CN112886619A - Active control method and device for power quality of energy storage power station - Google Patents
Active control method and device for power quality of energy storage power station Download PDFInfo
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- H—ELECTRICITY
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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Abstract
The invention provides an active control method and device for the power quality of an energy storage power station, wherein a harmonic impedance coefficient is determined based on harmonic waves and unbalanced voltage components in the voltage of a separation port of a resonator; determining the command voltage of a power electronic converter in the energy storage power station based on the harmonic impedance coefficient; and actively controlling the power quality of the energy storage power station based on the command voltage of the power electronic converter. The active control method and the active control device have the advantages that active control of the power quality of the energy storage power station is achieved based on the self-synchronizing voltage source, harmonic and fundamental frequency components do not need to be separated, harmonic impedance coefficients are obtained based on the residual power capacity of the energy storage power station, and the instruction voltage of an active control link of the power quality is obtained according to harmonic impedance.
Description
Technical Field
The invention relates to the technical field of energy storage, in particular to an active control method and device for the power quality of an energy storage power station.
Background
With the continuous improvement of the attention degree of human beings on environmental pollution and greenhouse effect, a new energy power generation system represented by wind power and photovoltaic needs to be rapidly applied in a large area, and gradually replaces the traditional energy power generation mode represented by thermal power. But wind power and illumination resources are not uniformly distributed, a power supply center is far away from a load center, the transmission loss is large, and the cost is high. The extra-high voltage direct current transmission end power grid takes a new energy power generation system and an energy storage power station as cores, and the problem of large-scale new energy power transmission is solved.
The energy storage power station in the extra-high voltage direct current transmission end power grid takes the power electronic converter as a grid-connected interface, and has the advantages of flexible control, high response speed and the like. If the energy storage power station is used for peak clipping and valley filling, the power grid power quality control function is integrated on the basis of supporting the power grid frequency and providing inertia, the energy storage power station function can be enriched, and the power system power quality control cost is reduced. However, the power electronic converter works in a maximum power tracking control mode represented by vector control and direct power control, and inertia and damping characteristics are lacked, so that the frequency stability of an extra-high voltage direct-current transmission end power grid is low.
Disclosure of Invention
In order to overcome the defect of low frequency stability of an extra-high voltage direct current transmission end power grid in the prior art, the invention provides an active control method for the power quality of an energy storage power station, which comprises the following steps:
determining a harmonic impedance coefficient based on harmonic and unbalanced voltage components in the resonator split port voltage;
determining the command voltage of a power electronic converter in the energy storage power station based on the harmonic impedance coefficient;
and actively controlling the power quality of the energy storage power station based on the command voltage of the power electronic converter.
The determining harmonic impedance coefficients based on harmonic and unbalanced voltage components in a resonator split port voltage includes:
calculating the voltage unbalance degree of a grid-connected point of the energy storage power station based on harmonic waves and unbalanced voltage components in the voltage of the separation port of the resonator;
calculating an initial value of a harmonic impedance coefficient based on the voltage unbalance degree of the energy storage power station grid-connected point;
and calculating the harmonic impedance coefficient based on the initial value of the harmonic impedance coefficient.
The voltage unbalance degree of the grid-connected point is calculated according to the following formula:
in the formula, VUF is the voltage unbalance degree of the grid-connected point of the energy storage power station, UdSeparating harmonic and unbalanced voltage d-axis components, U, in port voltage for resonatorsqHarmonics in the port voltage and unbalanced voltage q-axis components are separated for the resonator.
The initial value of the harmonic impedance coefficient is calculated according to the following formula:
in the formula, k0Is the initial value of harmonic impedance coefficient, VUF*For voltage unbalance target value, k, of grid-connected point of energy storage power stationpIs the proportionality coefficient, k, of the PI controlleriAnd s is the laplacian operator, which is the integral coefficient of the PI controller.
The harmonic impedance coefficient is calculated as follows:
in the formula, k is a harmonic impedance coefficient, P is active power of the energy storage power station, and Q is reactive power of the energy storage power station.
The step of determining the command voltage of the power electronic converter in the energy storage power station based on the harmonic impedance coefficient comprises the following steps:
calculating the command voltage of the active control link of the power quality based on the harmonic and unbalanced voltage components in the voltage of the separation port of the resonator and the harmonic impedance coefficient;
and determining the command voltage of the power electronic converter based on the command voltage of the active power quality control link.
The instruction voltage of the active control link of the power quality is calculated according to the following formula:
in the formula (I), the compound is shown in the specification,
for h-order harmonic command voltage of the active control link of the power quality,
separating the h harmonic and the unbalanced voltage component, omega, in the port voltage for the resonatorcIs the cut-off frequency, omega, of the resonator1For the resonant frequency of the resonator, k is the harmonic impedance coefficient and s is the laplacian operator.
The step of determining the command voltage of the power electronic converter based on the command voltage of the power quality active control link comprises the following steps:
calculating an internal potential instruction controlled by a self-synchronizing voltage source based on the reactive power of the energy storage power station;
and summing the internal potential command controlled by the self-synchronizing voltage source and the command voltage of the active power quality control link to obtain the command voltage of the power electronic converter.
The internal potential instruction controlled by the self-synchronizing voltage source is calculated according to the following formula:
wherein E is an internal potential command controlled by a self-synchronizing voltage source, JQTo a reactive voltage squareCoefficient of inertia of stroke, DQDamping coefficient, Q, being reactive voltage equation*For reactive power reference values, U, of energy-storing power stations0Is a rated voltage amplitude, U is a port voltage amplitude, Q is the reactive power of the energy storage power station, and t is time.
The active control of the power quality of the energy storage power station based on the command voltage of the power electronic converter comprises the following steps:
performing coordinate transformation on the command voltage of the power electronic converter based on the virtual coordinate transformation phase angle to obtain a modulation voltage vector under an alpha beta coordinate system;
generating a pulse width modulation switching signal by adopting a space vector pulse width modulation algorithm based on the modulation voltage vector under the alpha beta coordinate system;
controlling power switches in the power electronic converter based on the pulse width modulated switching signals.
The virtual coordinate transformation phase angle is determined according to the following formula:
where θ is a virtual coordinate transformation phase angle, JPIs the inertia coefficient of the equation of motion of the rotor, DPIs the damping coefficient of the rotor equation of motion, P is the active power of the energy storage power station, P*For active power reference value, omega, of energy-storing power station0Is the fundamental angular frequency, ω is the self-synchronizing angular frequency, and t is time.
On the other hand, this application still provides an energy storage power station electric energy quality active control device, includes:
a first determination module to determine a harmonic impedance coefficient based on harmonic and unbalanced voltage components in a resonator disconnect port voltage;
the second determination module is used for determining the command voltage of a power electronic converter in the energy storage power station based on the harmonic impedance coefficient;
and the control module is used for actively controlling the power quality of the energy storage power station based on the instruction voltage of the power electronic converter.
The first determining module includes:
the first calculation unit is used for calculating the voltage unbalance degree of the energy storage power station grid-connected point based on the harmonic wave and the unbalanced voltage component in the voltage of the resonator separation port;
the second calculation unit is used for calculating an initial value of the harmonic impedance coefficient based on the voltage unbalance degree of the energy storage power station grid-connected point;
and the third calculation unit is used for calculating the harmonic impedance coefficient based on the initial value of the harmonic impedance coefficient.
The first calculating unit calculates the voltage unbalance of the grid-connected point according to the following formula:
in the formula, VUF is the voltage unbalance degree of the grid-connected point of the energy storage power station, UdSeparating harmonic and unbalanced voltage d-axis components, U, in port voltage for resonatorsqHarmonics in the port voltage and unbalanced voltage q-axis components are separated for the resonator.
The second calculating unit calculates the initial value of the harmonic impedance coefficient according to the following formula:
in the formula, k0Is the initial value of harmonic impedance coefficient, VUF*For voltage unbalance target value, k, of grid-connected point of energy storage power stationpIs the proportionality coefficient, k, of the PI controlleriAnd s is the laplacian operator, which is the integral coefficient of the PI controller.
The third calculating unit calculates the harmonic impedance coefficient according to the following formula:
in the formula, k is a harmonic impedance coefficient, P is active power of the energy storage power station, and Q is reactive power of the energy storage power station.
The second determining module includes:
the fourth calculation unit is used for calculating the command voltage of the active control link of the power quality based on the harmonic and unbalanced voltage components in the voltage of the separation port of the resonator and the harmonic impedance coefficient;
and the fifth calculation unit is used for determining the command voltage of the power electronic converter based on the command voltage of the active power quality control link.
The fourth calculating unit calculates the command voltage of the active control link of the power quality according to the following formula:
in the formula (I), the compound is shown in the specification,
for h-order harmonic command voltage of the active control link of the power quality,
separating the h harmonic and the unbalanced voltage component, omega, in the port voltage for the resonatorcIs the cut-off frequency, omega, of the resonator1For the resonant frequency of the resonator, k is the harmonic impedance coefficient and s is the laplacian operator.
The fifth calculation unit includes:
the internal potential instruction calculating unit is used for calculating an internal potential instruction controlled by a self-synchronizing voltage source based on the reactive power of the energy storage power station;
and the command voltage calculation unit is used for summing the internal potential command controlled by the self-synchronizing voltage source and the command voltage of the active power quality control link to obtain the command voltage of the power electronic converter.
The internal potential instruction calculating unit calculates an internal potential instruction controlled by the self-synchronizing voltage source according to the following formula:
wherein E is an internal potential command controlled by a self-synchronizing voltage source, JQIs the inertia coefficient of the reactive voltage equation, DQDamping coefficient, Q, being reactive voltage equation*For reactive power reference values, U, of energy-storing power stations0Is a rated voltage amplitude, U is a port voltage amplitude, Q is the reactive power of the energy storage power station, and t is time.
The control module includes:
the transformation unit is used for carrying out coordinate transformation on the command voltage of the power electronic converter based on a virtual coordinate transformation phase angle to obtain a modulation voltage vector under an alpha beta coordinate system;
the generating unit is used for generating a pulse width modulation switching signal by adopting a space vector pulse width modulation algorithm based on the modulation voltage vector under the alpha beta coordinate system;
and the control unit is used for controlling a power switch device in the power electronic converter based on the pulse width modulation switching signal.
The transformation unit determines a virtual coordinate transformation phase angle as follows:
where θ is a virtual coordinate transformation phase angle, JPIs the inertia coefficient of the equation of motion of the rotor, DPIs the damping coefficient of the rotor equation of motion, P is the active power of the energy storage power station, P*For active power reference value, omega, of energy-storing power station0Is the fundamental angular frequency, ω is the self-synchronizing angular frequency, and t is time.
The technical scheme provided by the invention has the following beneficial effects:
in the active control method for the power quality of the energy storage power station, a harmonic impedance coefficient is determined based on harmonic and unbalanced voltage components in the voltage of a separation port of a resonator; determining the command voltage of a power electronic converter in the energy storage power station based on the harmonic impedance coefficient; the power quality of the energy storage power station is actively controlled based on the instruction voltage of the power electronic converter, the harmonic impedance coefficient is considered (namely the harmonic impedance coefficient of a resonator in the power electronic converter is considered), and the frequency stability of the extra-high voltage direct current transmission end power grid is improved.
According to the method and the device, the voltage unbalance is obtained through the harmonic wave and the unbalanced voltage component in the resonator separation port voltage, the harmonic wave impedance of the energy storage power station based on the self-synchronous voltage source control is changed, and the self-synchronous voltage source energy storage power station is enabled to participate in the electric energy quality control.
The active control method and the active control device have the advantages that active control of the power quality of the energy storage power station is achieved based on the self-synchronizing voltage source, harmonic and fundamental frequency components do not need to be separated, harmonic impedance coefficients are obtained based on the residual power capacity of the energy storage power station, and the instruction voltage of an active control link of the power quality is obtained according to harmonic impedance.
Drawings
FIG. 1 is a flow chart of an active control method for power quality of an energy storage power station in an embodiment of the present application;
FIG. 2 is a structural diagram of an active control device for power quality of an energy storage power station in the embodiment of the application;
FIG. 3 is a schematic diagram of an energy storage power station connecting a sending end power grid and a load in the embodiment of the application;
FIG. 4 is a schematic diagram illustrating a result of closed-loop control performed by an energy storage power station on a voltage imbalance of a grid-connected point in an embodiment of the present application;
FIG. 5 is a diagram illustrating the output result of power quality control without considering the remaining power capacity in the embodiment of the present application;
fig. 6 is a schematic diagram of an output result of power quality control considering the remaining power capacity in the embodiment of the present application.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Example 1
The embodiment 1 of the application provides an active control method for power quality of an energy storage power station, and a specific flow chart is shown in fig. 1, and the specific process is as follows:
s101: determining a harmonic impedance coefficient based on harmonic and unbalanced voltage components in the resonator split port voltage;
s102: determining the command voltage of a power electronic converter in the energy storage power station based on the harmonic impedance coefficient;
s103: and actively controlling the power quality of the energy storage power station based on the command voltage of the power electronic converter.
Before determining the harmonic impedance coefficient based on the harmonic and unbalanced voltage components in the voltage of the resonator split port in S101, the embodiment of the present application may collect the output current I of the energy storage power station firstabcAnd port voltage Uabc. Then, the port voltage U is converted by using a virtual coordinate transformation phase angleabcAnd the output current I of the energy storage power stationabcPerforming coordinate transformation (such as PARK transformation) to obtain a voltage vector U under dq coordinate systemdqSum current vector Idq. Then, according to the voltage vector UdqSum current vector IdqAnd calculating the active power P and the reactive power Q of the energy storage power station. The active power P is used here in combination with the rotor motion equation to calculate the virtual coordinate transformation phase angle θ, and the reactive power Q is used here in combination with the reactive voltage equation to calculate the internal potential command E for the self-synchronizing voltage source control. Wherein the equation of motion of the rotor is
JPIs the inertia coefficient of the equation of motion of the rotor, DPDamping coefficient, P, of the equation of motion of the rotor*For active power reference value, omega, of energy-storing power station0Is the fundamental angular frequency and ω is the self-synchronizing angular frequency. The reactive voltage equation here is
E is an internal potential command controlled by a self-synchronizing voltage source, JQIs the inertia coefficient of the reactive voltage equation, DQDamping coefficient, Q, being reactive voltage equation*For reactive power reference values, U, of energy-storing power stations0Is a rated voltage amplitude, U is a port voltage amplitude, Q is the reactive power of the energy storage power station, and t is time.
Determining harmonic impedance coefficients based on harmonic and unbalanced voltage components in the resonator split port voltage, comprising:
and calculating the voltage unbalance degree of the grid-connected point of the energy storage power station based on the harmonic wave and the unbalanced voltage component in the voltage of the separation port of the resonator. Calculating an initial value of a harmonic impedance coefficient based on the voltage unbalance degree of the energy storage power station grid-connected point; and calculating the harmonic impedance coefficient based on the initial value of the harmonic impedance coefficient.
Here, the harmonic and unbalanced voltage components in the resonator split port voltage include the harmonic and unbalanced voltage d-axis components U in the resonator split port voltagedAnd harmonic and unbalanced voltage q-axis components U in resonator split port voltagesq. More specifically, the voltage imbalance of the grid-connected point is calculated as follows:
in the formula, VUF is the voltage unbalance degree of the grid-connected point of the energy storage power station, UdSeparating harmonic and unbalanced voltage d-axis components, U, in port voltage for resonatorsqHarmonics in the port voltage and unbalanced voltage q-axis components are separated for the resonator.
When the voltage unbalance degree of the grid-connected point of the energy storage power station is calculated, the harmonic wave in the voltage of the separation port of the resonator and the h-th harmonic wave in the voltage of the separation port of the resonator in the unbalanced voltage component and the unbalanced voltage axial component can be further used
And h-order harmonic and unbalanced voltage components in the resonator split port voltage
And h-order harmonic voltage distortion THD of the energy storage power station grid-connected point is calculated, more specifically,
the resonator may be modeled as
k is the harmonic impedance coefficient of the resonator. OmegacIs the cut-off frequency, omega, of the resonator1The resonance frequency of the resonator can be set according to the harmonic frequency, the resonance frequency is 100Hz and 300Hz under the virtual synchronous coordinate system, and s is Laplace operator.
The total harmonic distortion THD and the voltage unbalance VUF obtained by calculation are compared with a set value of the electric energy quality (THD)*And VUF*) And performing closed-loop regulation, and obtaining an initial value of the harmonic impedance coefficient based on a PI controller.
Further, the initial value of the harmonic impedance coefficient is calculated according to the following formula:
in the formula, k0Is the initial value of harmonic impedance coefficient, VUF*For voltage unbalance target value, k, of grid-connected point of energy storage power stationpIs the proportionality coefficient, k, of the PI controlleriAnd s is the laplacian operator, which is the integral coefficient of the PI controller.
And calculating the residual power capacity of the energy storage power station according to the active power P and the reactive power Q of the energy storage power station, and calculating the harmonic impedance coefficient according to the residual power capacity of the energy storage power station.
Further, the harmonic impedance coefficient is calculated as follows:
in the formula, k is a harmonic impedance coefficient, P is active power of the energy storage power station, and Q is reactive power of the energy storage power station.
Determining the command voltage of a power electronic converter in an energy storage power station based on the harmonic impedance coefficient, comprising:
calculating the command voltage of the active control link of the power quality based on harmonic and unbalanced voltage components and harmonic impedance coefficients in the voltage of the resonator separation port; and determining the command voltage of the power electronic converter based on the command voltage of the power quality active control link.
And carrying out closed-loop regulation on harmonic and unbalanced voltage components in the voltage of the separation port of the resonator, controlling the harmonic and unbalanced components based on the resonator, and changing the gain of the resonator through a harmonic impedance coefficient k so as to obtain the command voltage of the active control link of the electric energy quality.
Further, the command voltage of the active control link of the power quality is calculated according to the following formula:
in the formula (I), the compound is shown in the specification,
for h-order harmonic command voltage of the active control link of the power quality,
separating the h harmonic and the unbalanced voltage component, omega, in the port voltage for the resonatorcIs the cut-off frequency, omega, of the resonator1For the resonant frequency of the resonator, k is the harmonic impedance coefficient and s is the laplacian operator.
Determining the command voltage of the power electronic converter based on the command voltage of the power quality active control link, wherein the method comprises the following steps:
calculating an internal potential command controlled by a self-synchronizing voltage source based on the reactive power of the energy storage power station, wherein the internal potential command controlled by the self-synchronizing voltage source can be represented by E; more specifically, the internal potential command controlled by the self-synchronizing voltage source is calculated as follows:
wherein E is an internal potential command controlled by a self-synchronizing voltage source, JQIs the inertia coefficient of the reactive voltage equation, DQDamping coefficient, Q, being reactive voltage equation*For reactive power reference values, U, of energy-storing power stations0Is a rated voltage amplitude, U is a port voltage amplitude, Q is the reactive power of the energy storage power station, and t is time.
The internal potential instruction E controlled by the self-synchronizing voltage source and the instruction voltage of the active control link of the power quality
And summing to obtain the command voltage of the power electronic converter.
The power quality of an energy storage power station is actively controlled based on the command voltage of a power electronic converter, and the method comprises the following steps:
performing coordinate transformation on the command voltage of the power electronic converter based on the virtual coordinate transformation phase angle to obtain a modulation voltage vector under an alpha beta coordinate system;
generating a pulse width modulation switching signal by adopting a space vector pulse width modulation algorithm based on the modulation voltage vector under the alpha beta coordinate system;
and controlling a power switch device in the power electronic converter based on a pulse width modulation switching signal.
Further, the virtual coordinate transformation phase angle is determined according to the following formula:
where θ is a virtual coordinate transformation phase angle, JPIs the inertia coefficient of the equation of motion of the rotor, DPDamping coefficient of rotor equation of motion, P is stored energyActive power of the plant, P*For active power reference value, omega, of energy-storing power station0Is the fundamental angular frequency, ω is the self-synchronizing angular frequency, and t is time.
Example 2
Based on the same inventive concept, embodiment 2 of the present invention further provides an active control device for power quality of an energy storage power station, as shown in fig. 2, including:
a first determination module to determine a harmonic impedance coefficient based on harmonic and unbalanced voltage components in a resonator disconnect port voltage;
the second determination module is used for determining the command voltage of a power electronic converter in the energy storage power station based on the harmonic impedance coefficient;
and the control module is used for actively controlling the power quality of the energy storage power station based on the instruction voltage of the power electronic converter.
The first determining module includes:
the first calculation unit is used for calculating the voltage unbalance degree of the energy storage power station grid-connected point based on the harmonic wave and the unbalanced voltage component in the voltage of the resonator separation port;
the second calculation unit is used for calculating an initial value of the harmonic impedance coefficient based on the voltage unbalance degree of the energy storage power station grid-connected point;
and the third calculation unit is used for calculating the harmonic impedance coefficient based on the initial value of the harmonic impedance coefficient.
The first calculating unit calculates the voltage unbalance of the grid-connected point according to the following formula:
in the formula, VUF is the voltage unbalance degree of the grid-connected point of the energy storage power station, UdSeparating harmonic and unbalanced voltage d-axis components, U, in port voltage for resonatorsqHarmonics in the port voltage and unbalanced voltage q-axis components are separated for the resonator.
The second calculating unit calculates the initial value of the harmonic impedance coefficient according to the following formula:
in the formula, k0Is the initial value of harmonic impedance coefficient, VUF*For voltage unbalance target value, k, of grid-connected point of energy storage power stationpIs the proportionality coefficient, k, of the PI controlleriAnd s is the laplacian operator, which is the integral coefficient of the PI controller.
The third calculating unit calculates the harmonic impedance coefficient according to the following formula:
in the formula, k is a harmonic impedance coefficient, P is active power of the energy storage power station, and Q is reactive power of the energy storage power station.
The second determining module includes:
the fourth calculation unit is used for calculating the command voltage of the active control link of the power quality based on the harmonic and unbalanced voltage components in the voltage of the separation port of the resonator and the harmonic impedance coefficient;
and the fifth calculation unit is used for determining the command voltage of the power electronic converter based on the command voltage of the active power quality control link.
The fourth calculating unit calculates the command voltage of the active control link of the power quality according to the following formula:
in the formula (I), the compound is shown in the specification,
for h-order harmonic command voltage of the active control link of the power quality,
splitting the h-th harmonic in the port voltage for the resonatorWave and unbalanced voltage component, omegacIs the cut-off frequency, omega, of the resonator1For the resonant frequency of the resonator, k is the harmonic impedance coefficient and s is the laplacian operator.
The fifth calculation unit includes:
the internal potential instruction calculating unit is used for calculating an internal potential instruction controlled by a self-synchronizing voltage source based on the reactive power of the energy storage power station;
and the command voltage calculation unit is used for summing the internal potential command controlled by the self-synchronizing voltage source and the command voltage of the active power quality control link to obtain the command voltage of the power electronic converter.
The internal potential instruction calculating unit calculates an internal potential instruction controlled by the self-synchronizing voltage source according to the following formula:
wherein E is an internal potential command controlled by a self-synchronizing voltage source, JQIs the inertia coefficient of the reactive voltage equation, DQDamping coefficient, Q, being reactive voltage equation*For reactive power reference values, U, of energy-storing power stations0Is a rated voltage amplitude, U is a port voltage amplitude, Q is the reactive power of the energy storage power station, and t is time.
The control module includes:
the transformation unit is used for carrying out coordinate transformation on the command voltage of the power electronic converter based on a virtual coordinate transformation phase angle to obtain a modulation voltage vector under an alpha beta coordinate system;
the generating unit is used for generating a pulse width modulation switching signal by adopting a space vector pulse width modulation algorithm based on the modulation voltage vector under the alpha beta coordinate system;
and the control unit is used for controlling a power switch device in the power electronic converter based on the pulse width modulation switching signal.
The transformation unit determines a virtual coordinate transformation phase angle as follows:
where θ is a virtual coordinate transformation phase angle, JPIs the inertia coefficient of the equation of motion of the rotor, DPIs the damping coefficient of the rotor equation of motion, P is the active power of the energy storage power station, P*For active power reference value, omega, of energy-storing power station0Is the fundamental angular frequency, ω is the self-synchronizing angular frequency, and t is time.
Example 3
A simulation model for controlling the power quality active control of the energy storage power station based on the self-synchronizing voltage source is established in MATLAB/Simulink software, and parameters used by the converter of the energy storage power station in the example are shown in a table 1.
TABLE 1
An active control arithmetic example structure schematic diagram for controlling the energy quality of the energy storage power station based on the self-synchronizing voltage source in MATLAB/Simulink is shown in FIG. 3. As shown in fig. 3, the energy storage power station is connected to the extra-high voltage dc transmission terminal S1 through a converter T1 and a transformer T2, the load is connected to the line, the load includes a three-phase symmetric load L1, a three-phase symmetric load L2 and a single-phase load L3, and Z in fig. 3 is line impedance. The single-phase load is used for simulating an electric energy quality fault scene such as an unbalance characteristic and an unbalance fault of an extra-high voltage direct current transmission end power grid.
The schematic diagram of the result of the closed-loop control of the energy storage power station on the voltage unbalance of the grid-connected point in the embodiment of the application is shown in fig. 4, the energy quality is not enabled to be controlled in a closed-loop mode at the initial stage of calculation, and the voltage unbalance of the grid-connected point is about 4.5%; enabling the unbalance degree to be controlled in a closed loop mode at the simulation moment of 1 second, setting the unbalance degree instruction to be 3.5%, and reducing the voltage unbalance degree of a grid-connected point to 3.5% within 0.2 second; at simulation time 1.5 and 2 seconds, the unbalance degree instruction is set to be 2.5% and 1.5% respectively, and the voltage unbalance degree of the grid-connected point tracks the instruction value within 0.2 second. Fig. 4 illustrates the effectiveness of the active closed-loop control of power quality provided by the embodiments of the present application.
A schematic diagram of an electric energy quality control output result without considering the residual power capacity in the embodiment of the application is shown in fig. 5, an active power instruction and a reactive power instruction of an energy storage power station based on self-synchronizing voltage source control are 0 at the beginning, and an imbalance control instruction is set to be 2%; and under the action of the modulation or self-synchronization primary frequency modulation at 0.5 second, the active power instruction rises to 1pu, the power quality control output current of the energy storage power station keeps unchanged when the residual power capacity is not considered, the final actual output current exceeds 1.3pu after the active power current is superposed, and the current peak value exceeds the threshold value, so that the safe operation stability of the energy storage power station conversion is influenced. A schematic diagram of an electric energy quality control output result considering the residual power capacity in the embodiment of the application is shown in fig. 6, an active power instruction and a reactive power instruction of an energy storage power station based on self-synchronizing voltage source control are 0 at the beginning, and an imbalance control instruction is set to be 2%; and under the action of the primary frequency modulation of the modulation or self-synchronization at 0.5 second, the active power instruction rises to 1pu, the power quality compensation coefficient is automatically adjusted and reduced along with the increase of the power output, the power quality control output current is reduced, the final actual output current is 1pu, and the current peak value is in the safe operation range of the converter of the energy storage power station. Fig. 5 and 6 illustrate the effectiveness of the control strategy for automatically adjusting the power quality control parameters according to the remaining power capacity, thereby ensuring the self-operation performance of the energy storage power station.
For convenience of description, each part of the above-described apparatus is separately described as being functionally divided into various modules or units. Of course, the functionality of the various modules or units may be implemented in the same one or more pieces of software or hardware when implementing the present application.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the same, and a person of ordinary skill in the art can make modifications or equivalent substitutions to the specific embodiments of the present invention with reference to the above embodiments, and any modifications or equivalent substitutions which do not depart from the spirit and scope of the present invention are within the protection scope of the present invention as claimed in the appended claims.
Claims (12)
1. An active control method for the power quality of an energy storage power station is characterized by comprising the following steps:
determining a harmonic impedance coefficient based on harmonic and unbalanced voltage components in the resonator split port voltage;
determining the command voltage of a power electronic converter in the energy storage power station based on the harmonic impedance coefficient;
and actively controlling the power quality of the energy storage power station based on the command voltage of the power electronic converter.
2. The active control method of energy storage power station power quality of claim 1 wherein determining harmonic impedance coefficients based on harmonic and unbalanced voltage components in the resonator split port voltage comprises:
calculating the voltage unbalance degree of a grid-connected point of the energy storage power station based on harmonic waves and unbalanced voltage components in the voltage of the separation port of the resonator;
calculating an initial value of a harmonic impedance coefficient based on the voltage unbalance degree of the energy storage power station grid-connected point;
and calculating the harmonic impedance coefficient based on the initial value of the harmonic impedance coefficient.
3. The active control method for the power quality of the energy storage power station as claimed in claim 2, wherein the voltage unbalance degree of the grid-connected point is calculated according to the following formula:
in the formula, VUF is the voltage unbalance degree of the grid-connected point of the energy storage power station, UdSeparating harmonic and unbalanced voltage d-axis components, U, in port voltage for resonatorsqDecoupling harmonic and unbalanced voltages in port voltages for resonatorsThe q-axis component.
4. The active control method for the power quality of the energy storage power station as claimed in claim 3, wherein the initial value of the harmonic impedance coefficient is calculated according to the following formula:
in the formula, k0Is the initial value of harmonic impedance coefficient, VUF*For voltage unbalance target value, k, of grid-connected point of energy storage power stationpIs the proportionality coefficient, k, of the PI controlleriAnd s is the laplacian operator, which is the integral coefficient of the PI controller.
5. The active control method of energy storage power station power quality of claim 4, characterized in that the harmonic impedance coefficients are calculated as follows:
in the formula, k is a harmonic impedance coefficient, P is active power of the energy storage power station, and Q is reactive power of the energy storage power station.
6. The active control method for power quality of energy storage power stations of claim 1, wherein the determining command voltages for power electronic converters in energy storage power stations based on the harmonic impedance coefficients comprises:
calculating the command voltage of the active control link of the power quality based on the harmonic and unbalanced voltage components in the voltage of the separation port of the resonator and the harmonic impedance coefficient;
and determining the command voltage of the power electronic converter based on the command voltage of the active power quality control link.
7. The active power quality control method for the energy storage power station as claimed in claim 6, wherein the command voltage of the active power quality control link is calculated according to the following formula:
in the formula (I), the compound is shown in the specification,
for h-order harmonic command voltage of the active control link of the power quality,
separating the h harmonic and the unbalanced voltage component, omega, in the port voltage for the resonatorcIs the cut-off frequency, omega, of the resonator1For the resonant frequency of the resonator, k is the harmonic impedance coefficient and s is the laplacian operator.
8. The active power quality control method for energy storage power stations of claim 7, wherein the determining the command voltage of the power electronic converter based on the command voltage of the active power quality control link comprises:
calculating an internal potential instruction controlled by a self-synchronizing voltage source based on the reactive power of the energy storage power station;
and summing the internal potential command controlled by the self-synchronizing voltage source and the command voltage of the active power quality control link to obtain the command voltage of the power electronic converter.
9. The active control method for the power quality of the energy storage power station of claim 8, wherein the internal potential command controlled by the self-synchronizing voltage source is calculated according to the following formula:
wherein E is a self-synchronous voltage sourceCommand of internal potential of control, JQIs the inertia coefficient of the reactive voltage equation, DQDamping coefficient, Q, being reactive voltage equation*For reactive power reference values, U, of energy-storing power stations0Is a rated voltage amplitude, U is a port voltage amplitude, Q is the reactive power of the energy storage power station, and t is time.
10. The active control method for the power quality of the energy storage power station of claim 1, wherein the active control of the power quality of the energy storage power station based on the command voltage of the power electronic converter comprises:
performing coordinate transformation on the command voltage of the power electronic converter based on the virtual coordinate transformation phase angle to obtain a modulation voltage vector under an alpha beta coordinate system;
generating a pulse width modulation switching signal by adopting a space vector pulse width modulation algorithm based on the modulation voltage vector under the alpha beta coordinate system;
controlling power switches in the power electronic converter based on the pulse width modulated switching signals.
11. The active control method of energy storage power plant power quality of claim 10 wherein the virtual coordinate transformation phase angle is determined according to the following equation:
where θ is a virtual coordinate transformation phase angle, JPIs the inertia coefficient of the equation of motion of the rotor, DPIs the damping coefficient of the rotor equation of motion, P is the active power of the energy storage power station, P*For active power reference value, omega, of energy-storing power station0Is the fundamental angular frequency, ω is the self-synchronizing angular frequency, and t is time.
12. An active control device for the power quality of an energy storage power station is characterized by comprising:
a first determination module to determine a harmonic impedance coefficient based on harmonic and unbalanced voltage components in a resonator disconnect port voltage;
the second determination module is used for determining the command voltage of a power electronic converter in the energy storage power station based on the harmonic impedance coefficient;
and the control module is used for actively controlling the power quality of the energy storage power station based on the instruction voltage of the power electronic converter.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114301067A (en) * | 2021-12-27 | 2022-04-08 | 国网青海省电力公司电力科学研究院 | Steady-state harmonic modeling method for static synchronous compensator |
| CN117691645A (en) * | 2023-12-08 | 2024-03-12 | 江苏海德森能源有限公司 | Energy storage system for intelligent micro-grid |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114301067A (en) * | 2021-12-27 | 2022-04-08 | 国网青海省电力公司电力科学研究院 | Steady-state harmonic modeling method for static synchronous compensator |
| CN114301067B (en) * | 2021-12-27 | 2023-08-29 | 国网青海省电力公司电力科学研究院 | Steady state harmonic modeling method for static synchronous compensator |
| CN117691645A (en) * | 2023-12-08 | 2024-03-12 | 江苏海德森能源有限公司 | Energy storage system for intelligent micro-grid |
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