine a three-phase AC output voltage instantaneous value reference value according to the AC voltage frequency target value, the three-phase AC voltage instantaneous value and the AC voltage target value; A target value determination module is used to obtain a submodule capacitor voltage value and a submodule capacitor voltage average value corresponding to a full-bridge modular multilevel converter in a new energy power generation transmission system, and determine a DC voltage target value according to the submodule capacitor voltage value and the submodule capacitor voltage average value; The system control module is used to determine the bridge arm reference voltage set corresponding to the full-bridge modular multi-level converter according to the three-phase AC output voltage instantaneous value reference value and the DC voltage target value, so as to control the new energy power generation and transmission system.

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