New energy system sending end power balancing method and device, electronic equipment and medium

Abstract

The invention discloses a new energy system sending end power balancing method and device, electronic equipment and a medium, which are used for solving the technical problems that the capacity configuration of an alternating current energy consumption device is relatively redundant and the capacity configuration is inaccurate when energy balancing is carried out on a new energy system with direct current blocking. The method comprises the steps of obtaining operation data of a new energy system when the new energy system has a direct current locking fault; according to the operation data, system capacitance energy, alternating current tie line energy, direct current power transmission system output energy and new energy system output energy are calculated respectively, and an energy consumption device energy model is constructed; based on the system capacitance energy, the AC tie line energy, the DC power transmission system output energy and the new energy system output energy, reversely solving the energy consumption device capacity to be solved in the energy consumption device energy model according to energy conservation; and inputting the capacity of the energy consumption device to carry out power balance on the sending end of the new energy system.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy systems, and particularly to a method, device, electronic device and medium for power balance at the sending end of a new energy system. Background Art

[0002] At present, China is gradually developing large-scale new energy systems in the northwest and southwest regions. The terrain in the western region is special, and most of it is located in high-altitude areas, resulting in problems of external insulation that are not suitable for the construction of DC converter stations. At the same time, the power grid framework in the western region is weak, and large-scale new energy transmission to the outside causes the near-area AC system to be unable to carry too much load. It is necessary to adopt the form of an isolated grid for transmission, that is, not to connect with the local power grid. Figure 1 A schematic structural diagram of an isolated grid system or a system weakly connected to an AC system is shown. Among them, S ij represents different new energy collection stations, and S AC represents the substations existing in the AC system. For the wiring schematic of the new energy collection station, Figure 1 only a typical radial wiring diagram is given, and there may also be different wiring diagrams such as a ring shape in the actual system.

[0003] For the DC transmission system with isolated grid transmission, the factor that has the greatest impact on the system stability is the DC transmission system blocking. When the DC transmission system blocks, since the active power generated by the new energy cannot be transmitted outside through DC, a large amount of energy will cause overvoltage in the isolated grid system, resulting in random tripping of new energy units and triggering system collapse.

[0004] The current method for solving the energy imbalance after the isolated grid system blocks is mainly to configure AC energy-consuming devices. The energy-consuming device is actually composed of switching devices and resistors. When energy imbalance occurs in the system, the energy-consuming device is quickly put into operation in a short time, and energy is consumed through the resistor, so as to achieve power balance at the sending end system.

[0005] The capacity configuration of the current AC energy-consuming device often matches the capacity of the converter station. However, for large-scale new energy transmission systems, the above capacity configuration is relatively redundant and often does not need to reach the capacity configuration of the converter station. That is, the current power balance method has the problem of inaccurate capacity configuration. Excessive configuration of energy-consuming devices will not only greatly increase the investment cost and floor area of the converter station, but also increase the difficulty of later operation and maintenance. Summary of the Invention

[0006] The present invention provides a method, device, electronic device and medium for power balance at the sending end of a new energy system, which is used to solve or partially solve the technical problem that the capacity configuration of the AC energy-consuming device is relatively redundant and inaccurate when balancing the energy of a new energy system with DC blocking.

[0007] The present invention provides a method for power balance at the sending end of a new energy system, and the method includes:

[0008] When a DC blocking fault occurs in the new energy system, obtain the operation data of the new energy system;

[0009] According to the operation data, calculate the system capacitor energy, the AC tie line energy, the energy output by the DC transmission system, and the energy generated by the new energy system respectively, and construct an energy model of the energy-consuming device;

[0010] Based on the system capacitor energy, the AC tie line energy, the energy output by the DC transmission system, and the energy generated by the new energy system, inversely solve the capacity of the energy-consuming device to be solved in the energy model of the energy-consuming device according to the law of conservation of energy;

[0011] Input the capacity of the energy-consuming device to balance the power at the sending end of the new energy system.

[0012] Optionally, the operation data includes the time interval from the occurrence of the fault to the generator tripping of the new energy system; the method further includes:

[0013] When the DC blocking fault is a single-pole blocking, obtain the first single restart time, the first restart times of the DC transmission system after the occurrence of the fault, and the starting time of the generator tripping strategy after the restart fails, and calculate the first generator tripping time interval according to the first single restart time, the first restart times, and the starting time of the generator tripping strategy;

[0014] When the DC blocking fault is a bipolar blocking, obtain the second single restart time and the second restart times of the DC transmission system after the occurrence of the fault, and calculate the second generator tripping time interval according to the second single restart time and the second restart times.

[0015] Optionally, the operation data further includes the power upper limit value and the power before the fault of the AC tie line in the new energy system; the calculation process of the AC tie line energy includes:

[0016] When the new energy system is not an islanded system and the DC blocking fault is a single-pole blocking, calculate the AC tie line energy according to the power upper limit value, the power before the fault, and the first generator tripping time interval;

[0017] When the new energy system is not an islanded system and the DC blocking fault is a bipolar blocking, calculate the AC tie line energy according to the power upper limit value, the power before the fault, and the second generator tripping time interval;

[0018] When the new energy system is an islanded system, the AC tie line energy is zero.

[0019] Optionally, the operating data further includes the monopole rated operating power of the DC transmission system in the new energy system and the overload start time interval after a fault occurs; the calculation process of the energy output by the DC transmission system includes:

[0020] When the DC blocking fault is a monopole block, calculate the energy output by the DC transmission system according to the monopole rated operating power, the overload start time interval, and the first generator tripping time interval;

[0021] When the DC blocking fault is a bipolar block, the energy output by the DC transmission system is zero.

[0022] Optionally, the operating data further includes the monopole rated operating power of the DC transmission system in the new energy system and the overload start time interval after a fault occurs; the calculation process of the energy generated by the new energy system includes:

[0023] When the DC blocking fault is a monopole block, calculate the energy generated by the new energy system based on the monopole rated operating power and the first generator tripping time interval;

[0024] When the DC blocking fault is a bipolar block, calculate the energy generated by the new energy system based on the monopole rated operating power and the second generator tripping time interval.

[0025] Optionally, the operating data further includes the AC operating voltage of the converter station in the new energy system before a fault occurs and the upper voltage limit value after the fault occurs; the construction process of the energy model of the energy-consuming device includes:

[0026] When the DC blocking fault is a monopole block, use the capacity of the energy-consuming device to be put into operation as the parameter to be solved, and construct an energy model of the energy-consuming device according to the AC operating voltage, the upper voltage limit value, and the first generator tripping time interval, while considering the input time of the energy-consuming device;

[0027] When the DC blocking fault is a bipolar block, use the capacity of the energy-consuming device to be put into operation as the parameter to be solved, and construct an energy model of the energy-consuming device according to the AC operating voltage, the upper voltage limit value, and the second generator tripping time interval, while considering the input time of the energy-consuming device.

[0028] Optionally, the operating data further includes the equivalent concentrated capacitance, the post-fault voltage, and the initial operating voltage of different collection sites in the new energy system; the calculation process of the system capacitance energy includes:

[0029] Calculate the system capacitance energy based on each of the equivalent concentrated capacitances, each of the post-fault voltages, and each of the initial operating voltages.

[0030] The present invention also provides a power balance device for the sending end of a new energy system, including:

[0031] An operating data acquisition unit, configured to acquire the operating data of the new energy system when a DC blocking fault occurs in the new energy system;

[0032] An energy calculation unit, configured to calculate the system capacitance energy, the AC tie line energy, the energy sent out by the DC transmission system, and the energy generated by the new energy system respectively according to the operating data, and construct an energy model of the energy-consuming device;

[0033] An energy-consuming device capacity calculation unit, configured to reversely solve the capacity of the energy-consuming device to be solved in the energy model of the energy-consuming device based on the system capacitance energy, the AC tie line energy, the energy sent out by the DC transmission system, and the energy generated by the new energy system according to the law of conservation of energy;

[0034] An energy-consuming device capacity input unit, configured to input the capacity of the energy-consuming device to balance the power at the sending end of the new energy system.

[0035] The present invention also provides an electronic device, which includes a processor and a memory:

[0036] The memory is used to store program codes and transmit the program codes to the processor;

[0037] The processor is configured to execute the power balance method for the sending end of the new energy system as described in any one of the above according to the instructions in the program codes.

[0038] The present invention also provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the power balance method for the sending end of the new energy system as described in any one of the above.

[0039] It can be seen from the above technical solutions that the present invention has the following advantages:

[0040] A method for power balance at the sending end of a new energy system is provided. When a DC blocking fault occurs in the new energy system, the operating data of the new energy system is acquired; based on the operating data, the system capacitance energy, the AC tie line energy, the energy sent out by the DC transmission system, and the energy generated by the new energy system are calculated respectively, and an energy model of the energy-consuming device is constructed; based on the system capacitance energy, the AC tie line energy, the energy sent out by the DC transmission system, and the energy generated by the new energy system, the capacity of the energy-consuming device to be solved in the energy model of the energy-consuming device is reversely solved according to the law of conservation of energy; the capacity of the energy-consuming device is put into operation to balance the power at the sending end of the new energy system. Thus, when an overvoltage phenomenon occurs due to a DC blocking fault in the system, combined with the law of conservation of energy, by comprehensively considering the energy changes in the energy imbalance process, it is possible to make full use of the overvoltage capacity of the large-scale new energy base and the overload capacity of the energy-consuming device under overvoltage conditions, perform a more accurate and appropriate evaluation and calculation of the economic capacity configuration of the energy-consuming device in the large-scale new energy system, reduce the capacity configuration of the AC energy-consuming device in the large-scale new energy base, and on the basis of realizing the rapid power balance at the sending end of the new energy system, reduce the construction cost of the converter station and the subsequent operation and maintenance difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a schematic structural diagram of an islanded power system or a power system weakly connected to an AC system;

[0043] Figure 2 It is a schematic structural diagram of an energy-consuming device;

[0044] Figure 3 It is a flowchart of the steps of a method for power balance at the sending end of a new energy system;

[0045] Figure 4 It is a block diagram of the structure of a device for power balance at the sending end of a new energy system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] Embodiments of the present invention provide a method, a device, an electronic device, and a medium for power balance at the sending end of a new energy system, which are used to solve or partially solve the technical problems that the capacity configuration of the AC energy-consuming device is relatively redundant and inaccurate when balancing the energy of a new energy system with a DC blocking fault.

[0047] In order to make the objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] As an example, for a DC power transmission system with isolated grid output, the factor that has the greatest impact on system stability is the DC power transmission system lockout. When the DC power transmission system locks out, since the active power generated by new energy cannot be transmitted externally through DC, a large amount of energy will cause overvoltage in the isolated grid system, resulting in random tripping of new energy units and triggering system collapse.

[0049] The current method for solving the energy imbalance after the isolation of the isolated grid system is mainly to configure AC energy-consuming devices. The structural schematic diagram of the energy-consuming device is as Figure 2 shown. Combining Figure 2 , the energy-consuming device actually consists of a switching device and a resistor. When an energy imbalance occurs in the system, the energy-consuming device is quickly put into operation in a short time, and energy is consumed through the resistor, thereby achieving power balance in the sending-end system.

[0050] The current capacity configuration of AC energy-consuming devices often coincides with the capacity of the converter station. However, for large-scale new energy transmission systems, the above capacity configuration is relatively redundant and often does not need to reach the capacity configuration of the converter station. That is, the current power balance method has the problem of inaccurate capacity configuration. Excessive configuration of energy-consuming devices will not only greatly increase the investment cost and floor area of the converter station, but also increase the difficulty of later operation and maintenance.

[0051] Therefore, one of the core inventive points of the embodiments of the present invention is: to propose a method for power balance at the sending end of a new energy system. When a DC lockout fault occurs in the system, resulting in overvoltage, in combination with the law of conservation of energy, by comprehensively considering the energy changes during the energy imbalance process, making full use of the overvoltage capacity of large-scale new energy bases and the overload capacity of energy-consuming devices under overvoltage conditions, a more accurate and appropriate evaluation and calculation of the economic capacity configuration of energy-consuming devices in large-scale new energy systems is carried out, thereby reducing the capacity configuration of AC energy-consuming devices in large-scale new energy bases, and reducing the construction cost and subsequent operation and maintenance difficulty of the converter station on the basis of achieving rapid power balance at the sending end of the new energy system.

[0052] Referring to Figure 3 , a flowchart of the steps of a method for power balance at the sending end of a new energy system provided by an embodiment of the present invention is shown, which may specifically include the following steps:

[0053] Step 301, when a DC blocking fault occurs in the new energy system, obtain the operation data of the new energy system;

[0054] In some embodiments, the obtained operation data includes the time interval from the occurrence of the fault to the generator trip of the new energy system. Among them, the time interval of generator trip can be calculated as follows:

[0055] When the DC blocking fault is a single-pole blocking, obtain the first single restart time, the first restart times of the DC power transmission system after the occurrence of the fault, and the generator trip strategy start time after the restart fails, and calculate the first generator trip time interval according to the first single restart time, the first restart times, and the generator trip strategy start time.

[0056] When the DC blocking fault is a bipolar blocking, obtain the second single restart time and the second restart times of the DC power transmission system after the occurrence of the fault, and calculate the second generator trip time interval according to the second single restart time and the second restart times.

[0057] Specifically, the generator trip time interval can be understood as the system action time sequence after the occurrence of the fault.

[0058] After the occurrence of the fault, the DC power transmission system in the new energy system will attempt to restart. Record the time of a single restart as t r .t r Generally, it does not exceed 700 ms. After the restart fails, the generator trip strategy of the new energy system (i.e., the new energy base) will be started, and its action time is recorded as t q .t q The length of time of t is determined by the size of the new energy base and the communication design, and generally does not exceed 1 s.

[0059] After a single-pole blocking of the DC occurs, in order to ensure the stable operation of the DC system after a single-pole fault, a restart mechanism is set up according to strict consideration. The number of restarts after a single-pole blocking is recorded as N times. After failure, consider cutting off the corresponding capacity of new energy (i.e., the new energy with the same capacity as the DC single-pole). The time experienced in this process (to distinguish from the generator trip time interval of the bipolar blocking fault, it is defined as the first generator trip time interval here) is:

[0060]

[0061] After a bipolar blocking of the DC occurs, in accordance with strict consideration, a restart mechanism is also set up. The number of restarts is recorded as N times. When the N restarts fail, the entire system will enter generator tripping and load shedding. At this time, the load shedding time can be not considered, and all equipment in the system is cut off according to their respective voltage setting values. Therefore, the time considered to be experienced in this process (to distinguish from the generator trip time interval of the single-pole blocking fault, it is defined as the second generator trip time interval here) is:

[0062]

[0063] It should be noted that, for the sake of simplicity in description, both the first generator tripping time interval and the second generator tripping time interval are represented by the parameter t0, and the number of restart times is represented by the parameter N. However, in actual calculations, it is necessary to consider the use in combination with the blocking fault type (single-pole or double-pole). The bipolar fault is relatively severe for the receiving-end AC system. Usually, the number of restart times N does not exceed 1, while the number of restart times N for the single-pole fault usually does not exceed 3. It can be understood that the present invention does not limit this.

[0064] Step 302: Calculate the system capacitance energy, AC tie line energy, DC transmission system output energy, and new energy system generated energy respectively according to the operation data, and construct an energy model of the energy-consuming device;

[0065] In some embodiments, the operation data further includes the equivalent concentrated capacitance, post-fault voltage, and initial operating voltage of different collection sites in the new energy system. Then, the calculation process of the system capacitance energy can be: calculate the system capacitance energy based on each equivalent concentrated capacitance, each post-fault voltage, and each initial operating voltage.

[0066] According to the relevant grid standards, the high voltage that the new energy system is required to withstand is K p ×U acmax . Among them, K p is the multiple of overvoltage. According to the standard regulations, K p is usually 1.3 times. U acmax is the highest operating voltage of the AC system. The highest operating voltages of different voltage levels are slightly different, and specific implementation can refer to the relevant standard regulations.

[0067] In a specific implementation, the following formula can be used to calculate the increase in the voltage in the system (i.e., the energy borne by the system capacitance during this process) during the energy imbalance (i.e., after the fault occurs):

[0068]

[0069] Among them, i and j respectively represent different collection sites; C ij represents the equivalent concentrated capacitance of different collection sites, which may specifically include the capacitive reactive power compensation configured at the collection station, the filtering capacitance of the new energy device, the equivalent capacitance of the system collection line, etc.; U ij is the voltage value reached at different collection sites after the energy imbalance (i.e., the post-fault voltage). In order to reserve a certain margin, U ij shall not exceed K a ×K p ×U acmax , K aLet the safety factor be \(K\), which is usually considered as \(0.8\) to ensure sufficient equipment margin in the calculation; \(U\) ij0 Let the initial operating voltage be \(U_{ini}\), and the initial operating voltage of each site can be considered according to the highest operating voltage of the system, that is \(U_{ini}=U_{max}\) acmax .

[0070] For the special scenario of hydropower, due to the light load of the system, the frequency of the hydro turbine unit will gradually increase to absorb the excess energy. The calculation formula is as follows:

[0071]

[0072] where \(J\) ij is the equivalent moment of inertia of any hydropower collection station; \(f_2\) is the maximum frequency limit value after the fault occurs; \(f_1\) is the frequency before the fault occurs. Before the fault, the system will strictly control the operating frequency, which is usually considered to be around \(50Hz\). \(f_2\) is the limit frequency for short-term operation of the system and is usually considered as \(65Hz\).

[0073] Thus, the frequency capacity of large-capacity hydropower can be fully utilized to reduce the capacity configuration of AC energy-consuming devices in the hydropower base.

[0074] In some embodiments, the operation data further includes the power upper limit value and the power before the fault of the AC tie line in the new energy system. Then the calculation process of the AC tie line energy can be as follows: when the new energy system is not an islanded system, calculate the AC tie line energy according to the power upper limit value, the power before the fault and the generator tripping time interval. When the new energy system is an islanded system, the AC tie line energy is zero.

[0075] More specifically, considering the DC block fault type, when the new energy system is not an islanded system and the DC block fault is a single-pole block, calculate the AC tie line energy according to the power upper limit value, the power before the fault and the first generator tripping time interval. When the new energy system is not an islanded system and the DC block fault is a bipolar block, calculate the AC tie line energy according to the power upper limit value, the power before the fault and the second generator tripping time interval. When the new energy system is an islanded system, the AC tie line energy is zero.

[0076] Specifically, if the large-scale new energy system is an islanded system and not connected to the AC system, the power of the AC system tie line is zero. If it is connected to the AC system, the maximum power that the AC system tie line can carry needs to be considered. Assume that before the fault occurs, the power of the AC system tie line is \(P\) ac0 (i.e., the power before the fault). This value can be obtained by power system security and stability calculation personnel through electromechanical transient simulation software and controlled in daily dispatching.

[0077] The maximum power that the AC tie line can carry is \(P_{max}\)acmax (i.e., the upper power limit value). This value can be determined by two factors. One is the thermal load of the tie line, i.e., the maximum carrying power that cannot exceed the thermal load of the tie line. The other is the security and stability constraints of the AC system connected to the new energy base, and this value can be obtained by power system security and stability calculation personnel through electromechanical transient simulation software. P acmax can take the minimum value of the above two values.

[0078] Therefore, the energy borne by the AC tie line during this process is:

[0079]

[0080] In some embodiments, the operating data further includes the monopole rated operating power of the DC transmission system in the new energy system and the overload start time interval after a fault occurs. Then, the calculation process of the energy output by the DC transmission system can be as follows: when the DC blocking fault is a monopole blocking, calculate the energy output by the DC transmission system according to the monopole rated operating power, the overload start time interval, and the first generator tripping time interval. When the DC blocking fault is a bipolar blocking, the energy output by the DC transmission system is zero.

[0081] Specifically, after a monopole blocking occurs in the DC transmission system, the other pole has a short-term overload capacity, which reduces the lost power output. Assume that the overload coefficient of the DC transmission system after monopole blocking is K o . Then, after monopole blocking, the energy output by the DC transmission system is:

[0082]

[0083] where, P0 is the monopole rated operating power of the DC transmission system; t2 is the time from the occurrence of the fault to the start of overload, usually within 5 ms.

[0084] After bipolar blocking, all the operating power of the DC transmission system is lost, so the energy output is:

[0085]

[0086] In some embodiments, the energy generated by the new energy system is calculated based on the monopole rated operating power and the generator tripping time interval.

[0087] More specifically, considering the type of DC blocking fault, the calculation process of the energy generated by the new energy system can be as follows: when the DC blocking fault is a monopole blocking, calculate the energy generated by the new energy system based on the monopole rated operating power and the first generator tripping time interval. When the DC blocking fault is a bipolar blocking, calculate the energy generated by the new energy system based on the monopole rated operating power and the second generator tripping time interval.

[0088] W np is the energy generated by the new energy system within time t0. Considering strictly, during this process, since the only transmission channel outside the new energy base is DC, its maximum transmission power is the DC bipolar power. Therefore, the power generated by the new energy is the DC bipolar transmission power. The calculation formula for the energy generated by the new energy is as follows:

[0089]

[0090] For the special scenario of hydropower, assume W w is the energy generated by the hydropower system within time t0. On the one hand, during the fault process, the power output by the hydropower unit cannot be quickly reduced and still continues to send out energy. Its calculation formula is as follows:

[0091]

[0092] When a large-scale new energy base has an energy imbalance caused by DC blocking, the key point of the stability control is to promptly put into operation the energy-consuming device to quickly form an energy balance in the system, thereby avoiding excessive energy from charging the capacitors in the AC system and causing overvoltage in the entire system.

[0093] In some embodiments, the operation data further includes the AC operating voltage of the converter station in the new energy system before the fault occurs and the voltage upper limit value after the fault occurs. Then, the construction process of the energy model of the energy-consuming device can be: taking the capacity of the energy-consuming device to be put into operation as the parameter to be solved, and constructing the energy model of the energy-consuming device according to the AC operating voltage, the voltage upper limit value, and the generator tripping time interval, while considering the input time of the energy-consuming device.

[0094] More specifically, considering the DC blocking fault type, when the DC blocking fault is single-pole blocking, taking the capacity of the energy-consuming device to be put into operation as the parameter to be solved, and constructing the energy model of the energy-consuming device according to the AC operating voltage, the voltage upper limit value, and the first generator tripping time interval, while considering the input time of the energy-consuming device. When the DC blocking fault is bipolar blocking, taking the capacity of the energy-consuming device to be put into operation as the parameter to be solved, and constructing the energy model of the energy-consuming device according to the AC operating voltage, the voltage upper limit value, and the second generator tripping time interval, while considering the input time of the energy-consuming device.

[0095] Specifically, since the energy-consuming device is actually a resistor, as the AC voltage increases, the power of the resistor actually also increases. Therefore, after the energy imbalance, the energy actually consumed by the energy-consuming device can be calculated using the following formula (i.e., the corresponding constructed energy model of the energy-consuming device):

[0096]

[0097] where, U conThe highest voltage that the converter station can reach after energy imbalance (i.e., the upper limit of voltage after the fault occurs) does not exceed K a ×K p ×U acmax where K a is the safety factor, usually considered to be 0.8; U ac is the AC operating voltage of the converter station before energy imbalance (i.e., the AC operating voltage before the fault occurs). Since the voltage of the converter station is restricted by the flexible DC, it can be considered according to the rated voltage of the AC system, which is U acN . P R is the rated capacity of the energy-consuming device to be solved, that is, the target to be determined in the present invention; t1 is the input time of the energy-consuming device, usually not exceeding 2 ms.

[0098] Step 303, based on the system capacitance energy, the AC tie line energy, the DC transmission system output energy, and the new energy system output energy, reversely solve the capacity of the energy-consuming device to be solved in the energy model of the energy-consuming device according to the law of conservation of energy;

[0099] Consider the law of conservation of energy during the fault process:

[0100]

[0101] By substituting the formula and reversely solving, the capacity of the energy-consuming device to be solved can be obtained.

[0102] In the case of a single-pole fault, the capacity of the energy-consuming device can be solved by the following expression:

[0103]

[0104] In the case of a bipolar fault, the capacity of the energy-consuming device can be solved by the following expression:

[0105]

[0106] where the required tolerance time of the energy-consuming device is t0 - t1.

[0107] For the special scenario of hydropower (when the power of the AC system tie line is not considered at this time), then consider the law of conservation of energy during the fault process, and there is:

[0108]

[0109] Similarly, by substituting the formula and reversely solving, the capacity of the energy-consuming device to be solved can be obtained.

[0110] In the case of a single-pole fault, the capacity of the energy-consuming device in the hydropower scenario can be solved by the following expression:

[0111]

[0112] In the case of a bipolar fault, the capacity of the energy-consuming device in the hydropower scenario can be solved by the following expression:

[0113]

[0114] Among them, the required tolerance time of the energy-consuming device is t0 - t1.

[0115] Step 304, input the capacity of the energy-consuming device to balance the power at the sending end of the new energy system.

[0116] After calculating the capacity of the energy-consuming device, by promptly inputting the energy-consuming device, the system can quickly form an energy balance, avoiding excessive energy from charging the capacitors in the AC system and causing overvoltage in the entire system.

[0117] In the embodiment of the present invention, a method for power balance at the sending end of a new energy system is proposed. When a DC blocking fault occurs in the system, resulting in an overvoltage phenomenon, combining the law of conservation of energy, by comprehensively considering the energy changes during the energy imbalance process, making full use of the overvoltage capacity of the large-scale new energy base and the overload capacity of the energy-consuming device under overvoltage conditions, a more accurate and appropriate evaluation and calculation of the economic capacity configuration of the energy-consuming device in the large-scale new energy system is carried out, thereby reducing the capacity configuration of the AC energy-consuming device in the large-scale new energy base, and on the basis of achieving rapid power balance at the sending end of the new energy system, reducing the construction cost and subsequent operation and maintenance difficulty of the converter station.

[0118] To enable those skilled in the art to better understand the technical solution of the present invention, the following briefly describes the embodiments of the present invention through two specific examples.

[0119] Example 1:

[0120] Considering that the capacity of the DC transmission system is 8000 MW, the power of single-pole operation is 4000 MW.

[0121] The collection system is considered as a 500 kV AC system. Considering the voltage stability margin, the rated operating voltage of the new energy system is controlled at 500 kV, and the highest operating voltage is 550 kV.

[0122] The centralized capacitor compensation amount of the entire system is considered according to 20% of the operating power, then the centralized capacitor of the system is 20.38 uF.

[0123] The new energy system is considered to operate in an island mode, that is, the P of the AC system acmax and P ac0 are both zero.

[0124] The voltage safety factor is according to K aConsider 0.8, the number of single - pole blocking restart times is considered as 3 times, and the number of double - pole blocking restart times is considered as 1 time.

[0125] The input time t1 of the energy - consuming device is considered as 2 ms, the DC overload operation time is considered as 2 ms. The single restart time is 600 ms, and the generator - tripping time is considered as 1 s.

[0126] Based on the above conditions, when considering a single - pole blocking fault, the required AC energy - consuming device capacity is 2142 MW, and the tolerance time is 2.8 s. When considering a double - pole blocking fault, the required AC energy - consuming device capacity is 6133 MW, and the tolerance time is 0.6 s.

[0127] Example 2:

[0128] For the hydropower scenario, considering the DC transmission system capacity of 8000 MW, the single - pole operation power is 4000 MW. The total inertia of the hydropower system is considered as 150, the highest operating frequency after the fault is considered as 65 Hz, and the frequency before the fault is considered as 50 Hz.

[0129] The number of single - pole blocking restart times is considered as 3 times, and the number of double - pole blocking restart times is considered as 1 time.

[0130] The input time t1 of the energy - consuming device is considered as 2 ms, the DC overload operation time is considered as 2 ms. The single restart time is 600 ms, and the generator - tripping time is considered as 1 s.

[0131] Based on the above conditions, when considering a single - pole blocking fault, the required AC energy - consuming device capacity is 980 MW, and the tolerance time is 2.8 s. When considering a double - pole blocking fault, the required AC energy - consuming device capacity is 0 MW, and the tolerance time is 0.6 s.

[0132] It can be seen that by executing according to the above requirements, whether it is the capacity of the AC energy - consuming device put into operation or the tolerance time, both are much lower compared to the DC rated power, thus verifying the effectiveness of the technical solution of the present invention.

[0133] Refer to Figure 4 , which shows the structural block diagram of a sending - end power balance device for a new - energy system provided by an embodiment of the present invention, and specifically may include:

[0134] An operation data acquisition unit 401, configured to acquire the operation data of the new - energy system when a DC blocking fault occurs in the new - energy system;

[0135] An energy calculation unit 402, configured to calculate the system capacitance energy, the AC tie - line energy, the DC transmission system output energy, and the new - energy system generated energy respectively according to the operation data, and construct an energy - consuming device energy model;

[0136] An energy consumption device capacity calculation unit 403 is configured to, based on the system capacitance energy, the AC tie line energy, the energy transmitted by the HVDC system, and the energy generated by the new energy system, inversely solve the energy consumption device capacity to be solved in the energy consumption device energy model according to the law of conservation of energy;

[0137] An energy consumption device capacity input unit 404 is configured to input the energy consumption device capacity to balance the power at the sending end of the new energy system.

[0138] In an alternative embodiment, the operating data includes the time interval from the occurrence of the fault to the generator tripping of the new energy system; the device further includes:

[0139] A first generator tripping time interval calculation unit is configured to, when the DC blocking fault is a single-pole blocking, obtain the first single restart time, the first restart times of the HVDC system after the occurrence of the fault, and the generator tripping strategy start time after the restart fails, and calculate a first generator tripping time interval according to the first single restart time, the first restart times, and the generator tripping strategy start time;

[0140] A second generator tripping time interval calculation unit is configured to, when the DC blocking fault is a bipolar blocking, obtain the second single restart time and the second restart times of the HVDC system after the occurrence of the fault, and calculate a second generator tripping time interval according to the second single restart time and the second restart times.

[0141] In an alternative embodiment, the operating data further includes the power upper limit value and the power before the fault of the AC tie line in the new energy system; the calculation process of the AC tie line energy in the energy calculation unit 402 includes:

[0142] When the new energy system is not an islanded system and the DC blocking fault is a single-pole blocking, calculate the AC tie line energy according to the power upper limit value, the power before the fault, and the first generator tripping time interval;

[0143] When the new energy system is not an islanded system and the DC blocking fault is a bipolar blocking, calculate the AC tie line energy according to the power upper limit value, the power before the fault, and the second generator tripping time interval;

[0144] When the new energy system is an islanded system, the AC tie line energy is zero.

[0145] In an alternative embodiment, the operating data further includes the single-pole rated operating power of the HVDC system in the new energy system and the overload start time interval after the occurrence of the fault; the calculation process of the energy transmitted by the HVDC system in the energy calculation unit 402 includes:

[0146] When the DC blocking fault is a single - pole blocking, calculate the energy output by the HVDC transmission system according to the single - pole rated operating power, the overload start time interval, and the first generator tripping time interval.

[0147] When the DC blocking fault is a bipolar blocking, the energy output by the HVDC transmission system is zero.

[0148] In an alternative embodiment, the operating data further includes the single - pole rated operating power of the HVDC transmission system in the new energy system and the overload start time interval after the fault occurs; the calculation process of the energy generated by the new energy system in the energy calculation unit 402 includes:

[0149] When the DC blocking fault is a single - pole blocking, calculate the energy generated by the new energy system based on the single - pole rated operating power and the first generator tripping time interval.

[0150] When the DC blocking fault is a bipolar blocking, calculate the energy generated by the new energy system based on the single - pole rated operating power and the second generator tripping time interval.

[0151] In an alternative embodiment, the operating data further includes the AC operating voltage of the converter station in the new energy system before the fault occurs and the voltage upper limit value after the fault occurs; the process of constructing the energy model of the energy - consuming device in the energy calculation unit 402 includes:

[0152] When the DC blocking fault is a single - pole blocking, taking the capacity of the energy - consuming device to be put into operation as the parameter to be solved, construct an energy model of the energy - consuming device according to the AC operating voltage, the voltage upper limit value, and the first generator tripping time interval, while considering the input time of the energy - consuming device.

[0153] When the DC blocking fault is a bipolar blocking, taking the capacity of the energy - consuming device to be put into operation as the parameter to be solved, construct an energy model of the energy - consuming device according to the AC operating voltage, the voltage upper limit value, and the second generator tripping time interval, while considering the input time of the energy - consuming device.

[0154] In an alternative embodiment, the operating data further includes the equivalent concentrated capacitance of different collection sites in the new energy system, the post - fault voltage, and the initial operating voltage; the calculation process of the system capacitance energy in the energy calculation unit 402 includes:

[0155] Calculate the system capacitance energy based on each of the equivalent concentrated capacitances, each of the post - fault voltages, and each of the initial operating voltages.

[0156] For the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For related parts, refer to the corresponding description in the foregoing method embodiment.

[0157] It should be noted that, in order to enable those skilled in the art to better distinguish data with the same type but different actual pointing meanings, in the embodiments of the present invention, some technical features are distinguished and described by using first and second. First and second are only used for data distinction and have no other special meanings. It can be understood that the present invention makes no limitation in this regard.

[0158] The embodiments of the present invention also provide an electronic device, which includes a processor and a memory:

[0159] The memory is used for storing program codes and transmitting the program codes to the processor;

[0160] The processor is used for executing the power balance method for the sending end of the new energy system according to any one of the embodiments of the present invention according to the instructions in the program codes.

[0161] The embodiments of the present invention also provide a computer-readable storage medium, which is used for storing program codes, and the program codes are used for executing the power balance method for the sending end of the new energy system according to any one of the embodiments of the present invention.

[0162] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the above-described systems, devices, and units can refer to the corresponding processes in the foregoing method embodiments, and will not be elaborated herein.

[0163] In several embodiments provided by the present invention, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces, and the indirect couplings or communication connections of the devices or units can be in electrical, mechanical, or other forms.

[0164] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place, or can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0165] In addition, in each embodiment of the present invention, each functional unit can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software functional unit.

[0166] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present invention. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0167] As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; 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 each embodiment of the present invention.

Claims

1. A method for power balance at the sending end of a new energy system, characterized in that, Including: When a DC blocking fault occurs in the new energy system, obtain the operation data of the new energy system; According to the operation data, calculate the system capacitance energy, AC tie line energy, DC transmission system output energy, and new energy system generated energy respectively, and construct an energy consumption device energy model; Based on the system capacitance energy, the AC tie line energy, the DC transmission system output energy, and the new energy system generated energy, inversely solve the capacity of the energy consumption device to be solved in the energy consumption device energy model according to energy conservation; Input the capacity of the energy consumption device to balance the power at the sending end of the new energy system.

2. The method for balancing the sending-end power of the new energy system according to claim 1, wherein The operation data includes the time interval from the occurrence of the fault to the generator tripping of the new energy system; the method further includes: When the DC blocking fault is a single-pole blocking, obtain the first single restart time, the first restart times, and the generator tripping strategy start time of the DC transmission system after the occurrence of the fault, and calculate the first generator tripping time interval according to the first single restart time, the first restart times, and the generator tripping strategy start time; When the DC blocking fault is a bipolar blocking, obtain the second single restart time and the second restart times of the DC transmission system after the occurrence of the fault, and calculate the second generator tripping time interval according to the second single restart time and the second restart times.

3. The method for balancing the power at the sending end of the new energy system according to claim 2, characterized in that, The operation data further includes the power upper limit value and the power before the fault of the AC tie line in the new energy system; the calculation process of the AC tie line energy includes: When the new energy system is not an islanded system and the DC blocking fault is a single-pole blocking, calculate the AC tie line energy according to the power upper limit value, the power before the fault, and the first generator tripping time interval; When the new energy system is not an islanded system and the DC blocking fault is a bipolar blocking, calculate the AC tie line energy according to the power upper limit value, the power before the fault, and the second generator tripping time interval; When the new energy system is an islanded system, the AC tie line energy is zero.

4. The method for balancing the sending-end power of the new energy system according to claim 2, characterized in that, The operation data further includes the single-pole rated operating power of the DC transmission system in the new energy system and the overload start time interval after the occurrence of the fault; the calculation process of the DC transmission system output energy includes: When the DC blocking fault is a single-pole blocking, calculate the DC transmission system output energy according to the single-pole rated operating power, the overload start time interval, and the first generator tripping time interval; When the DC blocking fault is a bipolar blocking, the DC transmission system output energy is zero.

5. The method for balancing the sending-end power of the new energy system according to claim 2, wherein The operation data further includes the single-pole rated operating power of the DC transmission system in the new energy system and the overload start time interval after the occurrence of the fault; the calculation process of the new energy system generated energy includes: When the DC blocking fault is a single-pole blocking, calculate the new energy system generated energy based on the single-pole rated operating power and the first generator tripping time interval; When the DC blocking fault is a bipolar blocking, calculate the new energy system generated energy based on the single-pole rated operating power and the second generator tripping time interval.

6. The method for balancing the sending-end power of the new energy system according to claim 2, characterized in that, The operating data further includes the AC operating voltage of the converter station in the new energy system before a fault occurs and the voltage upper limit value after the fault occurs; the construction process of the energy consumption device energy model includes: When the DC blocking fault is a single-pole blocking, taking the capacity of the energy consumption device to be put into operation as the parameter to be solved, and constructing an energy consumption device energy model according to the AC operating voltage, the voltage upper limit value, and the first generator tripping time interval, while considering the energy consumption device input time; When the DC blocking fault is a bipolar blocking, taking the capacity of the energy consumption device to be put into operation as the parameter to be solved, and constructing an energy consumption device energy model according to the AC operating voltage, the voltage upper limit value, and the second generator tripping time interval, while considering the energy consumption device input time.

7. The method for balancing the sending-end power of the new energy system according to any one of claims 1 to 6, characterized in that, The operating data further includes the equivalent concentrated capacitance, the post-fault voltage, and the initial operating voltage of different collection sites in the new energy system; The calculation process of the system capacitance energy includes: Calculating the system capacitance energy based on each of the equivalent concentrated capacitances, each of the post-fault voltages, and each of the initial operating voltages.

8. A power balance device for the sending end of a new energy system, characterized in that, Including: An operating data acquisition unit, configured to acquire the operating data of the new energy system when a DC blocking fault occurs in the new energy system; An energy calculation unit, configured to calculate the system capacitance energy, the AC tie line energy, the DC transmission system output energy, and the new energy system generated energy respectively according to the operating data, and construct an energy consumption device energy model; An energy consumption device capacity calculation unit, configured to, based on the system capacitance energy, the AC tie line energy, the DC transmission system output energy, and the new energy system generated energy, inversely solve the capacity of the energy consumption device to be solved in the energy consumption device energy model according to energy conservation; An energy consumption device capacity input unit, configured to input the energy consumption device capacity to balance the power at the sending end of the new energy system.

9. An electronic device, characterized in that, The device includes a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is configured to execute the new energy system sending end power balance method according to any one of claims 1-7 based on the instructions in the program codes.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program codes, and the program codes are used to execute the new energy system sending end power balance method according to any one of claims 1-7.

Images