Inverter, power station, control method and related device
By controlling the DC-AC circuit of the inverter to achieve the preset voltage and current during the black start process, the problem of how to stably supply power to the inverter after the grid is disconnected is solved, realizing a low-cost and low-risk black start process.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2026-03-27
AI Technical Summary
After a grid failure, how the inverters of a microgrid system can perform a black start to supply power to the load is a critical issue that existing technologies cannot effectively address.
By controlling the DC-AC circuit of the inverter to reach the preset voltage before outputting the AC phase voltage, and by adjusting the amplitude and phase of the AC phase voltage, the phase current is controlled to the target current, ensuring the stable start-up of the inverter.
This enables low-cost black start of the inverter, reduces the risk of overcurrent, and ensures the reliability and current quality of power grid restoration.
Smart Images
Figure CN121749346A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of power electronics, in particular to an inverter, a power station, a control method and related devices. BACKGROUND
[0002] The power station of the current micro-grid system includes new energy and multiple inverters. The micro-grid system can effectively support the power grid, such as power fluctuation suppression, peak clipping and valley filling, power grid strength improvement, frequency or voltage fluctuation suppression, etc. Multiple inverters are connected to the AC bus through an isolation transformer, and the AC bus is connected to the power grid through a main transformer.
[0003] When a major accident occurs in the power grid, the power station is disconnected from the power grid, and the inverter of the power station needs to be restarted to establish an AC bus voltage for power supply to the load, which is called black start.
[0004] After the power station enters the off-grid mode, how the inverter performs black start in the case of disconnection between the power station and the power grid is a key problem to be solved. SUMMARY
[0005] Therefore, the present application provides an inverter, a power station, a control method and related devices, which can control the inverter to perform black start, and has low cost and reduces the risk of overcurrent.
[0006] The present application provides an inverter, comprising: a direct current-alternating current circuit and a processor; a first end of the direct current-alternating current circuit is used for connecting a direct current source, and a second end of the direct current-alternating current circuit is used for connecting an alternating current bus; the processor is used for controlling a direct current side voltage of the direct current-alternating current circuit to reach a preset voltage before the direct current-alternating current circuit outputs an alternating current phase voltage; the processor is used for giving a wave to the direct current-alternating current circuit to make the direct current-alternating current circuit output the alternating current phase voltage, controlling an amplitude value of an alternating current side phase voltage of the direct current-alternating current circuit, and making a phase current of the direct current-alternating current circuit be a target current.
[0007] In a possible implementation manner, the inverter further comprises a filter; the filter is connected at the second end of the direct current-alternating current circuit; the processor is specifically used for controlling the direct current side voltage of the direct current-alternating current circuit to reach the preset voltage before the direct current-alternating current circuit outputs the alternating current phase voltage; in a case where a load voltage exceeds a first voltage value, the processor is used for giving a wave to the direct current-alternating current circuit to make the direct current-alternating current circuit output the alternating current phase voltage, and controlling the alternating current side phase voltage of the direct current-alternating current circuit according to a load voltage vector and an inductance voltage vector in the filter, so that the phase current of the direct current-alternating current circuit is the target current; the inductance voltage vector is obtained according to the target current and an inductance of the filter.
[0008] In a possible implementation, the processor is further configured to adjust the phase of the modulation voltage sent to the DC-AC circuit, and the phase of the modulation voltage corresponding to when the load voltage reaches the maximum value or the load current reaches the maximum value is taken as the final phase of the inverter.
[0009] In a possible implementation, the processor is further configured to superimpose the phase difference between the AC-side phase voltage and the phase current of the inverter on the phase of the modulation voltage sent by the power conversion circuit.
[0010] In a possible implementation, the power conversion circuit further includes a DC-DC circuit, a first end of the DC-DC circuit is configured to be connected to a DC source, and a second end of the DC-DC circuit is configured to be connected to the first end of the DC-AC circuit.
[0011] The processor is specifically configured to control the DC-DC conversion circuit to make the voltage at the first end of the DC-AC circuit reach a preset voltage before the DC-AC circuit outputs an AC phase voltage.
[0012] In a possible implementation, the first end of the DC-AC circuit is configured to be connected to a DC source, and the second end of the DC-AC circuit is configured to be connected to an AC bus.
[0013] The processor is specifically configured to control the DC source to make the voltage at the first end of the DC-AC circuit reach a preset voltage before the DC-AC circuit outputs an AC phase voltage.
[0014] In a possible implementation, the preset voltage is in a positive correlation with a target current, and the processor is specifically configured to control the AC-side phase voltage amplitude of the DC-AC circuit to make the phase current of the DC-AC circuit be the target current and make the ratio of the AC-side phase voltage amplitude to the DC-side half bus voltage be a preset ratio.
[0015] The application further provides a power station, including: m inverters; the AC side of the m inverters is configured to be connected to an AC bus; and the DC side of the m inverters is configured to be connected to corresponding DC sources.
[0016] Before an i-th inverter that is not black started outputs an AC phase voltage, the voltage at the DC side of the DC-AC circuit in the i-th inverter is controlled to reach a preset voltage; the i-th inverter is sent a wave to make the i-th inverter output an AC phase voltage; the AC-side phase voltage amplitude of the DC-AC circuit in the i-th inverter is controlled to make the phase current of the DC-AC circuit in the i-th inverter be a target current, the m is an integer greater than or equal to 2, and the i-th inverter is any inverter that is black started.
[0017] In a possible implementation, the i-th inverter further includes a filter, and the filter is connected to the second end of the DC-AC circuit; the i-th inverter is specifically configured to, before the i-th inverter outputs the AC phase voltage, control the DC side voltage of the DC-AC circuit to reach a preset voltage; in a case where the load voltage exceeds a first voltage value, the i-th inverter is enabled to output the AC phase voltage, and the AC side phase voltage of the i-th inverter is controlled according to a load voltage vector and an inductance voltage vector in the filter, so that the phase current of the i-th inverter is the target current; the inductance voltage vector is obtained according to the target current and the inductance of the filter.
[0018] In a possible implementation, the i-th inverter is further configured to adjust the phase of the modulation voltage sent to the i-th inverter, and the phase of the corresponding modulation voltage when the load voltage reaches a maximum value or the load current reaches a maximum value is taken as the final phase of the inverter.
[0019] In a possible implementation, the i-th inverter is further configured to, in a case where a synchronization instruction sent by a local controller of the power station is received, superimpose a phase difference between the AC side phase voltage and the phase current of the i-th inverter on the phase of the modulation voltage sent by the i-th inverter.
[0020] In a possible implementation, the i-th inverter is further configured to, in a case where the load voltage of the i-th inverter exceeds a second voltage value, control the AC side phase voltage amplitude and the phase of the i-th inverter by using a droop control mode.
[0021] In a possible implementation, the power station further includes a host computer; the host computer sends a black start instruction to an inverter that has not been black started, and the inverter that has not been black started detects the voltage of the AC bus to perform a synchronous start.
[0022] In a possible implementation, the host computer is further configured to gradually increase a control voltage, and send the control voltage to the m inverter, so that the m inverter controls the AC side phase voltage of the m inverter according to the control voltage.
[0023] The application further provides a control method of an inverter, including: before a DC-AC circuit in the inverter outputs an AC phase voltage, controlling a DC side voltage of the DC-AC circuit to reach a preset voltage; enabling the DC-AC circuit to output the AC phase voltage, and controlling an AC side phase voltage amplitude of the DC-AC circuit, so that a phase current of the DC-AC circuit is a target current.
[0024] In a possible implementation, the DC-AC circuit is enabled to output an AC phase voltage, the AC side phase voltage of the DC-AC circuit is controlled, and the phase current of the DC-AC circuit is controlled to be the target current, and the method specifically includes the following steps.
[0025] Before the DC-AC circuit outputs the AC phase voltage, the DC side voltage of the DC-AC circuit is controlled to reach a preset voltage; in a case where the load voltage exceeds a first voltage value, the DC-AC circuit is enabled to output the AC phase voltage, the AC side phase voltage of the DC-AC circuit is controlled according to a load voltage vector and an inductor voltage vector in the filter, and the phase current of the DC-AC circuit is controlled to be the target current; and the inductor voltage vector is obtained according to the target current and the inductor of the filter.
[0026] In a possible implementation, the method further includes adjusting the phase of the modulation voltage used to enable the DC-AC circuit, and the phase of the modulation voltage corresponding to a time when the load voltage reaches a maximum value or the load current reaches a maximum value is taken as the final phase of the inverter.
[0027] In a possible implementation, the method further includes superimposing a phase difference between the AC side phase voltage and the phase current of the inverter on the phase of the modulation voltage used to enable the power conversion circuit.
[0028] In a possible implementation, the AC side phase voltage of the DC-AC circuit is controlled, and the phase current of the DC-AC circuit is controlled to be the target current, and the method specifically includes the following steps.
[0029] The AC side phase voltage of the DC-AC circuit is controlled, the phase current of the DC-AC circuit is controlled to be the target current, and a ratio of the AC side phase voltage to the DC side half bus voltage is a preset ratio; and the preset voltage is in a positive correlation with the target current.
[0030] The application further provides a control device, including a processor and a memory, the memory is used for storing programs, instructions or codes, and the processor is used for executing the programs, instructions or codes in the memory to complete the control method of the power converter as described above.
[0031] The application further provides a computer readable storage medium, which stores a computer program, and the computer program is loaded by a processor to execute the control method of the power converter as described above.
[0032] The inverter provided by the embodiment of the present application is used for black start. Before outputting an AC phase voltage of a DC-AC circuit, the processor controls a DC side voltage of the DC-AC circuit to reach a preset voltage, so as to facilitate control of a phase current of an output end of the inverter. After the DC side voltage reaches the preset voltage, the phase current of the inverter is controlled to reach a target current by adjusting an amplitude of the AC side phase voltage. Specifically, a driving signal sent to the DC-AC circuit, that is, a wave sending, is adjusted, so as to ensure the quality of the output current of the inverter, thereby realizing the black start of the inverter. Each inverter is started in the manner, so that overcurrent of the inverter can be avoided. BRIEF DESCRIPTION OF DRAWINGS
[0033] Figure 1 A schematic diagram of a power station provided by the embodiment of the present application;
[0034] Figure 2 A schematic diagram of an inverter provided by the embodiment of the present application;
[0035] Figure 3 A schematic diagram of another inverter provided by the embodiment of the present application;
[0036] Figure 4 A schematic diagram of another inverter provided by the embodiment of the present application;
[0037] Figure 5 A flowchart of a control method of an inverter provided by the embodiment of the present application;
[0038] Figure 6 A schematic diagram of a control device provided by the embodiment of the present application. DETAILED DESCRIPTION
[0039] In order for those skilled in the art to better understand and implement the technical solutions provided by the embodiment of the present application, the application scenario of black start is introduced below in combination with a hardware architecture diagram.
[0040] Referring to Figure 1 The diagram is a schematic diagram of a power station provided by the embodiment of the present application.
[0041] The power station provided by the embodiment of the present application includes multiple energy storage systems, such as Figure 1 As shown in the figure, the energy storage systems include multiple, respectively, a first energy storage system BESS1, a second energy storage system BESS2, and an Nth energy storage system BESSN. One of the energy storage systems can include one or more inverters. The inverters in each energy storage system can be connected to a corresponding DC source, for example, the DC source can be one or both of a photovoltaic panel or an energy storage battery.
[0042] Each energy storage system is connected to an AC bus MVBUS through a corresponding isolation transformer, as Figure 1As shown, the first energy storage system BESS1 is connected to the AC bus MVBUS through the first isolation transformer T1, the second energy storage system BESS2 is connected to the AC bus MVBUS through the second isolation transformer T2, and the Nth energy storage system BESSN is connected to the AC bus MVBUS through the Nth isolation transformer TN.
[0043] The AC bus MVBUS is connected to the power grid through the series-connected circuit breaker MCB and the main transformer MT. The load is connected to the AC bus MVBUS.
[0044] The power station further comprises a local controller, which can control the inverters in the energy storage system to perform black start. In addition, the power station can further comprise a host computer, which can send instructions to the local controller.
[0045] Black start refers to the disconnection of the AC bus MVBUS from the power grid, i.e., the AC side of each inverter is not supported by the power grid, and each inverter needs to be started and supply power to the load.
[0046] To make the above objectives, features and advantages of the present application more apparent and understandable, the embodiments of the present application are further described in detail below with reference to the accompanying drawings and specific embodiments.
[0047] Referring to Figure 2 , the figure is a schematic diagram of an inverter provided by an embodiment of the present application.
[0048] The inverter provided by the embodiment of the present application comprises a processor 20, and in addition, the inverter further comprises at least a DC-AC circuit 12. The inverter provided by the embodiment of the present application can be any one of the following inverters. Figure 1
[0049] The first end of the DC-AC circuit 12 is used to connect to a DC source 30, and the second end of the DC-AC circuit 12 is used to connect to an AC bus MVBUS. It should be understood that in actual work, the inverter can be connected to the AC bus MVBUS through an isolation transformer.
[0050] The embodiment of the present application does not specifically limit the way in which the inverter controls the DC side voltage, and two different inverter architectures are introduced below with reference to the accompanying drawings. The inverter can be a single-stage inverter, i.e., the inverter does not comprise a DC-DC circuit, but only comprises a DC-AC circuit. In addition, the inverter can also be a two-stage inverter, i.e., the inverter comprises both a DC-DC circuit and a DC-AC circuit.
[0051] The processor 20 is configured to control the DC side voltage of the DC-AC circuit 12 to reach a preset voltage before the DC-AC circuit 12 outputs the AC phase voltage; and control the amplitude of the AC side phase voltage of the DC-AC circuit 12 to make the phase current of the DC-AC circuit 12 be the target current. When the processor 20 adjusts the phase current, the amplitude of the AC side phase voltage can be adjusted to achieve the adjustment of the phase current, for example, the amplitude of the AC side phase voltage is increased or decreased by a preset step to adjust the phase current, and the open-loop mode can be used to achieve the control, which is simple.
[0052] For the convenience of understanding, the modulation degree M is introduced, which refers to the ratio of the amplitude of the AC side phase voltage of the DC-AC circuit to the half bus voltage of the DC side. The modulation degree M is generally greater than 0 and less than or equal to 1, and can be set according to actual needs, which is not limited in the embodiments of the present application, for example, 0.8, 0.9 or 1, etc. The processor is specifically configured to control the amplitude of the AC side phase voltage of the DC-AC circuit to make the phase current of the DC-AC circuit be the target current, and the ratio of the amplitude of the AC side phase voltage to the half bus voltage of the DC side be a preset proportion, i.e., the modulation degree. The preset proportion of the modulation degree in the present application is to make the ratio of the amplitude of the AC side phase voltage of the inverter to the half bus voltage of the DC side be in a suitable range, which is beneficial to improve the quality of the output current of the inverter. Generally, the smaller the modulation degree is, the greater the voltage harmonic is, and then the greater the current harmonic is. Therefore, it is generally not desirable that the modulation degree is too small, for example, it can be set to a relatively large value such as 0.8 or 0.9, so as to reduce the voltage harmonic and then reduce the current harmonic, and ensure the quality of the output current of the inverter. In addition, when the modulation degree is relatively large, the proportion of narrow pulses in the modulation process can be reduced, and then the influence of the dead time can be reduced, so that the quality of the output current can also be improved. In order to be consistent with the AC side phase voltage, the output current of the inverter in the embodiments of the present application is represented by the phase current.
[0053] Specifically, the processor 20 controls the AC side voltage by controlling the amplitude of the AC modulation voltage, i.e., the amplitude of the AC modulation voltage is used to control the amplitude of the AC side phase voltage.
[0054] The inverter provided by the embodiments of the present application has a set target current, and therefore, in order to facilitate the control of the DC side voltage, the preset voltage can be set to be in a proportional relationship with the target current. When the preset voltage is set to be in a proportional relationship with the target current, the control of the modulation degree is also facilitated, because the modulation degree is related to the DC side voltage. In a specific implementation, the preset voltage Uset can be the ratio of the inductance voltage UL of the filter connected to the AC side of the inverter to the modulation degree M, i.e., Uset=UL / M. In addition, the influence of the effective value is considered, For example, the target current is denoted as Iset, then the inductance voltage UL = 2πfL*Iset. L represents the inductance value of the inductance. f represents the frequency of the output voltage of the inverter, which can be 50Hz for example. Since UL is proportional to the target current, it can also be understood that the preset voltage is proportional to the target current.
[0055] The DC side voltage of the DC-AC circuit 10 refers to the voltage at the first end of the DC-AC circuit, and the second end of the DC-AC circuit is used to connect an isolation transformer, and the first end of the DC-AC circuit is used to connect a DC source or a previous stage DC-DC circuit.
[0056] The inverter provided by the embodiment of the present application first controls the DC side voltage to be a preset voltage when controlling the inverter to perform black start, and the preset voltage can be set according to the target current. The purpose of adjusting the DC side voltage before the inverter outputs an AC phase voltage is to adjust the DC side voltage to the preset voltage, which facilitates subsequent control of the output current of the DC-AC circuit. When the DC side voltage is small, the corresponding voltage harmonic is small, and therefore the current harmonic is also small, which is conducive to improving the quality of the output current of the inverter.
[0057] Referring to Figure 3 , which is a schematic diagram of another inverter provided by the embodiment of the present application.
[0058] The inverter provided by the embodiment of the present application includes a DC-DC circuit 11 and a DC-AC circuit 12; the first end of the DC-DC circuit 11 is used to connect a DC source, the second end of the DC-DC circuit 11 is used to connect the first end of the DC-AC circuit 12, and the second end of the DC-AC circuit 12 is used to connect an AC bus; it should be understood that in actual application, the second end of the DC-AC circuit 12 is generally connected to the AC bus through an isolation transformer.
[0059] The processor 20 is specifically configured to control the DC-DC conversion circuit 11 to make the voltage at the first end of the DC-AC circuit 12 reach a preset voltage, i.e. Figure 3 Ubus in the formula (1) before the inverter outputs a wave to the DC-AC circuit. For a two-stage inverter, the DC side voltage refers to the DC bus voltage.
[0060] For example, when the DC source is a photovoltaic panel, the processor 20 can control the DC voltage at the second end of the DC-DC conversion circuit 11 according to the current-voltage IV curve of the photovoltaic panel, so that Ubus reaches the preset voltage, for example, the preset voltage is Uset. For example, Uset can be set as 400V. Similarly, when the DC source is an energy storage battery, the processor 20 can also adjust the DC voltage at the second end of the DC-DC conversion circuit 11.
[0061] Referring to Figure 4Fig. 2 is a schematic diagram of another inverter provided by the embodiments of the present application.
[0062] The inverter provided by the embodiments of the present application includes a DC-AC circuit 12. The first end of the DC-AC circuit 12 is used to connect a DC source, and the second end of the DC-AC circuit 12 is used to connect an AC bus. For a single-stage inverter, the DC-side voltage Ubus refers to the input voltage of the inverter, i.e., the input voltage of the DC-AC circuit 12.
[0063] The processor 20 is specifically configured to control the DC source to make the voltage at the first end of the DC-AC circuit 12 reach a preset voltage before the DC-AC circuit outputs an AC phase voltage. For example, when the DC source is a battery, the number of batteries connected can be controlled to adjust the voltage at the first end of the DC-AC circuit 12, so that the DC-side voltage reaches the preset voltage.
[0064] The inverter provided by the embodiments of the present application is used for black start. Before the DC-AC circuit outputs an AC phase voltage, the processor controls the DC-side voltage to reach a preset voltage, so as to facilitate the control of the phase current at the output end of the inverter. After the DC-side voltage reaches the preset voltage, the phase current of the inverter is controlled to reach a target current by adjusting the AC-side phase voltage, specifically by adjusting the drive signal sent to the DC-AC circuit, i.e., wave generation. When the inverter outputs the target current, the modulation degree of the inverter is ensured to be within a preset proportion, so as to ensure the quality of the output current of the inverter, thereby realizing the black start of the inverter. Each inverter is started in this way, so as to ensure that the inverter will not overcurrent.
[0065] The power station includes multiple inverters. When the load voltage is less than or equal to a first voltage value, the inverters in the power station can be started in the above-mentioned manner. However, when the load voltage exceeds the first voltage value, if the inverters are started in the above-mentioned manner, the newly started inverters will generate an impact current because the phase is inconsistent with the phase of the load voltage. The size of the impact current is positively correlated with the size of the load voltage, i.e., the larger the load voltage, the larger the impact current. In order to avoid generating a large impact current, the starting manner of the inverter that needs to be started when the load voltage exceeds the first voltage value is introduced below.
[0066] The embodiments of the present application do not specifically limit the value of the first voltage value. For example, the first voltage value can be 5% of the rated voltage of the load.
[0067] The inverter provided by the embodiments of the present application further includes a filter.
[0068] The filter is connected to the second end of the DC-AC circuit.
[0069] The processor is specifically configured to, before the DC-AC circuit outputs the AC phase voltage, in the case that the load voltage exceeds the first voltage value, send a wave to the DC-AC circuit, control the AC side phase voltage of the power converter according to the load voltage vector and an inductor voltage vector in the filter, and make the phase current of the DC-AC circuit the target current. The inductor voltage vector is obtained according to the target current and the inductor of the filter. Since the AC sides of the multiple inverters are connected together to supply power to the load, other inverters can have been started to supply power to the load, that is, the load voltage already exists on the load, and the load voltage can exist on the load even if the inverter has not output the AC phase voltage.
[0070] For example, the processor can obtain the modulation voltage according to the load voltage vector and the inductor voltage vector in the filter .
[0071]
[0072] The load voltage vector is the load voltage vector at the time when the inverter is black started.
[0073] The following describes a way in which the inverter keeps the phase synchronized with other inverters that have been started.
[0074] Since the power station includes multiple inverters, the multiple inverters can be controlled to start according to constant currents, and the constant currents corresponding to the black start of the multiple inverters are equal. However, since the multiple inverters can be started in sequence, the phases of the multiple inverters that have been started can be different. Taking two inverters that are started first as an example, for example, the constant currents are I npk The two inverters are controlled to start according to constant currents, and the output currents of the two inverters after starting are both I npk If the phases of the output currents of the two inverters are the same, that is, the phase difference is 0, the current superimposed on the load is 2*I npk If the phases of the output currents of the two inverters are opposite, that is, the phase difference is 180 degrees, the current superimposed on the load is exactly offset, that is, the current of the load is 0. The phase difference between the two inverters is the remaining angle, and the current of the load is located between 0 and 2*I npk .
[0075] At this time, the multiple inverters need to be synchronized, and the synchronization means that the phases of the inverters are consistent.
[0076] The first kind is:
[0077] The processor is further configured to adjust the phase of the modulation voltage sent to the DC-AC circuit, and the phase of the modulation voltage corresponding to the time when the load voltage reaches the maximum value or the load current reaches the maximum value is taken as the final phase of the inverter.
[0078] For example, for the started inverter, a bias angle Δθ is superimposed on the phase of the modulated voltage, Δθ gradually changes from 0 to 360 degrees, and in the process of changing, the change of the load current or the load voltage is detected, and when the load current reaches the maximum or the load voltage reaches the maximum, Δθ is taken as the final bias angle of the inverter, and the bias angle is superimposed on the phase of the modulated voltage as the final voltage phase, and the inverter completes the phase synchronization.
[0079] Secondly:
[0080] The processor is further configured to superimpose a phase difference between the phase voltage and the phase current of the AC side of the inverter on the phase of the modulated voltage generated by the DC-AC circuit.
[0081] It should be understood that in the case of the second type of inverter, the local controller sends a synchronization instruction to each inverter, and the phase difference is superimposed on the phase of the modulated voltage, and the local controller sends a synchronization instruction to each inverter at the same time, and each inverter superimposes its own phase difference at the same time. Since the AC sides of the inverters are connected in parallel, the phase of the AC side phase voltage becomes the phase of the load voltage, and thus each inverter can superimpose its own phase difference to complete the phase synchronization.
[0082] When the inverter is synchronized with other inverters, the preliminary black start is completed, and the subsequent control of the inverter can be completed according to the instructions of the upper computer, for example, when the load voltage exceeds the second voltage value, each inverter can end the open-loop control and perform closed-loop control. The application does not specifically limit the measurement of closed-loop control, for example, it can be voltage frequency VF control, droop control (Droop control), power synchronization control (PSC control), virtual synchronous generator control (VSG control), etc.
[0083] The inverter provided in the application embodiment does not require communication between the inverters during black start, thereby reducing the cost of hardware communication. The synchronization between the multiple inverters can be completed according to the above-mentioned method, and the synchronization method is simple and reliable. Since the inverters can be synchronized during the black start process, the circulating current between the inverters can be reduced or avoided.
[0084] Based on the inverter provided in the above embodiment, the application embodiment further provides a power station, which will be specifically introduced below.
[0085] Please continue to refer to Figure 1 The power station provided in the application embodiment comprises m inverters, the AC side of the m inverters is used to connect an AC bus, and the DC side of the m inverters is used to connect corresponding DC sources.
[0086] The DC-AC circuit of the i-th inverter is controlled to reach a preset voltage on the DC side before the i-th inverter outputs an AC phase voltage, the preset voltage being in a positive correlation with the target current; the i-th inverter is given a wave to control the AC side phase voltage amplitude of the DC-AC circuit in the i-th inverter, so that the phase current of the DC-AC circuit in the i-th inverter is the target current, and the ratio of the AC side phase voltage amplitude to the DC side half bus voltage is a preset ratio, and m is an integer greater than or equal to 2; the i-th inverter is any inverter for black start.
[0087] In a possible implementation, the i-th inverter further includes: a filter; the filter is connected to the second end of the DC-AC circuit; and the i-th inverter is specifically configured to, before the i-th inverter outputs an AC phase voltage, control the DC side voltage of the DC-AC circuit to reach a preset voltage; in a case where the load voltage exceeds a first voltage value, give the i-th inverter a wave, and control the AC side phase voltage of the i-th inverter according to the load voltage vector and an inductance voltage vector in the filter, so that the phase current of the i-th inverter is the target current; and the inductance voltage vector is obtained according to the target current and the inductance of the filter.
[0088] In a possible implementation, the i-th inverter is further configured to adjust the phase of the modulation voltage given to the i-th inverter, and the phase of the corresponding modulation voltage when the load voltage reaches a maximum value or the load current reaches a maximum value is taken as the final phase of the inverter.
[0089] In a possible implementation, the i-th inverter is further configured to, in a case where a synchronization instruction sent by a local controller of the power station is received, superimpose the phase difference between the AC side phase voltage and the phase current of the i-th inverter on the phase of the modulation voltage given to the i-th inverter.
[0090] In a possible implementation, the i-th inverter is further configured to, in a case where the load voltage of the i-th inverter exceeds a second voltage value, control the AC side phase voltage amplitude and the phase of the i-th inverter by using a droop control mode.
[0091] In a possible implementation, the power station further includes: a host computer; the host computer sends a black start instruction to an inverter that has not been started, and the inverter that has not been started detects the voltage of an AC bus to start synchronously.
[0092] In a possible implementation, the host computer is further configured to gradually increase a control voltage, and send the control voltage to the m inverters, so that the m inverters control the AC side phase voltage of the m inverters according to the control voltage.
[0093] The specific control of the power station can be referred to the specific description of the inverter embodiments.
[0094] Based on the inverter and power station provided in the above embodiments, the embodiment of the present application further provides a control method of the inverter, and the power station is specifically introduced below.
[0095] Referring to Figure 5 The figure is a flow chart of the control method of the inverter provided in the embodiment of the present application.
[0096] The control method of the inverter provided in the embodiment of the present application comprises:
[0097] S501: Before the DC-AC circuit in the inverter outputs an AC phase voltage, the DC side voltage of the DC-AC circuit is controlled to reach a preset voltage.
[0098] In the embodiment of the present application, before the inverter outputs an AC phase voltage, the DC side voltage is first controlled to reach a preset voltage, so as to reduce voltage harmonics and then facilitate the reduction of current harmonics in subsequent control.
[0099] S502: The DC-AC circuit is given a wave to make the DC-AC circuit output an AC phase voltage, the AC side phase voltage amplitude of the DC-AC circuit is controlled, and the phase current of the DC-AC circuit is the target current.
[0100] The control method of the inverter provided in the embodiment of the present application, before the DC-AC circuit outputs an AC phase voltage during black start, the DC side voltage of the DC-AC circuit is first controlled to reach a preset voltage, the purpose is to facilitate the control of the phase current of the output end of the inverter, and after the DC side voltage reaches the preset voltage, the phase current of the inverter is controlled to reach the target current by adjusting the AC side phase voltage amplitude, specifically, the driving signal sent to the DC-AC circuit, i.e. the wave, is adjusted to ensure the quality of the output current of the inverter, so as to realize the black start of the inverter, each inverter is started in this way, so as to ensure that the inverter will not overcurrent.
[0101] A possible implementation manner, the DC-AC circuit is given a wave to make the DC-AC circuit output an AC phase voltage, the AC side phase voltage amplitude of the DC-AC circuit is controlled, and the phase current of the DC-AC circuit is the target current, specifically comprising: before the DC-AC circuit outputs an AC phase voltage, the DC side voltage of the DC-AC circuit is controlled to reach a preset voltage; in the case that the load voltage exceeds a first voltage value, the DC-AC circuit is given a wave to make the DC-AC circuit output an AC phase voltage, the AC side phase voltage of the power converter is controlled according to the load voltage vector and the inductor voltage vector in the filter, so that the phase current of the DC-AC circuit is the target current; the inductor voltage vector is obtained according to the target current and the inductance of the filter.
[0102] In a possible implementation, the phase of the modulation voltage sent by the DC-AC circuit is adjusted, and the phase of the corresponding modulation voltage when the load voltage reaches the maximum value or the load current reaches the maximum value is taken as the final phase of the inverter.
[0103] In a possible implementation, the phase difference between the AC side of the inverter and the phase current is superimposed on the phase of the modulation voltage sent by the power conversion circuit.
[0104] In a possible implementation, the AC side phase voltage amplitude of the DC-AC circuit is controlled to make the phase current of the DC-AC circuit the target current, and specifically, the AC side phase voltage amplitude of the DC-AC circuit is controlled to make the phase current of the DC-AC circuit the target current, and the ratio of the AC side phase voltage amplitude to the DC side half bus voltage is a preset ratio; the preset voltage is in a positive correlation with the target current.
[0105] For the specific working principle and advantages of the method embodiment, refer to the above description of the inverter embodiment, which will not be repeated here.
[0106] In a possible implementation, refer to Figure 6 , which is a schematic diagram of a control device provided by the embodiment of the application.
[0107] The control device can include a memory 1011 and a processor 1012. The processor 1012 can be connected with the power converter and can drive the switches in each DC-AC circuit in the inverter. As Figure 6 shown, the memory can be a random access memory (RAM), a flash memory, a read only memory (ROM), an EPROM memory, a non-volatile read only memory (Electronic Programmable ROM, EPROM), a register, a hard disk, a removable disk, etc.
[0108] The memory 1011 can store computer instructions, and when the computer instructions stored in the memory 1011 are executed by the processor 1012, the processor 1012 can be configured to execute the control method of the inverter. The memory 1011 can also store data, such as the preset voltage and the target current information involved in the above embodiments.
[0109] In the embodiments described above, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions according to the embodiments of the present application are generated. The computer can be a general purpose computer, a special purpose computer, a computer network, or other programmable apparatus. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another computer readable storage medium, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. The computer readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. integrated with one or more available media. The available media can be magnetic media (such as floppy disk, hard disk, magnetic tape), or semiconductor media (such as solid state disk (SSD)) and the like.
[0110] The embodiments of the present application also provide a readable storage medium for storing the method provided by the above-mentioned embodiments. For example, random access memory (RAM), flash memory, read only memory (ROM), EPROM memory, non-volatile read only memory (Electronic Programmable ROM, EPROM), register, hard disk, removable disk or any other form of storage medium in the art.
[0111] It should be noted that the embodiments in the specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts of each embodiment can be referred to each other. For the method disclosed by the embodiments, since it corresponds to the product embodiments disclosed by the embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the product embodiments.
[0112] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Therefore, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. An inverter, characterized by comprising: The method comprises the following steps: A direct-current alternating-current circuit and a processor are included; A first end of the direct-current alternating-current circuit is used for connecting a direct-current source, and a second end of the direct-current alternating-current circuit is used for connecting an alternating-current bus; The processor is used for controlling a direct-current side voltage of the direct-current alternating-current circuit to reach a preset voltage before the direct-current alternating-current circuit outputs an alternating-current phase voltage; and the processor is used for controlling the direct-current alternating-current circuit to output the alternating-current phase voltage, controlling an alternating-current side phase voltage amplitude of the direct-current alternating-current circuit, and making a phase current of the direct-current alternating-current circuit be a target current.
2. The inverter of claim 1, wherein, The inverter further comprises a filter; The filter is connected to the second end of the direct-current alternating-current circuit; The processor is specifically used for controlling the direct-current side voltage of the direct-current alternating-current circuit to reach the preset voltage before the direct-current alternating-current circuit outputs the alternating-current phase voltage; and the processor is used for controlling the direct-current alternating-current circuit to output the alternating-current phase voltage in the case that a load voltage exceeds a first voltage value, controlling the alternating-current side phase voltage of the direct-current alternating-current circuit according to a load voltage vector and an inductance voltage vector in the filter, and making the phase current of the direct-current alternating-current circuit be the target current; the inductance voltage vector is obtained according to the target current and an inductance of the filter.
3. The inverter according to claim 1 or 2, characterized by The processor is further used for adjusting a phase of a modulation voltage used for the direct-current alternating-current circuit, and a phase of a corresponding modulation voltage when the load voltage reaches a maximum value or the load current reaches a maximum value is taken as a final phase of the inverter.
4. The inverter according to claim 1 or 2, characterized by The processor is further used for superimposing a phase difference between the alternating-current side phase voltage and the phase current of the inverter on the phase of the modulation voltage used for the power conversion circuit.
5. The inverter according to claim 1 or 2, characterized by A direct-current-direct-current circuit is further included; a first end of the direct-current-direct-current circuit is used for connecting a direct-current source, a second end of the direct-current-direct-current circuit is used for connecting the first end of the direct-current alternating-current circuit, and a second end of the direct-current alternating-current circuit is used for connecting an alternating-current bus; The processor is specifically used for controlling the direct-current-direct-current conversion circuit to make the voltage of the first end of the direct-current alternating-current circuit reach a preset voltage before the direct-current alternating-current circuit outputs the alternating-current phase voltage.
6. The inverter according to claim 1 or 2, characterized by A first end of the direct-current alternating-current circuit is used for connecting a direct-current source, and a second end of the direct-current alternating-current circuit is used for connecting an alternating-current bus; The processor is specifically used for controlling the direct-current source to make the voltage of the first end of the direct-current alternating-current circuit reach a preset voltage before the direct-current alternating-current circuit outputs the alternating-current phase voltage.
7. The inverter according to claim 1 or 2, characterized by The preset voltage is in a positive correlation with the target current; the processor is specifically used for controlling the alternating-current side phase voltage amplitude of the direct-current alternating-current circuit to make the phase current of the direct-current alternating-current circuit be the target current, and making a ratio of the alternating-current side phase voltage amplitude to a direct-current side half bus voltage be a preset ratio.
8. A power plant, characterized in that The method comprises the following steps: m inverters are included; Alternating-current sides of the m inverters are used for connecting an alternating-current bus; Direct-current sides of the m inverters are used for connecting corresponding direct-current sources; Before the i-th inverter outputs an AC phase voltage, a DC side voltage of a DC-AC circuit in the i-th inverter is controlled to reach a preset voltage; the i-th inverter is given a wave to make the i-th inverter output an AC phase voltage, an AC side phase voltage amplitude of the DC-AC circuit in the i-th inverter is controlled, and a phase current of the DC-AC circuit in the i-th inverter is the target current, where m is an integer greater than or equal to 2; the i-th inverter is any inverter for black start.
9. A power station according to claim 8, characterised in that The i-th inverter further comprises a filter. The filter is connected to a second end of the DC-AC circuit. Before the i-th inverter outputs an AC phase voltage, a DC side voltage of a DC-AC circuit in the i-th inverter is controlled to reach a preset voltage; in a case where a load voltage exceeds a first voltage value, the i-th inverter is given a wave to make the i-th inverter output an AC phase voltage, an AC side phase voltage amplitude of the DC-AC circuit in the i-th inverter is controlled, and a phase current of the DC-AC circuit in the i-th inverter is the target current; the inductance voltage vector is obtained according to the target current and the inductance of the filter.
10. A power station according to claim 8 or 9, characterised in that The i-th inverter is further configured to adjust a phase of a modulation voltage given to the i-th inverter, and a phase of a corresponding modulation voltage when the load voltage reaches a maximum value or the load current reaches a maximum value is taken as a final phase of the inverter.
11. A power station according to claim 8 or 9, characterised in that In a case where the i-th inverter receives a synchronization instruction sent by a local controller of the power station, the i-th inverter is further configured to superimpose a phase difference between an AC side phase voltage and a phase current of the i-th inverter on the phase of the modulation voltage given to the i-th inverter.
12. A power station according to claim 8 or 9, characterised in that In a case where a load voltage of the i-th inverter exceeds a second voltage value, the i-th inverter is further configured to control an AC side phase voltage amplitude and a phase of the i-th inverter by using a droop control mode.
13. The power plant of claim 12, wherein, The power station further comprises a host computer. The host computer sends a black start instruction to an inverter that has not been started, and the inverter that has not been started detects a voltage of an AC bus to start synchronously.
14. A power station according to claim 13, characterised in that The host computer is further configured to gradually increase a control voltage and send the control voltage to the m inverters, and the m inverters control AC side phase voltages of the m inverters according to the control voltage.
15. A control method of an inverter, characterized by, Before an AC phase voltage is output by a DC-AC circuit in the inverter, a DC side voltage of the DC-AC circuit is controlled to reach a preset voltage; The DC-AC circuit is given a wave to make the DC-AC circuit output an AC phase voltage, an AC side phase voltage amplitude of the DC-AC circuit is controlled, and a phase current of the DC-AC circuit is a target current. The DC-AC circuit is given a wave to make the DC-AC circuit output an AC phase voltage, an AC side phase voltage amplitude of the DC-AC circuit is controlled, and a phase current of the DC-AC circuit is a target current, and specifically includes:
16. The control method according to claim 14, characterized by Before the AC phase voltage outputted by the DC-AC circuit, the DC side voltage of the DC-AC circuit is controlled to reach a preset voltage; when the load voltage exceeds a first voltage value, the DC-AC circuit is given a wave to make the DC-AC circuit output an AC phase voltage, the AC side phase voltage of the DC-AC circuit is controlled according to the load voltage vector and the inductor voltage vector in the filter, so that the phase current of the DC-AC circuit is the target current; the inductor voltage vector is obtained according to the target current and the inductor of the filter.
17. The control method according to claim 14 or 15, characterized by, Further comprising: The phase of the modulation voltage given to the DC-AC circuit is adjusted, and the phase of the corresponding modulation voltage when the load voltage reaches a maximum value or the load current reaches a maximum value is taken as the final phase of the inverter.
18. The control method according to claim 14 or 15, characterized by, Further comprising: The phase difference between the AC side phase voltage and the phase current of the inverter is superimposed on the phase of the modulation voltage given to the power conversion circuit.
19. The control method according to claim 14 or 15, characterized by, The control of the AC side phase voltage amplitude of the DC-AC circuit, so that the phase current of the DC-AC circuit is the target current, specifically includes: The AC side phase voltage amplitude of the DC-AC circuit is controlled, so that the phase current of the DC-AC circuit is the target current, and the ratio of the AC side phase voltage amplitude to the DC side half bus voltage is a preset ratio; the preset voltage is in a positive correlation with the target current.
20. A control device characterized by comprising: The processor and the memory are included, the memory is used to store programs, instructions or codes, and the processor is used to execute the programs, instructions or codes in the memory to complete the control method of the power converter as claimed in any one of claims 15-19.
21. A computer-readable storage medium, characterized in that, The computer program is stored, and the computer program is loaded by the processor to execute the control method of the power converter as claimed in any one of claims 15-19.