CN115694275A - Negative sequence power control method, device and equipment - Google Patents
Negative sequence power control method, device and equipment Download PDFInfo
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- CN115694275A CN115694275A CN202110861331.4A CN202110861331A CN115694275A CN 115694275 A CN115694275 A CN 115694275A CN 202110861331 A CN202110861331 A CN 202110861331A CN 115694275 A CN115694275 A CN 115694275A
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Abstract
The invention provides a negative sequence power control method, a device and equipment, wherein the method comprises the following steps: when the asymmetric fault of the power grid voltage is determined, the operation parameters of the converter and the power grid are obtained; determining a generator power fluctuation value according to the operation parameters, determining a first given value of a rotor negative sequence current for inhibiting the generator power fluctuation, and/or determining a second given value of the rotor negative sequence current for inhibiting the grid voltage negative sequence component corresponding to the upper limit of the direct current bus voltage and the rotor current; and 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 utilizing the method provided by the invention, the negative sequence power and the negative sequence voltage of the power grid are inhibited, and the problems of generator power oscillation and power grid voltage unbalance caused by power grid asymmetric faults are solved.
Description
Technical Field
The invention relates to the technical field of electricity, in particular to a negative sequence power control method, device and equipment.
Background
Wind power generation is a renewable pollution-free new energy power generation technology, and the proportion of the total generated energy in China is increased year by year. The converter is used as a core control part of wind power generation, and the optimal efficiency and the optimal power quality are obtained through variable-speed constant-frequency control.
In the prior art, when the grid voltage has an asymmetric fault, a common control method of a converter is to issue a certain positive sequence capacitive reactive power to support the grid positive sequence voltage recovery on the premise of sending positive sequence active power. There are two problems in the above scheme:
firstly, the influence of the negative sequence component of the grid voltage is not considered, and the negative sequence component can cause the power oscillation of the generator to cause damage to the whole engine transmission chain system.
And secondly, how to restrain the negative sequence component of the power grid voltage is not considered, so that the unbalance degree of the power grid voltage is reduced.
Disclosure of Invention
The invention provides a negative sequence power control method which is used for solving the problems of generator power oscillation and power grid voltage unbalance caused by the fact that the influence of a negative sequence component of power grid voltage is not considered in the prior art.
In a first aspect, an embodiment of the present invention provides a negative sequence power control method, where the method includes:
when the asymmetric fault of the power grid voltage is determined, the operation parameters of the converter and the power grid are obtained;
determining a generator power fluctuation value according to the operation parameters, determining a first set value of a rotor negative sequence current for inhibiting the generator power fluctuation, and/or determining a second set value of the rotor negative sequence current which does not exceed an inhibition voltage negative sequence component corresponding to the bus voltage and the rotor current upper limit according to the operation parameters;
and 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.
In a possible embodiment, determining a value of the generator power fluctuation from the operating parameter and determining a first setpoint value of the negative rotor sequence current that suppresses the generator power fluctuation comprises:
determining a calculation formula of a power fluctuation value of the generator according to the three-phase voltage and the three-phase current of the stator of the generator;
and determining a first given value of the corresponding rotor negative sequence current when the value of the calculation formula of the generator power fluctuation value is zero by combining the relational expression of the rotor current and the stator current.
In a possible embodiment, the 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 comprises:
converting the three-phase voltage of the stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active voltage of the stator, positive sequence reactive voltage of the stator, negative sequence active voltage of the stator and negative sequence reactive voltage of the stator;
converting a three-phase current of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the stator, a positive sequence reactive current of the stator, a negative sequence active current of the stator and a negative sequence reactive current of the stator;
and determining a calculation formula of the power fluctuation value of the generator 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.
In one possible embodiment, the first setpoint value of the rotor negative-sequence current comprises a first setpoint value i of the rotor negative-sequence active current rdref- And a first given value i of the negative sequence inductive reactive current of the rotor rqref- And when the calculation formula of the power fluctuation value of the generator is determined to be zero, the corresponding first given value of the negative sequence current of the rotor is calculated in the following mode:
wherein u is sd+ Is a positive-sequence active voltage of the stator, u sq+ Representing positive-sequence reactive voltage of stator, u sd- Representing the stator negative-sequence active voltage u sq- Representing the negative-sequence reactive voltage of the stator, i rd+ Representing the rotor positive sequence active current, i, calculated from the stator positive sequence active current, the stator negative sequence active current and the stator-rotor current relational expression rq+ And the rotor positive sequence reactive current is calculated according to the relation among the stator positive sequence reactive current, the stator negative sequence reactive current and the stator and rotor currents.
In a possible embodiment, determining, according to the operating parameter, a second given value of the negative-sequence current of the rotor that does not exceed the grid voltage negative-sequence component suppression component corresponding to the dc bus voltage and the rotor current upper limit includes:
determining a first range within which the residual direct-current bus voltage can send out negative sequence active current and negative sequence inductive reactive current according to the direct-current bus voltage upper limit and the positive sequence direct-current bus voltage required value;
determining a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the requirement of the rotor positive sequence current;
and determining a second given value of the negative sequence current of the rotor for inhibiting the negative sequence component of the grid voltage from the intersection of the first range and the second range.
In one possible embodiment, according to the upper limit of the dc bus voltage and the positive sequence dc bus voltage requirement value, the following formula is used to determine a first range within which the remaining dc bus voltage can emit negative sequence active current and negative sequence inductive reactive current:
wherein i rdref -a second setpoint value for the negative-sequence active current of the rotor, i rqref- For a second given value of negative-sequence inductive reactive current of the rotor, u sd- Expressing the active voltage of the negative sequence of the stator, s is the slip ratio of the positive sequence, omega is the frequency of the power grid, sigma is the leakage reactance coefficient and L r Is the rotor inductance, L s Is a stator inductance, L rm Is mutual inductance of u dcmax Is the upper limit of the DC bus voltage u dc+ A value is required for the positive sequence dc bus voltage.
In one possible embodiment, determining the second range of negative sequence active current and negative sequence inductive reactive current according to the upper rotor current limit and the rotor positive sequence current demand comprises:
the rotor positive sequence current demand comprises rotor positive sequence active current and rotor positive sequence reactive current;
converting a three-phase current of a rotor of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the rotor, a positive sequence reactive current of the rotor, a negative sequence active current of the rotor and a negative sequence reactive current of the rotor;
calculating out
Wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current, i, of the rotor rmax Upper limit of rotor current, i rd+ For positive-sequence active current of rotor, i rq+ Is rotor positive sequence reactive current.
In a possible embodiment, determining the negative rotor sequence current of the negative rotor sequence control loop as a function of the first and/or second setpoint comprises:
when the first given value is in 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;
and when the first given value is not at 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.
In one possible embodiment, determining the negative rotor sequence current of the negative rotor sequence control loop based on the first or second setpoint comprises:
according to the current negative rotor sequence current of the negative rotor sequence control loop, determining a current adjustment value of the negative rotor sequence current by taking the first given value or the second given value as a target;
and adjusting the current negative sequence current of the rotor according to the current adjustment value.
In one possible embodiment, adjusting the present rotor negative-sequence current according to the adjustment value includes:
inputting the current adjustment value into a proportional integral PI controller, and superposing an output result and a feedforward compensation term to obtain a voltage under dq coordinates;
converting the voltage under the dq coordinate into a voltage under an alpha beta coordinate system, and inputting the voltage into a Space Vector Pulse Width Modulation (SVPWM) module to generate a Pulse Width Modulation (PWM) signal;
and generating a control rotor current according to the PWM signal.
In a second aspect, an embodiment of the present invention provides a negative sequence power control apparatus, including:
the parameter acquisition module is used for acquiring the operating parameters of the converter and the power grid when the asymmetric fault of the power grid voltage is determined;
the set value determining module is used for determining a generator power fluctuation value according to the operation parameters, determining a first set value of a negative sequence current of a rotor for inhibiting the power fluctuation of the generator, and/or determining a second set value of the negative sequence current of the rotor for inhibiting the negative sequence component of the power grid voltage corresponding to the upper limit of the direct-current bus voltage and the upper limit of the rotor current, wherein the second set value does not exceed the negative sequence current of the rotor for inhibiting the negative sequence component of the power grid voltage corresponding to the upper limit of the direct-current bus voltage and the upper limit of the rotor current;
and the negative sequence control module is used for 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 utilizing the rotor negative sequence current.
In one possible embodiment, the set point determination module determines a generator power fluctuation value from the operating parameter and determines a first set point of a rotor negative sequence current that suppresses the generator power fluctuation, including:
determining a calculation formula of a power fluctuation value of the generator according to the three-phase voltage and the three-phase current of the stator of the generator;
and determining a first given value of the corresponding rotor negative sequence current when the value of the calculation formula of the generator power fluctuation value is zero according to the relational expression of the rotor current and the stator current.
In one possible embodiment, the set point determination module determines the calculation formula of the generator power fluctuation value according to the stator three-phase voltage and the stator three-phase current of the generator, and the calculation formula comprises:
converting the three-phase voltage of the stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active voltage of the stator, positive sequence reactive voltage of the stator, negative sequence active voltage of the stator and negative sequence reactive voltage of the stator;
converting three-phase currents of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active currents, positive sequence reactive currents, negative sequence active currents and negative sequence reactive currents of the stator;
and determining a calculation formula of the power fluctuation value of the generator 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.
In one possible embodiment, the determining a second given value of the negative-sequence current of the rotor, which does not exceed the grid voltage negative-sequence component suppression component corresponding to the direct-current bus voltage and the rotor current upper limit, according to the operating parameter by the given value determining module includes:
determining a first range within which the residual direct-current bus voltage can send out negative sequence active current and negative sequence inductive reactive current according to the direct-current bus voltage upper limit and the positive sequence direct-current bus voltage required value;
determining a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the three-phase current of the rotor;
and determining a second given value of the negative sequence current of the rotor for inhibiting the voltage negative sequence component from the intersection of the first range and the second range.
In a possible embodiment, the given value determining module determines, according to the upper limit of the dc bus voltage and the positive sequence dc bus voltage requirement value, a first range in which the remaining dc bus voltage can generate a negative sequence active current and a negative sequence inductive reactive current by using the following formula:
wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current of the rotor, u sd- The active voltage of the negative sequence of the stator is represented, s is the slip ratio of the positive sequence, omega is the frequency of the power grid, sigma is the leakage reactance coefficient, and L r Is the rotor inductance, L s Is a stator inductance, L rm Is mutual inductance of u dcmax Upper limit of bus voltage, u dc+ A value is required for the positive sequence dc bus voltage.
In one possible embodiment, the given value determining module determines the second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper rotor current limit and the rotor positive sequence current demand, and includes:
the rotor positive sequence current demand comprises rotor positive sequence active current and rotor positive sequence reactive current;
converting three-phase current of a rotor of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active current of the rotor, positive sequence reactive current of the rotor, negative sequence active current of the rotor and negative sequence reactive current of the rotor;
computing
Wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current, i, of the rotor rmax Upper limit of rotor current, i rd+ For positive-sequence active current of rotor, i rq+ Is rotor positive sequence reactive current.
In one possible embodiment, the set point determination module determines a negative rotor sequence current of a negative rotor sequence control loop based on the first set point and/or the second set point, comprising:
when the first given value is in 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;
and when the first given value is not at 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.
In one possible embodiment, the negative sequence control module determines a negative rotor sequence current of a negative rotor sequence control loop based on the first or second setpoint, including:
determining a current adjustment value of the negative sequence current of the rotor by taking the first given value or the second given value as a target according to the current negative sequence current of the negative sequence control loop of the rotor;
and adjusting the current negative sequence current of the rotor according to the current adjustment value.
In a third aspect, an embodiment of the present application provides a negative sequence power control device, including a memory and a processor, where the memory stores a computer program executable on the processor, and when the computer program is executed by the processor, the negative sequence power control device implements any one of the negative sequence power control methods of the first aspect;
in a fourth aspect, the present application provides a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processor, the steps of the negative sequence power control method in any one of the above first aspects are implemented.
The embodiment of the invention provides a negative sequence power control method, which comprises the steps of determining a power fluctuation value of a generator based on operation parameters of a converter and a power grid, determining a first given value of negative sequence current of a rotor for inhibiting the power fluctuation of the generator, and/or determining a second given value of the negative sequence current of the rotor for inhibiting the negative sequence component of the voltage of the power grid corresponding to the upper limit of direct current bus voltage and the upper limit of the rotor current according to the operation parameters; and 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 utilizing the method provided by the invention, the negative sequence power and the negative sequence voltage of the power grid are inhibited, and the problems of generator power oscillation and power grid voltage unbalance caused by power grid asymmetric faults are solved.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a flow chart of negative sequence power control according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a method for determining a second setpoint of a negative-sequence rotor current for suppressing a negative-sequence component of a grid voltage according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a negative sequence loop control system according to an embodiment of the present invention;
FIG. 4 is a flowchart of a first method provided by the embodiment of the present invention;
FIG. 5 is a flowchart of a second method provided by the embodiment of the present invention;
fig. 6 is a structural diagram of a negative sequence power control apparatus according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a negative sequence power control apparatus according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The term "and/or" in the embodiments of the present invention describes an association relationship of associated objects, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist simultaneously, and B exists alone. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship.
The application scenario described in the embodiment of the present invention is for more clearly illustrating the technical solution of the embodiment of the present invention, and does not form a limitation on the technical solution provided in the embodiment of the present invention, and it can be known by a person skilled in the art that, with the occurrence of a new application scenario, the technical solution provided in the embodiment of the present invention is also applicable to similar technical problems.
Wind power generation is a renewable pollution-free new energy power generation technology, and the proportion of the total generated energy in China is increased year by year. The converter is used as a core control part of wind power generation, and the optimal efficiency and the optimal power quality are obtained through variable-speed constant-frequency control. When the voltage of a power grid has an asymmetric fault, a current commonly used control method of a converter is to send certain positive sequence reactive power again on the premise of sending enough positive sequence active power, but the method does not consider the harm of the negative sequence component of the voltage.
Example 1
The invention provides a negative sequence power control method, which is used for solving the problems of generator power oscillation and grid voltage unbalance caused by grid asymmetric faults, and comprises the following steps of:
the voltage asymmetry fault of the power grid is represented as follows: when the voltage of the power grid has single-phase or two-phase faults, the three-phase voltage of the power grid is changed from an original symmetrical state to an asymmetrical state;
the operating parameters of the converter and the grid may include parameters of the generator, parameters of the grid, operating parameters of the converter, and the like.
102, determining a generator power fluctuation value according to the operation parameters, determining a first given value of a rotor negative sequence current for inhibiting the generator power fluctuation, and/or determining a second given value of the rotor negative sequence current for inhibiting the grid voltage negative sequence component corresponding to the upper limit of the direct current bus voltage and the rotor current;
according to the related technology, after the operation parameters of the converter and the power grid are obtained, the power of the generator can be calculated according to the operation parameters of the converter and the power grid, wherein the power of the generator comprises two parts, one part is useful power of the generator, and the other part is a fluctuation value of the power of the generator.
In the related art, the influence of a negative sequence component of a grid voltage is not considered, the negative sequence component can cause the power oscillation of a generator and cause damage to an integral drive train system. Because the rotor negative sequence current is a factor parameter influencing the power fluctuation value of the generator, after the corresponding power fluctuation value of the generator is obtained, the first given value of the rotor negative sequence current can be determined, and the power fluctuation value of the generator is eliminated in a mode of inhibiting the power fluctuation of the generator.
As described above, how to suppress the negative sequence component of the grid voltage, and further reduce the imbalance of the grid voltage, is not considered in the related art. Another possible implementation manner of the embodiment of the invention is to reduce the negative sequence component of the voltage of the power grid as much as possible by injecting the negative sequence inductive reactive current into the power grid, so that the damage of power fluctuation and the like of the generator is fundamentally avoided.
The invention takes the negative sequence component of the voltage of the power grid as a starting point, one solving method is to determine the corresponding rotor negative sequence current for inhibiting the power fluctuation of the generator according to the power fluctuation condition of the generator after the power fluctuation of the generator caused by the negative sequence component of the voltage of the power grid occurs, and the other solving method is to inject negative sequence inductive reactive current into the power grid as much as possible by controlling the rotor negative sequence current according to the voltage of a direct current bus and the upper limit of the rotor current, so as to reduce the negative sequence component of the voltage of the power grid and reduce the power fluctuation of the generator.
And 103, 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 utilizing the scheme provided by the embodiment of the invention, when the power grid has an asymmetric fault, the active power oscillation of the generator can be inhibited, and the stable operation of the unit is ensured; or the negative sequence voltage of the power grid can be restrained from rising, the unbalance degree of the power grid is reduced, and smooth fault ride-through of the wind turbine generator is facilitated.
In specific implementation, only the first given value of the negative sequence current of the rotor can be determined, the negative sequence current of the rotor of the negative sequence control loop of the rotor can be determined according to the first given value, and the negative sequence current of the rotor can be used for controlling the current of the rotor; or only determining a second given value of the rotor negative sequence current, determining the rotor negative sequence current of the rotor negative sequence control loop according to the second given value, and controlling the rotor current by using the rotor negative sequence current; alternatively, it may be implemented by a combination of both, that is, determining a first specified value and a second specified value of the negative-sequence rotor current, determining the negative-sequence rotor current of the negative-sequence rotor control loop based on the first specified value and the second specified value, and controlling the rotor current by using the negative-sequence rotor current.
As an alternative implementation manner, a first given value of the negative sequence current of the rotor is determined, the negative sequence current of the rotor of the negative sequence control loop is determined according to the first given value, and when the negative sequence current of the rotor is used for controlling the rotor current, the current adjustment value of the negative sequence current of the rotor is determined according to the current negative sequence current of the negative sequence control loop of the rotor by taking the first given value as a target; and adjusting the current negative sequence current of the rotor according to the current adjustment value.
As another alternative embodiment, a second given value of the negative-sequence rotor current is determined, the negative-sequence rotor current of the negative-sequence rotor control loop is determined according to the second given value, and when the negative-sequence rotor current is used for controlling the rotor current, the current adjustment value of the negative-sequence rotor current is determined according to the current negative-sequence rotor current of the negative-sequence rotor control loop and taking the second given value as a target; and adjusting the current negative sequence current of the rotor according to the current adjustment value.
The second given value is a given value selected from a range of available given values, and as another alternative embodiment, the first given value and the second given value of the negative-sequence rotor current are determined, the negative-sequence rotor current of the negative-sequence rotor control loop is determined according to the first given value and the second given value, and when the negative-sequence rotor current is used for controlling the rotor current, the negative-sequence rotor current of the negative-sequence rotor control loop is determined according to the first given value when the first given value is within the range of available given values; and when the first given value is not in the available given value range, determining the negative rotor sequence current of the negative rotor sequence control loop according to 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 in accordance with the determination of the first/second setpoint is described with reference to the above-described embodiment and will not be repeated here.
Two possible implementations of step 102 are described in detail below.
Mode one, restraining the power fluctuation of the generator
When the mode of restraining the power fluctuation of the generator is adopted, the operation parameters comprise the stator three-phase voltage, the stator three-phase current and the rotor three-phase current of the generator.
As an alternative embodiment, determining a generator power fluctuation value from the operating parameters and determining a first setpoint value of a negative rotor sequence current that suppresses the generator power fluctuation comprises:
determining a calculation formula of a power fluctuation value of the generator according to the three-phase voltage and the three-phase current of the stator of the generator;
and determining a first given value of the corresponding rotor negative sequence current when the value of the calculation formula of the generator power fluctuation value is zero according to the relational expression of the rotor current and the stator current.
The rotor current comprises rotor negative sequence current, the stator current comprises positive and negative sequence components corresponding to coordinate transformation of converting stator three-phase current into a two-phase synchronous rotation dq coordinate system, so that when the calculation formula of the generator power fluctuation value is 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, and the stator three-phase voltage of the generator is a fixed value, so that the first given value of the corresponding rotor negative sequence current can be calculated.
The initially obtained stator three-phase voltage, stator three-phase current and rotor three-phase current are values in a three-phase coordinate system, and when the first given value of the rotor negative sequence current is calculated, the values can be uniformly converted into coordinate transformation of a two-phase synchronous rotation dq coordinate system for calculation.
Specifically, according to the stator three-phase voltage and the stator three-phase current of the generator, the calculation formula of the generator power fluctuation value is determined, and the calculation formula comprises the following steps:
converting the three-phase voltage of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active voltage, positive sequence reactive voltage, negative sequence active voltage and negative sequence reactive voltage of the stator;
converting three-phase currents of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active currents, positive sequence reactive currents, negative sequence active currents and negative sequence reactive currents of the stator;
and determining a calculation formula of the power fluctuation value of the generator 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.
Specifically, the power of the generator and the power of the generator when the power grid voltage has asymmetric faults are determinedp s (t) can be calculated using the following expression:
as can be seen from the above equations, the generator stator power contains a useful generator power component and a generator power fluctuation component,
useful generator power; the calculation formula of the power fluctuation value of the generator comprises two terms, namely:
wherein u is sd+ Is a positive-sequence active voltage of the stator, u sq+ Representing positive-sequence reactive voltage of stator, u sd- Representing stator negative sequence active voltage, u sq- Representing the negative-sequence reactive voltage of the stator, i sd+ Representing stator positive sequence active current, i sq+ Representing positive-sequence reactive current of stator, i sd- Representing stator negative sequence active current, i sq- Representing the negative sequence reactive current of the stator, wherein omega is the frequency of the power grid;
because the positive sequence system uses stator positive sequence voltage orientation, the negative sequence system uses stator negative sequence voltage orientation, where u sq+ And u sq- All 0, so that the above expression can be simplified, the calculation formula for determining the generator power fluctuation value includes the following two terms:
wherein the cosine twice power frequency fluctuation part is
The sine double power frequency fluctuation part is
According to a relational expression of rotor current and stator current, when a cosine double power frequency fluctuation part is calculated, the stator positive sequence active current and the stator negative sequence active current in the formula can be replaced by the rotor positive sequence active current and the rotor negative sequence active current according to the relation between the stator positive sequence active current and the stator negative sequence active current and the rotor positive sequence active current and the rotor negative sequence active current;
when the sine double power frequency fluctuation part is calculated, the stator positive sequence reactive current and the stator negative sequence reactive current in the formula can be replaced by the rotor positive sequence reactive current and the rotor negative sequence reactive current according to the relation between the stator positive sequence reactive current and the stator negative sequence reactive current and the rotor positive sequence reactive current and the rotor negative sequence reactive current;
the calculation formula of the power fluctuation value of the generator is set to be zero to solve, namely, a cosine double power frequency fluctuation part and a sine double power frequency fluctuation part in the formula are respectively set to be 0 to solve, and the corresponding first given value of the rotor negative sequence current can be calculated by the following expression:
wherein i rdref- For a first given value of the negative-sequence active current of the rotor, i rqref- For a first given value of negative sequence inductive reactive current, i, of the rotor rd+ Represents the rotor positive sequence active current, i, calculated according to the stator positive sequence active current, the stator negative sequence active current and the relational expression of the rotor current and the stator current rq+ Shows that the stator positive sequence reactive current and the stator negative sequence are notAnd calculating the rotor positive sequence reactive current by using a power current and stator and rotor current relational expression.
With the first mode, referring to fig. 4, a specific flow of the negative sequence power control method in the embodiment of the present invention specifically includes:
and step 406, adjusting the current negative-sequence rotor current according to the current adjustment value.
Mode two, restraining the negative sequence component of the network voltage
When the mode of restraining the power fluctuation of the generator is adopted, the operation parameters comprise the three-phase current of the rotor of the generator and the required value of the positive sequence direct current bus voltage.
When the power grid has an asymmetric fault, the negative sequence voltage of the power grid can be increased, and further negative sequence current and negative sequence power are caused, so that serious damage is caused to the system. According to the method, the negative sequence voltage is restrained to a certain degree, so that the unbalance degree of the power grid voltage can be reduced from the source, and the running of a unit is facilitated. The specific mode is that as much negative sequence inductive reactive current as possible is injected into the power grid, the negative sequence voltage and the unbalance degree of the power grid can be restrained to a certain degree, and the successful barrier crossing of the wind turbine generator is facilitated.
The injection of the negative sequence inductive reactive power is limited by the upper voltage limit of the direct current bus of the converter and the upper current limit of the rotor of the converter.
Determining a second given value of the negative sequence current of the rotor, which does not exceed the suppression voltage negative sequence component corresponding to the bus voltage and the rotor current upper limit, according to the operation parameters, and the method comprises the following steps:
determining a first range within which the residual direct-current bus voltage can send out negative sequence active current and negative sequence inductive reactive current according to the direct-current bus voltage upper limit and the positive sequence direct-current bus voltage required value;
determining a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the requirement of the rotor positive sequence current;
and determining a second given value of the negative sequence current of the rotor for inhibiting the voltage negative sequence component from the intersection of the first range and the second range.
The limitation condition of the direct current bus voltage is that the emitted negative sequence active current and negative sequence inductive reactive current do not exceed the residual voltage range of the direct current bus voltage upper limit minus the positive sequence direct current bus voltage required value, so that the first range of the second given value of the negative sequence active current and the negative sequence inductive reactive current which can be emitted by the residual direct current bus voltage can be determined according to the bus voltage upper limit and the positive sequence direct current bus voltage required value.
The limitation condition of the rotor current is that the sum of the emitted positive sequence current module value and the negative sequence current module value does not exceed the upper limit of the rotor current.
According to the limitation condition of the bus voltage, the voltage limitation equation of the first range for determining the second given value of the negative sequence active current and the negative sequence inductive reactive current is as follows:
wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current of the rotor, u sd- The active voltage of the negative sequence of the stator is shown, s is the slip ratio of the positive sequence, omega is the frequency of the power grid, and sigma is the leakage reactanceCoefficient, L r Is the rotor inductance, L s Is a stator inductance, L rm Is a mutual inductance of u dcmax Is the upper limit of the bus voltage u dc+ A value is required for the positive sequence direct current bus voltage;
wherein the content of the first and second substances,
the initially obtained three-phase current of the rotor is a value under a three-phase coordinate system, and when the second range of the negative sequence active current and the negative sequence inductive reactive current is calculated, the coordinate of the two-phase synchronous rotation dq coordinate system needs to be converted for calculation.
Specifically, determining a second range of a second given value of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the requirement of the rotor positive sequence current includes:
the rotor positive sequence current demand comprises rotor positive sequence active current and rotor positive sequence reactive current;
converting a three-phase current of a rotor of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the rotor, a positive sequence reactive current of the rotor, a negative sequence active current of the rotor and a negative sequence reactive current of the rotor;
the current limit equation for determining the second range of the second given value of the negative sequence active current and the negative sequence inductive reactive current according to the limit condition of the rotor current is as follows:
wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current, i, of the rotor rmax Upper limit of rotor current, i rd+ For positive-sequence active current of rotor, i rq+ Is rotor positive sequence reactive current.
Specifically, as shown in fig. 2, a second given value of the negative sequence current of the rotor for suppressing the negative sequence component of the voltage is determined from the intersection of the first range and the second range;
according to the voltage limit equation, determining the first range as the center of a circle
Radius of
The radius of the voltage limit circle is reduced along with the increase of the rotating speed;
according to the current limit equation, the second range is determined as the circle center being (0, 0) and the radius being
The radius of the current limit circle is reduced along with the increase of the positive sequence current; and determining a second given value of the rotor negative-sequence current for inhibiting the voltage negative-sequence component from the intersection of the first range and the second range, namely the second given value is within the intersection of the voltage limit circle and the current limit circle.
By adopting the second mode, a specific process of the negative sequence power control method according to the embodiment of the present invention is shown in fig. 5, and specifically includes:
and step 506, adjusting the current negative-sequence rotor current according to the current adjustment value.
The negative sequence power control method is controlled based on a negative sequence loop control system, the negative sequence loop control system is shown in figure 3, and 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;
the given value calculation module can be divided into a first calculation module 10 for calculating a first given value and a second calculation module 20 for calculating a second given value, wherein the first given value calculation module can calculate the first given value according to the algorithm for suppressing the power fluctuation, and the second given value calculation module can calculate the second given value according to the algorithm for suppressing the negative sequence component of the grid voltage; the given value selection module is in a selection switch form, specifically comprises a first switch K1 and a second switch K2, and selects a given value according to the control method; the current calculation module D1 obtains a current adjustment value by taking the input current as a target according to the current rotor negative sequence current of the rotor negative sequence control loop; and the voltage calculation module D2 superposes the input voltage and the feedforward compensation to obtain a rotor voltage value.
The control flow of the system comprises the following steps: inputting the obtained parameters into a given value calculation module to obtain a first given value and a second given value, taking the given values as input, selecting a proper given value by a given value selector, taking the given values as input by a current calculation module D1 to calculate a current regulation value, taking the regulation value as input of a PI controller module, inputting the obtained voltage into a voltage calculation module D2 to obtain rotor voltage, performing coordinate transformation from a two-phase synchronous rotation dq coordinate system to a two-phase alpha beta coordinate system by a coordinate transformation module, inputting the obtained voltage under the alpha beta coordinate system into an SVPWM module to obtain PWM pulse signals, controlling an insulated gate bipolar transistor IGBT module and further controlling the rotor current.
The control method of the negative sequence loop specifically comprises the following steps:
determining a current adjustment value of the negative sequence current of the rotor by taking the first given value or the second given value as a target according to the current negative sequence current of the negative sequence control loop of the rotor;
inputting the current adjustment value into a proportional integral PI controller, and superposing an output result and a feedforward compensation term to determine the rotor voltage under dq coordinates;
converting the rotor voltage under the dq coordinate into the rotor voltage under an alpha beta 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;
and controlling the on-off state of an Insulated Gate Bipolar Transistor (IGBT) in the rotor of the frequency converter according to the PWM pulse signal, and further controlling the current of the rotor.
Example 2
A negative sequence power control method according to the present invention is explained above, and an apparatus for performing the negative sequence power control is explained below.
Referring to fig. 6, an embodiment of the present invention provides a negative sequence power control apparatus, including:
the parameter acquisition module 601 is used for acquiring the operating parameters of the converter and the power grid when the asymmetric fault of the power grid voltage is determined;
a given value determining module 602, configured to determine a generator power fluctuation value according to the operation parameter, determine a first given value of a negative sequence current of a rotor that suppresses generator power fluctuation, and/or determine a second given value of the negative sequence current of the rotor that does not exceed a negative sequence component of a grid voltage corresponding to an upper limit of a dc bus voltage and a rotor current according to the operation parameter;
and the negative sequence control module 603 is used for 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.
Optionally, the determining a first set value of a negative sequence current of the rotor for suppressing the power fluctuation of the generator according to the operating parameter by the set value determining module includes:
determining a calculation formula of a power fluctuation value of the generator according to the stator three-phase voltage and the stator three-phase current of the generator;
and determining a first given value of the corresponding rotor negative sequence current when the value of the calculation formula of the generator power fluctuation value is zero according to the relational expression of the rotor current and the stator current.
Optionally, the given value determining module determines a calculation formula of the generator power fluctuation value according to the stator three-phase voltage and the stator three-phase current of the generator, and the calculation formula includes:
converting the three-phase voltage of the stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active voltage of the stator, positive sequence reactive voltage of the stator, negative sequence active voltage of the stator and negative sequence reactive voltage of the stator;
converting a three-phase current of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the stator, a positive sequence reactive current of the stator, a negative sequence active current of the stator and a negative sequence reactive current of the stator;
and determining a calculation formula of the power fluctuation value of the generator 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.
Optionally, the first given value of the rotor negative sequence current comprises a first given value i of the rotor negative sequence active current rdref- And a first given value i of the negative sequence inductive reactive current of the rotor rqref- The given value determining module determines that the value of the calculation formula of the power fluctuation value of the generator is zero, and the corresponding first given value of the negative sequence current of the rotor is calculated in the following mode:
wherein u is sd+ Is the positive-sequence active voltage of the stator,u sq+ representing positive-sequence reactive voltage of stator, u sd- Representing stator negative sequence active voltage, u sq- Representing the negative-sequence reactive voltage of the stator, i rd+ Representing the rotor positive sequence active current, i, calculated from the stator positive sequence active current, the stator negative sequence active current and the stator-rotor current relational expression rq+ And the rotor positive sequence reactive current is calculated according to the relation among the stator positive sequence reactive current, the stator negative sequence reactive current and the stator and rotor currents.
Optionally, the determining, by the given value determining module, a second given value of the negative sequence current of the rotor, which does not exceed the negative sequence component of the grid voltage and corresponds to the upper limit of the direct-current bus voltage and the upper limit of the rotor current, includes:
determining a first range within which the residual direct-current bus voltage can send out negative sequence active current and negative sequence inductive reactive current according to the direct-current bus voltage upper limit and the positive sequence direct-current bus voltage required value;
determining a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the three-phase current of the rotor;
and determining a second given value of the negative sequence current of the rotor for inhibiting the voltage negative sequence component from the intersection of the first range and the second range.
Optionally, the given value determining module determines, according to the upper limit of the dc bus voltage and the positive sequence dc bus voltage required value, a first range within which the remaining dc bus voltage can generate negative sequence active current and negative sequence inductive reactive current by using the following formula:
wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative-sequence inductive reactive current of the rotor, u sd- The active voltage of the negative sequence of the stator is represented, s is the slip ratio of the positive sequence, omega is the frequency of the power grid, sigma is the leakage reactance coefficient, and L r Is the rotor inductance, L s Is a stator inductance, L rm To be connected with each otherFeeling of u dcmax Is the upper limit of the bus voltage u dc+ A value is required for the positive sequence dc bus voltage.
Optionally, the determining, by the given value determining module, a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the requirement of the rotor positive sequence current includes:
the rotor positive sequence current demand comprises rotor positive sequence active current and rotor positive sequence reactive current;
converting three-phase current of a rotor of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active current of the rotor, positive sequence reactive current of the rotor, negative sequence active current of the rotor and negative sequence reactive current of the rotor;
computing
Wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current, i, of the rotor rmax Upper limit of rotor current, i rd+ For positive-sequence active current of rotor, i rq+ Is rotor positive sequence reactive current.
Optionally, the given value determining module determines a negative rotor sequence current of a negative rotor sequence control loop according to the first given value and/or the second given value, and includes:
when the first given value is in 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;
and when the first given value is not at 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.
Optionally, the negative sequence control module determines a negative sequence current of a rotor negative sequence control loop according to the first given value or the second given value, and includes:
determining a current adjustment value of the negative sequence current of the rotor by taking the first given value or the second given value as a target according to the current negative sequence current of the negative sequence control loop of the rotor;
and adjusting the current negative sequence current of the rotor according to the current adjustment value.
Optionally, the negative sequence control module adjusts the current negative sequence current of the rotor according to the adjustment value, and includes:
inputting the current adjustment value into a proportional integral PI controller, and superposing an output result and a feedforward compensation term to obtain a voltage under a dq coordinate;
converting the voltage under the dq coordinate into a voltage under an alpha beta coordinate system, and inputting the voltage into a Space Vector Pulse Width Modulation (SVPWM) module to generate a Pulse Width Modulation (PWM) signal;
and generating a control rotor current according to the PWM signal.
Referring to fig. 7, an apparatus for negative sequence power control according to an embodiment of the present invention includes:
at least one processor 701 and at least one memory 702, and a bus system 709;
wherein the memory stores program code that, when executed by the processor, causes the processor to perform the following:
when the asymmetric fault of the power grid voltage is determined, the operation parameters of the converter and the power grid are obtained;
determining a generator power fluctuation value according to the operation parameters, determining a first given value of a rotor negative sequence current for inhibiting the generator power fluctuation, and/or determining a second given value of the rotor negative sequence current which does not exceed an inhibition voltage negative sequence component corresponding to the upper limit of the direct current bus voltage and the rotor current according to the operation parameters;
and 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.
Fig. 7 is a schematic diagram of a negative-sequence power control apparatus 700 according to an embodiment of the present invention, which may have a relatively large difference due to different configurations or performances, and may include one or more processors (CPU) 701 (e.g., one or more processors) and a memory 702, and one or more storage media 703 (e.g., one or more mass storage devices) for storing applications 704 or data 705. Memory 702 and storage medium 703 may be, among other things, transient storage or persistent storage. The program stored in the storage medium 703 may include one or more modules (not shown), each of which may include a series of instructions operating on the information processing apparatus. Further, the processor 701 may be configured to communicate with the storage medium 703 to execute a series of instruction operations in the storage medium 703 on the device 700.
The device 700 may 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.
Optionally, the processor determines a generator power fluctuation value according to the operating parameter, and determines a first given value of a negative sequence current of the rotor for suppressing the generator power fluctuation, including:
determining a calculation formula of a power fluctuation value of the generator according to the three-phase voltage and the three-phase current of the stator of the generator;
and determining a first given value of the corresponding rotor negative sequence current when the value of the calculation formula of the generator power fluctuation value is zero according to the relational expression of the rotor current and the stator current.
Optionally, the processor determines a calculation formula of the generator power fluctuation value according to the stator three-phase voltage and the stator three-phase current of the generator, and the calculation formula includes:
converting the three-phase voltage of the stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active voltage of the stator, positive sequence reactive voltage of the stator, negative sequence active voltage of the stator and negative sequence reactive voltage of the stator;
converting a three-phase current of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the stator, a positive sequence reactive current of the stator, a negative sequence active current of the stator and a negative sequence reactive current of the stator;
and determining a calculation formula of the power fluctuation value of the generator 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.
Optionally, the first given value of the rotor negative sequence current comprises a first given value i of the rotor negative sequence active current rdref- And a first given value i of negative sequence inductive reactive current of the rotor rqref- When the processor determines that the value of the calculation formula of the power fluctuation value of the generator is zero, the corresponding first given value of the negative sequence current of the rotor is calculated in the following mode:
wherein u is sd+ Is a positive-sequence active voltage of the stator, u sq+ Representing positive-sequence reactive voltage of stator, u sd- Representing stator negative sequence active voltage, u sq- Representing stator negative-sequence reactive voltage, i rd+ Representing the rotor positive sequence active current, i, calculated from the stator positive sequence active current, the stator negative sequence active current and the stator-rotor current relational expression rq+ And the rotor positive sequence reactive current is calculated according to the relation among the stator positive sequence reactive current, the stator negative sequence reactive current and the stator and rotor currents.
Optionally, the determining, by the processor, a second given value of the negative-sequence current of the rotor, which does not exceed the negative-sequence component of the grid voltage and is corresponding to the upper limit of the rotor current and the dc bus voltage, by the processor according to the operation parameter, includes:
determining a first range within which the residual direct-current bus voltage can send out negative sequence active current and negative sequence inductive reactive current according to the direct-current bus voltage upper limit and the positive sequence direct-current bus voltage required value;
determining a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the requirement of the rotor positive sequence current;
and determining a second given value of the negative sequence current of the rotor for inhibiting the voltage negative sequence component from the intersection of the first range and the second range.
Optionally, the processor determines, according to the upper limit of the dc bus voltage and the positive sequence dc bus voltage requirement value, a first range in which the remaining dc bus voltage can generate negative sequence active current and negative sequence inductive reactive current by using the following formula:
wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current of the rotor, u sd- Expressing the active voltage of the negative sequence of the stator, s is the slip ratio of the positive sequence, omega is the frequency of the power grid, sigma is the leakage reactance coefficient and L r Is the rotor inductance, L s Is a stator inductance, L rm Is mutual inductance of u dcmax Upper limit of bus voltage, u dc+ A value is required for the positive sequence dc bus voltage.
Optionally, the processor determines a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the requirement of the rotor positive sequence current, and the second range includes:
the rotor positive sequence current demand comprises rotor positive sequence active current and rotor positive sequence reactive current;
converting three-phase current of a rotor of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active current of the rotor, positive sequence reactive current of the rotor, negative sequence active current of the rotor and negative sequence reactive current of the rotor;
calculating out
Wherein i rdref- For a second given value of negative-sequence active current, i, of the rotor rqref- For a second given value of negative sequence inductive reactive current, i, of the rotor rmax Upper limit of rotor current, i rd+ For positive-sequence active current of rotor, i rq+ Is rotor positive sequence reactive current.
Optionally, the processor determines a negative rotor sequence current of a negative rotor sequence control loop according to the first given value and/or the second given value, and includes:
when the first given value is in the intersection of the first range and the second range, determining the rotor negative sequence current of a rotor negative sequence control loop according to the first given value;
and when the first given value is not at 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.
Optionally, the processor is configured to determine a negative rotor sequence current of a negative rotor sequence control loop according to the first given value or the second given value, and includes:
determining a current adjustment value of the negative sequence current of the rotor by taking the first given value or the second given value as a target according to the current negative sequence current of the negative sequence control loop of the rotor;
and adjusting the current negative sequence current of the rotor according to the current adjustment value.
Optionally, the processor adjusts the current negative-sequence rotor current according to the adjustment value, including:
inputting the current adjustment value into a proportional integral PI controller, and superposing an output result and a feedforward compensation term to obtain a voltage under dq coordinates;
converting the voltage under the dq coordinate into a voltage under an alpha beta coordinate system, and inputting the voltage into a Space Vector Pulse Width Modulation (SVPWM) module to generate a Pulse Width Modulation (PWM) signal;
and generating a control rotor current according to the PWM signal.
Embodiments of the present invention also provide a computer-readable storage medium, which includes instructions that, when executed on a computer, cause the computer to perform the method for negative sequence power control provided by the above embodiments.
Embodiments of the present application further provide a computer program product, including a computer program, where the computer program includes program instructions, and when the program instructions are executed by an electronic device, the electronic device is caused to execute the method for negative sequence power control provided in the foregoing embodiments.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described apparatuses and modules may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules is only one logical functional division, and other divisions may be realized in practice, for example, a plurality of modules or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or modules, and may be in an electrical, mechanical or other form.
The modules described as separate parts may or may not be physically separate, and parts displayed as modules may or may not be physical modules, may be located in one place, or may be distributed on a plurality of network modules. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, functional modules in the embodiments of the present application may be integrated into one processing module, or each of the modules may exist alone physically, or two or more modules are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a separate product, may be stored in a computer-readable storage medium.
In the above embodiments, all or part of the implementation may be realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product.
The computer program product includes one or more computer instructions. The procedures or functions described in accordance with the embodiments of the application are all or partially generated when the computer program instructions are loaded and executed on a computer. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, from one website site, computer, server, or data center to another website site, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital Subscriber Line (DSL)) or wireless (e.g., 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, a data center, etc., that is integrated with one or more available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid State Disk (SSD)), among others.
The technical solutions provided by the present application are introduced in detail, and the present application applies specific examples to explain the principles and embodiments of the present application, and the descriptions of the above examples are only used to help understand the method and the core ideas of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, the specific implementation manner and the application scope may be changed, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (19)
1. A negative sequence power control method, comprising:
when the voltage asymmetry fault of the power grid is determined, the operation parameters of the converter and the power grid are obtained;
determining a generator power fluctuation value according to the operation parameters, determining a first given value of a rotor negative sequence current for inhibiting the generator power fluctuation, and/or determining a second given value of the rotor negative sequence current for inhibiting the grid voltage negative sequence component corresponding to the upper limit of the direct current bus voltage and the rotor current;
and 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.
2. The method of claim 1, wherein determining a generator power fluctuation value from the operating parameters and determining a first setpoint value for negative rotor sequence current that suppresses generator power fluctuation comprises:
determining a calculation formula of a power fluctuation value of the generator according to the stator three-phase voltage and the stator three-phase current of the generator;
and determining a first given value of the corresponding rotor negative sequence current when the value of the calculation formula of the generator power fluctuation value is zero by combining the relational expression of the rotor current and the stator current.
3. The method of claim 2, wherein determining a calculation of the generator power ripple value based on the stator three-phase voltage and the stator three-phase current of the generator comprises:
converting the three-phase voltage of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active voltage, positive sequence reactive voltage, negative sequence active voltage and negative sequence reactive voltage of the stator;
converting a three-phase current of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the stator, a positive sequence reactive current of the stator, a negative sequence active current of the stator and a negative sequence reactive current of the stator;
and determining a calculation formula of the power fluctuation value of the generator 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.
4. A method according to claim 3, characterized in that the first setpoint of the rotor negative-sequence current comprises a first setpoint of the rotor negative-sequence active current i rdref- And a first given value i of the negative sequence inductive reactive current of the rotor rqref- And when the calculation formula of the power fluctuation value of the generator is determined to be zero, the corresponding first given value of the negative sequence current of the rotor is calculated in the following mode:
wherein u is sd+ Is a positive-sequence active voltage of the stator, u sq+ Representing positive-sequence reactive voltage of stator, u sd- Representing stator negative sequence active voltage, u sq- Representing stator negative-sequence reactive voltage, i rd+ Representing positive-sequence active current of rotor, i rq+ Rotor positive sequence reactive current.
5. The method of claim 1, wherein determining, based on the operating parameter, a second setpoint value for negative-sequence rotor current that does not exceed a grid voltage negative-sequence component rejection limit for the dc bus voltage and the upper rotor current limit comprises:
determining a first range within which the residual direct-current bus voltage can send out negative sequence active current and negative sequence inductive reactive current according to the direct-current bus voltage upper limit and the positive sequence direct-current bus voltage required value;
determining a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the requirement of the rotor positive sequence current;
and determining a second given value of the negative sequence current of the rotor for inhibiting the negative sequence component of the grid voltage from the intersection of the first range and the second range.
6. The method of claim 5, wherein the first range within which the remaining DC bus voltage can deliver negative sequence active current and negative sequence inductive reactive current is determined based on the upper DC bus voltage limit and the positive sequence DC bus voltage requirement using the following equation:
wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current of the rotor, u sd- Expressing the active voltage of the negative sequence of the stator, s is the slip ratio of the positive sequence, omega is the frequency of the power grid, sigma is the leakage reactance coefficient and L r Is the rotor inductance, L s Is a stator inductance, L rm Is mutual inductance of u dcmax Is the upper limit of the DC bus voltage u dc+ A value is required for the positive sequence dc bus voltage.
7. The method of claim 5, wherein determining the second range of negative sequence active current and negative sequence inductive reactive current based on the upper rotor current limit and the rotor positive sequence current demand comprises:
the rotor positive sequence current demand comprises rotor positive sequence active current and rotor positive sequence reactive current;
converting a three-phase current of a rotor of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the rotor, a positive sequence reactive current of the rotor, a negative sequence active current of the rotor and a negative sequence reactive current of the rotor;
computing
Wherein i rdref- For a second given value of the negative-sequence active current of the rotor, i rqref- For a second given value of negative sequence inductive reactive current, i, of the rotor rmax Upper limit of rotor current, i rd+ For positive-sequence active current of rotor, i rq+ Is rotor positive sequence reactive current.
8. Method according to claim 5, characterized in that determining the rotor negative sequence current of a rotor negative sequence control loop from the first and/or second setpoint value comprises:
when the first given value is in the intersection of the first range and the second range, determining the rotor negative sequence current of a rotor negative sequence control loop according to the first given value;
and when the first given value is not at 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.
9. The method of claim 1, wherein determining a negative rotor sequence current of a negative rotor sequence control loop based on the first or second setpoint comprises:
determining a current adjustment value of the negative sequence current of the rotor by taking the first given value or the second given value as a target according to the current negative sequence current of the negative sequence control loop of the rotor;
and adjusting the current negative sequence current of the rotor according to the current adjustment value.
10. The method of claim 9, wherein adjusting the present rotor negative sequence current according to the adjustment value comprises:
inputting the current adjustment value into a proportional integral PI controller, and superposing an output result and a feedforward compensation term to obtain a voltage under dq coordinates;
converting the voltage under the dq coordinate into a voltage under an alpha beta coordinate system, and inputting the voltage into a Space Vector Pulse Width Modulation (SVPWM) module to generate a Pulse Width Modulation (PWM) signal;
and generating a control rotor current according to the PWM signal.
11. A negative sequence power control apparatus, comprising:
the parameter acquisition module is used for acquiring the operating parameters of the converter and the power grid when the asymmetric fault of the power grid voltage is determined;
the set value determining module is used for determining a generator power fluctuation value according to the operation parameters, determining a first set value of a rotor negative sequence current for inhibiting the generator power fluctuation, and/or determining a second set value of the rotor negative sequence current for inhibiting the grid voltage negative sequence component corresponding to the direct current bus voltage and the rotor current upper limit;
and the negative sequence control module is used for 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 utilizing the rotor negative sequence current.
12. The apparatus of claim 11, wherein the set point determination module determines a generator power fluctuation value from the operating parameter and determines a first set point of a negative rotor sequence current that suppresses generator power fluctuation, comprising:
determining a calculation formula of a power fluctuation value of the generator according to the stator three-phase voltage and the stator three-phase current of the generator;
and determining a first given value of the corresponding rotor negative sequence current when the value of the calculation formula of the generator power fluctuation value is zero by combining the relational expression of the rotor current and the stator current.
13. The apparatus of claim 12, wherein the set point determination module determines a calculation of the generator power fluctuation value based on the stator three-phase voltage and the stator three-phase current of the generator, comprising:
converting the three-phase voltage of the stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain positive sequence active voltage of the stator, positive sequence reactive voltage of the stator, negative sequence active voltage of the stator and negative sequence reactive voltage of the stator;
converting a three-phase current of a stator of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the stator, a positive sequence reactive current of the stator, a negative sequence active current of the stator and a negative sequence reactive current of the stator;
and determining a calculation formula of the power fluctuation value of the generator 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.
14. The apparatus of claim 11, wherein the set point determination module determines a second set point of the negative sequence current of the rotor that does not exceed the grid-voltage-negative-sequence-component-rejection-limit-for-dc-bus voltage and the upper rotor-current-limit according to the operating parameter, and comprises:
determining a first range within which the residual direct-current bus voltage can send out negative sequence active current and negative sequence inductive reactive current according to the direct-current bus voltage upper limit and the positive sequence direct-current bus voltage required value;
determining a second range of the negative sequence active current and the negative sequence inductive reactive current according to the upper limit of the rotor current and the requirement of the rotor positive sequence current;
and determining a second given value of the negative sequence current of the rotor for restraining the negative sequence component of the grid voltage from the intersection of the first range and the second range.
15. The apparatus of claim 14, wherein the set point determination module determines a first range within which the remaining dc bus voltage can emit 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 demand value using the following formula:
wherein i rdref- For a second given value of negative-sequence active current, i, of the rotor rqref- For a second given value of negative sequence inductive reactive current of the rotor, u sd- The active voltage of the negative sequence of the stator is represented, s is the slip ratio of the positive sequence, omega is the frequency of the power grid, sigma is the leakage reactance coefficient, and L r Is the rotor inductance, L s Is a stator inductance, L rm Is mutual inductance of u dcmax Is the upper limit of the DC bus voltage u dc+ A value is required for the positive sequence dc bus voltage.
16. The apparatus of claim 14, wherein the set point determination module determines the second range of negative sequence active current and negative sequence inductive reactive current based on the upper rotor current limit and the rotor positive sequence current demand, comprising:
the rotor positive sequence current demand comprises rotor positive sequence active current and rotor positive sequence reactive current;
converting a three-phase current of a rotor of the generator from a three-phase coordinate system to a two-phase synchronous rotation dq coordinate system, and simultaneously extracting positive and negative sequence components to obtain a positive sequence active current of the rotor, a positive sequence reactive current of the rotor, a negative sequence active current of the rotor and a negative sequence reactive current of the rotor;
calculating out
Wherein i rdref- For a second given value of negative-sequence active current, i, of the rotor rqref- For a second given value of negative sequence inductive reactive current, i, of the rotor rmax Upper limit of rotor current, i rd+ For positive-sequence active current of rotor, i rq+ Is rotor positive sequence reactive current.
17. The apparatus of claim 14, wherein the set point determination module determines a negative rotor sequence current of a negative rotor sequence control loop based on the first set point and/or the second set point, comprising:
when the first given value is in the intersection of the first range and the second range, determining the rotor negative sequence current of a rotor negative sequence control loop according to the first given value;
and when the first given value is not at 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.
18. The apparatus of claim 11, wherein the negative sequence control module determines a negative rotor sequence current of a negative rotor sequence control loop based on the first or second setpoint, comprising:
determining a current adjustment value of the negative sequence current of the rotor by taking the first given value or the second given value as a target according to the current negative sequence current of the negative sequence control loop of the rotor;
and adjusting the current negative sequence current of the rotor according to the current adjustment value.
19. A negative sequence power control device comprising a memory and a processor, said memory having stored thereon a computer program operable on said processor, said computer program, when executed by said processor, implementing the method of any of claims 1 to 10.
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| CN116436043A (en) * | 2023-06-13 | 2023-07-14 | 国网江西省电力有限公司电力科学研究院 | Asymmetric fault ride-through control method for multiple converters |
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| CN116436043A (en) * | 2023-06-13 | 2023-07-14 | 国网江西省电力有限公司电力科学研究院 | Asymmetric fault ride-through control method for multiple converters |
| CN116436043B (en) * | 2023-06-13 | 2023-10-20 | 国网江西省电力有限公司电力科学研究院 | Asymmetric fault ride-through control method for multiple converters |
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