CN114784891A - Emergency frequency control method, device and medium for cluster energy storage participating power system - Google Patents

Emergency frequency control method, device and medium for cluster energy storage participating power system Download PDF

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Publication number
CN114784891A
CN114784891A CN202210544757.1A CN202210544757A CN114784891A CN 114784891 A CN114784891 A CN 114784891A CN 202210544757 A CN202210544757 A CN 202210544757A CN 114784891 A CN114784891 A CN 114784891A
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energy storage
storage system
cluster energy
power
droop coefficient
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杨银国
于珍
陆秋瑜
朱誉
杨璧瑜
华威
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Guangdong Power Grid Co Ltd
Electric Power Dispatch Control Center of Guangdong Power Grid Co Ltd
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Guangdong Power Grid Co Ltd
Electric Power Dispatch Control Center of Guangdong Power Grid Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin

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  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses an emergency frequency control method, device and medium for a cluster energy storage participation power system. The method comprises the steps that a first droop coefficient of a cluster energy storage system in the power system and a second droop coefficient of a synchronous machine are subjected to collaborative optimization to obtain a first optimal droop coefficient and a second optimal droop coefficient; monitoring the frequency deviation of a power system and the SOC value of a cluster energy storage system in the power system, and when the frequency deviation is greater than a first preset threshold and the SOC value is greater than a second preset threshold, performing droop control on the cluster energy storage system according to the first optimal droop coefficient and performing droop control on a synchronous machine in the power system according to the second optimal droop coefficient. The technical scheme of the invention improves the stability of emergency frequency control of the power system.

Description

Emergency frequency control method, device and medium for cluster energy storage participating power system
Technical Field
The invention relates to the technical field of emergency frequency control of power systems, in particular to an emergency frequency control method, device and storage medium for a cluster energy storage participating power system.
Background
With the continuous development and utilization of renewable energy sources and the implementation and application of multiple energy storage technologies, the development of power grids in China shows the trend of power electronization, and power electronization power systems face more complex stable control problems. Considering the frequency stability of the power system, due to the large amount of feed-in of the renewable energy power generation, insufficient inertia of the system or insufficient standby frequency modulation may cause the frequency modulation requirement to be difficult to meet, so that when the system may have a fault with a large power unbalance amount, the frequency stability of the system is difficult to ensure by the conventional frequency control strategy, and an emergency frequency control strategy is required.
Traditional power system emergency frequency control strategies are mainly emergency generator tripping load operation, but these strategies can cause serious economic losses. Considering the cluster development of the energy storage system, the cluster energy storage has the characteristic that the power can be quickly adjusted, so that when the cluster energy storage participates, more economic and effective emergency frequency control is designed to improve the frequency stability of the system. The existing methods for the energy storage system to participate in the grid frequency modulation are all conventional frequency modulation aiming at the primary frequency modulation and the secondary frequency modulation of the system, and emergency frequency control under emergency faults is not involved.
The technology closest to the method is an emergency frequency control method in an alternating current-direct current hybrid system in the prior art, P-f droop control of a direct current transmission system is considered, and droop coefficients of the direct current transmission system are optimally selected. The method comprises the following specific steps:
(1) analyzing the active-frequency (P-f) droop characteristic of the direct-current transmission system through a static characteristic curve of the direct-current transmission system, and designing and applying the P-f droop characteristic to the P-f droop control in the direct-current transmission system;
(2) the method for arranging droop control in the direct current system is provided, and the control is only acted when an emergency fault occurs on the basis of the dead zone setting;
(3) under the condition of considering the power regulation margin of the direct current system, an optimization method of a droop coefficient is provided so as to realize reasonable distribution of unbalanced power among multiple-loop direct current systems.
The emergency frequency control method in the prior art has the following defects:
(1) an emergency frequency control strategy and an emergency frequency control method provided by a cluster energy storage system are not considered, the existing emergency frequency control strategy for a direct current system is based on the P-f droop characteristic of the direct current system, and if the method is expanded to the cluster energy storage system, the operation characteristic of the cluster energy storage and the feasibility of arranging emergency frequency control in the cluster energy storage need to be considered;
(2) in the existing method, only the power regulation margin is considered to give an optimization method of the droop coefficient, and when the cluster energy storage system is considered, not only the power regulation margin but also the SOC of the energy storage system need to be considered. Therefore, according to the actual engineering requirements, multiple objectives need to be considered when optimizing the droop coefficient, and the existing method cannot meet the requirements.
Disclosure of Invention
The invention provides an emergency frequency control method, device and medium for a cluster energy storage-involved power system, which improve the stability of emergency frequency control of the power system by controlling the cooperative droop of a cluster energy storage system and a synchronous machine in the power system during an emergency fault according to an optimal droop coefficient.
An embodiment of the invention provides an emergency frequency control method for a cluster energy storage participating power system, which comprises the following steps:
performing collaborative optimization on a first droop coefficient of a cluster energy storage system in the power system and a second droop coefficient of a synchronous machine to obtain a first optimal droop coefficient and a second optimal droop coefficient;
monitoring the frequency deviation of a power system and the SOC value of a cluster energy storage system in the power system, and when the frequency deviation is greater than a first preset threshold and the SOC value is greater than a second preset threshold, performing droop control on the cluster energy storage system according to a first optimal droop coefficient and performing droop control on a synchronous machine in the power system according to a second optimal droop coefficient.
Further, droop control is performed on the cluster energy storage system according to the first optimal droop coefficient, and the droop control method comprises the following steps:
calculating a power instruction value of the cluster energy storage system according to the frequency of the cluster energy storage system grid-connected point, the rated value of the cluster energy storage system grid-connected point, the rated operating power of the cluster energy storage system and the first optimal droop coefficient, and inputting the power instruction value to an energy storage converter;
and the energy storage converter adjusts and responds to the power of the cluster energy storage system in case of emergency fault according to the received power command value.
Further, performing collaborative optimization on a first droop coefficient of a cluster energy storage system in the power system and a second droop coefficient of a synchronous machine to obtain a first optimal droop coefficient and a second optimal droop coefficient, and the method includes the following steps:
respectively calculating a first power regulating quantity of the cluster energy storage system and a second power regulating quantity of the synchronous machine according to the first droop coefficient of the cluster energy storage system and the second droop coefficient of the synchronous machine;
establishing a total cost function of the cluster energy storage system and the synchronous machine cooperative droop control according to the first power adjustment amount, the second power adjustment amount, the first control target and the second control target;
and performing optimal droop control verification on the total cost function according to the state equation of the power system, and obtaining a first optimal droop coefficient of the cluster energy storage system and a second optimal droop coefficient of the synchronous machine according to an optimal droop control verification result and the total cost function.
Further, the calculation formulas of the first optimal droop coefficient and the second optimal droop coefficient are respectively:
Figure BDA0003651700070000031
in the formula, λ1iAnd λ2iIs a weight coefficient, λ1i+λ2i＝1；
Figure BDA0003651700070000032
For the second optimum droop coefficient of the synchronous machine i,
Figure BDA0003651700070000033
for a first optimal droop coefficient of the cluster energy storage system i,
Figure BDA0003651700070000034
a connection node of the cluster energy storage system is indicated,
Figure BDA0003651700070000041
representing the synchronizer node, αiAnd betaiCost factors for the first control objective and the second control objective respectively,
Figure BDA0003651700070000042
for the power regulation margin of the cluster energy storage system i,
Figure BDA0003651700070000043
is the SOC of the cluster energy storage system i.
Further, the state equation of the power system is as follows:
Figure BDA0003651700070000044
Figure BDA0003651700070000045
Figure BDA0003651700070000046
Figure BDA0003651700070000047
wherein i and j are node numbers, thetaiAnd thetajPhase angles, ω, at node i and node j, respectivelyiFor frequency deviation from nominal frequency, Mi>0 is the inertia constant of the synchronous machine i, PiFor power injection or demand at node i, Pi ERated value of output power for the cluster energy storage system i, BijFor effective admittance of the line, ViAnd VjIs a voltage of a magnitude that is preset,
Figure BDA0003651700070000048
Figure BDA0003651700070000049
a connection node of the cluster energy storage system is indicated,
Figure BDA00036517000700000410
a node of a synchronous machine is represented,
Figure BDA00036517000700000411
representing a passive load node.
Further, the total cost equation of the cluster energy storage system and the synchronous machine cooperative droop control is as follows:
Figure BDA00036517000700000412
in the formula of lambda1jAnd λ2iIs a weight coefficient, λ1i+λ2i＝1；
Figure BDA00036517000700000413
First work of energy storage system for clusterA rate adjustment amount;
Figure BDA00036517000700000414
a second power adjustment for the synchronous machine;
Figure BDA00036517000700000415
for the first droop coefficient of synchronous machine i,
Figure BDA00036517000700000416
the second droop coefficient of the cluster energy storage system i is obtained; alpha (alpha) ("alpha")iAnd betaiCost factors for the first control objective and the second control objective respectively,
Figure BDA00036517000700000417
for the power regulation margin of the cluster energy storage system i,
Figure BDA00036517000700000418
to be the SOC of the cluster energy storage system i,
Figure BDA00036517000700000419
a control cost function representing the synchronous machine is shown,
Figure BDA00036517000700000420
representing a control cost function of the cluster energy storage system associated with a first control objective,
Figure BDA00036517000700000421
a control cost function of the cluster energy storage system associated with the second control objective is expressed.
Further, according to the frequency of the grid-connected point of the cluster energy storage system, the rated value of the grid-connected point of the cluster energy storage system, the rated operating power of the cluster energy storage system, and the first optimal droop coefficient, calculating a power instruction value of the cluster energy storage system, specifically:
according to the formula
Figure BDA0003651700070000051
Computing the clusterA power command value of the energy storage system, wherein,
Figure BDA0003651700070000052
power command, P, for the cluster energy storage systemERated operating power, k, of the cluster energy storage systemEFor the first optimum droop coefficient, ωcFrequency, omega, of a grid-connected point of the cluster energy storage systemcNAnd the rated value of the grid-connected point of the cluster energy storage system.
The invention provides a power dispatching device applied to an incremental power distribution network, which comprises an emergency frequency control module and an optimal droop coefficient acquisition module;
the emergency frequency control module is used for monitoring the frequency deviation of a power system and the SOC value of a cluster energy storage system in the power system, and when the frequency deviation is greater than a first preset threshold and the SOC value is greater than a second preset threshold, droop control is performed on the cluster energy storage system according to a first optimal droop coefficient and droop control is performed on a synchronous machine in the power system according to a second optimal droop coefficient;
the optimal droop coefficient acquisition module is used for obtaining a first optimal droop coefficient and a second optimal droop coefficient by performing collaborative optimization on the first droop coefficient of the cluster energy storage system in the power system and the second droop coefficient of the synchronous machine.
Further, in the emergency frequency control module, performing droop control on the cluster energy storage system according to a first optimal droop coefficient, including the following steps:
calculating a power instruction value of the cluster energy storage system according to the frequency of the cluster energy storage system grid-connected point, the rated value of the cluster energy storage system grid-connected point, the rated operating power of the cluster energy storage system and the first optimal droop coefficient, and inputting the power instruction value to an energy storage converter;
and the energy storage converter adjusts and responds to the power of the cluster energy storage system in case of emergency fault according to the received power command value.
Another embodiment of the present invention provides a readable storage medium, where the readable storage medium includes a stored computer program, and when the computer program is executed, the apparatus where the readable storage medium is located is controlled to execute the emergency frequency control method for a cluster energy storage participation power system according to any one of the method embodiments of the present invention.
The embodiment of the invention has the following beneficial effects:
the invention provides an emergency frequency control method, device and medium for a cluster energy storage-involved power system, wherein the method comprises the steps of carrying out collaborative optimization on a first droop coefficient of a cluster energy storage system in the power system and a second droop coefficient of a synchronous machine to obtain a first optimal droop coefficient and a second optimal droop coefficient; and monitoring the frequency deviation of the power system and the SOC value of the cluster energy storage system in the power system, and when the frequency deviation is greater than a first preset threshold and the SOC value is greater than a second preset threshold, performing droop control on the cluster energy storage system according to the first optimal droop coefficient and performing droop control on a synchronous machine in the power system according to the second optimal droop coefficient, so that the stability of emergency frequency control of the power system is improved.
Drawings
Fig. 1 is a schematic flowchart of an emergency frequency control method for a cluster energy storage participation power system according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an emergency frequency control device of a cluster energy storage participating power system according to an embodiment of the present invention;
fig. 3 is a schematic flow chart illustrating droop control on the cluster energy storage system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.
As shown in fig. 1, an embodiment of the present invention provides an emergency frequency control method for a cluster energy storage participating power system, including the following steps:
step S101: and performing collaborative optimization on a first droop coefficient of a cluster energy storage system in the power system and a second droop coefficient of a synchronous machine to obtain a first optimal droop coefficient and a second optimal droop coefficient.
And performing cooperative optimization on the first droop coefficient and the second droop coefficient, mainly to realize reasonable distribution of unbalanced power between the plurality of cluster energy storage systems and the plurality of synchronous machines.
Step S102: monitoring the frequency deviation of a power system and the SOC value of a cluster energy storage system in the power system, and when the frequency deviation is greater than a first preset threshold and the SOC value is greater than a second preset threshold, carrying out droop control on the cluster energy storage system according to the first optimal droop coefficient and carrying out droop control on a synchronous machine in the power system according to the second optimal droop coefficient.
The coordinated droop control provided by the embodiment of the invention mainly realizes the coordination between the droop control of the cluster energy storage system and the primary frequency modulation of a conventional synchronous machine, namely, the droop control of the cluster energy storage system only plays a role in emergency fault and is used as a backup support for the primary frequency modulation of the synchronous machine.
As an embodiment, the droop control of the cluster energy storage system according to the first optimal droop coefficient includes the following steps:
calculating a power instruction value of the cluster energy storage system according to the frequency of the cluster energy storage system grid-connected point, the rated value of the cluster energy storage system grid-connected point, the rated operating power of the cluster energy storage system and the first optimal droop coefficient, and inputting the power instruction value to an energy storage converter; in particular, according to the formula
Figure BDA0003651700070000071
Calculating a power command value for the cluster energy storage, wherein,
Figure BDA0003651700070000072
power command, P, for the cluster energy storage systemERated operating power, k, of the cluster energy storage systemEFor the first optimum droop coefficient, ωcFrequency, omega, of a grid-connected point of the cluster energy storage systemcNAnd the rated value of the grid-connected point of the cluster energy storage system.
As shown in fig. 3, when an emergency frequency failure occurs in the power system, the frequency of the power system changes, and at this time, the frequency signal of the cluster energy storage grid-connected point can be measured by a phase-locked loop (PLL)
Figure BDA0003651700070000073
Frequency signal
Figure BDA0003651700070000074
After filtering processing, the signal becomes omegacInputting to a droop control link; after the frequency signal is input to the droop control link, the droop control equation is used
Figure BDA0003651700070000081
Outputting a power instruction value of the cluster energy storage system (corresponding to the energy storage system in FIG. 2)
Figure BDA0003651700070000082
Power command value of the cluster energy storage system
Figure BDA0003651700070000083
The output voltage is input into a power storage converter PCS, and power regulation response of the cluster energy storage system in an emergency fault is realized through constant power control of the PCS.
The energy storage converter receives the power instruction value
Figure BDA0003651700070000084
And adjusting and responding the power of the cluster energy storage system in case of an emergency fault.
The principle on which the embodiments of the present invention are based is: the power control of the cluster energy storage system is mainly realized by a Power Conversion System (PCS). Taking battery energy storage as an example, the PCS of the system is composed of a DC-AC bidirectional converter and a control unit, and is connected between a battery system and a power grid to realize bidirectional conversion of electric energy. The PCS enables an energy storage system to have control modes such as constant power control, constant power factor control and constant current control. Meanwhile, according to the specification of the national standard GB/T36547-2018 electrochemical energy storage system access power grid technology, it can be known that when the frequency of the energy storage grid connection point is less than 49.5Hz, the energy storage is not in a charging state; at frequencies above 50.2Hz, the stored energy should not be in a discharged state. Based on the operating characteristics of the energy storage system, when the cluster energy storage system adopts a constant power control mode, P-f droop control for the cluster energy storage system can be designed, and the control can be realized by constructing the correlation between the output power of the cluster energy storage system and the frequency of an energy storage grid-connected point, namely: and measuring the frequency at the grid-connected point, and feeding back the frequency to the instruction value of the power control unit of the cluster energy storage system through a droop control link so as to adjust the output active power of the cluster energy storage system.
Obtaining a state equation of the power system according to the following steps:
the power system may be represented as a graph
Figure BDA0003651700070000085
Wherein the node
Figure BDA0003651700070000086
Representing bus bars, edges in said power system
Figure BDA0003651700070000087
Representing a transmission line in the power system. In the power system where cluster energy storage participates, the bus bars can be classified into the following three types:
Figure BDA0003651700070000088
number of synchronizer nodes nG；
Figure BDA0003651700070000089
The number of the connection nodes of the cluster energy storage system is nE；
Figure BDA00036517000700000810
Passive load nodes of number nP；
And has the following components:
Figure BDA0003651700070000091
n＝nG+nE+nP。
considering that the cluster energy storage system has the characteristic that the power can be rapidly adjusted, only considering the synchronous machine under a second-order dynamic model after ignoring the cluster energy storage system dynamics, the state equation of the power system is as follows:
Figure BDA0003651700070000092
wherein i and j are node numbers, θiAnd thetajThe phase angles, ω, at node i and node j, respectivelyiFor frequency deviations from the nominal frequency (50Hz or 60Hz), Mi>0 is the inertia constant of the synchronous machine i, PiFor power injection at node i>0) Or the need (<0)，Pi EFor the output power rating of the cluster energy storage system i,
Figure BDA0003651700070000093
is the effective admittance of the line (i, j), wherein
Figure BDA0003651700070000094
Is the actual admittance value, the voltage amplitude ViAnd VjAssumed to be constant.
Figure BDA0003651700070000095
To a synchronous machine
Figure BDA0003651700070000096
Is determined by the second optimum droop coefficient of (a),
Figure BDA0003651700070000097
for cluster energy storage system
Figure BDA0003651700070000098
Is determined.
As an embodiment, the method for obtaining the first optimal droop coefficient and the second optimal droop coefficient by performing collaborative optimization on a first droop coefficient of a cluster energy storage system in the power system and a second droop coefficient of a synchronous machine includes the following steps:
respectively calculating a first power regulating quantity of the cluster energy storage system and a second power regulating quantity of the synchronous machine according to the first droop coefficient of the cluster energy storage system and the second droop coefficient of the synchronous machine;
establishing a total cost function of the coordinated droop control of the cluster energy storage system and the synchronous machine according to the first power adjustment amount, the second power adjustment amount, the first control target and the second control target;
and performing optimal droop control verification on the total cost function according to the state equation of the power system, and obtaining a first optimal droop coefficient of the cluster energy storage system and a second optimal droop coefficient of the synchronous machine according to an optimal droop control verification result and the total cost function.
As an embodiment, the first optimal droop coefficient and the second optimal droop coefficient are obtained according to the following steps:
respectively calculating a first power regulating quantity of the cluster energy storage system according to the first droop coefficient of the cluster energy storage system and the second droop coefficient of the synchronous machine
Figure BDA0003651700070000101
And a second power adjustment of the synchronous machine
Figure BDA0003651700070000102
Determining a first control objective and a second control objective when the droop coefficient is cooperatively optimized, wherein the first control objective provides more power support for a cluster energy storage system with a larger Power Regulation Margin (PRM), and the second control objective provides more power support for a cluster energy storage system with a larger SOC value. The second control target has the implicit meaning that the SOC values of all the cluster energy storage systems are consistent as much as possible after the emergency frequency control is finished. In engineering practice, both of the two objectives may need to be considered, so that the two control objectives can be considered together by a weighting method.
Correspondingly, the generalized control cost function of the synchronous machine is as follows:
Figure BDA0003651700070000103
the generalized control cost function of the cluster energy storage system has two parts, including a control cost function associated with a first control objective:
Figure BDA0003651700070000104
wherein, the first and the second end of the pipe are connected with each other,
Figure BDA0003651700070000105
for the power regulation margin:
Figure BDA0003651700070000106
wherein, Pi EFor the output power rating of the cluster energy storage system i,
Figure BDA0003651700070000107
and
Figure BDA0003651700070000108
respectively an upper limit and a lower limit of the output power of the cluster energy storage system i.
A control cost function associated with the second control objective:
Figure BDA0003651700070000109
wherein the content of the first and second substances,
Figure BDA00036517000700001010
is the SOC of the cluster energy storage system i.
Obtaining a total cost function of the cluster energy storage system according to the formulas (2) and (4) as follows:
Figure BDA0003651700070000111
wherein λ1i+λ2iWhen a weight is 0, the total cost function considers only a single control target. The optimization problem can now be expressed as:
Figure BDA0003651700070000112
wherein the constraint condition of equation (6) is a power balance constraint.
Performing optimality verification on equation (6) according to the state equation of the power system, comprising the following steps:
converting said equation (6) into lagrangian dual function:
Figure BDA0003651700070000113
wherein, PiFor power injection at node i>0) Or the need (<0) And λ is a dual variable. Then, the lower bound problem for the inner layer can be solved explicitly, resulting in:
Figure BDA0003651700070000114
defining a vector
Figure BDA0003651700070000115
Wherein λiCorresponding to node i, and therefore has the best solution when it is obtained
Figure BDA0003651700070000116
Then the dual problem of the original optimization problem is:
Figure BDA0003651700070000117
the lagrange function of the dual problem of said equation (9) is:
Figure BDA0003651700070000121
wherein
Figure BDA0003651700070000122
Is a lagrange multiplier. Further, a partial primitive-dual distributed algorithm is applied to solve the dual problem, resulting in the following form:
Figure BDA0003651700070000123
wherein tau isi>0，γij>0 is the calculation step size. If the variable lambdaiV and vijRespectively replaced by omegaiAnd PijAnd setting step length taui＝1/Mi，γij＝Bijcos(θi-θj) Integration to obtain Pij＝-Bijsin(θi-θj) It can be seen that equation (10) is the same as equation (1) for dynamics of the power system.
The equation (6) calculates the first and second optimal droop coefficients by considering only a single control target at a time:
Figure BDA0003651700070000124
wherein i is the node number, alphaiAnd betaiCost factors for the first control objective and the second control objective respectively,
Figure BDA0003651700070000125
for the power regulation margin of the cluster energy storage system i,
Figure BDA0003651700070000126
is the SOC of the cluster energy storage system i. Since the formula (10) is the same as the dynamic equation (1) of the power system, under droop control and the setting of two optimal droop coefficients, the power system achieves the optimal trajectory according to a part of the trajectory of the primal-dual distributed algorithm, and the optimality of the first optimal droop coefficient and the second optimal droop coefficient is ensured. Therefore, the first and second optimum droop coefficients can be calculated according to equation (11).
The embodiment of the invention provides a control parameter optimization selection method for reasonably distributing unbalanced power between a plurality of cluster energy storage systems and a plurality of synchronous units, and can comprehensively consider the SOC and the power regulation margin of the cluster energy storage systems, realize optimal control on the emergency frequency of the cluster energy storage participating power system, and improve the control stability of the emergency frequency of the power system.
On the basis of the above embodiment of the invention, the present invention correspondingly provides an embodiment of an apparatus, as shown in fig. 2;
another embodiment of the present invention provides an emergency frequency control apparatus for a cluster energy storage participating power system, including an emergency frequency control module and an optimal droop coefficient acquisition module;
the emergency frequency control module is used for monitoring the frequency deviation of a power system and the SOC value of a cluster energy storage system in the power system, and when the frequency deviation is greater than a first preset threshold and the SOC value is greater than a second preset threshold, droop control is performed on the cluster energy storage system according to a first optimal droop coefficient and droop control is performed on a synchronous machine in the power system according to a second optimal droop coefficient;
the optimal droop coefficient acquisition module is used for obtaining a first optimal droop coefficient and a second optimal droop coefficient by performing collaborative optimization on the first droop coefficient of the cluster energy storage system in the power system and the second droop coefficient of the synchronous machine.
For convenience and simplicity of description, the embodiments of the apparatus of the present invention include all the embodiments of the emergency frequency control method for a cluster energy storage participating power system, and are not described herein again.
On the basis of the above embodiment of the invention, the invention correspondingly provides an embodiment of a readable storage medium item; another embodiment of the present invention provides a readable storage medium, which includes a stored computer program, and when the computer program is executed, the apparatus on which the readable storage medium is controlled to execute the emergency frequency control method for a clustered energy storage participation electric power system according to any one of the method items in the present invention.
Illustratively, the computer program may be partitioned into one or more modules, stored in the memory and executed by the processor, to implement the invention. The one or more modules may be a series of computer program instruction segments capable of performing specific functions, which are used for describing the execution process of the computer program in the terminal device.
The terminal device can be a desktop computer, a notebook, a palm computer, a cloud server and other computing devices. The terminal device may include, but is not limited to, a processor, a memory.
The Processor may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), an off-the-shelf Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may be any conventional processor or the like, said processor being the control center of said terminal device, and various interfaces and lines are used to connect the various parts of the whole terminal device.
The memory may be used to store the computer programs and/or modules, and the processor may implement various functions of the terminal device by executing or executing the computer programs and/or modules stored in the memory and calling data stored in the memory. The memory may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required by at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the cellular phone, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one magnetic disk storage device, a Flash memory device, or other volatile solid state storage device.
Wherein, the terminal device integrated module/unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, can be stored in a computer readable storage medium (i.e. the above readable storage medium). Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may also be implemented by a computer program, which may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like.
It should be noted that the above-described embodiments of the apparatus are merely illustrative, where the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. 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, in the drawings of the embodiment of the apparatus provided by the present invention, the connection relationship between the modules indicates that there is a communication connection therebetween, and may be specifically implemented as one or more communication buses or signal lines. One of ordinary skill in the art can understand and implement it without inventive effort.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
It will be understood by those skilled in the art that all or part of the processes of the above embodiments may be implemented by hardware related to instructions of a computer program, and the computer program may be stored in a computer readable storage medium, and when executed, may include the processes of the above embodiments. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.

Claims (10)

1. An emergency frequency control method for a cluster energy storage participation power system is characterized by comprising the following steps:
obtaining a first optimal droop coefficient and a second optimal droop coefficient by performing collaborative optimization on a first droop coefficient of a cluster energy storage system in the power system and a second droop coefficient of a synchronous machine;
monitoring the frequency deviation of a power system and the SOC value of a cluster energy storage system in the power system, and when the frequency deviation is greater than a first preset threshold and the SOC value is greater than a second preset threshold, carrying out droop control on the cluster energy storage system according to a first optimal droop coefficient and carrying out droop control on a synchronous machine in the power system according to a second optimal droop coefficient.
2. The emergency frequency control method of the cluster energy storage participating power system according to claim 1, wherein the droop control of the cluster energy storage system is performed according to a first optimal droop coefficient, comprising the following steps:
calculating a power instruction value of the cluster energy storage system according to the frequency of the cluster energy storage system grid-connected point, the rated value of the cluster energy storage system grid-connected point, the rated operating power of the cluster energy storage system and the first optimal droop coefficient, and inputting the power instruction value to an energy storage converter;
and the energy storage converter adjusts and responds to the power of the cluster energy storage system in case of emergency fault according to the received power command value.
3. The emergency frequency control method of the power system with cluster energy storage participation of claim 2, wherein the first droop coefficient and the second droop coefficient of the synchronous machine in the power system are cooperatively optimized to obtain the first optimal droop coefficient and the second optimal droop coefficient, and the method comprises the following steps:
respectively calculating a first power regulating quantity of the cluster energy storage system and a second power regulating quantity of the synchronous machine according to the first droop coefficient of the cluster energy storage system and the second droop coefficient of the synchronous machine;
establishing a total cost function of the coordinated droop control of the cluster energy storage system and the synchronous machine according to the first power adjustment amount, the second power adjustment amount, the first control target and the second control target;
and performing optimal droop control verification on the total cost function according to the state equation of the power system, and obtaining a first optimal droop coefficient of the cluster energy storage system and a second optimal droop coefficient of the synchronous machine according to an optimal droop control verification result and the total cost function.
4. The emergency frequency control method of the clustered energy storage involved power system as claimed in claim 3, wherein the calculation formulas of the first optimal droop coefficient and the second optimal droop coefficient are respectively:
Figure FDA0003651700060000021
Figure FDA0003651700060000022
in the formula of lambda1iAnd λ2iIs a weight coefficient, λ1i+λ2i＝1；
Figure FDA0003651700060000023
For the second optimum droop coefficient of the synchronous machine i,
Figure FDA0003651700060000024
for a first optimal droop coefficient of the cluster energy storage system i,
Figure FDA0003651700060000025
representing the connection nodes of the cluster energy storage system,
Figure FDA0003651700060000026
representing a synchronous machine node, alphaiAnd betaiCost factors for the first control objective and the second control objective respectively,
Figure FDA0003651700060000027
for the power regulation margin of the cluster energy storage system i,
Figure FDA0003651700060000028
is the SOC of the cluster energy storage system i.
5. The emergency frequency control method of the cluster energy storage participating power system of claim 4, wherein the state equation of the power system is:
Figure FDA0003651700060000029
Figure FDA00036517000600000210
Figure FDA00036517000600000211
Figure FDA00036517000600000212
wherein i and j are node numbers, θiAnd thetajPhase angles, ω, at node i and node j, respectivelyiFor frequency deviation from nominal frequency, Mi>0 is the inertia constant of the synchronous machine i, PiFor power injection or demand at node i, Pi EOutput rating for a clustered energy storage system i, BijFor effective admittance of the line, ViAnd VjIs a voltage of a magnitude that is preset,
Figure FDA00036517000600000213
Figure FDA00036517000600000214
representing the connection nodes of the cluster energy storage system,
Figure FDA0003651700060000031
a node of a synchronous machine is represented,
Figure FDA0003651700060000032
representing a passive load node.
6. The emergency frequency control method of the cluster energy storage participation power system according to claim 5, wherein the total cost equation of the cluster energy storage system and the synchronous machine cooperative droop control is as follows:
Figure FDA0003651700060000033
in the formula, λ1iAnd λ2iIs a weight coefficient, λ1i+λ2i＝1；
Figure FDA0003651700060000034
Adjusting a first power adjustment amount for the cluster energy storage system;
Figure FDA0003651700060000035
a second power adjustment for the synchronous machine; alpha is alphaiAnd betaiCost factors for the first control objective and the second control objective respectively,
Figure FDA0003651700060000036
for the power regulation margin of the cluster energy storage system i,
Figure FDA0003651700060000037
for the SOC of the cluster energy storage system i,
Figure FDA0003651700060000038
a control cost function of the synchronous machine is represented,
Figure FDA0003651700060000039
a control cost function representing a relationship of the cluster energy storage system to a first control objective,
Figure FDA00036517000600000310
a control cost function of the cluster energy storage system associated with the second control objective is expressed.
7. The emergency frequency control method of the cluster energy storage participation electric power system according to any one of claims 1 to 6, wherein a power command value of the cluster energy storage system is calculated according to the frequency of the cluster energy storage system grid-connected point, a rated value of the cluster energy storage system grid-connected point, a rated operating power of the cluster energy storage system, and the first optimal droop coefficient, and specifically:
according to the formula
Figure FDA00036517000600000311
Calculating a power command value for the cluster energy storage system, wherein,
Figure FDA00036517000600000312
power command, P, for the cluster energy storage systemERated operating power, k, of the cluster energy storage systemEFor the first optimum droop coefficient, ωcFrequency, omega, of a grid-connected point of the cluster energy storage systemcNAnd setting the rated value of the grid-connected point of the cluster energy storage system.
8. An emergency frequency control device of a cluster energy storage participation electric power system is characterized by comprising an emergency frequency control module and an optimal droop coefficient acquisition module;
the emergency frequency control module is used for monitoring the frequency deviation of a power system and the SOC value of a cluster energy storage system in the power system, and when the frequency deviation is greater than a first preset threshold and the SOC value is greater than a second preset threshold, droop control is performed on the cluster energy storage system according to a first optimal droop coefficient and droop control is performed on a synchronous machine in the power system according to a second optimal droop coefficient;
the optimal droop coefficient acquisition module is used for obtaining a first optimal droop coefficient and a second optimal droop coefficient by performing collaborative optimization on the first droop coefficient of the cluster energy storage system in the power system and the second droop coefficient of the synchronous machine.
9. The emergency frequency control device of the cluster energy storage participating power system of claim 8, wherein the emergency frequency control module performs droop control on the cluster energy storage system according to a first optimal droop coefficient, and comprises the following steps:
calculating a power instruction value of the cluster energy storage system according to the frequency of the cluster energy storage system grid-connected point, the rated value of the cluster energy storage system grid-connected point, the rated operating power of the cluster energy storage system and the first optimal droop coefficient, and inputting the power instruction value to an energy storage converter;
and the energy storage converter adjusts and responds to the power of the cluster energy storage system in case of emergency fault according to the received power command value.
10. A readable storage medium, characterized in that the readable storage medium comprises a stored computer program which, when executed, controls a device in which the readable storage medium is located to perform the emergency frequency control method of a clustered energy storage participating power system as claimed in any one of claims 1 to 7.
CN202210544757.1A 2022-05-19 2022-05-19 Emergency frequency control method, device and medium for cluster energy storage participating power system Pending CN114784891A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117748664A (en) * 2023-12-18 2024-03-22 东莞市维能新能源有限公司 BMS control method and system based on cloud AI control

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117748664A (en) * 2023-12-18 2024-03-22 东莞市维能新能源有限公司 BMS control method and system based on cloud AI control

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