Converter control method, controller, converter and power conversion system

Abstract

The invention provides a converter control method, a controller, a converter and a power conversion system, and relates to the technical field of power conversion. The converter control method comprises the following steps: acquiring a grid-connected voltage of a converter, and determining a reactive current local instruction value according to the grid-connected voltage in a voltage fault ride-through mode; in the voltage fault ride-through mode, at least one received station control power instruction is responded, and a reactive current station control instruction value is determined according to the station control power instruction; the larger absolute value, matched with the voltage fault ride-through mode, of the reactive current local instruction value and the reactive current station control instruction value serves as a reactive current instruction value, and reactive current output adjustment is conducted on the converter; namely, in a voltage fault ride-through mode, real-time response to a received station control power instruction is kept, a dynamic comparison mechanism based on a reactive current local instruction value and a reactive current station control instruction value is introduced, and cooperative response to local reactive control and a power station overall control target is achieved.

Description

Technical Field

[0001] This disclosure relates to the field of power conversion technology, and in particular to a converter control method, controller, converter and power conversion system. Background Technology

[0002] During power system operation, voltage fault ride-through (LVRT) is a crucial mechanism for ensuring stable interaction between the converter and the power grid. In related technologies, the converter typically calculates the corresponding reactive current command based on the real-time changes in its grid-connected port voltage, according to preset LVRT (Low Voltage Ride Through) or HVRT (High Voltage Ride Through) rules. Based on the obtained reactive current command, the converter adjusts the reactive current output at the grid-connected port to support the grid voltage.

[0003] However, the aforementioned reactive power support strategy is prone to mismatch with the overall control objectives of the power plant. Summary of the Invention

[0004] In view of the above problems, this disclosure provides a converter control method, controller, converter, and power conversion system to achieve coordinated response between reactive power support strategies and overall power plant control objectives. The specific solution is as follows:

[0005] The first aspect of this disclosure provides a converter control method, comprising:

[0006] Obtain the grid-connected voltage of the converter, and determine the local command value of reactive current based on the grid-connected voltage in voltage fault ride-through mode;

[0007] In the voltage fault ride-through mode, in response to at least one received station control power command, the reactive current station control command value is determined according to the station control power command;

[0008] The reactive current output of the converter is regulated by taking the larger absolute value of the local reactive current command value and the station reactive current command value that matches the voltage fault ride-through mode as the reactive current command value.

[0009] In one possible implementation, the larger of the absolute values ​​of the local reactive current command value and the station reactive current command value that match the voltage fault ride-through mode is used as the reactive current command value, including:

[0010] In low voltage ride-through mode, if the reactive current station control command value is an inductive current value, then the reactive current local command value is used as the reactive current command value; if the reactive current station control command value is a capacitive current value, then the larger of the absolute values ​​of the reactive current local command value and the reactive current station control command value is used as the reactive current command value.

[0011] In high-voltage ride-through mode, if the reactive current station control command value is a capacitive current value, then the local reactive current command value is used as the reactive current command value; if the reactive current station control command value is an inductive current value, then the larger of the absolute values ​​of the local reactive current command value and the reactive current station control command value is used as the reactive current command value.

[0012] In one possible implementation, determining the local reactive current command value based on the grid-connected voltage during voltage fault ride-through mode includes:

[0013] The converter is controlled to enter the corresponding voltage fault ride-through mode according to the grid-connected voltage; the voltage fault ride-through mode is either a low voltage ride-through mode or a high voltage ride-through mode.

[0014] When entering the low voltage ride-through mode, the local command value of the capacitive reactive current is determined based on the grid voltage.

[0015] When entering the high voltage ride-through mode, the local command value of the inductive reactive current is determined based on the grid voltage.

[0016] In one possible implementation, the local reactive current command value is the product of the difference between the reference voltage value of the voltage fault ride-through mode and the grid voltage, and the reactive power regulation coefficient.

[0017] In one possible implementation, the converter control method further includes:

[0018] In normal operating mode, the power of the converter is regulated according to the station control power command.

[0019] A second aspect of this disclosure provides a controller, comprising: a calculation module, an instruction receiving module, an instruction determining module, and a current control execution module; wherein...

[0020] The calculation module is configured to: determine the local command value of reactive current based on the grid-connected voltage of the converter in voltage fault ride-through mode;

[0021] The instruction receiving module is configured to: respond to at least one received station control power instruction in the voltage fault ride-through mode, and determine the reactive current station control instruction value according to the station control power instruction;

[0022] The instruction determination module is configured to use the larger absolute value of the reactive current local instruction value and the reactive current station control instruction value that matches the voltage fault ride-through mode as the reactive current instruction value.

[0023] The current control execution module is configured to generate a control signal for the converter based on the reactive current command value, so that the converter adjusts the output of reactive current according to the reactive current command value.

[0024] In one possible implementation, the instruction determining module is specifically configured as follows:

[0025] In low voltage ride-through mode, if the reactive current station control command value is an inductive current value, then the reactive current local command value is used as the reactive current command value; if the reactive current station control command value is a capacitive current value, then the larger of the absolute values ​​of the reactive current local command value and the reactive current station control command value is used as the reactive current command value.

[0026] In high-voltage ride-through mode, if the reactive current station control command value is a capacitive current value, then the local reactive current command value is used as the reactive current command value; if the reactive current station control command value is an inductive current value, then the larger of the absolute values ​​of the local reactive current command value and the reactive current station control command value is used as the reactive current command value.

[0027] In one possible implementation, when the calculation module determines the local reactive current command value based on the grid voltage in voltage fault ride-through mode, it is specifically configured as follows:

[0028] The converter is controlled to enter the corresponding voltage fault ride-through mode according to the grid-connected voltage; the voltage fault ride-through mode is either a low voltage ride-through mode or a high voltage ride-through mode.

[0029] When entering the low voltage ride-through mode, the local command value of the capacitive reactive current is determined based on the grid voltage.

[0030] When entering the high voltage ride-through mode, the local command value of the inductive reactive current is determined based on the grid voltage.

[0031] In one possible implementation, the local reactive current command value is the product of the difference between the reference voltage value of the voltage fault ride-through mode and the grid voltage, and the reactive power regulation coefficient.

[0032] In one possible implementation, the calculation module is further configured to: determine the local reactive current command value to be zero in normal operating mode;

[0033] The instruction receiving module is also configured to: determine the active current station control instruction value according to the station control power instruction in the normal operation mode;

[0034] The instruction determination module is further configured to: in the normal operating mode, use the reactive current station control instruction value as the reactive current instruction value and use the active current station control instruction value as the active current instruction value.

[0035] The current control execution module is further configured to: in the normal operation mode, generate a control signal for the converter based on the reactive current command value and the active current command value, so that the converter performs power regulation according to the station control power command.

[0036] A third aspect of this disclosure provides a converter, comprising: a DC / AC conversion unit and a filter; wherein,

[0037] The DC side of the DC / AC conversion unit is used to connect to a DC source;

[0038] The AC side of the DC / AC conversion unit is connected to one side of the filter, and the other side of the filter is used to connect to the grid connection point.

[0039] The DC / AC conversion unit is controlled by a control unit; the control unit is used to execute the converter control method as described in the first aspect or any implementation thereof, or the control unit is a controller as described in the second aspect or any implementation thereof.

[0040] This disclosure provides a fourth aspect of a power conversion system, comprising: at least one converter as described in the third aspect or any implementation thereof.

[0041] The converter control method disclosed herein acquires the grid-connected voltage of the converter and determines the local reactive current command value based on the grid-connected voltage in voltage fault ride-through mode. Also in voltage fault ride-through mode, it responds to at least one received station control power command and determines the reactive current station control command value based on the station control power command. Then, it uses the larger absolute value of the reactive current local command value and the reactive current station control command value that matches the voltage fault ride-through mode as the reactive current command value to regulate the reactive current output of the converter. In other words, in voltage fault ride-through mode, it maintains real-time response to the received station control power command and introduces a dynamic comparison mechanism based on the reactive current local command value and the reactive current station control command value, thus achieving coordinated response to local reactive power control and the overall power station control objectives. Attached Figure Description

[0042] The features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and elements and actual parts are not necessarily drawn to scale.

[0043] Figure 1 A flowchart of a converter control method provided in an embodiment of this disclosure;

[0044] Figure 2 A partial flowchart of the converter control method provided in the embodiments of this disclosure;

[0045] Figure 3 This is a schematic diagram of the controller provided in an embodiment of the present disclosure;

[0046] Figure 4 This is a schematic diagram of a converter provided in an embodiment of the present disclosure. Detailed Implementation

[0047] The embodiments of this disclosure are described below with reference to the accompanying drawings. The terminology used in the Description of Embodiments section of this disclosure is for illustrative purposes only and is not intended to limit the scope of this disclosure.

[0048] The embodiments of this disclosure are described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure. Those skilled in the art will understand that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of this disclosure are also applicable to similar technical problems.

[0049] The terms “first,” “second,” etc., used in this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the description of embodiments of this disclosure. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of units is not necessarily limited to those units, but may include other units not expressly listed or inherent to those processes, methods, products, or apparatuses.

[0050] This disclosure provides a converter control method to achieve coordinated response between reactive power support strategies and overall power plant control objectives. The specific solution is as follows:

[0051] like Figure 1As shown, the converter control method includes:

[0052] S101. Obtain the grid-connected voltage of the converter, and determine the local command value of reactive current based on the grid-connected voltage in voltage fault ride-through mode.

[0053] In practical applications, local voltage measurement of the grid-connected voltage can be achieved through a voltage acquisition module; based on this grid-connected voltage, it can be determined whether it is necessary to enter voltage fault ride-through mode, such as low voltage ride-through mode or high voltage ride-through mode.

[0054] In voltage fault ride-through mode, the local reactive current command value can be further determined based on the grid-connected voltage. If the reactive current output of the converter is regulated based on this local reactive current command value, the grid-connected voltage can be maintained within an acceptable range by adjusting the reactive power output of the converter, preventing the converter from disconnecting from the grid and ensuring the continuous operation of the power system.

[0055] S102. In voltage fault ride-through mode, respond to at least one station control power command received, and determine the reactive current station control command value based on the station control power command.

[0056] When facing complex power grid operating conditions, the reactive power support strategy under the aforementioned local control logic is prone to inconsistency with the overall control objectives of the power plant, thereby affecting system stability and power quality. Specifically, in voltage fault ride-through mode, if only the local reactive power support strategy is used for reactive power control response, the overall control objectives of the power plant, such as the station control power commands sent by the PPC (Power Plant Controller), are ignored. As a power plant-level coordination and control unit, the PPC can issue globally optimized reactive current commands to the converters based on grid dispatch requirements, system operating status, and grid connection specifications.

[0057] The station control power command includes the globally optimized reactive current command mentioned above. The reactive current station control command value can be determined based on this reactive current command. Moreover, in voltage fault ride-through mode, the PPC may issue multiple station control power commands successively according to the real-time situation. This embodiment does not limit the number of station control power commands issued, as long as the received station control power commands are not frozen in voltage fault ride-through mode, but are responded to in real time.

[0058] After obtaining the local reactive current command value and the station reactive current control command value, S103 can be executed.

[0059] S103. The larger of the absolute values ​​of the local reactive current command value and the station reactive current command value that match the voltage fault ride-through mode is used as the reactive current command value to regulate the output of reactive current of the converter.

[0060] In practical applications, the local reactive current command value calculated based on the grid-connected voltage and the station control reactive current command value obtained after global optimization may not have the same direction. For example, they may both be positive or negative at the same time, or one may be positive while the other is negative. Therefore, the command value that matches the voltage fault ride-through mode should be considered first. If both match the voltage fault ride-through mode, the one with the larger absolute value should be selected as the final reactive current command value to regulate the reactive current output of the converter, such as as the reactive reference quantity of the converter's current loop. This allows for coordinated response to the two control methods.

[0061] The converter control method provided in this embodiment introduces a dynamic comparison mechanism based on local reactive current command values ​​and station control reactive current command values. This enables coordinated response to local reactive power control and overall power plant control objectives, achieving flexible scheduling and optimized response to converter reactive power output. Furthermore, maintaining timely identification and real-time response to received station control power commands during voltage fault ride-through mode allows for timely identification of overall power plant control objectives, avoiding impacts on the converter's rapid response capability to station control-level reactive power demands. This also avoids problems such as insufficient reactive power support or overcompensation that can result from relying solely on local reactive power support strategies.

[0062] In practical applications, in step S101 of this converter control method, the local reactive current command value is determined based on the grid voltage during voltage fault ride-through mode. Specifically, this may include:

[0063] (1) Control the converter to enter the corresponding voltage fault ride-through mode according to the grid connection voltage.

[0064] Among them, the voltage fault ride-through mode is either low voltage ride-through mode or high voltage ride-through mode.

[0065] Specifically, the voltage at the grid-connected port of the converter, i.e., the grid-connected voltage V, is collected and monitored. term After obtaining the amplitude and phase information, it is compared with the reference voltage value of the voltage fault ride-through mode; if the grid-connected voltage V term Below the low voltage threshold, i.e., the reference voltage value V for low voltage ride-through mode. Lset Then the control converter enters low voltage ride-through mode; if the grid voltage V term The voltage value V is higher than the high voltage threshold, i.e., the reference voltage value for high voltage ride-through mode. Hset Then the converter will enter the high voltage ride-through mode.

[0066] (2) When entering the low voltage ride-through mode, determine the local command value of the capacitive reactive current based on the grid voltage; or, when entering the high voltage ride-through mode, determine the local command value of the inductive reactive current based on the grid voltage.

[0067] In practical applications, the local reactive current command value can be calculated based on grid connection specifications or a preset reactive voltage support curve, depending on the specific application environment; no specific limitation is made here. For example, the local reactive current command value can be calculated based on a preset reactive voltage support curve, specifically set to be equal to the product of the difference between the reference voltage value in voltage fault ride-through mode and the grid connection voltage, and the reactive power regulation coefficient. That is, the formula for calculating the local reactive current command value is:

[0068] I qr_LVRT = (V Lset -V term )×K fL ;

[0069] I qr_HVRT = (V Hset -V term )×K fH .

[0070] Among them, I qr_LVRT This is the local reactive current command value in low voltage ride-through mode, which is also the capacitive local reactive current command value mentioned above; I qr_HVRT This is the local reactive current command value in high-voltage ride-through mode, which is also the aforementioned local reactive current command value for inductive applications; K fL K is the reactive power regulation coefficient in low voltage ride-through mode. fH This is the reactive power regulation coefficient in high voltage ride-through mode.

[0071] In low voltage ride-through mode, I qr_LVRT >0 indicates capacitive reactive current, which is also the local command value for capacitive reactive current; in high-voltage ride-through mode, I qr_HVRT <0 indicates inductive reactive current, which is also the local command value of inductive reactive current.

[0072] In practical applications, other methods can also be used to calculate the local command value of reactive current. This is just one example and is not limited to it.

[0073] Based on the above embodiments, this embodiment provides an example of the specific implementation of S103 in the converter control method. For example, it may include: in low voltage ride-through mode, if the reactive current station control command value is an inductive current value, then the local reactive current command value is used as the reactive current command value; if the reactive current station control command value is a capacitive current value, then the larger of the absolute values ​​of the local reactive current command value and the reactive current station control command value is used as the reactive current command value; in high voltage ride-through mode, if the reactive current station control command value is a capacitive current value, then the local reactive current command value is used as the reactive current command value; if the reactive current station control command value is an inductive current value, then the larger of the absolute values ​​of the local reactive current command value and the reactive current station control command value is used as the reactive current command value.

[0074] Specifically, during low-voltage ride-through, related technologies typically rely solely on capacitive reactive power support commands generated from changes in the grid-connected voltage amplitude. They fail to recognize globally optimized reactive current commands issued by the PPC (Power Control Platform) that represent higher capacitive reactive power demands. This leads to delayed reactive power response, impacting grid voltage recovery efficiency. In this embodiment, the following is implemented: if the reactive current station control command value is a capacitive current value with a large absolute value (i.e., higher than the local reactive current command value), then the reactive current station control command value is responded to. Only when the absolute value of the reactive current station control command value is small, or even an inductive current value, is the reactive current output adjusted according to the local reactive current command value. In other words, for situations where the reactive current station control command value represents a higher capacitive reactive power demand, this embodiment prioritizes responding to this command value, achieving faster and more accurate reactive power support. Especially when grid dispatch requires converters to provide additional reactive power support, the response speed can be improved by more than 30%, significantly enhancing the system's stability and recovery capability during voltage dips.

[0075] During high-voltage ride-through, related technologies employ inductive reactive power output strategies according to grid connection standards. Even if the PPC command is lower than the local command, the higher local command may still be executed, failing to further support the grid voltage. This embodiment, however, sets the following: if the reactive current station control command value is an inductive current value and its absolute value is large (i.e., the reactive current station control command value is lower than the reactive current local command value), then the reactive current station control command value is responded to; only when the absolute value of the reactive current station control command value is small, or even a capacitive current value, is the reactive current local command value responded to. In other words, during high-voltage ride-through, low-inductive reactive power commands issued by the PPC are prioritized, effectively improving the system's operational safety margin.

[0076] This embodiment achieves coordinated operation between local control and power plant-level control through a dynamic judgment and response mechanism, thereby improving reactive power support capability and system stability during grid fault ride-through.

[0077] Based on the above embodiments, the converter control method may further include: in normal operating mode, adjusting the power of the converter according to the station control power command. That is, after obtaining the grid-connected voltage, if there is no need to enter the voltage fault ride-through mode, i.e., it can enter the normal operating mode, the active and reactive power of the converter can be directly adjusted according to the received station control power command.

[0078] In conjunction with the above embodiments, Figure 2 The specific implementation process of some steps in the converter control method is demonstrated, including:

[0079] During low voltage ride-through, if the grid voltage V term Below the low voltage threshold, i.e., the reference voltage value V for low voltage ride-through mode. Lset Then the control converter enters the low voltage ride-through mode, and according to the current grid voltage V term Calculate the local command value I of the capacitive reactive current from the state. qr_LVRT At this time, if S102 determines the obtained reactive current station control command value I... qr_PPC Greater than the local reactive current command value I qr_LVRT That is, satisfying I qr_PPC >I qr_LVRT Then the control converter will preferentially use the reactive current station control command value I. qr_PPC As the final reactive current command; and if I is satisfied qr_PPC qr_LVRT Then the converter is controlled using the local reactive current command value I. qr_LVRT This is to ensure that the converter can provide sufficient capacitive reactive power support during voltage dips.

[0080] During high voltage ride-through, if the grid voltage V term The voltage value V is higher than the high voltage threshold, i.e., the reference voltage value for high voltage ride-through mode. Hset Then, the control converter enters the high-voltage ride-through mode, and the local command value I of the inductive reactive current is calculated. qr_HVRT At this time, if S102 determines the obtained reactive current station control command value I... qr_PPC , satisfying I qr_PPC qr_HVRT Then the control converter will prioritize responding to the reactive current station control command value I. qr_PPC If I is satisfied qr_PPC >I qr_HVRT Then the control converter responds to the locally calculated inductive reactive current local command value I. qr_HVRT To ensure that as much inductive reactive power as possible is generated during a fault, thereby reducing the grid-connected voltage V. term . ​​

[0081] In practical applications, after receiving the station control power command, it can first determine whether it is currently in or has entered the low voltage ride-through mode or the high voltage ride-through mode. Then, based on the comparison of the reactive current command value in the current mode, it can select the local reactive current command value or the station control reactive current command value.

[0082] This embodiment defines the reactive current priority response logic under different ride-through modes through piecewise functions, which can significantly improve the converter's response capability and system coordination during voltage fault ride-through. Furthermore, by prioritizing the response to station control power commands, the converter can better cooperate with the overall control objectives of the power station, achieving optimized reactive power allocation and dynamic adjustment under multi-machine collaboration. This makes it suitable for modern power grids with a large number of distributed power sources, effectively alleviating local voltage instability problems and improving grid operating efficiency and power quality.

[0083] Another embodiment of this disclosure also provides a controller, such as Figure 3 As shown, it includes: a calculation module 301, an instruction receiving module 302, an instruction determining module 303, and a current control execution module 304; wherein:

[0084] The calculation module 301 is configured to: calculate based on the obtained grid-connected voltage V of the converter. term In voltage fault ride-through mode, based on the grid-connected voltage V term Determine the local reactive current command value (such as the capacitive local reactive current command value I described in the above embodiments). qr_LVRT Or the local command value I of the inductive reactive current qr_HVRT In practical applications, the three-phase voltage signal at the grid-connected port of the converter can be acquired in real time by the voltage acquisition module and converted into real-time data of amplitude changes, so that the calculation module 301 can obtain the grid-connected voltage V. term .

[0085] The instruction receiving module 302 is configured to: in voltage fault ride-through mode, respond to at least one received station control power instruction, and determine the reactive current station control instruction value I based on the station control power instruction. qr_PPC The instruction receiving module 302 is responsible for receiving station control power instructions from the power plant level, such as receiving the station control power instruction from the PPC, and then obtaining the reactive current station control instruction value I calculated by the power plant level. qr_PPC .

[0086] The instruction determination module 303 is configured to: use the local reactive current instruction value and the station control reactive current instruction value I. qr_PPCThe larger absolute value matching the voltage fault ride-through mode is used as the reactive current command value. When a voltage fault ride-through event occurs, the command determination module 303 compares the local reactive current command value with the station control reactive current command value I. qr_PPC The magnitude of the reactive current is determined by the relationship between the values ​​of the reactive current and the reactive current command value executed by the final current loop control. In practical applications, the command determination module 303 can be implemented in software or hardware, and no limitation is made here.

[0087] The current control execution module 304 is configured to generate a control signal for the converter based on the reactive current command value, so that the converter can regulate the output of reactive current according to the reactive current command value. Specifically, this control signal can be a PWM (Pulse Width Modulation) signal, used to control the bridge arm switching devices in the converter, enabling the converter to regulate the output of reactive current.

[0088] In practical applications, the above modules can be program code written into the controller. The instruction determination module 303 can also be built using logic gates, and the instruction receiving module 302 can also include a communication interface for receiving station control power instructions. In addition, each module can be implemented using a corresponding processor, or it can be integrated into the same processor, depending on the specific application environment. No restrictions are imposed here.

[0089] The controller provided in this embodiment can realize the coordination function between the local reactive power support strategy and the station control power command. The specific control principle can be found in the above embodiment, and will not be repeated here.

[0090] In practical applications, the instruction determination module 303 is specifically configured as follows: In low-voltage ride-through mode, if the reactive current station control instruction value is an inductive current value, then the local reactive current instruction value is used as the reactive current instruction value; if the reactive current station control instruction value is a capacitive current value, then the larger of the absolute values ​​of the local reactive current instruction value and the reactive current station control instruction value is used as the reactive current instruction value; in high-voltage ride-through mode, if the reactive current station control instruction value is a capacitive current value, then the local reactive current instruction value is used as the reactive current instruction value; if the reactive current station control instruction value is an inductive current value, then the larger of the absolute values ​​of the local reactive current instruction value and the reactive current station control instruction value is used as the reactive current instruction value.

[0091] In addition, when the calculation module 301 determines the local reactive current command value based on the grid-connected voltage in the voltage fault ride-through mode, it is specifically configured to: control the converter to enter the corresponding voltage fault ride-through mode based on the grid-connected voltage; the voltage fault ride-through mode is either low voltage ride-through mode or high voltage ride-through mode; when entering low voltage ride-through mode, determine the local reactive current command value of capacitive reactive current based on the grid-connected voltage; when entering high voltage ride-through mode, determine the local reactive current command value of inductive reactive current based on the grid-connected voltage.

[0092] In one example, the local reactive current command value can be the product of the difference between the reference voltage value in voltage fault ride-through mode and the grid voltage, and the reactive power regulation coefficient.

[0093] Furthermore, the calculation module 301 can also be configured to: determine the local reactive current command value to be zero in normal operating mode; the command receiving module 302 is also configured to: determine the active current station control command value according to the station control power command in normal operating mode; the command determining module 303 is also configured to: use the reactive current station control command value as the reactive current command value and the active current station control command value as the active current command value in normal operating mode; the current control execution module 304 is also configured to: generate a control signal for the converter according to the reactive current command value and the active current command value in normal operating mode, so that the converter performs power regulation according to the station control power command.

[0094] This embodiment achieves coordinated operation between local control and power station-level control through a dynamic judgment and response mechanism, enhancing reactive power support and system stability during grid fault ride-through. It can promptly identify and prioritize responses to reactive current station control commands, avoiding impact on the converter's rapid response to station-level reactive power demands. Furthermore, it is applicable to modern power grids with numerous distributed power sources, effectively mitigating local voltage instability and improving grid operating efficiency and power quality.

[0095] Another embodiment of this disclosure also provides a converter, such as Figure 4The diagram shows a DC / AC conversion unit 01 and a filter 02. The DC side of the DC / AC conversion unit 01 is connected to a DC source, which can be at least one photovoltaic string or at least one battery cluster. The AC side of the DC / AC conversion unit 01 is connected to one side of the filter 02, and the other side of the filter 02 serves as a grid connection port for connecting to the grid connection point PCC. The DC / AC conversion unit 01 is controlled by a control unit 03. The control unit 03 executes the converter control method as described in any of the above embodiments, or the control unit 03 is a controller as described in the above embodiments. The specific process of the converter control method and the specific working principle of the controller can be found in the above embodiments. Other structural descriptions of the converter can be found in the relevant documentation, and will not be repeated here.

[0096] In practical applications, the control unit 03 can be integrated into the converter or it can be independent of the converter, depending on the specific application environment, and both are within the protection scope of this disclosure.

[0097] The converter provided in this embodiment, based on the real-time changes in the converter's grid-connected port voltage (i.e., the aforementioned grid-connected voltage), and combined with station control power commands, selectively executes reactive current commands through judgment logic, achieving coordinated response to local reactive power control and the overall power station control objectives. Furthermore, it can achieve superior reactive power support strategies and system stability during low-voltage and high-voltage ride-throughs. In addition, priority judgment logic implemented in software or hardware enables the converter to respond in real-time to PCC optimization commands during voltage fault ride-throughs, thereby ensuring local voltage stability while achieving a high degree of coordination with the overall power station control objectives. This not only improves the converter's dynamic response capability during grid faults but also enhances the system's robustness and adaptability, providing crucial support for building a highly reliable and coordinated modern smart grid.

[0098] Another embodiment of this disclosure provides a power conversion system, including at least one converter. The grid connection ports of each converter can be connected in parallel to the grid connection point to respectively realize the power conversion and transmission between their respective DC sources and the power grid. The specific structure and working principle of the converter can be found in the above embodiments, and will not be repeated here.

[0099] By employing the aforementioned control principles, this power conversion system can achieve coordinated responses to local reactive power control and overall power plant control objectives, enabling flexible scheduling and optimized response to the converter's reactive power output. Furthermore, by prioritizing responses to station control power commands, the converter can better cooperate with the overall power plant control objectives, achieving optimized reactive power allocation and dynamic adjustment under multi-machine collaboration. This makes it suitable for modern power grids containing numerous distributed power sources, effectively mitigating local voltage instability and improving grid operating efficiency and power quality.

[0100] Similar or identical parts between the various embodiments in this disclosure can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0101] Those skilled in the art will also recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this disclosure.

[0102] The above description of the disclosed embodiments shows that the features described in the various embodiments of this disclosure can be substituted for or combined with each other, enabling those skilled in the art to implement or use this disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this disclosure. Therefore, this disclosure is not 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. A converter control method, characterized in that, include: Obtain the grid-connected voltage of the converter, and determine the local command value of reactive current based on the grid-connected voltage in voltage fault ride-through mode; In the voltage fault ride-through mode, in response to at least one received station control power command, the reactive current station control command value is determined according to the station control power command; The reactive current output of the converter is regulated by taking the larger absolute value of the local reactive current command value and the station reactive current command value that matches the voltage fault ride-through mode as the reactive current command value.

2. The converter control method according to claim 1, characterized in that, The larger of the absolute values ​​of the local reactive current command value and the station reactive current command value that match the voltage fault ride-through mode is taken as the reactive current command value, including: In low voltage ride-through mode, if the reactive current station control command value is an inductive current value, then the reactive current local command value is used as the reactive current command value; if the reactive current station control command value is a capacitive current value, then the larger of the absolute values ​​of the reactive current local command value and the reactive current station control command value is used as the reactive current command value. In high-voltage ride-through mode, if the reactive current station control command value is a capacitive current value, then the local reactive current command value is used as the reactive current command value; if the reactive current station control command value is an inductive current value, then the larger of the absolute values ​​of the local reactive current command value and the reactive current station control command value is used as the reactive current command value.

3. The converter control method according to claim 1 or 2, characterized in that, In voltage fault ride-through mode, the local reactive current command value is determined based on the grid-connected voltage, including: The converter is controlled to enter the corresponding voltage fault ride-through mode according to the grid-connected voltage; the voltage fault ride-through mode is either a low voltage ride-through mode or a high voltage ride-through mode. When entering the low voltage ride-through mode, the local command value of the capacitive reactive current is determined based on the grid voltage. When entering the high voltage ride-through mode, the local command value of the inductive reactive current is determined based on the grid voltage.

4. The converter control method according to claim 1 or 2, characterized in that, The local reactive current command value is the product of the difference between the reference voltage value of the voltage fault ride-through mode and the grid voltage, and the reactive power regulation coefficient.

5. The converter control method according to claim 1 or 2, characterized in that, The converter control method further includes: In normal operating mode, the power of the converter is regulated according to the station control power command.

6. A controller, characterized in that, include: The module comprises a calculation module, an instruction receiving module, an instruction determining module, and a current control execution module; among which, The calculation module is configured to: determine the local command value of reactive current based on the grid-connected voltage of the converter in voltage fault ride-through mode; The instruction receiving module is configured to: respond to at least one received station control power instruction in the voltage fault ride-through mode, and determine the reactive current station control instruction value according to the station control power instruction; The instruction determination module is configured to use the larger absolute value of the reactive current local instruction value and the reactive current station control instruction value that matches the voltage fault ride-through mode as the reactive current instruction value. The current control execution module is configured to generate a control signal for the converter based on the reactive current command value, so that the converter adjusts the output of reactive current according to the reactive current command value.

7. The controller according to claim 6, characterized in that, The instruction determination module is specifically configured as follows: In low voltage ride-through mode, if the reactive current station control command value is an inductive current value, then the reactive current local command value is used as the reactive current command value; if the reactive current station control command value is a capacitive current value, then the larger of the absolute values ​​of the reactive current local command value and the reactive current station control command value is used as the reactive current command value. In high voltage ride-through mode, if the reactive current station control command value is a capacitive current value, then the local reactive current command value is used as the reactive current command value. If the reactive current station control command value is an inductive current value, then the larger of the absolute values ​​of the reactive current local command value and the reactive current station control command value shall be used as the reactive current command value.

8. The controller according to claim 6 or 7, characterized in that, When the calculation module determines the local reactive current command value based on the grid-connected voltage in voltage fault ride-through mode, it is specifically configured as follows: The converter is controlled to enter the corresponding voltage fault ride-through mode according to the grid-connected voltage; the voltage fault ride-through mode is either a low voltage ride-through mode or a high voltage ride-through mode. When entering the low voltage ride-through mode, the local command value of the capacitive reactive current is determined based on the grid voltage. When entering the high voltage ride-through mode, the local command value of the inductive reactive current is determined based on the grid voltage.

9. The controller according to claim 6 or 7, characterized in that, The local reactive current command value is the product of the difference between the reference voltage value of the voltage fault ride-through mode and the grid voltage, and the reactive power regulation coefficient.

10. The controller according to claim 6 or 7, characterized in that, The calculation module is also configured to: determine the local command value of the reactive current to be zero in normal operation mode; The instruction receiving module is also configured to: determine the active current station control instruction value according to the station control power instruction in the normal operation mode; The instruction determination module is further configured to: in the normal operating mode, use the reactive current station control instruction value as the reactive current instruction value and use the active current station control instruction value as the active current instruction value. The current control execution module is further configured to: in the normal operation mode, generate a control signal for the converter based on the reactive current command value and the active current command value, so that the converter performs power regulation according to the station control power command.

11. A converter, characterized in that, include: DC / AC converter unit and filter; among which... The DC side of the DC / AC conversion unit is used to connect to a DC source; The AC side of the DC / AC conversion unit is connected to one side of the filter, and the other side of the filter is used to connect to the grid connection point. The DC / AC conversion unit is controlled by a control unit; the control unit is used to execute the converter control method as described in any one of claims 1 to 5, or the control unit is a controller as described in any one of claims 6 to 10.

12. A power conversion system, characterized in that, include: At least one converter as described in claim 11.

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