CN112421693A - Electric automobile participation secondary frequency modulation control strategy considering power distribution network congestion - Google Patents
Electric automobile participation secondary frequency modulation control strategy considering power distribution network congestion Download PDFInfo
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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
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
- B60L53/60—Monitoring or controlling charging stations
- B60L53/63—Monitoring or controlling charging stations in response to network capacity
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L55/00—Arrangements for supplying energy stored within a vehicle to a power network, i.e. vehicle-to-grid [V2G] arrangements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
- B60L58/10—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries
- B60L58/12—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for monitoring or controlling batteries responding to state of charge [SoC]
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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
- H02J3/322—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means the battery being on-board an electric or hybrid vehicle, e.g. vehicle to grid arrangements [V2G], power aggregation, use of the battery for network load balancing, coordinated or cooperative battery charging
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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
- H02J2310/00—The network for supplying or distributing electric power characterised by its spatial reach or by the load
- H02J2310/40—The network being an on-board power network, i.e. within a vehicle
- H02J2310/48—The network being an on-board power network, i.e. within a vehicle for electric vehicles [EV] or hybrid vehicles [HEV]
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- 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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
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- Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
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Abstract
The invention discloses an electric automobile participation secondary frequency modulation control strategy considering power distribution network congestion, which comprises the steps of firstly collecting the SOC of the electric automobile, and dividing the electric automobile into an EVdc group in a V2G state and an EVc group in a charging state according to the SOC; respectively calculating the controllable capacity of the two groups of electric automobiles; then, according to the controllable capacity of the two groups of electric automobiles, distributing the frequency modulation power to each electric automobile; and finally, monitoring the running state of the power distribution network in real time, calculating the CCIF index of the power distribution network, limiting the charging power of the electric automobile when the CCIF index is too high, and distributing the frequency modulation power again by the limited part of frequency modulation capacity.
Description
Technical Field
The invention belongs to the field of optimized scheduling of power systems, and particularly relates to a secondary frequency modulation control strategy for participation of an electric automobile considering power distribution network congestion.
Background
The construction of a new energy power grid is a development trend of electric power systems in China, and large-scale integration of a new energy power supply with intermittency, uncertainty and volatility makes the problem of stable frequency control of the electric power systems increasingly complex. The electric automobile can be used as a mobile energy storage device without the load property of the electric automobile, the existing electric automobile is increased year by year, a large electric automobile group can contribute a large amount of frequency modulation capacity support for power system frequency regulation, and compared with a traditional unit, the electric automobile generally has a faster response speed, can make a quicker response to frequency change, and is suitable for participating in the frequency regulation of a power system. Therefore, more and more clustered electric vehicles are proposed to participate in frequency modulation, so as to solve the problem of grid frequency stability.
Only a large amount of EVs participate in scheduling and can realize secondary frequency modulation, but the electric automobile has strong social attributes, the intention of EV automobile owners needs to be solicited, for more automobile owners to agree with the interconnection of the electric automobile and the power grid, a certain communication protocol can be adopted, consideration of the power grid and the automobile owners is comprehensively considered aiming at the characteristics of electric automobile users, the protocol beneficial to both parties is provided, the intention of the automobile owners to agree with the synchronization of the electric automobile is enhanced, and a large amount of electric automobiles can participate in scheduling.
In addition, the estimation and distribution of the frequency modulation capacity after the grid connection of a large number of electric vehicles are also important problems. In order to solve the problem, a method for calculating the frequency modulation capacity of the electric automobile based on probability theory is provided at present, and the method can enable each electric automobile to reasonably distribute the frequency modulation capacity. However, in this method, the problem that the electric vehicle participates in frequency modulation is only considered from the higher-level of power grid scheduling, and the SOC of the electric vehicle and the coupling between the SOC and the frequency modulation power of the electric vehicle are not considered, so that it is difficult to fully exert the frequency modulation capability of the cluster electric vehicle.
In order to fully utilize the controllable frequency modulation capability of the electric automobile as much as possible, a control strategy which considers the influence of the SOC of the electric automobile and compares two charging modes of one-way charging and two-way V2G is provided, but all the electric automobiles are set to the same initial value of the SOC during simulation, the randomness of the grid-connected state of different electric automobiles in real conditions is not considered, and the influence of the SOC on the frequency modulation cannot be thoroughly researched.
In fact, there are two main reasons why the SOC of the electric vehicle should be extracted at the time of grid connection and the SOC should be extracted again at intervals in order to fully develop the frequency modulation capability of each electric vehicle. On one hand, the electric automobile is used as a vehicle, the initial SOC during grid connection has strong randomness, frequency modulation tasks can be distributed according to the condition of each automobile only according to the actual initial SOC, different electric automobiles have different charging and discharging power, and the SOC extracted again at intervals can guarantee that the SOC extracted every time has time effect. On the other hand, the electric automobile should satisfy the trip requirement of the automobile owner while participating in frequency modulation, and the SOC needs to be extracted again at intervals, so that the influence of over-discharge on the automobile owner is avoided.
In addition, the electric vehicle has not only the property of an energy storage power supply but also the property of a load. When the load is in a peak, the electric automobile is charged in a large quantity, so that the congestion of a power distribution network can be caused, the system safety can be threatened by the congestion, the scheduling and running difficulty can be increased, and the popularization of renewable energy power generation can be limited. The existing frequency modulation strategies for the electric automobile only consider the energy storage property of the electric automobile, and the frequency modulation strategy considering the load property of the electric automobile does not appear yet. Therefore, the electric automobile which considers the congestion of the power distribution network needs to be further explored to participate in the secondary frequency modulation control strategy.
Disclosure of Invention
The invention provides a power distribution network congestion involved electric automobile secondary frequency modulation control strategy, which comprises the following steps:
step A, collecting the SOC of the electric automobile, and dividing the electric automobile into two groups according to the SOC, wherein the two groups are an EVdc group in a V2G state and an EVc group in a charging state respectively;
b, calculating the controllable capacity of the two groups of electric vehicles in the step A;
c, distributing the frequency modulation power to each electric automobile on the basis of the capacity calculated in the step B;
and D, monitoring the running state of the power distribution network in real time, calculating the CCIF index of the power distribution network, limiting the charging power of the electric automobile when the CCIF index is too high, and returning the limited part of frequency modulation capacity to the step C to redistribute the frequency modulation power.
Preferably, in step a, counting the SOC of the electric vehicles in the whole electric vehicle group, setting a threshold value SOCb, and when detecting that a certain electric vehicle is in a lower SOC, the SOC of the certain electric vehicle is smaller than the SOCb, and the certain electric vehicle needs to be charged with a certain charging power to meet the trip requirement of the vehicle owner, dividing the certain electric vehicle into EVc groups, and the certain electric vehicle will be in a unidirectional charging state; when detecting that some electric automobile is at a higher SOC, the SOC of the electric automobile is greater than or equal to the SOCb, the traveling requirement of the owner can be met, the electric automobile is divided into an EVdc group, and the electric automobile is in a V2G state.
More preferably, in step B, the two groups of electric vehicles divided in step a are respectively subjected to controllable capacity calculation. For an electric automobile in a unidirectional charging state, the controllable capacity of the electric automobile is limited by the power of a charging pile, the frequency modulation capability is also considered, and the charging power is reduced as far as possible on the premise of meeting the travel requirement of a user. For the electric automobile in the V2G state, the electric automobile is normally in a state of neither charging nor discharging, and the controllable capacity is restricted by the maximum power value of the charging pile.
Still further preferably, in step C, the frequency modulation task is issued to the two train sets according to the controllable capacity of each set obtained in step B. When the system load is increased sharply and the frequency modulation rate is required to be increased, the individual in the EVc electric automobile group distributes the frequency modulation weight according to the SOC level per se, the EV with a high SOC value preferentially takes on the frequency modulation task, and more frequency modulation capacity is distributed; when system load reduction requires a turndown frequency, individuals with SOC values in the EVdc electric vehicle fleet have a higher priority for charging, can charge earlier and have a higher charge power.
Most preferably, in step D, to avoid the occurrence of power distribution network congestion, the load level of the power distribution network and the transformer capacity carrying capacity condition of the power distribution network are monitored in real time, and the CCIF index of the power distribution network is calculated according to the following formula:
during charging:
discharging:
wherein, PEVActual charging/discharging power, P, of the ith vehicle EVLFor the current load of the system, Δ PtieFor transmitting power to the junctor, PGeneral assemblyThe capacity carrying capacity of the transformer.
Charging and discharging power eta of ith vehicle EVch、ηdischRespectively the charging and discharging efficiency of the charging pile. And when the CCIF index exceeds the threshold value, the three-level system of the power distribution network congestion management system issues control signals step by step, the charging and discharging power of the electric automobile is limited through the one-level system, the upper limit of the charging power is limited, the frequency modulation tasks which are not completed due to the limited power are reported to a cluster charging station, and the frequency modulation tasks are redistributed according to the calculation method in the step C.
Drawings
FIG. 1 is a flow chart of an electric vehicle secondary frequency modulation control strategy taking power distribution network congestion into account
FIG. 2 is a control frame diagram of the electric vehicle participating in frequency modulation
FIG. 3 is a block diagram of a congestion management framework for a power distribution network according to the present invention
FIG. 4 is a graph comparing frequency fluctuation before and after a secondary frequency modulation control strategy for accounting congestion of a power distribution network according to the present invention
Fig. 5 is a comparison diagram of CCIF before and after a secondary frequency modulation control strategy for taking power distribution network congestion into account by adopting the method.
Detailed Description
The present invention is described in detail below with reference to the attached drawings. FIG. 1 is a control framework diagram of the electric vehicle of the present invention participating in frequency modulation. Each charging pile reports the real-time state of the electric automobile, such as SOC, power and other information to the cluster charging station, the adjustable capacity range, load prediction and other information provided by the cluster charging station are integrated, the distribution network management system obtains the controllable capacity and load information of the distribution network, and the information is reported to the power network dispatching center. And the power grid dispatching center collects information of all power distribution networks in the jurisdiction, issues the frequency modulation signals step by step through the power distribution network management system and the cluster charging station, and sends frequency modulation instructions to each EV to control the charging and discharging power of the charging pile. The distribution network congestion management framework diagram is shown in fig. 2, the distribution network congestion management framework diagram is provided with a hierarchical distribution network congestion management system, in the frequency modulation process of an electric vehicle, a first-level control system corresponds to a charging pile, a second-level control system corresponds to a cluster charging station, and a third-level control system corresponds to a distribution network management system.
Step A: collecting SOC of the electric automobile, and dividing the electric automobile into two groups according to the SOC, wherein the two groups are an EVdc group in a V2G state and an EVc group in a charging state respectively.
Step A1: when each electric automobile in the whole electric automobile group is connected to the grid, the SOC of each electric automobile is counted, and the SOC value is reported to the cluster charging station through the charging pile.
Step A2: the SOC of the electric automobile is changed due to the charging and discharging behaviors of the electric automobile, and the SOC of the electric automobile is counted again every half hour in order to not influence the normal use of a user.
Step A3: setting a threshold value SOCb, when detecting that a certain electric automobile is in a lower SOC (state of charge), the SOC of the electric automobile is smaller than the SOCb, and the electric automobile needs to be charged with certain charging power to meet the travel requirement of an owner, and is divided into EVc groups, and the electric automobile is in a unidirectional charging state; when detecting that some electric automobile is at a higher SOC, the SOC of the electric automobile is greater than or equal to the SOCb, the traveling requirement of the owner can be met, the electric automobile is divided into an EVdc group, and the electric automobile is in a V2G state.
And B: and C, calculating the controllable capacity of the two groups of electric vehicles in the step A.
Step B1: the dispatching center adopts a probability statistical method to estimate the frequency modulation capacity N of the electric automobile required in a period of time in the future according to the system operation historical data, and the dispatching capacity of the cluster charging station in the period of time is P. The power grid dispatching center can send a frequency modulation signal N which needs to be borne by the vehicle group to the cluster charging station, and when N is less than or equal to P, the electric vehicle can normally participate in frequency modulation; however, when the frequency modulation power is larger than the maximum value, the available P is called, the frequency modulation power of the electric vehicle is limited to the maximum value within the allowable range, the electric vehicle bears the frequency modulation power as much as possible, and finally the rest frequency modulation power is delivered to a frequency modulation unit or other types of frequency modulation resources for sharing. The electric vehicle has different controllable capacities in the two charging states, and therefore needs to be calculated separately.
Step B2: and calculating the controllable capacity of the electric automobile group of the EVc group. For an electric automobile in a one-way charging state, the controllable capacity of the electric automobile is limited by the power of a charging pile, the frequency modulation capability is also considered, and the charging power is reduced as far as possible on the premise of meeting the travel requirement of a user.
Δpi＝min(pmax，pmax-pbi) (1)
Wherein n1 is the number of EVc group electric automobiles, delta piFor controllable capacity of individual vehicle, pmaxFor charging and discharging power limits of the pile, pbiFor the electric vehicle charging power under normal conditions (not participating in frequency modulation), P1 is EVc controlled total capacity.
Step B3: and calculating the controllable capacity of the electric automobile group of the EVdc group. For the electric automobile in the V2G state, the electric automobile is normally in a state of neither charging nor discharging, and the controllable capacity is restricted by the maximum power value of the charging pile.
Δpj＝pmax (3)
Wherein n2 is the number of EVdc group electric vehicles, delta pjFor controllable capacity of individual vehicle, pmaxFor charging and discharging power limits of the charging pile, P2 is EVc controllable total capacity.
And C: and B, distributing the frequency modulation power to each electric automobile on the basis of the capacity calculated in the step B.
Step C1: and the power grid dispatching center distributes a dispatching task A to the cluster charging station, and the cluster charging station distributes the dispatching task to the two electric vehicle groups.
A1 and A2 are frequency modulation capacities required to be borne by train set EVc and EVdc, P1 is EVc controllable total capacity, and P2 is EVdc controllable total capacity.
Step C2: and issuing the tasks to each electric automobile according to the frequency modulation tasks distributed to the EVc vehicle groups by the cluster charging stations. When the system load is increased sharply and the frequency modulation rate is needed, the individual in the EVc electric automobile group distributes the frequency modulation weight according to the SOC level per se, the EV with the high SOC value preferentially takes the frequency modulation task, and more frequency modulation capacity is distributed.
p1＝(SOCb-SOCi)×Ei，i∈EVc (7)
Where p1 is the maximum charging power, SOC, that each EV in the EVc set can providei、 EiAnd delta is the willingness of the vehicle owner to accept the frequency modulation task, the value of the consent parameter is 1, and the value of the non-consent parameter is 0. EVciThe capacity is the single EV frequency modulation capacity of the unidirectional charging vehicle group.
Step C3: and distributing the frequency modulation tasks to the EVdc vehicle group according to the cluster charging station, and issuing the tasks to each electric vehicle. When the system load is reduced and the frequency is required to be adjusted downwards, the individuals in the EVc electric automobile group distribute the frequency modulation weight according to the SOC level of the individuals in the EVc electric automobile group according to the proportion, the individuals with low SOC values have higher charging priority, can be charged earlier and have higher charging power.
p2＝(SOCj-SOCb)×Ej，j∈EVdc (9)
Wherein p2 is the maximum discharge power, SOC, provided by each EV in the EVdc bankj、 EjThe electric vehicle single body charge state and the maximum capacity of the electric vehicle single body charge state are respectively an EVdc group, delta is whether a vehicle owner agrees to undertake the willingness of a frequency modulation task, the agreement parameter value is 1, and the disagreement parameter value is 0. EVdcjThe capacity is the single EV frequency modulation capacity of the V2G vehicle group.
Step D: and (3) monitoring the running state of the power distribution network in real time, calculating the CCIF index of the power distribution network, limiting the charging power of the electric automobile when the CCIF index is overhigh, and returning the limited part of frequency modulation capacity to the step C to redistribute the frequency modulation power.
Step D1: and monitoring the relation between the load level of the power distribution network and the capacity carrying capacity of the transformer in real time, and calculating the CCIF index of the power grid.
During charging:
during discharging:
wherein, PEVActual charging/discharging power, P, of the ith vehicle EVLFor the current load of the system, Δ PtieFor transmitting power to the junctor, PGeneral assemblyThe capacity carrying capacity of the transformer.
Charging and discharging power eta of ith vehicle EVch、ηdischRespectively the charging and discharging efficiency of the charging pile. At the same time, the limit of the battery capacity should be considered to ensure that the vehicle owner can meet the requirements when using the vehicleAnd (5) trip requirements.
For any EV, it should satisfy:
wherein the SOCiniFor the initial state of charge before the EV is connected into the power grid, ta and tb are respectively the time when the EV is connected into the power grid and the time when the EV leaves the power grid interconnection, and SOCdriThe minimum charge state required by the vehicle owner is met.
Step D2: setting a threshold value and grading, and carrying out different constraints on the charging and discharging power of the EV after the CCIF reaches different grade threshold values. Setting thresholds C1 and C2, charge/discharge limitation Plim1、Plim2. When CCIF < C1, the system is in a normal state levle 1; when C1 < CCIF < C2, the system is in a busy state levle 2; when CCIF is more than C2, the system is in endangered state.
Step D3: when the CCIF index exceeds the threshold value, the three-level system of the power distribution network congestion management system issues control signals step by step, and the electric automobile with high charging power is transferred to the automobile group EV in a busy state through the one-level systemlim1Limiting the charging and discharging power of the electric automobile according to the formula (14), and moving the electric automobile with high charging power into a vehicle group EV in a high-risk statelim2The charging and discharging power of the electric automobile is limited according to the formula (15), and the unfinished frequency modulation task A is ═ sigma (EVc) due to the limited poweri-plim1) Or sigma (EVc)j-plim2)， i∈EVlim1，j∈EVlim2And D, reporting to the cluster charging station, and redistributing according to the calculation method in the step C.
Effects of the invention
Compared with the prior art, the invention has the following advantages:
1. different from the conventional electric vehicle frequency modulation strategy, the strategy fully considers the load attribute of the electric vehicle, provides the frequency modulation strategy for controlling the electric vehicle through a power distribution network congestion management framework which is comprehensively measured and predicted on the basis of the control strategy for participating in secondary frequency modulation of the electric vehicle, and enables the electric vehicle to fully exert the mobile energy storage characteristic and avoid the load attribute from bringing negative effects to the power distribution network as much as possible by limiting the charging and discharging power at the electric vehicle end.
2. Different from the traditional centralized power distribution network congestion management system, the strategy builds a distributed hierarchical power distribution network congestion management framework. Compared with centralized control, in the centralized control process, the data transmission quantity between the control center and the control center is in direct proportion to the size of the controlled network and the quantity of controllable resources, and the calculation of the state estimation value and the optimal main controller setting value of the whole power distribution network in real time requires high calculation capacity. The system is divided into three levels, and only necessary data are transmitted between ACUs of different levels and the control center, so that the data transmission quantity is remarkably reduced, and the control speed and the control precision are remarkably improved.
3. Due to the existence of the hierarchical control system and the SACU, the system can more conveniently add new distributed energy sources to be connected to the power grid. The primary control system is specially used for local measurement and control, measured data are stored in the SACU database, the application range is wide, and the method is easy to popularize to application of various distributed energy except electric automobiles.
4. Because the SOC of the electric automobile is counted again every 30min by the strategy, the frequency modulation capacity of the electric automobile group acquired by the cluster charging station is real-time data, a frequency modulation task can be more accurately distributed, and the condition that the electric automobile cannot complete the issued frequency modulation task is avoided by fully utilizing the frequency modulation capacity of the electric automobile.
Claims (5)
1. An electric automobile participation secondary frequency modulation control strategy considering power distribution network congestion comprises the following steps:
step A, collecting the SOC of the electric automobile, and dividing the electric automobile into two groups according to the SOC, wherein the two groups are an EVdc group in a V2G state and an EVc group in a charging state respectively;
b, calculating the controllable capacity of the two groups of electric vehicles in the step A;
c, distributing the frequency modulation power to each electric automobile on the basis of the capacity calculated in the step B;
and D, monitoring the running state of the power distribution network in real time, calculating the CCIF index of the power distribution network, limiting the charging power of the electric automobile when the CCIF index is too high, and returning the limited part of frequency modulation capacity to the step C to redistribute the frequency modulation power.
2. The electric vehicle participation secondary frequency modulation control strategy considering the power distribution network congestion as claimed in claim 1, in the step a, counting the SOC of the electric vehicles in the whole electric vehicle group, setting a threshold value SOCb, when detecting that a certain electric vehicle is in a lower SOC, the SOC of the electric vehicle is smaller than the SOCb, and the electric vehicle needs to be charged with a certain charging power to meet the traveling requirement of the vehicle owner, and is divided into EVc groups, and the electric vehicle is in a unidirectional charging state; when detecting that some electric automobile is at a higher SOC, the SOC of the electric automobile is greater than or equal to the SOCb, the traveling requirement of the owner can be met, the electric automobile is divided into an EVdc group, and the electric automobile is in a V2G state.
3. The electric vehicle participation secondary frequency modulation control strategy considering the power distribution network congestion as claimed in claim 2, in the step B, the controllable capacity of the two groups of electric vehicles divided in the step a is calculated respectively, for the electric vehicle in the one-way charging state, the controllable capacity is limited by the power of the charging pile, the frequency modulation capacity is also considered, and the charging power is reduced as much as possible on the premise of meeting the traveling requirements of the user; for the electric automobile in the V2G state, the electric automobile is normally in a state of neither charging nor discharging, and the controllable capacity is restricted by the maximum power value of the charging pile.
4. The electric vehicle participation secondary frequency modulation control strategy considering the power distribution network congestion as claimed in claim 3, in step C, according to the controllable capacity of each group obtained in step B, frequency modulation tasks are issued to two vehicle groups, then the frequency modulation tasks of the two vehicle groups are issued to each electric vehicle, when the frequency modulation rate is required to be increased due to the steep increase of the system load, the individuals in the EVc electric vehicle group distribute the frequency modulation weight according to the SOC level, the EVs with high SOC values preferentially undertake the frequency modulation tasks, and more frequency modulation capacity is distributed; when system load reduction requires a turndown frequency, individuals with SOC values in the EVdc electric vehicle fleet have a higher priority for charging, can charge earlier and have a higher charge power.
5. The electric vehicle participation secondary frequency modulation control strategy in consideration of the power distribution network congestion as claimed in claim 4, wherein in step D, in order to avoid the power distribution network congestion, the load level of the power distribution network and the transformer capacity carrying capacity condition thereof are monitored in real time, and the CCIF index thereof is calculated by the calculation formula:
during charging:
during discharging:
wherein, PEVActual charging/discharging power, P, of the ith vehicle EVLFor the current load of the system, Δ PtieFor transmitting power to the junctor, PGeneral assemblyThe capacity carrying capacity of the transformer.
Charge and discharge power, eta, of the ith vehicle EVch、ηdschRespectively the charging and discharging efficiency of the charging pile. And when the CCIF index exceeds the threshold value, issuing control signals step by the three-level system of the power distribution network congestion management system, limiting the charging and discharging power of the electric automobile through the one-level system, limiting the upper limit of the charging power, reporting the frequency modulation tasks which are not completed because of the limited power to a cluster charging station, and redistributing according to the calculation method in the step C.
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| CN110829474A (en) * | 2019-11-21 | 2020-02-21 | 国电南瑞南京控制系统有限公司 | Method and system for supporting dynamic security of power grid by using big data intelligent energy storage |
| CN113602127A (en) * | 2021-06-21 | 2021-11-05 | 浙江清华长三角研究院 | Charging pile energy management method and device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110829474A (en) * | 2019-11-21 | 2020-02-21 | 国电南瑞南京控制系统有限公司 | Method and system for supporting dynamic security of power grid by using big data intelligent energy storage |
| CN113602127A (en) * | 2021-06-21 | 2021-11-05 | 浙江清华长三角研究院 | Charging pile energy management method and device |
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