Negative sequence power control method, device and equipment

Abstract

The application provides a negative sequence power control method, device and equipment, the method comprises the following steps: when the grid voltage appears asymmetric fault, obtaining the operation parameters of the converter and the grid; determining the generator power fluctuation value according to the operation parameters, and determining the first given value of the rotor negative sequence current for inhibiting the generator power fluctuation, and / or determining the second given value of the rotor negative sequence current for inhibiting the grid voltage negative sequence component according to the operation parameters, which does not exceed the upper limit of the DC bus voltage and the rotor current; determining the rotor negative sequence current of the rotor negative sequence control loop according to the first given value and / or the second given value, and controlling the rotor current by using the rotor negative sequence current. By using the method provided by the application, the negative sequence power and the grid negative sequence voltage are inhibited, and the problem of the generator power shock and the grid voltage imbalance caused by the grid asymmetric fault is solved.

Description

Technical Field

[0001] The present invention relates to the field of electrical technology, and in particular to a negative sequence power control method, device and equipment. Background Art

[0002] Wind power generation is a renewable, pollution-free, and renewable energy technology, and its share of my country's total power generation is increasing year by year. As the core control component of wind power generation, the converter achieves optimal efficiency and power quality through variable speed constant frequency control.

[0003] In the existing technology, when an asymmetric fault occurs in the grid voltage, the common control method for the converter is to generate a certain amount of positive-sequence capacitive reactive power to support the recovery of the grid positive-sequence voltage while still generating positive-sequence active power. This solution has the following two problems:

[0004] First, the influence of the negative sequence component of the grid voltage is not taken into account. The negative sequence component will cause the generator power to oscillate and cause damage to the entire transmission chain system.

[0005] Second, no consideration is given to how to suppress the negative sequence component of the grid voltage and thus reduce the grid voltage imbalance. Summary of the Invention

[0006] The present invention provides a negative sequence power control method for solving the problem that the prior art does not consider the influence of the negative sequence component of the grid voltage, resulting in generator power oscillation and grid voltage imbalance.

[0007] In a first aspect, an embodiment of the present invention provides a negative sequence power control method, the method comprising:

[0008] When an asymmetric fault occurs in the grid voltage, the operating parameters of the converter and the grid are obtained;

[0009] determining a generator power fluctuation value based on the operating parameters, and determining a first given value of a rotor negative-sequence current for suppressing the generator power fluctuation, and / or determining a second given value of the rotor negative-sequence current for suppressing a voltage negative-sequence component corresponding to a bus voltage and an upper limit of the rotor current based on the operating parameters;

[0010] A rotor negative sequence current of a rotor negative sequence control loop is determined according to the first given value and / or the second given value, and the rotor current is controlled using the rotor negative sequence current.

[0011] In one possible implementation, determining the generator power fluctuation value according to the operating parameter and determining a first given value of the rotor negative sequence current for suppressing the generator power fluctuation includes:

[0012] Determine the calculation formula of the generator power fluctuation value based on the generator's stator three-phase voltage and stator three-phase current;

[0013] In combination with the relationship between the rotor current and the stator current, a first given value of the rotor negative sequence current corresponding to when the calculation formula of the generator power fluctuation value is zero is determined.

[0014] In one possible implementation, a calculation formula for determining the generator power fluctuation value based on the stator three-phase voltage and the stator three-phase current of the generator includes:

[0015] The three-phase stator voltage of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active voltage, stator positive sequence reactive voltage, stator negative sequence active voltage and stator negative sequence reactive voltage;

[0016] The stator three-phase current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active current, stator positive sequence reactive current, stator negative sequence active current and stator negative sequence reactive current;

[0017] A calculation formula for the generator power fluctuation value is determined based on the stator positive-sequence active voltage, the stator positive-sequence reactive voltage, the stator negative-sequence active voltage, the stator negative-sequence reactive voltage, the stator positive-sequence active current, the stator positive-sequence reactive current, the stator negative-sequence active current and the stator negative-sequence reactive current.

[0018] In a possible implementation manner, the first given value of the rotor negative sequence current includes a first given value of the rotor negative sequence active current i rdref- and the first given value i of the rotor negative sequence inductive reactive current rqref- When the calculation formula for determining the generator power fluctuation value is zero, the corresponding first given value of the rotor negative sequence current is calculated as follows:

[0019]

[0020] Among them, u sd+ is the stator positive sequence active voltage, u sq+ Indicates the stator positive sequence reactive voltage, u sd- Indicates the stator negative sequence active voltage, u sq- Indicates the stator negative sequence reactive voltage, i rd+ It represents the rotor positive sequence active current calculated based on the relationship between the stator positive sequence active current, the stator negative sequence active current and the stator and rotor current, i rq+ It represents the rotor positive-sequence reactive current calculated based on the relationship between the stator positive-sequence reactive current, stator negative-sequence reactive current, and stator and rotor currents.

[0021] In one possible implementation, determining, based on the operating parameters, a second given value of the rotor negative-sequence current that does not exceed the DC bus voltage and the rotor current upper limit corresponding to suppressing the negative-sequence component of the grid voltage includes:

[0022] Determining a first range in which the remaining DC bus voltage can generate a negative-sequence active current and a negative-sequence inductive reactive current according to the DC bus voltage upper limit and the positive-sequence DC bus voltage demand value;

[0023] determining a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand;

[0024] A second given value of the rotor negative sequence current for suppressing the negative sequence component of the grid voltage is determined from the intersection of the first range and the second range.

[0025] In one possible implementation, based on the DC bus voltage upper limit and the positive-sequence DC bus voltage requirement, the following formula is used to determine a first range within which the remaining DC bus voltage can generate negative-sequence active current and negative-sequence inductive reactive current:

[0026]

[0027] Among them, i rdref - is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, u sd- represents the stator negative sequence active voltage, s is the positive sequence slip rate, ω is the grid frequency, σ is the leakage reactance coefficient, L r is the rotor inductance, L s is the stator inductance, L rm is the mutual inductance, u dcmax is the upper limit of DC bus voltage, u dc+ is the positive sequence DC bus voltage demand value.

[0028] In a possible implementation, determining the second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand includes:

[0029] The rotor positive sequence current demand includes rotor positive sequence active current and rotor positive sequence reactive current;

[0030] The three-phase rotor current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the rotor positive sequence active current, rotor positive sequence reactive current, rotor negative sequence active current and rotor negative sequence reactive current;

[0031] calculate

[0032] Among them, irdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, i rmax is the upper limit of the rotor current, i rd+ is the rotor positive sequence active current, i rq+ is the rotor positive sequence reactive current.

[0033] In a possible implementation, determining the rotor negative-sequence current of the rotor negative-sequence control loop according to the first given value and / or the second given value includes:

[0034] When the first given value is within the intersection of the first range and the second range, determining a rotor negative sequence current of a rotor negative sequence control loop according to the first given value;

[0035] When the first given value is not at the intersection of the first range and the second range, the rotor negative sequence current of the rotor negative sequence control loop is determined according to the second given value.

[0036] In a possible implementation, determining the rotor negative-sequence current of the rotor negative-sequence control loop according to the first given value or the second given value includes:

[0037] determining a current adjustment value of the rotor negative sequence current according to a current rotor negative sequence current of the rotor negative sequence control loop and with the first given value or the second given value as a target;

[0038] The current rotor negative sequence current is adjusted according to the current adjustment value.

[0039] In a possible implementation, adjusting the current rotor negative sequence current according to the adjustment value includes:

[0040] The current adjustment value is input into a proportional-integral (PI) controller, and the output result is superimposed with a feedforward compensation term to obtain a voltage in dq coordinates;

[0041] Converting the voltage under the dq coordinate system into the voltage under the αβ coordinate system, and inputting the voltage into a space vector pulse width modulation (SVPWM) module to generate a pulse width modulation (PWM) signal;

[0042] The rotor current is controlled according to the PWM signal.

[0043] In a second aspect, an embodiment of the present invention provides a negative sequence power control device, including:

[0044] The parameter acquisition module obtains the operating parameters of the converter and the grid when it determines that the grid voltage has an asymmetric fault;

[0045] a given value determination module, configured to determine a generator power fluctuation value based on the operating parameters, and determine a first given value of a rotor negative-sequence current for suppressing the generator power fluctuation, and / or determine a second given value of the rotor negative-sequence current for suppressing a negative-sequence component of a grid voltage that does not exceed an upper limit of a DC bus voltage and a rotor current based on the operating parameters;

[0046] The negative sequence control module is configured to determine a rotor negative sequence current of a rotor negative sequence control loop according to the first given value and / or the second given value, and to control the rotor current using the rotor negative sequence current.

[0047] In a possible implementation, the given value determination module determines the generator power fluctuation value according to the operating parameter, and determines a first given value of the rotor negative sequence current for suppressing the generator power fluctuation, including:

[0048] Determine the calculation formula of the generator power fluctuation value based on the generator's stator three-phase voltage and stator three-phase current;

[0049] According to the relationship between the rotor current and the stator current, a first given value of the rotor negative sequence current corresponding to when the calculation formula of the generator power fluctuation value takes a value of zero is determined.

[0050] In a possible implementation, the given value determination module determines a calculation formula for the generator power fluctuation value based on the stator three-phase voltage and the stator three-phase current of the generator, including:

[0051] The three-phase stator voltage of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active voltage, stator positive sequence reactive voltage, stator negative sequence active voltage and stator negative sequence reactive voltage;

[0052] The stator three-phase current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active current, stator positive sequence reactive current, stator negative sequence active current and stator negative sequence reactive current;

[0053] A calculation formula for the generator power fluctuation value is determined based on the stator positive-sequence active voltage, the stator positive-sequence reactive voltage, the stator negative-sequence active voltage, the stator negative-sequence reactive voltage, the stator positive-sequence active current, the stator positive-sequence reactive current, the stator negative-sequence active current and the stator negative-sequence reactive current.

[0054] In a possible implementation, the given value determination module determines, based on the operating parameters, a second given value of the rotor negative-sequence current that does not exceed the DC bus voltage and the rotor current upper limit corresponding to suppressing the negative-sequence component of the grid voltage, including:

[0055] Determining a first range in which the remaining DC bus voltage can generate a negative-sequence active current and a negative-sequence inductive reactive current according to the DC bus voltage upper limit and the positive-sequence DC bus voltage demand value;

[0056] Determining a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor three-phase current;

[0057] A second given value of the rotor negative sequence current for suppressing the voltage negative sequence component is determined from the intersection of the first range and the second range.

[0058] In one possible implementation, the given value determination module determines a first range within which the remaining DC bus voltage can generate negative-sequence active current and negative-sequence inductive reactive current based on the DC bus voltage upper limit and the positive-sequence DC bus voltage requirement using the following formula:

[0059]

[0060] Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, u sd- represents the stator negative sequence active voltage, s is the positive sequence slip rate, ω is the grid frequency, σ is the leakage reactance coefficient, L r is the rotor inductance, L s is the stator inductance, L rm is the mutual inductance, u dcmax is the upper limit of bus voltage, u dc+ is the positive sequence DC bus voltage demand value.

[0061] In a possible implementation manner, the given value determination module determines the second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand, including:

[0062] The rotor positive sequence current demand includes rotor positive sequence active current and rotor positive sequence reactive current;

[0063] The three-phase rotor current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the rotor positive sequence active current, rotor positive sequence reactive current, rotor negative sequence active current and rotor negative sequence reactive current;

[0064] calculate

[0065] Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, i rmax is the upper limit of the rotor current, ird+ is the rotor positive sequence active current, i rq+ is the rotor positive sequence reactive current.

[0066] In a possible implementation manner, the given value determination module determines the rotor negative-sequence current of the rotor negative-sequence control loop according to the first given value and / or the second given value, including:

[0067] When the first given value is within the intersection of the first range and the second range, determining a rotor negative sequence current of a rotor negative sequence control loop according to the first given value;

[0068] When the first given value is not at the intersection of the first range and the second range, the rotor negative sequence current of the rotor negative sequence control loop is determined according to the second given value.

[0069] In a possible implementation, the negative-sequence control module determines the rotor negative-sequence current of the rotor negative-sequence control loop according to the first given value or the second given value, including:

[0070] determining a current adjustment value of the rotor negative sequence current according to a current rotor negative sequence current of the rotor negative sequence control loop and with the first given value or the second given value as a target;

[0071] The current rotor negative sequence current is adjusted according to the current adjustment value.

[0072] In a third aspect, an embodiment of the present application provides a negative-sequence power control device, comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, and when the computer program is executed by the processor, any negative-sequence power control method according to the first aspect is implemented;

[0073] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the steps of any one of the negative-sequence power control methods in the first aspect are implemented.

[0074] An embodiment of the present invention provides a method for controlling negative-sequence power. Based on the operating parameters of the converter and the power grid, the method determines the generator power fluctuation value and a first given value of the rotor negative-sequence current to suppress the generator power fluctuation. Furthermore, based on the operating parameters, the method determines a second given value of the rotor negative-sequence current to suppress the negative-sequence component of the power grid voltage, which does not exceed the DC bus voltage and rotor current upper limit. Furthermore, based on the first given value and / or the second given value, the rotor negative-sequence current of the rotor negative-sequence control loop is determined, and the rotor current is controlled using the rotor negative-sequence current. The method provided by the present invention suppresses negative-sequence power and power grid negative-sequence voltage, thereby resolving the problems of generator power oscillation and power grid voltage imbalance caused by asymmetric power grid faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0076] Figure 1 A flowchart of negative sequence power control provided by an embodiment of the present invention;

[0077] Figure 2 A schematic diagram of determining a second given value of a rotor negative sequence current for suppressing a negative sequence component of a grid voltage provided by an embodiment of the present invention;

[0078] Figure 3 A schematic diagram of a negative sequence loop control system provided by an embodiment of the present invention;

[0079] Figure 4 A flowchart of a first method provided by an embodiment of the present invention;

[0080] Figure 5 A flowchart of a second method provided by an embodiment of the present invention;

[0081] Figure 6 A structural diagram of a negative sequence power control device provided by an embodiment of the present invention;

[0082] Figure 7 A schematic diagram of a negative sequence power control device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0083] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0084] In embodiments of the present invention, the term "and / or" describes the association relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0085] The application scenarios described in the embodiments of the present invention are intended to more clearly illustrate the technical solutions of the embodiments of the present invention and do not constitute a limitation on the technical solutions provided by the embodiments of the present invention. A person skilled in the art will appreciate that, with the emergence of new application scenarios, the technical solutions provided by the embodiments of the present invention are equally applicable to similar technical problems.

[0086] Wind power generation is a renewable, pollution-free, and renewable energy technology, contributing an increasing share of my country's total power generation annually. As the core control component of wind power generation, the converter achieves optimal efficiency and power quality through variable speed constant frequency control. When a grid voltage asymmetry fault occurs, the commonly used converter control method is to generate a certain amount of positive-sequence reactive power in addition to sufficient positive-sequence active power. However, this method does not consider the hazards of negative-sequence voltage components.

[0087] Example 1

[0088] The present invention provides a negative sequence power control method for solving the problem of generator power oscillation and grid voltage imbalance caused by asymmetric faults in the grid. Figure 1 Shown, including:

[0089] Step 101, when it is determined that an asymmetric fault occurs in the grid voltage, the operating parameters of the converter and the grid are obtained;

[0090] The specific manifestation of the voltage asymmetry fault of the power grid is: when a single-phase or two-phase fault occurs in the power grid voltage, the three-phase voltage of the power grid changes from the original symmetrical state to the asymmetrical state;

[0091] The operating parameters of the converter and the power grid may include parameters of the generator, parameters of the power grid, and operating parameters of the converter.

[0092] Step 102: Determine a generator power fluctuation value based on the operating parameters, and determine a first given value of a rotor negative-sequence current for suppressing the generator power fluctuation, and / or determine a second given value of a rotor negative-sequence current for suppressing a negative-sequence component of a grid voltage that does not exceed an upper limit of a DC bus voltage and a rotor current based on the operating parameters.

[0093] According to relevant technologies, after obtaining the operating parameters of the converter and the power grid, the generator power can be calculated based on the operating parameters of the converter and the power grid. The generator power includes two parts, one is the useful generator power, and the other is the generator power fluctuation value.

[0094] Related technologies fail to consider the impact of the negative-sequence component of the grid voltage, which can cause generator power oscillations and harm the entire drive train system. One possible implementation of the present invention involves determining the generator power fluctuation value based on the operating parameters, thereby determining the rotor negative-sequence current required to eliminate the generator power fluctuation value and determining a first given value of the rotor negative-sequence current to suppress the generator power fluctuation. Because the rotor negative-sequence current is a factor parameter that affects the generator power fluctuation value, after obtaining the corresponding generator power fluctuation value, the first given value of the rotor negative-sequence current can be determined, thereby eliminating the generator power fluctuation value by suppressing the generator power fluctuation.

[0095] As previously mentioned, the related art does not consider how to suppress the negative-sequence component of the grid voltage, thereby reducing grid voltage imbalance. Another possible implementation of the present invention is to inject negative-sequence inductive reactive current into the grid to minimize the negative-sequence component of the grid voltage, thereby fundamentally avoiding hazards such as generator power fluctuations.

[0096] Both of the above-mentioned two solutions of the present invention are based on the consideration of the negative-sequence component of the grid voltage. One solution is to determine the corresponding rotor negative-sequence current for suppressing the generator power fluctuation according to the generator power fluctuation after the generator power fluctuation caused by the negative-sequence component of the grid voltage occurs. The other solution is to control the rotor negative-sequence current according to the DC bus voltage and the upper limit of the rotor current to inject as much negative-sequence inductive reactive current as possible into the grid, thereby reducing the negative-sequence component of the grid voltage and reducing the generator power fluctuation.

[0097] Step 103: Determine a rotor negative-sequence current of a rotor negative-sequence control loop according to the first given value and / or the second given value, and use the rotor negative-sequence current to control the rotor current.

[0098] By utilizing the solution provided by the embodiment of the present invention, when an asymmetric fault occurs in the power grid, the active power oscillation of the generator can be suppressed to ensure stable operation of the unit; or the increase in the negative sequence voltage of the power grid can be suppressed to reduce the imbalance of the power grid, which is conducive to the smooth fault crossing of the wind turbine.

[0099] In specific implementation, only the first given value of the rotor negative-sequence current can be determined, and the rotor negative-sequence current of the rotor negative-sequence control loop can be determined based on the first given value, and the rotor current can be controlled by using the rotor negative-sequence current; or only the second given value of the rotor negative-sequence current can be determined, and the rotor negative-sequence current of the rotor negative-sequence control loop can be determined based on the second given value, and the rotor current can be controlled by using the rotor negative-sequence current; or, the two can be implemented in combination, that is, the first given value and the second given value of the rotor negative-sequence current are determined, and the rotor negative-sequence current of the rotor negative-sequence control loop can be determined based on the first given value and the second given value, and the rotor current can be controlled by using the rotor negative-sequence current.

[0100] As an optional implementation, a first given value of the rotor negative-sequence current is determined, and based on the first given value, the rotor negative-sequence current of the rotor negative-sequence control loop is determined, and when the rotor negative-sequence current is used to control the rotor current, based on the current rotor negative-sequence current of the rotor negative-sequence control loop, a current adjustment value of the rotor negative-sequence current is determined with the first given value as the target; and the current rotor negative-sequence current is adjusted according to the current adjustment value.

[0101] As another optional implementation, a second given value of the rotor negative-sequence current is determined, and based on the second given value, the rotor negative-sequence current of the rotor negative-sequence control loop is determined, and when the rotor negative-sequence current is used to control the rotor current, based on the current rotor negative-sequence current of the rotor negative-sequence control loop, a current adjustment value of the rotor negative-sequence current is determined with the second given value as a target; and the current rotor negative-sequence current is adjusted according to the current adjustment value.

[0102] The second given value is a given value selected from a range of available given values. As another optional embodiment, a first given value and a second given value are determined for the rotor negative-sequence current. The rotor negative-sequence current of the rotor negative-sequence control loop is determined based on the first and second given values, and the rotor current is controlled using the rotor negative-sequence current. When the first given value is within the range of available given values, the rotor negative-sequence current of the rotor negative-sequence control loop is determined based on the first given value; when the first given value is not within the range of available given values, the rotor negative-sequence current of the rotor negative-sequence control loop is determined based on the second given value. The process of determining the rotor negative-sequence current of the rotor negative-sequence control loop and controlling the rotor current based on the determination of the first given value / second given value is described in the above embodiment and will not be repeated here.

[0103] Two possible implementations of step 102 are described in detail below.

[0104] Method 1: Suppressing generator power fluctuations

[0105] When the generator power fluctuation suppression method is adopted, the above-mentioned operating parameters include the stator three-phase voltage and stator three-phase current, and the rotor three-phase current of the generator.

[0106] As an optional implementation manner, determining the generator power fluctuation value according to the operating parameter and determining a first given value of the rotor negative sequence current for suppressing the generator power fluctuation includes:

[0107] Determine the calculation formula of the generator power fluctuation value based on the generator's stator three-phase voltage and stator three-phase current;

[0108] According to the relationship between the rotor current and the stator current, a first given value of the rotor negative sequence current corresponding to when the calculation formula of the generator power fluctuation value takes a value of zero is determined.

[0109] The above-mentioned rotor current includes the rotor negative-sequence current, and the above-mentioned stator current includes the corresponding positive and negative sequence components under the coordinate transformation of the stator three-phase current converted into the two-phase synchronous rotating dq coordinate system. Therefore, when the calculation formula of the generator power fluctuation value takes a value of zero, the stator three-phase current in the calculation formula of the generator power fluctuation value can be converted into the rotor negative-sequence current. Since the stator three-phase voltage of the generator is a constant, the first given value of the corresponding rotor negative-sequence current can be calculated.

[0110] The initially acquired stator three-phase voltage, stator three-phase current, and rotor three-phase current are values ​​in a three-phase coordinate system. When calculating the first given value of the rotor negative-sequence current, they can be uniformly converted to a two-phase synchronously rotating dq coordinate system for coordinate transformation for calculation.

[0111] Specifically, the calculation formula for determining the generator power fluctuation value is determined based on the stator three-phase voltage and stator three-phase current of the generator, including:

[0112] The three-phase stator voltage of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active voltage, stator positive sequence reactive voltage, stator negative sequence active voltage and stator negative sequence reactive voltage;

[0113] The stator three-phase current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active current, stator positive sequence reactive current, stator negative sequence active current and stator negative sequence reactive current;

[0114] A calculation formula for the generator power fluctuation value is determined based on the stator positive-sequence active voltage, the stator positive-sequence reactive voltage, the stator negative-sequence active voltage, the stator negative-sequence reactive voltage, the stator positive-sequence active current, the stator positive-sequence reactive current, the stator negative-sequence active current and the stator negative-sequence reactive current.

[0115] Specifically, determine the generator power when the grid voltage fails due to asymmetric faults, the generator power p s (t) can be calculated using the following expression:

[0116]

[0117] It can be seen from the above formula that the generator stator power includes the useful generator power part and the generator power fluctuation value part. is the useful generator power; the calculation formula of the generator power fluctuation value includes two items, namely:

[0118]

[0119]

[0120] Among them, u sd+ is the stator positive sequence active voltage, u sq+ Indicates the stator positive sequence reactive voltage, u sd- Indicates the stator negative sequence active voltage, u sq- Indicates the stator negative sequence reactive voltage, i sd+ Indicates the stator positive sequence active current, i sq+ Represents the stator positive sequence reactive current, i sd- Indicates the stator negative sequence active current, i sq- represents the stator negative sequence reactive current, ω is the grid frequency;

[0121] Since the positive sequence system uses the stator positive sequence voltage orientation, the negative sequence system uses the stator negative sequence voltage orientation, where u sq+ and u sq- Both are 0, so the above expression can be simplified to determine the calculation formula of the generator power fluctuation value, which includes the following two items:

[0122]

[0123]

[0124] Among them, the cosine twice the power frequency fluctuation part is The sinusoidal fluctuation part of twice the power frequency is

[0125] According to the relationship between the rotor current and the stator current, when calculating the cosine twice power frequency fluctuation part, the stator positive sequence active current and the stator negative sequence active current in the formula can be replaced with the rotor positive sequence active current and the rotor negative sequence active current according to the relationship between the stator positive sequence active current, the stator negative sequence active current and the rotor positive sequence active current, and the rotor negative sequence active current;

[0126] When calculating the sinusoidal double power frequency fluctuation part, the stator positive-sequence reactive current and stator negative-sequence reactive current in the formula can be replaced with the rotor positive-sequence reactive current and rotor negative-sequence reactive current according to the relationship between the stator positive-sequence reactive current and stator negative-sequence reactive current and the rotor positive-sequence reactive current and rotor negative-sequence reactive current;

[0127] Let the calculation formula of the generator power fluctuation value be zero for solution, that is, let the cosine twice the power frequency fluctuation part and the sine twice the power frequency fluctuation part in the above formula be 0 respectively for solution, and the corresponding first given value of the rotor negative sequence current can be calculated by the following expression:

[0128]

[0129] Among them, i rdref- is the first given value of the rotor negative sequence active current, i rqref- is the first given value of the rotor negative sequence inductive reactive current, i rd+ It represents the rotor positive sequence active current calculated based on the stator positive sequence active current, stator negative sequence active current and the relationship between the rotor current and the stator current, i rq+ It represents the rotor positive-sequence reactive current calculated based on the relationship between the stator positive-sequence reactive current, stator negative-sequence reactive current, and stator and rotor currents.

[0130] Using the above-mentioned method 1, the specific process of the negative sequence power control method of the embodiment of the present invention can be found in Figure 4 , specifically including:

[0131] Step 401, obtaining the stator three-phase voltage, stator three-phase current and rotor three-phase current of the generator;

[0132] Step 402: transform the stator three-phase voltage, stator three-phase current, and rotor three-phase current of the generator into a two-term synchronous rotating dq coordinate system, and extract the positive and negative sequence components at the same time;

[0133] Step 403, determining a calculation formula for the generator power fluctuation value based on the stator three-phase voltage and the stator three-phase current of the generator;

[0134] Step 404, combining the relationship between the rotor current and the stator current, determining a first given value of the rotor negative sequence current corresponding to when the calculation formula for the generator power fluctuation value is zero;

[0135] Step 405, determining a current adjustment value of the rotor negative sequence current according to the current rotor negative sequence current of the rotor negative sequence control loop and the first given value;

[0136] Step 406: Adjust the current rotor negative sequence current according to the current adjustment value.

[0137] Method 2: Suppressing the negative sequence component of the grid voltage

[0138] When the generator power fluctuation suppression method is adopted, the above-mentioned operating parameters include the rotor three-phase current of the generator and the positive sequence DC bus voltage demand value.

[0139] When an asymmetric fault occurs in the power grid, the grid's negative-sequence voltage increases, causing negative-sequence current and power, which can seriously harm the system. The present invention adopts a second approach, suppressing the negative-sequence voltage to a certain extent. This can reduce grid voltage imbalance at the source, which is more conducive to unit operation. Specifically, by injecting as much negative-sequence inductive reactive current as possible into the grid, the negative-sequence voltage and imbalance can be suppressed to a certain extent, facilitating the successful obstacle ride-through of wind turbines.

[0140] The injection of negative sequence inductive reactive power is subject to the upper limit of the converter DC bus voltage and the upper limit of the converter rotor current.

[0141] Determining, based on the operating parameters, a second given value of the rotor negative sequence current that does not exceed the bus voltage and the upper limit of the rotor current that suppresses the negative sequence component of the voltage, including:

[0142] Determining a first range in which the remaining DC bus voltage can generate a negative-sequence active current and a negative-sequence inductive reactive current according to the DC bus voltage upper limit and the positive-sequence DC bus voltage demand value;

[0143] determining a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand;

[0144] A second given value of the rotor negative sequence current for suppressing the voltage negative sequence component is determined from the intersection of the first range and the second range.

[0145] The DC bus voltage restriction condition is that the generated negative-sequence active current and negative-sequence inductive reactive current must not exceed the residual voltage range obtained by subtracting the positive-sequence DC bus voltage demand value from the DC bus voltage upper limit. Thus, a first range of second given values ​​of the negative-sequence active current and negative-sequence inductive reactive current that can be generated by the residual DC bus voltage can be determined based on the bus voltage upper limit and the positive-sequence DC bus voltage demand value.

[0146] The limiting condition for the rotor current is that the sum of the positive sequence current modulus and the negative sequence current modulus must not exceed the upper limit of the rotor current.

[0147] According to the limiting condition of the bus voltage, the voltage limiting equation for the first range of the second given value of the negative-sequence active current and the negative-sequence inductive reactive current is determined as follows:

[0148]

[0149] Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, u sd- represents the stator negative sequence active voltage, s is the positive sequence slip rate, ω is the grid frequency, σ is the leakage reactance coefficient, L r is the rotor inductance, L s is the stator inductance, L rm is the mutual inductance, u dcmax is the upper limit of bus voltage, u dc+ is the positive sequence DC bus voltage demand value;

[0150] in,

[0151] The initially acquired rotor three-phase current is a value in a three-phase coordinate system. When performing the second range calculation of the negative-sequence active current and the negative-sequence inductive reactive current, the coordinates need to be converted to a two-phase synchronously rotating dq coordinate system for calculation.

[0152] Specifically, determining a second range of second given values ​​of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand includes:

[0153] The rotor positive sequence current demand includes rotor positive sequence active current and rotor positive sequence reactive current;

[0154] The three-phase rotor current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the rotor positive sequence active current, rotor positive sequence reactive current, rotor negative sequence active current and rotor negative sequence reactive current;

[0155] According to the limiting condition of the rotor current, the current limiting equation for the second range of the second given value of the negative-sequence active current and the negative-sequence inductive reactive current is determined as follows:

[0156]

[0157] Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, i rmax is the upper limit of the rotor current, i rd+ is the rotor positive sequence active current, i rq+ is the rotor positive sequence reactive current.

[0158] Specifically, such as Figure 2 As shown, a second given value of the rotor negative sequence current for suppressing the negative sequence component of the voltage is determined from the intersection of the first range and the second range;

[0159] According to the voltage limit equation, the first range is determined to be the circle center The radius is The voltage limit circle has a radius that decreases as the speed increases.

[0160] According to the current limiting equation, the second range is determined to be a circle with a center of (0,0) and a radius of The radius of the current limit circle decreases as the positive sequence current increases; from the intersection of the first range and the second range, a second given value of the rotor negative sequence current that suppresses the negative sequence component of the voltage is determined, that is, the second given value is within the intersection of the voltage limit circle and the current limit circle.

[0161] Using the above-mentioned method 2, the specific process of the negative sequence power control method of the embodiment of the present invention can be found in Figure 5 , specifically including:

[0162] Step 501, obtaining the rotor three-phase current and positive sequence DC bus voltage demand values ​​of the generator;

[0163] Step 502 , determining a first range within which the remaining DC bus voltage can generate negative-sequence active current and negative-sequence inductive reactive current based on the DC bus voltage upper limit and the positive-sequence DC bus voltage requirement value;

[0164] Step 503: Based on the rotor current upper limit and the rotor positive-sequence current requirement, coordinates are changed from a three-phase coordinate system to a two-phase synchronously rotating dq coordinate system, and positive and negative sequence components are extracted to determine a second range of negative-sequence active current and negative-sequence inductive reactive current.

[0165] Step 504: determining a second given value of the rotor negative sequence current for suppressing the voltage negative sequence component from the intersection of the first range and the second range;

[0166] Step 505 , determining a current adjustment value of the rotor negative sequence current based on the current rotor negative sequence current of the rotor negative sequence control loop and taking the second given value as a target;

[0167] Step 506: Adjust the current rotor negative sequence current according to the current adjustment value.

[0168] The negative sequence power control method described above is based on the negative sequence loop control system. Figure 3 As shown, the system consists of a given value calculation module, a given value selection module, a current calculation module D1, a PI controller module, a voltage calculation module D2, a coordinate transformation module, and an SVPWM module;

[0169] Among them, the given value calculation module can be divided into a first calculation module 10 for calculating the first given value and a second calculation module 20 for calculating the second given value. The first given value calculation module can calculate the first given value according to the algorithm for suppressing power fluctuations according to the present invention, and the second given value module can calculate the second given value according to the algorithm for suppressing the negative sequence component of the grid voltage according to the present invention; the given value selection module is in the form of a selection switch, and specifically can include a first switch K1 and a second switch K2, and selects the given value according to the control method described in the present invention; the current calculation module D1 obtains the current adjustment value based on the current rotor negative sequence current of the rotor negative sequence control loop and the input current as the target; the voltage calculation module D2 superimposes the input voltage with the feedforward compensation to obtain the rotor voltage value.

[0170] The control process of the system includes: inputting the obtained parameters into a given value calculation module to obtain a first given value and a second given value, using the given value as input, a given value selector selecting a suitable given value, the current calculation module D1 using the given value as input to calculate the current adjustment value, and using the adjustment value as input to the PI controller module, the obtained voltage is input to the voltage calculation module D2 to obtain the rotor voltage, and the coordinate transformation module is used to perform a coordinate transformation from a two-phase synchronous rotating dq coordinate system to a two-phase αβ coordinate system, the obtained voltage in the αβ coordinate system is input to the SVPWM module to obtain a PWM pulse signal, control the insulated gate bipolar transistor IGBT module, and further control the rotor current.

[0171] The control method of the negative sequence loop specifically includes:

[0172] determining a current adjustment value of the rotor negative sequence current according to a current rotor negative sequence current of the rotor negative sequence control loop and with the first given value or the second given value as a target;

[0173] The current adjustment value is input into a proportional-integral (PI) controller, and the output result is superimposed with a feedforward compensation term to determine the rotor voltage in the dq coordinates;

[0174] Converting the rotor voltage in the dq coordinate system into the rotor voltage in the αβ coordinate system, and inputting the rotor voltage into a space vector pulse width modulation (SVPWM) controller to generate a pulse width modulation (PWM) pulse signal;

[0175] According to the PWM pulse signal, the switching state of the insulated gate bipolar transistor IGBT in the inverter rotor is controlled to further control the rotor current.

[0176] Example 2

[0177] The above describes a negative sequence power control method in the present invention. The following describes an apparatus for performing the negative sequence power control method.

[0178] See also Figure 6 An embodiment of the present invention provides a negative sequence power control device, the device comprising:

[0179] The parameter acquisition module 601 acquires the operating parameters of the converter and the grid when it is determined that the grid voltage has an asymmetric fault;

[0180] a given value determination module 602, configured to determine a generator power fluctuation value based on the operating parameters, and determine a first given value of the rotor negative-sequence current for suppressing the generator power fluctuation, and / or determine a second given value of the rotor negative-sequence current for suppressing the negative-sequence component of the grid voltage, which does not exceed the DC bus voltage and rotor current upper limits, based on the operating parameters;

[0181] The negative-sequence control module 603 is configured to determine a rotor negative-sequence current of a rotor negative-sequence control loop according to the first given value and / or the second given value, and control the rotor current using the rotor negative-sequence current.

[0182] Optionally, the given value determination module determines the generator power fluctuation value according to the operating parameter, and determines a first given value of the rotor negative sequence current for suppressing the generator power fluctuation, including:

[0183] Determine the calculation formula of the generator power fluctuation value based on the generator's stator three-phase voltage and stator three-phase current;

[0184] According to the relationship between the rotor current and the stator current, a first given value of the rotor negative sequence current corresponding to when the calculation formula of the generator power fluctuation value takes a value of zero is determined.

[0185] Optionally, the given value determination module determines a calculation formula for the generator power fluctuation value based on the stator three-phase voltage and stator three-phase current of the generator, including:

[0186] The three-phase stator voltage of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active voltage, stator positive sequence reactive voltage, stator negative sequence active voltage and stator negative sequence reactive voltage;

[0187] The stator three-phase current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active current, stator positive sequence reactive current, stator negative sequence active current and stator negative sequence reactive current;

[0188] A calculation formula for the generator power fluctuation value is determined based on the stator positive-sequence active voltage, the stator positive-sequence reactive voltage, the stator negative-sequence active voltage, the stator negative-sequence reactive voltage, the stator positive-sequence active current, the stator positive-sequence reactive current, the stator negative-sequence active current and the stator negative-sequence reactive current.

[0189] Optionally, the first given value of the rotor negative sequence current includes a first given value of the rotor negative sequence active current i rdref- and the first given value i of the rotor negative sequence inductive reactive current rqref- When the given value determination module determines that the calculation formula for the generator power fluctuation value is zero, the corresponding first given value of the rotor negative sequence current is calculated in the following manner:

[0190]

[0191] Among them, u sd+ is the stator positive sequence active voltage, u sq+ Indicates the stator positive sequence reactive voltage, u sd- Indicates the stator negative sequence active voltage, usq- Indicates the stator negative sequence reactive voltage, i rd+ It represents the rotor positive sequence active current calculated based on the relationship between the stator positive sequence active current, the stator negative sequence active current and the stator and rotor current, i rq+ It represents the rotor positive-sequence reactive current calculated based on the relationship between the stator positive-sequence reactive current, stator negative-sequence reactive current, and stator and rotor currents.

[0192] Optionally, the given value determination module determines, based on the operating parameters, a second given value of the rotor negative-sequence current that does not exceed the DC bus voltage and the rotor current upper limit corresponding to suppressing the negative-sequence component of the grid voltage, including:

[0193] Determining a first range in which the remaining DC bus voltage can generate a negative-sequence active current and a negative-sequence inductive reactive current according to the DC bus voltage upper limit and the positive-sequence DC bus voltage demand value;

[0194] Determining a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor three-phase current;

[0195] A second given value of the rotor negative sequence current for suppressing the voltage negative sequence component is determined from the intersection of the first range and the second range.

[0196] Optionally, the given value determination module determines a first range within which the remaining DC bus voltage can generate negative-sequence active current and negative-sequence inductive reactive current based on the DC bus voltage upper limit and the positive-sequence DC bus voltage requirement using the following formula:

[0197]

[0198] Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, u sd- represents the stator negative sequence active voltage, s is the positive sequence slip rate, ω is the grid frequency, σ is the leakage reactance coefficient, L r is the rotor inductance, L s is the stator inductance, L rm is the mutual inductance, u dcmax is the upper limit of bus voltage, u dc+ is the positive sequence DC bus voltage demand value.

[0199] Optionally, the given value determination module determines a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current requirement, including:

[0200] The rotor positive sequence current demand includes rotor positive sequence active current and rotor positive sequence reactive current;

[0201] The three-phase rotor current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the rotor positive sequence active current, rotor positive sequence reactive current, rotor negative sequence active current and rotor negative sequence reactive current;

[0202] calculate

[0203] Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, i rmax is the upper limit of the rotor current, i rd+ is the rotor positive sequence active current, i rq+ is the rotor positive sequence reactive current.

[0204] Optionally, the given value determination module determines the rotor negative sequence current of the rotor negative sequence control loop according to the first given value and / or the second given value, including:

[0205] When the first given value is within the intersection of the first range and the second range, determining a rotor negative sequence current of a rotor negative sequence control loop according to the first given value;

[0206] When the first given value is not at the intersection of the first range and the second range, the rotor negative sequence current of the rotor negative sequence control loop is determined according to the second given value.

[0207] Optionally, the negative-sequence control module determines the rotor negative-sequence current of the rotor negative-sequence control loop according to the first given value or the second given value, including:

[0208] determining a current adjustment value of the rotor negative sequence current according to a current rotor negative sequence current of the rotor negative sequence control loop and with the first given value or the second given value as a target;

[0209] The current rotor negative sequence current is adjusted according to the current adjustment value.

[0210] Optionally, the negative-sequence control module adjusts the current rotor negative-sequence current according to the adjustment value, including:

[0211] The current adjustment value is input into a proportional-integral (PI) controller, and the output result is superimposed with a feedforward compensation term to obtain a voltage in dq coordinates;

[0212] Converting the voltage under the dq coordinate system into the voltage under the αβ coordinate system, and inputting the voltage into a space vector pulse width modulation (SVPWM) module to generate a pulse width modulation (PWM) signal;

[0213] The rotor current is controlled according to the PWM signal.

[0214] Referring to Figure 7 The device for negative sequence power control in the embodiment of the present application comprises:

[0215] at least one processor 701 and at least one memory 702, and a bus system 709;

[0216] The memory stores program codes, when the program codes are executed by the processor, the processor executes the following processes:

[0217] When the grid voltage appears asymmetric fault, the operating parameters of the converter and the grid are obtained;

[0218] According to the operating parameters, the generator power fluctuation value is determined, and the first given value of the rotor negative sequence current for suppressing the generator power fluctuation is determined, and / or according to the operating parameters, the second given value of the rotor negative sequence current for suppressing the voltage negative sequence component corresponding to the upper limit of the DC bus voltage and the rotor current is determined;

[0219] According to the first given value and / or the second given value, the rotor negative sequence current of the rotor negative sequence control loop is determined, and the rotor current is controlled by using the rotor negative sequence current.

[0220] Figure 7 The device 700 can have great differences due to different configurations or performances, and can include one or more processors (English full name: central processing units, English abbreviation: CPU) 701 (for example, one or more processors) and a memory 702, and one or more storage media 703 (for example, one or more mass storage devices) for storing application programs 704 or data 705. Among them, the memory 702 and the storage medium 703 can be temporary storage or persistent storage. The program stored in the storage medium 703 can include one or more modules (not shown in the figure), and each module can include a series of instruction operations in the information processing device. Further, the processor 701 can be configured to communicate with the storage medium 703, and execute a series of instruction operations in the storage medium 703 on the device 700.

[0221] The device 700 can also include one or more wired or wireless network interfaces 707, one or more input / output interfaces 708, and / or one or more operating systems 706, such as Windows Server, Mac OS X, Unix, Linux, FreeBSD, etc.

[0222] Optionally, the processor determines a generator power fluctuation value according to the operating parameter, and determines a first given value of a rotor negative sequence current for suppressing the generator power fluctuation, comprising:

[0223] A calculation formula for determining the generator power fluctuation value according to the stator three-phase voltage and the stator three-phase current of the generator;

[0224] When the calculation formula for determining the generator power fluctuation value is zero, the first given value of the rotor negative sequence current is determined according to a relationship between the rotor current and the stator current.

[0225] Optionally, the processor determines a calculation formula for determining the generator power fluctuation value according to the stator three-phase voltage and the stator three-phase current of the generator, comprising:

[0226] The stator three-phase voltage of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and positive and negative sequence components are extracted to obtain a stator positive sequence active voltage, a stator positive sequence reactive voltage, a stator negative sequence active voltage, and a stator negative sequence reactive voltage;

[0227] The stator three-phase current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and positive and negative sequence components are extracted to obtain a stator positive sequence active current, a stator positive sequence reactive current, a stator negative sequence active current, and a stator negative sequence reactive current;

[0228] The calculation formula for determining the generator power fluctuation value is determined according to the stator positive sequence active voltage, the stator positive sequence reactive voltage, the stator negative sequence active voltage, the stator negative sequence reactive voltage, the stator positive sequence active current, the stator positive sequence reactive current, the stator negative sequence active current, and the stator negative sequence reactive current.

[0229] Optionally, the first given value of the rotor negative sequence current comprises a first given value of a rotor negative sequence active current i rdref- and a first given value of a rotor negative sequence inductive reactive current i rqref- When the calculation formula for determining the generator power fluctuation value is zero, the first given value of the rotor negative sequence current is calculated in the following manner:

[0230]

[0231] wherein, u sd+ is the stator positive sequence active voltage, u sq+ represents the stator positive sequence reactive voltage, u sd- represents the stator negative sequence active voltage, u sq- represents the stator negative sequence reactive voltage, i rd+ represents a rotor positive sequence active current calculated according to a relationship between the stator positive sequence active current, the stator negative sequence active current, and the rotor current, and i rq+It represents the rotor positive-sequence reactive current calculated based on the relationship between the stator positive-sequence reactive current, stator negative-sequence reactive current, and stator and rotor currents.

[0232] Optionally, the processor determines, based on the operating parameters, a second given value of the rotor negative-sequence current for suppressing a negative-sequence component of a grid voltage that does not exceed an upper limit of a DC bus voltage and a rotor current, including:

[0233] Determining a first range in which the remaining DC bus voltage can generate a negative-sequence active current and a negative-sequence inductive reactive current according to the DC bus voltage upper limit and the positive-sequence DC bus voltage demand value;

[0234] determining a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand;

[0235] A second given value of the rotor negative sequence current for suppressing the voltage negative sequence component is determined from the intersection of the first range and the second range.

[0236] Optionally, the processor determines a first range within which the remaining DC bus voltage can generate negative-sequence active current and negative-sequence inductive reactive current according to the DC bus voltage upper limit and the positive-sequence DC bus voltage requirement value using the following formula:

[0237]

[0238] Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, u sd- represents the stator negative sequence active voltage, s is the positive sequence slip rate, ω is the grid frequency, σ is the leakage reactance coefficient, L r is the rotor inductance, L s is the stator inductance, L rm is the mutual inductance, u dcmax is the upper limit of bus voltage, u dc+ is the positive sequence DC bus voltage demand value.

[0239] Optionally, the processor determines a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand, including:

[0240] The rotor positive sequence current demand includes rotor positive sequence active current and rotor positive sequence reactive current;

[0241] The three-phase rotor current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the rotor positive sequence active current, rotor positive sequence reactive current, rotor negative sequence active current and rotor negative sequence reactive current;

[0242] computing

[0243] wherein, i rdref- is a second given value of a rotor negative sequence active current, i rqref- is a second given value of a rotor negative sequence inductive reactive current, i rmax is a rotor current upper limit, i rd+ is a rotor positive sequence active current, i rq+ is a rotor positive sequence reactive current.

[0244] Optionally, the processor determines the rotor negative sequence current of the rotor negative sequence control loop according to the first given value and / or the second given value, including:

[0245] when the first given value is within the intersection of the first range and the second range, determining the rotor negative sequence current of the rotor negative sequence control loop according to the first given value;

[0246] when the first given value is not within the intersection of the first range and the second range, determining the rotor negative sequence current of the rotor negative sequence control loop according to the second given value.

[0247] Optionally, the processor is configured to determine the rotor negative sequence current of the rotor negative sequence control loop according to the first given value or the second given value, including:

[0248] determining a current adjustment value of the rotor negative sequence current according to the first given value or the second given value, with a current of the rotor negative sequence control loop as a target;

[0249] adjusting the current of the rotor negative sequence control loop according to the current adjustment value.

[0250] Optionally, the processor adjusts the current of the rotor negative sequence control loop according to the adjustment value, including:

[0251] inputting the current adjustment value into a proportional-integral (PI) controller, and superimposing an output result and a feedforward compensation term to obtain a voltage in a dq coordinate system;

[0252] converting the voltage in the dq coordinate system into a voltage in an αβ coordinate system, and inputting the voltage into a space vector pulse width modulation (SVPWM) module to generate a pulse width modulation (PWM) signal;

[0253] generating a control rotor current according to the PWM signal.

[0254] The embodiment of the present application further provides a computer readable storage medium, including instructions, when the instructions are executed on a computer, the computer executes the method for negative sequence power control provided by the above embodiment.

[0255] The embodiment of the present application further provides a computer program product comprising a computer program, the computer program comprising program instructions, which, when executed by an electronic device, cause the electronic device to perform the method for negative sequence power control provided in the above embodiment.

[0256] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and modules can refer to the corresponding processes in the foregoing method embodiments, which will not be repeated here.

[0257] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other manners. For example, the above-described device embodiments are merely schematic, and the division of the modules is merely a logical function division, and there can be another division manner in actual implementation, for example, a plurality of modules or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection between the modules can be indirect coupling or communication connection through some interfaces, devices or modules, and can be electrical, mechanical or other forms.

[0258] The modules described as separated components can or can not be physically separated, and the components displayed as modules can or can not be physical modules, that is, can be located in one place, or can be distributed on a plurality of network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0259] In addition, each functional module in each embodiment of the present application can be integrated in one processing module, or each module can be physically present alone, or two or more modules can be integrated in one module. The integrated module can be realized in the form of hardware or in the form of a software functional module. When the integrated module is realized in the form of a software functional module and sold or used as an independent product, it can be stored in a computer readable storage medium.

[0260] In the above embodiments, all or part can be realized by software, hardware, firmware or any combination thereof. When realized by software, it can be realized in the form of a computer program product in whole or in part.

[0261] The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the flow or function described in the embodiments of the present application is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. 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.). The computer-readable storage medium can be any available medium that a computer can store or a data storage device such as a server, data center, etc. integrated with one or more available media. The available media can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)), etc.

[0262] The above describes the technical solutions provided by the present application in detail, and the principles and implementation manners of the present application are described by applying specific examples. The above examples are only used to help understand the method and core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, the specific implementation manner and application range will be changed, and the above description should not be understood as a limitation of the present application.

Claims

1. A negative sequence power control method, characterized in that: The method includes: When a voltage asymmetry fault is detected in the power grid, the operating parameters of the converter and the power grid are obtained; determining a generator power fluctuation value based on the operating parameters, and determining a first given value of a rotor negative-sequence current for suppressing the generator power fluctuation, and / or determining a second given value of the rotor negative-sequence current for suppressing a negative-sequence component of a grid voltage that does not exceed an upper limit of a DC bus voltage and a rotor current based on the operating parameters; determining a rotor negative-sequence current of a rotor negative-sequence control loop according to the first given value and / or the second given value, and controlling a rotor current using the rotor negative-sequence current; Determining, based on the operating parameters, a second given value of the rotor negative sequence current for suppressing the negative sequence component of the grid voltage corresponding to the DC bus voltage and the upper limit of the rotor current, comprising: Determining a first range in which the remaining DC bus voltage can generate a negative-sequence active current and a negative-sequence inductive reactive current according to the DC bus voltage upper limit and the positive-sequence DC bus voltage demand value; determining a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand; A second given value of the rotor negative sequence current for suppressing the negative sequence component of the grid voltage is determined from the intersection of the first range and the second range.

2. The method according to claim 1, characterized in that Determining the generator power fluctuation value according to the operating parameter and determining a first given value of the rotor negative sequence current for suppressing the generator power fluctuation includes: Determine the calculation formula of the generator power fluctuation value based on the generator's stator three-phase voltage and stator three-phase current; In combination with the relationship between the rotor current and the stator current, a first given value of the rotor negative sequence current corresponding to when the calculation formula of the generator power fluctuation value is zero is determined.

3. The method according to claim 2, characterized in that The calculation formula for determining the generator power fluctuation value based on the generator's stator three-phase voltage and stator three-phase current includes: The three-phase stator voltage of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active voltage, stator positive sequence reactive voltage, stator negative sequence active voltage and stator negative sequence reactive voltage; The stator three-phase current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active current, stator positive sequence reactive current, stator negative sequence active current and stator negative sequence reactive current; A calculation formula for the generator power fluctuation value is determined based on the stator positive-sequence active voltage, the stator positive-sequence reactive voltage, the stator negative-sequence active voltage, the stator negative-sequence reactive voltage, the stator positive-sequence active current, the stator positive-sequence reactive current, the stator negative-sequence active current and the stator negative-sequence reactive current.

4. The method according to claim 3, characterized in that The first given value of the rotor negative sequence current includes the first given value of the rotor negative sequence active current i rdref- and the first given value i of the rotor negative sequence inductive reactive current rqref- When the calculation formula for determining the generator power fluctuation value is zero, the corresponding first given value of the rotor negative sequence current is calculated as follows: Among them, u sd+ is the stator positive sequence active voltage, u sq+ Indicates the stator positive sequence reactive voltage, u sd- Indicates the stator negative sequence active voltage, u sq- Indicates the stator negative sequence reactive voltage, i rd+ Indicates the rotor positive sequence active current, i rq+ Rotor positive sequence reactive current.

5. The method according to claim 1, wherein According to the DC bus voltage upper limit and the positive-sequence DC bus voltage requirement, the following formula is used to determine a first range in which the remaining DC bus voltage can generate negative-sequence active current and negative-sequence inductive reactive current: Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, u sd- represents the stator negative sequence active voltage, s is the positive sequence slip rate, ω is the grid frequency, σ is the leakage reactance coefficient, L r is the rotor inductance, L s is the stator inductance, L rm is the mutual inductance, u dcmax is the upper limit of DC bus voltage, u dc+ is the positive sequence DC bus voltage demand value.

6. The method according to claim 1, characterized in that The rotor positive-sequence current demand includes a rotor positive-sequence active current and a rotor positive-sequence reactive current. Determining a second range of a negative-sequence active current and a negative-sequence inductive reactive current based on the rotor current upper limit and the rotor positive-sequence current demand includes: The three-phase rotor current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the rotor positive sequence active current, rotor positive sequence reactive current, rotor negative sequence active current and rotor negative sequence reactive current; The current limiting equation for determining the second range of the second given values ​​of the negative-sequence active current and the negative-sequence inductive reactive current is as follows: Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, i rmax is the upper limit of the rotor current, i rd+ is the current value of the rotor positive sequence active current, i rq+ is the current value of the rotor positive sequence reactive current.

7. The method according to claim 1, characterized in that Determining a rotor negative sequence current of a rotor negative sequence control loop according to the first given value and / or the second given value includes: When the first given value is within the intersection of the first range and the second range, determining a rotor negative sequence current of a rotor negative sequence control loop according to the first given value; When the first given value is not at the intersection of the first range and the second range, the rotor negative sequence current of the rotor negative sequence control loop is determined according to the second given value.

8. The method according to claim 1, characterized in that Determining a rotor negative-sequence current of a rotor negative-sequence control loop according to the first given value or the second given value includes: determining a current adjustment value of the rotor negative sequence current according to a current rotor negative sequence current of the rotor negative sequence control loop and with the first given value or the second given value as a target; The current rotor negative sequence current is adjusted according to the current adjustment value.

9. The method according to claim 8, characterized in that Adjusting the current rotor negative sequence current according to the adjustment value includes: The current adjustment value is input into a proportional-integral (PI) controller, and the output result is superimposed with a feedforward compensation term to obtain a voltage in dq coordinates; Converting the voltage under the dq coordinate system into the voltage under the αβ coordinate system, and inputting the voltage into a space vector pulse width modulation (SVPWM) module to generate a pulse width modulation (PWM) signal; The rotor current is controlled according to the PWM signal.

10. A negative sequence power control device, characterized in that: The device includes: The parameter acquisition module obtains the operating parameters of the converter and the grid when it determines that the grid voltage has an asymmetric fault; a given value determination module, configured to determine a generator power fluctuation value based on the operating parameters, and determine a first given value of a rotor negative-sequence current for suppressing the generator power fluctuation, and / or determine a second given value of the rotor negative-sequence current for suppressing a negative-sequence component of a grid voltage that does not exceed an upper limit of a DC bus voltage and a rotor current based on the operating parameters; a negative-sequence control module, configured to determine a rotor negative-sequence current of a rotor negative-sequence control loop according to the first given value and / or the second given value, and control a rotor current using the rotor negative-sequence current; The given value determination module determines, based on the operating parameters, a second given value of the rotor negative sequence current that does not exceed the DC bus voltage and the upper limit of the rotor current corresponding to suppressing the negative sequence component of the grid voltage, including: Determining a first range in which the remaining DC bus voltage can generate a negative-sequence active current and a negative-sequence inductive reactive current according to the DC bus voltage upper limit and the positive-sequence DC bus voltage demand value; determining a second range of the negative-sequence active current and the negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand; A second given value of the rotor negative sequence current for suppressing the negative sequence component of the grid voltage is determined from the intersection of the first range and the second range.

11. The device according to claim 10, characterized in that The given value determination module determines the generator power fluctuation value according to the operating parameter, and determines a first given value of the rotor negative sequence current for suppressing the generator power fluctuation, including: Determine the calculation formula of the generator power fluctuation value based on the generator's stator three-phase voltage and stator three-phase current; In combination with the relationship between the rotor current and the stator current, a first given value of the rotor negative sequence current corresponding to when the calculation formula of the generator power fluctuation value is zero is determined.

12. The device according to claim 11, characterized in that The given value determination module determines a calculation formula for the generator power fluctuation value based on the stator three-phase voltage and stator three-phase current of the generator, including: The three-phase stator voltage of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active voltage, stator positive sequence reactive voltage, stator negative sequence active voltage and stator negative sequence reactive voltage; The stator three-phase current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the stator positive sequence active current, stator positive sequence reactive current, stator negative sequence active current and stator negative sequence reactive current; A calculation formula for the generator power fluctuation value is determined based on the stator positive-sequence active voltage, the stator positive-sequence reactive voltage, the stator negative-sequence active voltage, the stator negative-sequence reactive voltage, the stator positive-sequence active current, the stator positive-sequence reactive current, the stator negative-sequence active current and the stator negative-sequence reactive current.

13. The device according to claim 10, characterized in that The given value determination module determines a first range within which the remaining DC bus voltage can generate negative-sequence active current and negative-sequence inductive reactive current based on the DC bus voltage upper limit and the positive-sequence DC bus voltage requirement using the following formula: Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, u sd- represents the stator negative sequence active voltage, s is the positive sequence slip rate, ω is the grid frequency, σ is the leakage reactance coefficient, L r is the rotor inductance, L s is the stator inductance, L rm is the mutual inductance, u dcmax is the upper limit of DC bus voltage, u dc+ is the positive sequence DC bus voltage demand value.

14. The device according to claim 10, characterized in that The rotor positive-sequence current demand includes a rotor positive-sequence active current and a rotor positive-sequence reactive current. The given value determination module determines a second range of a negative-sequence active current and a negative-sequence inductive reactive current according to the rotor current upper limit and the rotor positive-sequence current demand, including: The three-phase rotor current of the generator is converted from a three-phase coordinate system to a two-phase synchronous rotating dq coordinate system, and the positive and negative sequence components are extracted at the same time to obtain the rotor positive sequence active current, rotor positive sequence reactive current, rotor negative sequence active current and rotor negative sequence reactive current; The current limiting equation for determining the second range of the second given values ​​of the negative-sequence active current and the negative-sequence inductive reactive current is as follows: Among them, i rdref- is the second given value of the rotor negative sequence active current, i rqref- is the second given value of the rotor negative sequence inductive reactive current, i rmax is the upper limit of the rotor current, i rd+ is the current value of the rotor positive sequence active current, i rq+ is the current value of the rotor positive sequence reactive current.

15. The device according to claim 10, characterized in that The given value determination module determines the rotor negative sequence current of the rotor negative sequence control loop according to the first given value and / or the second given value, including: When the first given value is within the intersection of the first range and the second range, determining a rotor negative sequence current of a rotor negative sequence control loop according to the first given value; When the first given value is not at the intersection of the first range and the second range, the rotor negative sequence current of the rotor negative sequence control loop is determined according to the second given value.

16. The device according to claim 10, characterized in that The negative-sequence control module determines the rotor negative-sequence current of the rotor negative-sequence control loop according to the first given value or the second given value, including: determining a current adjustment value of the rotor negative sequence current according to a current rotor negative sequence current of the rotor negative sequence control loop and with the first given value or the second given value as a target; The current rotor negative sequence current is adjusted according to the current adjustment value.

17. A negative sequence power control device, characterized in that: The device includes a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the computer program is executed by the processor, the method according to any one of claims 1 to 9 is implemented.

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