CN114221366B - Control method, controller and power station for multi-PCS time sequence response of energy storage power station - Google Patents

Control method, controller and power station for multi-PCS time sequence response of energy storage power station Download PDF

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Publication number
CN114221366B
CN114221366B CN202111564180.2A CN202111564180A CN114221366B CN 114221366 B CN114221366 B CN 114221366B CN 202111564180 A CN202111564180 A CN 202111564180A CN 114221366 B CN114221366 B CN 114221366B
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pcs
power
energy storage
station
instruction
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CN114221366A (en
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陈霞
李偲
林钰钧
杨丘帆
周建宇
文劲宇
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Huazhong University of Science and Technology
State Grid Hubei Electric Power Co Ltd
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Huazhong University of Science and Technology
State Grid Hubei Electric Power 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
    • H02J3/28—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
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
    • H02J13/00022—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment using wireless data transmission
    • 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
    • H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
    • H02J13/00032—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for
    • 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
    • H02J3/381—Dispersed generators
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/70—Smart grids as climate change mitigation technology in the energy generation sector
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/12—Monitoring or controlling equipment for energy generation units, e.g. distributed energy generation [DER] or load-side generation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S10/00—Systems supporting electrical power generation, transmission or distribution
    • Y04S10/14—Energy storage units
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S40/00—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them
    • Y04S40/12—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment
    • Y04S40/126—Systems for electrical power generation, transmission, distribution or end-user application management characterised by the use of communication or information technologies, or communication or information technology specific aspects supporting them characterised by data transport means between the monitoring, controlling or managing units and monitored, controlled or operated electrical equipment using wireless data transmission

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses a control method, a controller and a power station for multi-PCS time sequence response of an energy storage power station, and belongs to the technical field of electrical engineering. The invention screens the PCS corresponding to the highest SOC and sends power instructions to the PCS through the SOC screening of the energy storage battery and the multi-PCS time sequence response control, and the station-level EMS screens the PCS corresponding to the highest SOC and reduces the working PCS power in the last control time sequence to 0, the whole energy storage power station only outputs power by one PCS, the rest PCS keeps the standby state, and the PCS is switched according to the rule when the next control time sequence arrives, so that the sufficient active standby of the energy storage power station is reserved, the orderly use of the multi-PCS in the station and the stable transition of the power station output power are realized. Under emergency control, breaking through the limitation of normal operation instructions, sending power scheduling initial instructions to all PCS according to capacity proportion, and realizing emergency power support of the energy storage power station by means of communication between PCS; and the dynamic distribution of the power of the energy storage power station is realized through the multi-PCS transient state quick response control and the steady state SOC balance control.

Description

Control method, controller and power station for multi-PCS time sequence response of energy storage power station
Technical Field
The invention belongs to the technical field of electrical engineering, and in particular relates to a control method, a controller and a power station for multi-PCS (power conversion system, power Convert System) time sequence response of an energy storage power station.
Background
In recent years, as the duty ratio of renewable energy sources in an electric power system is gradually increased, energy storage is also increasingly widely applied in an electric network. The battery energy storage system has the characteristics of high response speed, wide adjustment range and easiness in bidirectional adjustment, can provide flexibility for a power grid, improves the operation management capability of the power grid, and is a main power unit in an energy storage power station. The energy storage power station mainly comprises a battery energy storage system, active power is absorbed and released according to a dispatching instruction of a power grid, and the energy storage power station has the advantages of stable performance, flexible control, accurate and rapid response, and better response characteristic compared with the traditional thermal power generating unit.
When the energy storage power station faces to power dispatching of a power grid, coordinated operation among a plurality of PCS in the power station needs to be considered so as to present good overall characteristics. However, the control method adopted by the existing energy storage power station is mainly grid-connected power control, active standby and emergency supporting capacity of the energy storage power station cannot be guaranteed, the method is only based on the capacity when power distribution is carried out, dynamic power distribution among multiple PCSs cannot be achieved, and the method is a passive response mode, so that the response speed of the energy storage power station is low, and the energy storage batteries are used out of order.
Disclosure of Invention
Aiming at the defects and improvement demands that the active standby and emergency supporting capability of an energy storage power station cannot be ensured, the dynamic power distribution among multiple PCSs cannot be realized, the response speed of the energy storage power station is slow, and the unordered use of an energy storage battery is required in the prior art, the invention provides a control method, a controller and a power station for the multi-PCS time sequence response of the energy storage power station, which aim at ensuring the power standby and realizing the energy demand of normal operation on the power station through the dynamic selection of the PCS in each control period, and can provide enough and rapid power support during emergency call; the method comprehensively considers the difference of capacity, SOC (system on chip) and response speed, can realize dynamic power distribution and more reasonably responds to power grid dispatching.
To achieve the above object, according to a first aspect of the present invention, there is provided a control method for multi-PCS timing response of an energy storage power station, the method being applied to a station-level EMS (energy management system), the method including:
receiving a dispatching instruction issued by a power grid dispatching center and analyzing the instruction;
if the received normal operation instruction is received, collecting the uploaded battery SOC information according to each PCS, selecting a PCS corresponding to the highest SOC in the initial stage of each control time sequence, sending a power instruction contained in the normal operation instruction to the PCS, reducing the power of the PCS working in the last control time sequence to 0, and keeping the rest PCS in a standby state;
if the received emergency control command is an emergency control command, dividing the total power demand into n power dispatching commands according to a power distribution standard of grid-connected power control, and respectively issuing the n power dispatching commands to each PCS, wherein n represents the number of the PCS in the energy storage power station.
To achieve the above object, according to a second aspect of the present invention, there is provided a control method for multi-PCS timing response of an energy storage power station, the method being applied to a PCS in the energy storage power station, the method comprising:
receiving a power scheduling initial instruction issued by the station-level EMS;
calculating a local estimated overall average power instruction and overall average active output power in real time, and calculating a steady-state power consistency state variable in real time;
the three variables calculated in real time and the output power, the SOC and the capacity of the battery collected by the PCS are communicated with all adjacent PCS, a transient state instruction and a steady state instruction are calculated, and the transient state instruction and the steady state instruction are added to obtain a PCS actual power instruction;
the active power output of the battery is made to follow the PCS actual power command by dq decoupling control.
Preferably, the ensemble average power commandThe calculation formula is as follows:
wherein ,mean power command, a, respectively representing i, j-th PCS calculation ij Indicating the communication weight between the ith and the j PCS, if the ith and the j PCS are adjacent, a ij >0, otherwise, a ij ＝0。
The beneficial effects are that: aiming at the problem that only a steady-state power instruction is given in the existing grid-connected power control, the invention completes the convergence of a designated variable by means of communication exchange information with adjacent PCS through an average consistency algorithm, and obtains a dynamically corrected average power instruction.
Preferably, the ensemble average active outputThe calculation formula is as follows:
wherein ,representing the average active output, a, of the i, j th PCS calculations, respectively ij Indicating the communication weight between the ith and the j PCS, if the ith and the j PCS are adjacent, a ij >0, otherwise, a ij ＝0。
The beneficial effects are that: aiming at the problem that the output power of the PCS is limited by a PI controller in the prior grid-connected power control, the invention completes the convergence of a designated variable by means of the communication exchange information with the adjacent PCS through an average consistency algorithm, and obtains the average active output of dynamic change.
Preferably, the steady state power consistency state variable x i The calculation formula is as follows:
wherein ,Pi ,SOC i ,C ei The output power, SOC, and capacity of the battery collected by the ith PCS are shown, respectively.
The beneficial effects are that: aiming at the problem that the existing grid-connected power control only takes capacity as a power distribution standard, the invention designs the steady-state power consistency state variable, and as the ratio of the output power, the SOC and the capacity product is related, when the designed state variable is consistent, the distribution of each PCS steady-state output power according to the ratio of the SOC and the capacity product is realized, and the residual available energy of each battery is reflected more truly.
Preferably, the transient instruction P it The calculation formula is as follows:
wherein ,representing the overall average power command, +.>Representing the ensemble average active output.
The beneficial effects are that: aiming at the problems that only a steady-state power instruction is given and PCS output power is limited by a PI controller in the existing grid-connected power control, the invention makes a difference between the overall average power instruction and the overall average active output power calculated by a transient controller, takes the difference as a power correction instruction of each PCS, reduces one PI controller link at the same time, and realizes that each PCS provides power support as much as possible according to the response speed of the PCS in the transient process, thereby improving the overall transient response speed of the energy storage power station.
Preferably, steady state instruction P is The calculation formula is as follows:
wherein ,bij Indicating the communication weight between the ith and the j PCS, if the ith and the j PCS are adjacent, b ij >0, otherwise, b ij ＝0，x i ,x j And respectively represent steady-state power consistency state variables of the ith PCS and the jth PCS.
The beneficial effects are that: aiming at the problem that the reasonable distribution of steady-state power cannot be realized by the existing grid-connected power control, the invention ensures that the designed steady-state power consistency state variables are consistent through an average consistency algorithm, realizes the distribution of the output power of each PCS according to the ratio of the product of the SOC and the capacity, and achieves the effect of progressive equalization of the SOC of each energy storage battery.
To achieve the above object, according to a third aspect of the present invention, there is provided a controller comprising: a computer readable storage medium and a processor;
the computer-readable storage medium is for storing executable instructions;
the processor is configured to read executable instructions stored in the computer readable storage medium, and execute the control method for multi-PCS timing response of the energy storage power station according to the first aspect or the second aspect.
To achieve the above object, according to a fourth aspect of the present invention, there is provided an energy storage power station comprising: a station-level EMS, a plurality of PCS and a battery;
the station-level EMS is controlled using the method as described in the first aspect;
the PCS is controlled as described in the second aspect.
In general, through the above technical solutions conceived by the present invention, the following beneficial effects can be obtained:
(1) Aiming at the problem that the active standby and emergency supporting capacity of an energy storage power station cannot be ensured by the existing grid-connected power control method, the invention screens out the PCS corresponding to the highest SOC and sends a power instruction to the PCS through the SOC of the energy storage battery and multi-PCS time sequence response control, and the power instruction is screened out by the station-level EMS at the initial stage of each control period of normal operation, so that the PCS power working in the last control time sequence is reduced to 0, the whole energy storage power station is only output by one PCS, the rest PCS is kept in a standby state, and the PCS is continuously switched according to the rule when the next control time sequence arrives, so that the sufficient active standby capacity of the energy storage power station is reserved, and the orderly use of the multi-PCS in the station and the stable transition of the output power of the power station are realized. Under emergency control, the limitation of normal operation instructions is broken through, power scheduling initial instructions are sent to all PCS according to capacity proportion, and emergency power support of the energy storage power station is achieved.
(2) Aiming at the problem that the active standby and emergency supporting capacity of an energy storage power station cannot be guaranteed by the existing grid-connected power control method, in the transient process, in order to meet the total power demand at first, the actual global information is judged by the average information obtained by calculation of a transient controller through transient quick response control and steady state SOC balance control of a plurality of PCSs, if the difference value is not 0, the integral average power instruction and the integral average active output power are made to be poor, the integral actual active output is not yet achieved to be the integral actual power instruction, and the difference value is fed back to each PCS as a power instruction correction value, so that the PCS with high response speed can always increase the power output, respond to the power demand as quickly as possible until the integral actual active output reaches the actual power instruction value, thereby improving the integral transient response speed and realizing the transient object in emergency control; and in the steady state, the actual output power, capacity and SOC of each PCS form steady state power consistency variables, the real residual available energy of the energy storage battery can be reflected, and then the power of each PCS is redistributed according to the product ratio of the capacity and the SOC, so that the output force is reasonably adjusted, the excessive use is avoided, and the steady state target in the emergency control is realized. The PCS side controller combines transient state and steady state control, and realizes dynamic distribution of power of the energy storage power station.
Drawings
FIG. 1 is a schematic diagram of the primary topology of an energy storage power station;
FIG. 2 is a schematic diagram of a control method for multi-PCS timing response of an energy storage power station according to the present invention;
FIG. 3 is a schematic diagram of a communication topology of a plurality of PCS's within an energy storage power station;
FIG. 4 is a schematic diagram of a transient power controller control method provided by an embodiment;
FIG. 5 is a schematic diagram of a steady state power controller control method provided by an embodiment;
FIG. 6 is a graph of a multi-PCS timing response of an energy storage power station provided by an embodiment;
fig. 7 is a graph showing SOC variation curves of the energy storage batteries according to the embodiment in normal operation;
fig. 8 is a graph showing SOC variation curves during emergency control of each energy storage battery according to the embodiment;
FIG. 9 is a graph comparing overall response speed of the proposed control method and conventional grid-tie power control for the same total power demand provided by the example;
FIGS. 10 (a) and 10 (b) are graphs showing power response of the PCS under the proposed control method and conventional grid-tied power control, respectively, provided by the embodiments;
FIG. 11 is a system response curve for PCS4 failure and recovery provided by an embodiment;
FIGS. 12 (a) and 12 (b) are schematic diagrams of communication failures and system response curves when PCS4 becomes a communication island, respectively, provided by the embodiments;
fig. 13 (a) and 13 (b) are a schematic diagram of communication failure and a system response curve under chain communication, respectively, provided by the embodiment.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
As shown in fig. 1, the invention provides a control method and a system for multi-PCS time sequence response of an energy storage power station, wherein the system is mainly divided into four parts, specifically a battery energy storage unit, a PCS controller, an energy storage power station communication system and a large power grid.
As shown in fig. 2, the invention provides a control method for multi-PCS time sequence response of an energy storage power station, which specifically comprises the following steps:
as shown in fig. 3, each PCS in the energy storage power station is regarded as an independent node, a communication topology of multiple PCS in the energy storage power station is constructed, and two-way communication is performed between each PCS and between the PCS and the station-level energy management system EMS.
When operating normally, the station-level EMS issues a power instruction P according to the output plan of the upper dispatching center ref Then, the SOC information of each energy storage battery is calculated byAnd the PCS collects and compares the communication between adjacent nodes to determine that the energy storage battery with the highest SOC responds to the instruction, and the corresponding PCS controls the output of active power. When the next control time sequence arrives, the sequencing screening is carried out again, the PCS is switched to output power, the original PCS power gradually drops to 0, and the new PCS power gradually rises to a power command value P ref The whole power output of the energy storage power station is kept stable.
The SOC calculation method of each energy storage battery comprises the following steps:
wherein ,SOC0 、SOC t SOC values, i, V, at initial time and t time, respectively dc Output current and terminal voltage of the energy storage battery respectively P, C e The output power and the capacity of the energy storage battery respectively. In the original PCS power P of Gradually decreasing and new PCS Power P on In the process of gradually rising, the time satisfies
P on ＝P ref -P of
The whole energy storage power station shows that the external power output is always stable and unchanged.
During emergency control, the station-level EMS receives the power instruction P total Then, the total power demand P is firstly calculated according to the power distribution standard of grid-connected power control total Is divided into P 1ref -P nref And issuing initial scheduling instructions to all PCS in the energy storage power station, wherein the expression is as follows:
further, the PCS of node i (i=1, 2, …, n) receives the initial instruction P iref After that, the system starts to respond and outputs active power P in real time i . Meanwhile, the PCS controller of the node i needs to obtain the information of the adjacent node j by means of communication, which comprises the following steps: average power commandAverage active output +.>Steady state power consistency variable x j . As shown in fig. 4, according to the received neighboring node information, the local estimated average power command +_is calculated and updated by the transient power controller>And average active outputAs shown in FIG. 5, a steady-state power consistency variable x is calculated and updated by the steady-state power controller i These three variables are then communicated to the PCS of all neighboring nodes.
The designed transient, steady state power controller is described by the following theory and equations.
Based on basic knowledge of graph theory, the communication topology of the multi-PCS system of the energy storage power station can be defined as an undirected graph wherein />Is a limited number of non-empty node sets, a->A collection of node-ordered pairs is referred to as an edge set, i.e., a communication link. Laplace matrix L epsilon R corresponding to undirected graph topology N×N Can be expressed as:
a ij the size of (2) reflects the communication weight of the communication link. If it isThen a ij >0; otherwise, a ij ＝0。
The transient power controller equation is:
wherein ,the average power instruction and the average active output obtained by calculation for the node i are respectively expressed as follows:
wherein ,average active outputs calculated for nodes i, j, respectively, +. ij Representing the communication weight between nodes i and j, and if i and j are adjacent nodes, a ij >0, otherwise, a ij ＝0。
The basic principle of the transient controller is an average consistency principle, the control method does not need to know the total PCS quantity of the energy storage power station, only relies on information exchange among adjacent nodes to continuously calculate and update the designed state variable information, and finally all estimated values are converged to the arithmetic average of actual values, namely the average value of the required global information is calculated, and the expression is as follows:
during transient state, whenI.e. when there is a difference between the average power command calculated by each node and the average active output, it indicates that the actual output active of the whole has not reached the total power command, this difference P it Feedback is fed to each PCS, which adjusts the active power output of the plant until the total power command is met.
The transient controller takes the average information as the adjustment basis, so that PCS output which is originally low in distributed power and has adjustment potential can be obviously improved, and the PCS output is not constrained by a given power instruction, so that the overall transient response speed is improved; for PCS with more power distribution and slower response speed, the response pressure can be relieved by the method.
Further, after the total power command is reached, a reasonable steady-state power allocation mode needs to be considered. The steady-state power controller adopts a PI controller to make the steady-state power consistency variable x of the node i i The power correction value P in steady state can be obtained by PI controller is The equation is:
wherein ,P、Ce The subscript i marks the ith PCS for the output power and capacity of the energy storage battery, respectively.
At steady state, all x are made based on a consistency protocol i When the two are consistent, the following steps are obtained:
the actual active power output of each PCS in steady state is ensured to be distributed according to the ratio of the product of the capacity and the SOC.
Further, the obtained transient instruction P is processed it And steady state instruction P is Adding to obtain the actual active power instruction P 'of the PCS of the node i' iref ：
P′ iref ＝P it +P is
According to PCS bottom control, the energy storage power station can output active power P i Following the actual active power command P' iref And meet the followingDynamic power distribution can be realized, the overall transient response speed of the multi-PCS in the energy storage power station is improved, and the proportional distribution and orderly use of power among the multi-PCS in a steady state are ensured.
Based on the control method for multi-PCS time sequence response of the energy storage power station, the invention provides a corresponding multi-PCS time sequence response control system of the energy storage power station, which comprises the following steps:
the energy storage power station level instruction communication module is used for obtaining the instruction of each control period of the energy storage power station and dividing the instruction into a normal operation instruction and an emergency control instruction.
And the SOC calculation module of the energy storage battery is used for obtaining the SOC value of the energy storage battery at the initial moment of each control period.
And the SOC sorting and screening module is used for determining the battery with the highest SOC at the initial moment of each control period in normal running and outputting power by the PCS of the battery.
The power distribution module for grid-connected power control is used for obtaining an initial power scheduling instruction P according to the capacity of each of n PCS during emergency control 1ref -P nref 。
A transient power controller for controlling the power according to the initial instruction P of the node i iref Active power output P i Average power instruction for neighboring nodesAverage active output +.>Computing the average power instruction local to node i +.>And average active output +.>And get the transient instruction P it 。
A steady-state power controller for controlling the power according to the capacity C of the node i ei 、SOC i Output power P i And adjacent nodes, calculates steady-state power consistency state variables x i And obtain steady-state instruction P is 。
PCS communication module for PCS communication of adjacent node, exchangex i Three variable information.
A PCS converter actual active power instruction determining module for determining a transient instruction P it And steady state instruction P is Adding to obtain the actual active power instruction P 'of the PCS' iref 。
A PCS converter control module for dq decoupling control of the converter to make the PCS output active power P i Following the actual active power command P' iref 。
In the control system for multi-PCS time sequence response of an energy storage power station, the division of each module is only used for illustration, and in other embodiments, the system can be divided into different modules according to the need to complete all or part of the functions of the system.
The control method provided by the invention considers the response unit screening method considering the SOC of the energy storage battery and the multi-PCS time sequence response problem of the centralized output of the whole station under active standby and emergency control reserved under normal operation of the energy storage power station, and can ensure the power standby and realize the energy requirement of normal operation on the power station through dynamic selection of PCS in each control period, and can provide enough and quick power support during emergency call.
The power distribution method provided by the invention is different from the existing method that only capacity is used as a standard of power distribution among a plurality of PCSs in the energy storage power station, and the difference of capacity, SOC (system on chip) and response speed is comprehensively considered, so that dynamic power distribution can be realized, and power grid dispatching can be more reasonably responded. And in normal operation, according to the output plan, a small part of battery output power is called, a large part of battery power is reserved for standby, and only the battery output force with the highest SOC is called each time, so that all the energy storage batteries are orderly used, and the final SOC level tends to be consistent. In emergency control, transient and steady-state targets are distinguished, and in the transient process, each PCS is not constrained by a power instruction in normal operation and responds to power requirements as fast as possible and as much as possible, so that the overall transient response speed is improved. After compensating the power shortage, the PCS power is redistributed in a steady state according to the product ratio of the capacity and the SOC, and the output is reasonably adjusted to avoid excessive use.
The control method changes the process of passive scheduling of a plurality of PCS in the energy storage power station into active coordination among groups, fully utilizes the regulating capability of the whole energy storage power station, can realize automatic complementation of power when a certain PCS fails, and keeps the power output by the whole energy storage power station to the outside stable and unchanged.
Examples
The method comprises the steps of setting 4 energy storage batteries and PCS (Power control System) thereof in an energy storage power station, representing by PCS1-PCS4, sequentially slowing down the response speed, sequentially increasing the capacity, and setting the capacity ratio as 1 for convenient calculation: 2:3:4.
the values of the system parameters are shown in Table 1:
TABLE 1
Fig. 6 shows a timing response of 4 PCS in an energy storage plant under 4 normal operating commands and 1 emergency control command. During normal operation, after the power command is responded by PCS1, PCS2, PCS4 and PCS3 in sequence after the screening and sequencing are carried out in 4 control periods, and the stability of the integral output of the power station is maintained in the process of switching the PCS. After the emergency control command comes, 4 PCS concentrate the output, is not constrained by the original power command, wherein the PCS1 responds fastest, the instantaneous output power is highest, and the PCS4 continues to increase the power under the condition of the existing normal output power, so that the whole energy storage power station can provide rapid power support. After the total power demand is reached, the PCS adjusts the output under the control strategy, the PCS1 and the PCS2 gradually reduce the output due to smaller product of the capacity and the SOC, and PCS3 and PCS4 bear the main output. The time sequence response process proves that the proposed control method can effectively realize the ordered scheduling of a plurality of PCSs in the station under the condition of keeping the active reserve of the energy storage power station, promote the overall transient response speed when the emergency power support is needed, redistribute the steady-state power of each PCS in proportion after the power demand is met, realize the dynamic power distribution and reasonably respond to the scheduling of the power grid. Fig. 7 and 8 show SOC variation curves of the respective energy storage batteries under normal operation and emergency control, respectively.
The comparison of the effects of the proposed control method and the conventional grid-connected power control is shown in fig. 9, the total power instruction issued by the upper layer scheduling center is set to be 3kW when t=0.5 s, the total power instruction value is reached by the system through 0.03s under the proposed control method, and the total power instruction value can be reached only by 0.07s under the conventional grid-connected power control. It can be seen that the control method can obviously improve the transient response speed of the whole multi-PCS of the energy storage power station.
The response curves of the PCS under the two control methods are shown in fig. 10 (a) and 10 (b), and the two graphs are observed at the stage of 0.5s-0.6s, so that the provided control method has obvious transient regulation effect, and PCS1 and PCS2 with high response speed rapidly output at the transient stage; in a steady state stage, PCS4 with large capacity and SOC product bears main output, and the active power output of PCS1-PCS4 in the steady state is respectively 0.36kW, 0.72kW and 1.2kW, and the ratio of output power is 1:2:2:3.3, equal to the ratio of the capacity to the SOC product, proves that the control method can improve the transient response speed and ensure the proportional distribution of steady-state power. The traditional grid-connected power control has no transient regulation process, rapid power support cannot be provided in emergency control, the power distribution in steady state only considers the proportion of capacity, and the actual available residual energy of the stored energy represented by the product of the capacity and the SOC cannot be reflected more comprehensively.
As shown in fig. 11, to verify the effect of the proposed control method in the failure state, when other conditions are consistent with the above-described case, PCS4 is set to fail at t=1.0 s. As can be seen from the figure, after the PCS4 fails, its output power drops to 0, which results in a drop of the overall total output power, but due to the existence of the control strategy, the rest PCS learn about the change of the actual total output power by means of communication, and the proposed controller automatically adjusts, redistributes power according to the capacity size among the rest PCS, and rapidly reacts to increase the power, thereby realizing the overall power complement. At t=1.5 s PCS4 is restored and each PCS is briefly adjusted back to the pre-fault power distribution state. The actual active output in the whole process can be quickly restored to the instruction value without generating larger deviation, and the method has good expandability.
Since the proposed control method needs to be implemented based on communication between nodes, robustness against communication failures is particularly important. Fig. 12 (a) to 13 (b) show system response curves in two communication failure states. As shown in fig. 12 (a) and 12 (b), when other conditions coincide with the initial situation, the communication of the PCS4 is set to be completely disconnected from the neighboring nodes, i.e., the communication links 1-4 and 3-4 are disconnected, and the PCS4 becomes a communication island, but this does not affect the normal operation of the PCS4 itself. Because the PCS4 cannot receive the information of the neighboring nodes, the average information variable in the controller cannot be updated, and the control mode is equivalent to degradation to grid-connected power control. However, for the whole system, since the PCS4 no longer participates in transient regulation, the transient response speed of the whole system is slightly reduced.
When other conditions coincide with the initial situation, as shown in fig. 13 (a), the communication links 1-4 are set to fail and open, which causes the original bidirectional ring communication to become chained communication, and the response curve of the system is shown in fig. 13 (b). As the communication link becomes longer, the steady state convergence speed of each PCS becomes slower, the steady state response time becomes longer, and the simulation result accords with theory and actual conditions. Under two communication fault states, the proposed control method can ensure the stable operation of the whole system, and the effectiveness of the proposed control method is proved.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.

Claims (6)

1. A control method for multi-PCS timing response of an energy storage power station, the method being applied to a station-level EMS, the method comprising:
receiving a dispatching instruction issued by a power grid dispatching center and analyzing the instruction;
if the received normal operation instruction is received, collecting the uploaded battery SOC information according to each PCS, selecting a PCS corresponding to the highest SOC in the initial stage of each control time sequence, sending a power instruction contained in the normal operation instruction to the PCS, reducing the power of the PCS working in the last control time sequence to 0, and keeping the rest PCS in a standby state;
if the received emergency control command is an emergency control command, dividing the total power demand into n power dispatching commands according to a power distribution standard of grid-connected power control, and respectively issuing the n power dispatching commands to each PCS, wherein n represents the number of the PCS in the energy storage power station.
2. A control method for multi-PCS timing response of an energy storage power station, the method being applied to a PCS in the energy storage power station, the method comprising:
receiving a power scheduling initial instruction issued by the station-level EMS;
calculating a local estimated overall average power instruction and overall average active output power in real time, and calculating a steady-state power consistency state variable in real time;
the three variables calculated in real time and the output power, the SOC and the capacity of the battery collected by the PCS are communicated with all adjacent PCS, a transient state instruction and a steady state instruction are calculated, and the transient state instruction and the steady state instruction are added to obtain a PCS actual power instruction;
the active power output of the battery follows the PCS actual power instruction through dq decoupling control;
wherein the steady state power consistency state variable x i The calculation formula is as follows:
wherein ,Pi ,SOC i ,C ei Output power, SOC, and capacity of the battery collected by the ith PCS are respectively represented;
the transient instruction P it The calculation formula is as follows:
wherein ,representing the overall average power command, +.>Representing the overall average active output of the device,
the steady state instruction P is The calculation formula is as follows:
wherein ,bij Indicating the communication weight between the ith and the j PCS, if the ith and the j PCS are adjacent, b ij >0, otherwise, b ij ＝0，x i ,x j And respectively represent steady-state power consistency state variables of the ith PCS and the jth PCS.
3. The method of claim 2, wherein the ensemble average power commandThe calculation formula is as follows:
wherein ,mean power command, a, respectively representing i, j-th PCS calculation ij Indicating the communication weight between the ith and the j PCS, if the ith and the j PCS are adjacent, a ij >0, otherwise, a ij ＝0。
4. The method of claim 2, wherein the ensemble average active outputThe calculation formula is as follows:
wherein ,representing the average active output, a, of the i, j th PCS calculations, respectively ij Indicating the communication weight between the ith and the j PCS, if the ith and the j PCS are adjacent, a ij >0, otherwise, a ij ＝0。
5. A controller, comprising: a computer readable storage medium and a processor;
the computer-readable storage medium is for storing executable instructions;
the processor is configured to read executable instructions stored in the computer readable storage medium and execute the control method for an energy storage plant multi-PCS timing response as claimed in any one of claims 1 to 4.
6. An energy storage power station, the energy storage power station comprising: a station-level EMS, a plurality of PCS and a battery;
the station-level EMS is controlled using the method of claim 1;
the PCS is controlled using the method of any one of claims 2 to 4.
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