CN114512988A

CN114512988A - Regulation and control method and device based on low-voltage distribution area flexible-direct interconnection

Info

Publication number: CN114512988A
Application number: CN202210420859.2A
Authority: CN
Inventors: 李春海; 陈贺; 王强; 刘海涛; 郭殿聪; 孙腾飞; 刘晓龙; 马跃; 刘腾飞; 刘义粉
Original assignee: Shijiazhuang Kelin Internet Of Things Technology Co ltd; Shijiazhuang Kelin Electric Co Ltd
Current assignee: Shijiazhuang Kelin Internet Of Things Technology Co ltd; Shijiazhuang Kelin Electric Co Ltd
Priority date: 2022-04-21
Filing date: 2022-04-21
Publication date: 2022-05-17
Anticipated expiration: 2042-04-21
Also published as: CN114512988B

Abstract

The invention provides a regulation and control method and a regulation and control device based on low-voltage distribution transformer area flexible-direct interconnection, and relates to the field of distribution networks and electric energy storage. Through managing direct current side distributing type energy and energy storage, realize the synchronous parallel management in many districts, realize that the full local consumption of distributing type green energy, both can maximize and guarantee that the distributed energy is incorporated into the power networks and fully consumes on the spot, also can improve the electric wire netting quality, guarantee that the electric wire netting operation is stable, economical.

Description

Regulation and control method and device based on low-voltage distribution area flexible-direct interconnection

Technical Field

The invention relates to the field of power distribution networks and electric energy storage, in particular to a regulation and control method based on low-voltage distribution transformer area flexible-direct interconnection and a device for realizing the regulation and control method.

Background

The distribution station area is generally an alternating current distribution mode, a closed-loop design and a split-loop operation mode are generally adopted, transformer substations are isolated from each other, and parallel operation of a plurality of station areas cannot be realized.

One solution is an annular interconnection structure of a transformer substation, and power support is realized by connecting interconnection switches with various transformer areas, but the traditional mechanical switch has short service life, slow response, discontinuous power regulation and no capability of flexibly regulating a power distribution network.

With the rapid development of power electronic technology and equipment in a power grid, a brand new carrier and technology selection is provided for the flexible control capability of a system and a flexible direct-current power distribution system in response to the requirements of consuming distributed new energy and load grid connection. The flexible direct current power distribution system has received wide attention from various countries due to its better controllability, better power quality, larger power supply radius and capacity, and more flexible operation mode.

The flexible direct current power distribution system is mainly divided into two parts, wherein the first part is to construct a transformer area direct current bus, and photovoltaic, energy storage, charging pile, direct current load and the like are directly connected to a direct current network, and the second part is to flexibly interconnect direct current among transformer areas, so that power transfer and resource sharing among different transformer areas are realized.

Chinese patent application 201910853450.8 proposes a flexible switching station interconnection structure with comprehensive distribution of multiple electric energies, wherein each area is connected through a flexible switching station, the input end of each flexible switching station is connected with a high-voltage ac bus, and the output end of each flexible switching station is connected with a low-voltage ac bus and a low-voltage dc bus respectively; the tail ends of the low-voltage alternating-current buses are connected through the flexible multi-state switch, and the tail ends of the low-voltage direct-current buses are connected through the DC-DC converter; the low-voltage AC bus and the low-voltage DC bus are connected with a load, an energy storage element and a distributed power supply, but how to regulate and control resources of each area is not disclosed.

Disclosure of Invention

The invention aims to provide a method for realizing mutual communication and mutual assistance of different transformer areas by controlling the output and power distribution of energy storage equipment in the transformer areas through a plurality of transformer areas connected by flexible bidirectional converters and ensuring that a power distribution network is in an optimal operation state.

In order to achieve the purpose, the invention adopts the following technical scheme: a regulation and control method based on low-voltage distribution transformer area flexible-direct interconnection is realized based on n transformer areas connected through a switch and a direct-current bus, the direct-current bus is connected with a transformer area alternating-current power supply circuit through an FCS, direct-current equipment is connected to a transformer area side of the switch on the direct-current bus, the direct-current equipment comprises photovoltaic power generation equipment and an energy storage system, and the regulation and control method comprises the following steps:

step 1, obtaining operation data of each distribution area, including:

capacity S of transformer₁、S₂、... ... 、S_n；

Adjusting the target +/-X%;

the heavy load threshold value of the transformer load rate is +/-Y%;

energy storage systemRated output power Sa of₁、Sa₂、... ... 、Sa_n。

Step 2, acquiring the operation data of each distribution area in real time, including:

real-time power P of transformer₁、P₂、... ... 、P_n；

Load factor D of transformer₁%、D₂%、... ... 、D_n%；

Current output power Pa of energy storage system₁、Pa₂、... ... 、Pa_n。

Step 3, if the transformer load factor D of a certain transformer area_i% is larger than Y% and lasts for more than 5 minutes, the station is provided with a heavy load mark; load factor D of transformer_i% is less than-Y% and lasts for more than 5 minutes, the station is provided with a reverse heavy load mark; load factor D of transformer_i% is recovered to-Y%, and the area is set as a normal area after the time lasts for 1 minute;

wherein i is more than or equal to 1 and less than or equal to n;

if the platform area is the overload mark or the reverse overload mark, executing the step 4.

Step 4, calculating the total power to be adjusted in the heavy load area: a = Δ P₁+ΔP₂+ ... ... +ΔP_n，

Wherein the power Δ P to be adjusted for the ith cell_i=（S_i*X%）―P_iIf the ith station zone does not have a reload flag, Δ P_i =0；

Calculating the total power to be regulated of the reverse heavy-load platform area: b = Δ Q₁+ΔQ₂+ ... ... +ΔQ_n，

Wherein the power Δ Q of the ith cell to be adjusted_i=（S_i*（―X%））―P_iIf the ith station zone does not have a reverse reload flag, Δ Q_i =0；

If a ≠ 0 and B =0, perform step 4.1;

if a =0 and B ≠ 0, perform step 4.2;

if A ≠ 0 and B ≠ 0, step 4.3 is performed.

Step 4.1, calculating the surplus of the energy storage systemTotal power: p_{Store up}=ΔP_{1 store up}+ΔP_{2 store up}+ ... ... +ΔP_{n store}，

Wherein, the residual power Delta P of the energy storage system of the ith station area_{i store}=Sa_i―Pa_i，

If | P_{Store up}| ≧ A |, allocating A to the energy storage system of each district; otherwise, P is added_{Store up}Energy storage system allocated to each zone, unregulated power P_Surplus=│A│―│P_{Store up}And | executing the step 5.

Step 4.2, calculating the adjustable total power Px = delta Px of the load ratio of the normal distribution area adjusted to X%₁+ΔPx₂+ ... ... +ΔPx_n，

Wherein the ith cell loading rate is adjusted to an adjustable power Δ Px of-X%_i=（S_i*（―X%））―P_iIf the ith cell is not a normal cell, Δ Px_i=0；

If | B | Px | then all normal distribution areas and all reverse heavy-load distribution areas adjust the load rate of the transformer to-X%;

otherwise, B is distributed to the normal distribution area according to the principle that the load rates of the distribution background areas are equal.

Step 4.3, if the | A | is less than or equal to the | B | the load rate of the transformer is adjusted to X% by the heavy load area, and the load rate of the transformer is adjusted to-X% by the reverse heavy load area;

otherwise, calculating the remaining total power of the energy storage system: p_{Store up}=ΔP_{1 store up}+ΔP_{2 store up}+ ... ... +ΔP_{n store}，

If | A ≦ B + P_{Store up}Allocating | A | B | to the energy storage systems of the various areas;

if-A-l>│B+ P_{Store up}Forced discharge of the energy storage system at rated power, unregulated power P_Surplus=│A│―│B+ P_{Store up}And | executing the step 5.

Step 5, adding P_SurplusAnd allocating to a normal station area, including:

calculating the total power that all normal transformer areas can release to regulate the transformer to X%:

C=ΔPc₁+ΔPc₂+ ... ... +ΔPc_n，

wherein, the power Δ Pc that the ith station zone can release_i=（S_i*X%）―P_iIf the ith station zone is not the positive station zone, Δ Pc_i =0；

if-P_Surplus│<C, according to the principle that the load rates of normal districts after allocation are equal, P is divided into_SurplusAllocating to a normal station area; otherwise, adjusting the load rate of the normal distribution area to X%.

The invention further provides a device based on the flexible-direct interconnection of the low-voltage distribution transformer areas, the device is an intelligent transformer area integration terminal and comprises a communication module, a parameter storage module, a heavy-load regulation and control module, an equipment judgment module, an energy storage system control module and a photovoltaic power generation equipment regulation and control module, and the regulation and control method based on the flexible-direct interconnection of the low-voltage distribution transformer areas is realized.

Compared with the prior art, the invention has the following advantages:

and the direct current buses are connected with the areas, and the energy storage system resources of the areas are interconnected and shared. By managing the direct-current side distributed energy and the stored energy, synchronous parallel management of a plurality of areas is realized, full local consumption of the distributed green energy is realized, electric energy loss caused by energy internet access recycling is reduced, and risks of impact, voltage difficulty in control, harmonic superposition, frequency out-of-limit and the like caused by centralized uploading of the distributed energy to a power grid are eliminated.

Drawings

Fig. 1 is a schematic diagram of a station configuration and connection.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

A regulation and control method based on low-voltage distribution transformer area flexible-direct interconnection is achieved based on n transformer areas connected through switches and direct-current buses, the direct-current buses are connected with transformer area alternating-current power supply circuits through FCS, direct-current equipment is connected to transformer area sides of the switches on the direct-current buses, and the direct-current equipment comprises photovoltaic power generation equipment and an energy storage system.

The regulation strategy of each station area is as follows: fully utilizes green energy and is consumed on the spot. The priority order of use of the electrical energy is:

1, generating electricity by direct current side photovoltaic; 2, an energy storage system; 3 grid (by means of district coordination).

Referring to fig. 1, there are 3 stations in this embodiment, n =3, and the three stations are connected via a switch via a 750V dc bus. And on the station area side, the direct current bus is connected to an alternating current power supply line of the station area through the FCS and the intelligent switch, and the direct current bus is connected with direct current equipment.

The intelligent fusion terminal collects FCS, bidirectional DC/DC of the energy storage system, table data of the direct-current side photovoltaic power generation equipment and station area cross collection data, and controls equipment such as a switch, the FCS and the bidirectional DC/DC after judgment to complete regulation and control.

And adjusting the load rate of the transformer in the transformer area, determining an FCS outlet parameter according to the power value required to be adjusted, and adjusting the outlet parameter of the FCS.

In the invention, all the photovoltaic power generation equipment in one distribution area are taken as a whole; a plurality of energy storage devices in one platform area are regarded as one energy storage system.

The intelligent fusion terminal is arranged in the middle station area, and the regulation and control method is completed at the intelligent fusion terminal. The intelligent integrated terminal is in communication connection with branch terminals in other transformer area JP cabinets, and can acquire transformer area parameters and control FCS and energy storage systems of each transformer area.

FCS: the bidirectional converter is a bidirectional converter product containing a transformer, is connected with a direct current bus and an alternating current 380V conversion device, provides an interface between a power grid and the direct current bus, realizes alternating current/direct current conversion, and automatically realizes constant voltage rectification and voltage limiting discharge so as to keep the voltage of the direct current bus constant. The inter-station regulation is completed by FCS.

And the energy storage system is provided with a BMS (battery management system) to realize a protection function. The intelligent fusion terminal is in DC/DC communication with the energy storage bidirectional controller, and can acquire energy storage data and control energy storage charging and discharging. Under the condition that the intelligent fusion terminal issues a command to enable the energy storage bidirectional controller DC/DC to discharge, when the energy storage electric quantity is released to a certain degree (remaining 40%), the BMS is triggered to protect the energy storage system, and the energy storage is cut off to be output externally. When the energy storage capacity is recovered to more than 40%, the energy storage capacity can be automatically recovered.

The invention mainly aims to realize the mutual communication among different transformer areas through resource sharing, ensure that a power distribution network is in an optimal running state, and ensure that transformers in each controlled transformer area work in a reasonable load interval as much as possible.

The present embodiment completes the regulation by the following steps.

Step 1, obtaining operation data of each distribution area, wherein the operation data is mainly static data and comprises the following steps:

capacity S of transformer₁、S₂、... ... 、S_n；

Adjust target to ± X%, default X = 70;

the transformer load factor overload threshold value is +/-Y%, and the default value is Y = 80;

rated output power Sa of energy storage system₁、Sa₂、... ... 、Sa_n。

The adjustment target is the more ideal load rate of the transformer in each transformer area, and is smaller than the heavy load threshold of the transformer load rate. Although the capacity S of each transformer_iThere may be a difference, and in the present embodiment, the adjustment target setting is uniform.

In this embodiment, the energy storage system is mainly used as a power source for regulation and control, and the energy storage systems of each region are listed in a regulation list.

Step 2, acquiring the operation data of each area in real time, wherein the operation data is dynamic data and comprises the following steps:

real-time power P of transformer₁、P₂、... ... 、P_n；

Load factor D of transformer₁%、D₂%、... ... 、D_n%；

Energy storageCurrent output power Pa of the system₁、Pa₂、... ... 、Pa_n。

The above parameters are used as the judgment basis.

The load rate of the transformer has a negative value, which indicates that the photovoltaic power generation in the area is too much and cannot be digested in situ, and the redundant electricity is transmitted back to the power grid through the transformer.

Step 3, judging the station area states one by one

If the transformer load factor D of a certain area_i% is larger than Y% and lasts for more than 5 minutes, the station is provided with a heavy load mark; load factor D of transformer_i% is less than-Y% and lasts for more than 5 minutes, the station is provided with a reverse heavy load mark; load factor D of transformer_i% is recovered to-Y%, and after the duration lasts for 1 minute, the heavy load mark is reset to be set as a normal platform area; wherein i is more than or equal to 1 and less than or equal to n.

The station area state is divided into a normal state, a heavy load state (forward heavy load) and a reverse heavy load state.

And if the platform area is the heavy load mark or the reverse heavy load mark, regulating and controlling, and executing the step 4.

Step 4, heavy load regulation and control

Calculating the total power to be regulated when the heavy load platform area is regulated to the regulation target X%:

A=ΔP₁+ΔP₂+ ... ... +ΔP_n，

if heavy load occurs in the ith transformer area, the load rate of the transformer needs to be adjusted from Di% to an adjustment target X%, and the power delta P needs to be adjusted_i=（S_i*X%）―P_iIf the ith station zone does not have a reload flag, Δ P_i =0；

Calculating the total power to be regulated of the reverse heavy-load platform area to a regulation target-X%:

B=ΔQ₁+ΔQ₂+ ... ... +ΔQ_n，

if the ith transformer area has reverse heavy load, the load rate of the transformer needs to be adjusted from Di% to an adjustment target of-X%, and the power delta Q needs to be adjusted_i=（S_i*（―X%））―P_iIf the ith station zone is not invertedTo the heavy load mark, Δ Q_i =0；

If A ≠ 0 and B =0, there is only a forward reload, execute step 4.1;

if a =0 and B ≠ 0, there is only a reverse reload, execute step 4.2;

if A ≠ 0 and B ≠ 0, there is both a forward reload and a reverse reload, step 4.3 is performed.

Step 4.1 Forward heavy load control

When the forward heavy load occurs, the photovoltaic power generation can be considered to be sufficient.

Calculating the remaining total power of the energy storage system: p_{Store up}=ΔP_{1 store up}+ΔP_{2 store up}+ ... ... +ΔP_{n store}，

if-P_{Store up}L ≧ A |, which indicates that regulation and control can be completed only by depending on the residual power of the energy storage system, and A is distributed to the energy storage systems in each district in the regulation list according to the principle that the output of all the energy storage systems after distribution is equal;

if-P_{Store up}│<If A-indicates that the regulation cannot be completed only by the residual power of the energy storage system, P is selected_{Store up}An energy storage system assigned to each zone; unregulated power P_Surplus=│A│―│P_{Store up}And executing step 5, compensating by means of the mutual economy of the channel areas.

Step 4.2 reverse heavy load regulation

Calculating an adjustable total power Px = Δ Px for a normal cell load ratio adjusted to-X%₁+ΔPx₂+ ... ... +ΔPx_n，

if-B-l>Px |, under this condition, the platform district can not fully take up photovoltaic power generation equipment's output, through adjusting FCS parameter, discards partial photovoltaic power generation equipment's electric energy: all normal stations according to the delta Px of the station_iAll reverse heavy-load areas are according to the delta Q of the areas_iAdjusting the load factor of the transformer to-X%;

otherwise, | B ≦ | Px |, the distribution area can absorb the output of the photovoltaic power generation equipment, and B is distributed to the normal distribution area according to the principle that the load rate of the distribution back-end area is equal.

Step 4.3, the regulation and control of the simultaneous existence of forward and reverse heavy loads

If the A-B-is less than or equal to the B-A, the photovoltaic power generation surplus in the reverse heavy-load platform area can compensate the heavy-load platform area to achieve an adjustment target, at the moment, the heavy-load platform area adjusts the load rate of the transformer to X%, the reverse heavy-load platform area adjusts the load rate of the transformer to X%, and the normal platform area does not adjust;

otherwise-A-l>B, explaining that the redundant photovoltaic power generation allowance coming out of the reverse heavy load area is not enough to compensate the heavy load area, needing the support of the energy storage system, calculating the residual total power of the energy storage system at the moment: p_{Store up}=ΔP_{1 store up}+ΔP_{2 store up}+ ... ... +ΔP_{n store}，

If | A ≦ B + P_{Store up}Adjusting the load rate of the transformer to-X% by the reverse heavy-load transformer area, and distributing the-A-B-to the energy storage systems of the transformer areas according to the principle that the output of all the energy storage systems after distribution is equal;

if-A-l>│B+ P_{Store up}Forced discharge of the energy storage system at rated power, unregulated power P_Surplus=│A│―│B+ P_{Store up}L, go to step 5, and P is processed_SurplusAnd distributing to a normal station area, and compensating by the mutual aid of the station areas.

In the above embodiments, the energy storage systems of the respective regions are used for regulation, but there are cases where the regulation target cannot be achieved.

The mutual compensation of the transformer areas means that another transformer area gets power from a power grid, transfers the power to a heavy-load transformer area through a direct current power grid, and is realized by setting FCS.

The path is as follows: AC 10kV supply network-transformer providing mutual compensation-intelligent switch (AC 380V) -FCS-switch-DC bus (DC 750V) -switch-FCS of mutual compensation area-intelligent switch (380V) -switch-AC 380V supply line of mutual compensation area.

Step 5, in the regulation and control process, if the power P which is not regulated still exists_SurplusA 1 is to P_SurplusAnd distributing to a normal station area, and starting a station area mutual aid function.

C=ΔPc₁+ΔPc₂+ ... ... +ΔPc_n，

If | P_Surplus│<C, the normal area can meet the requirement without adjusting the load rate of the transformer to X%, and P is adjusted according to the principle that the load rates of the allocated normal areas are equal_SurplusAllocating to a normal station area;

otherwise, the load rate of the normal area is adjusted to X%, the mutual-aid power is output to the maximum extent, and the output is less than P_SurplusThe power C of (a) is partially compensated for.

And the regulation and control of the electric energy through the power grid are realized through mutual assistance of the transformer areas.

The method comprises the following steps of (1) regulating and controlling the transformer area and an energy storage system in the transformer area:

the intelligent convergence terminal judges the state of each district, if a certain district is in a power failure state or a communication failure state, the district is not regulated, the equipment of the district is removed in the regulation process, and the FCS under the district is automatically changed from a running state to a standby state. If the communication of the photovoltaic power generation equipment in a certain area fails or the acquisition of the data collected by the intersection of the area fails, the energy storage system of the area is changed into an automatic state, the FCS output percentage is set to be M%, and the regulation strategy is not executed.

The M% default is 50% of the total rated power of the photovoltaic inverter.

The energy storage system needs the photovoltaic power generation equipment to supplement energy, and if the energy storage system in an output state cannot be supplemented in time and in sufficient quantity, the battery of the energy storage system is damaged.

In this embodiment, the intelligent convergence terminal obtains the battery protection threshold Z of the energy storage system₁% and energy storage system battery recovery threshold Z₂Percent; acquiring the residual electric quantity Zi of each energy storage system in real time, and if the residual electric quantity Zi% of each energy storage system is lower than a protection threshold value Z₁% and in a forced discharge mode, modifying the working mode of the energy storage system into an automatic mode, removing the energy storage system from an adjustment list, canceling the regulation qualification, and subsequently not participating in regulation.

If the energy storage system in the automatic mode exists and the residual capacity Zi% is greater than the recovery threshold value Z₂And percent, restoring the strain to a regulation list, restoring regulation qualification and subsequently participating in regulation.

The above process realizes the regulation and control of the station area state, and each station area enters a normal state through one or more times of regulation and control.

The embodiment detects the change of the running condition in real time and adjusts the running condition.

Controlling the energy storage system:

automatic mode of the energy storage system: the operation mode control word is modified into constant voltage control, and a set voltage stabilization value of the energy storage system is set according to the operation voltage range of the FCS (the voltage stabilization value needs an interval of at least 10V from the upper limit and the lower limit of the operation voltage range of the FCS), and the power is adaptive at the moment and is maximum rated power. If the operating voltage range of the FCS is 700V-730V, the stable voltage value of the stored energy should be selected from 710V-720V, and 715V can be selected.

Forced discharge mode of the energy storage system: and modifying the 'operation mode control word' into 'constant power control', setting a power value, and setting the power to be rated output power.

Forced charging mode of the energy storage system: the 'operation mode control word' is modified into 'constant power control', and a power value is set, wherein the power is set to be 10% of rated output power.

If the energy storage system in the forced discharge state exists, calculating the current state of each regionPower difference Δ Pq for state transition to heavy-duty state_i=（Y%―D_i%）*S_iTaking the minimum value; if the output power of the energy storage system in the forced discharge state is smaller than the minimum value, under the condition, if the output of the energy storage system is stopped, the station area with the minimum value can obtain electric energy from the alternating current network through the transformer, and the load rate of the transformer is not larger than Y%, namely heavy load does not occur, at the moment, the output of the energy storage system is stopped, and the energy storage system is set to be in an automatic mode.

If the above condition is not met, the output of the energy storage system remains unchanged.

Controlling the mutual aid of the station areas:

the transformer load of each area changes in real time, and if the FCS is maintained to work all the time, loss, such as line loss and equipment damage, can also be caused.

Obtaining the actual output power value Ps of each FCS₁、Ps₂、... ... 、Ps_nJudging whether FCS for supplying power from AC side to DC side exists, if FCS exists, calculating power difference delta Pq for converting station area receiving mutual assistance from normal state to heavy load state_i=（Y%―D_i%）*S_iAnd taking the minimum value, if certain FCS output power supplied from the alternating current side to the direct current side is smaller than the minimum value, in the case that the output of the FCS is stopped, the station area with the minimum value obtains electric energy from the alternating current network through the transformer, and the load rate of the transformer is not greater than Y%, namely, heavy load does not occur, the FCS output is stopped, the FCS supplied from the alternating current side to the direct current side is set to be 0, and the rest FCS is output in proportion.

Setting FCS for supplying power from AC to DC side to 0, stopping the station area from providing mutual aid to other station areas; in the cell receiving the cross, the power of the FCS is reduced according to the receiving rate.

If the above condition is not satisfied, the set value of the current FCS is maintained.

Detection of the photovoltaic power generation equipment:

when all the transformer areas are in a normal state, the power Pb of the photovoltaic power generation equipment on the direct current side is obtained in real time₁、Pb₂、... ... 、Pb_nDetecting the output of the photovoltaic power generation equipment, and when the output Pb of the photovoltaic power generation equipment in a certain area_iClose to 0 (e.g. Pb)_iLess than Sa_i5%) and this state lasts for 2 cycles, the regulation target is corrected from ± X% to 0%, with the aim of avoiding the electric energy of the energy storage system from being sent back to the grid while meeting the load demand of the platform.

When the photovoltaic is not used for generating electricity, the electric energy of the energy storage system is not sent back to a power grid, and the alternating current load is stored with energy preferentially. To achieve this, the adjustment target is set to 0%, including forward and reverse adjustment targets; when the system is required to reach the regulation target, the electric energy of the energy storage system is not sent to a power grid, and the use of the platform area is ensured; and green energy is preferentially utilized, and if the energy storage power is insufficient, the power grid is used for supplementing.

Although the adjustment target is set to 0%, the judgment of the heavy-load cell area is not influenced (the judgment basis is Y%), and the realization of cell area mutual aid (calculated by the load rate target X%) is also not influenced.

If the photovoltaic power generation equipment of all the transformer areas is recovered to be normal, the output power value Pb_iGreater than Sa_iAfter 10% and this state lasted 2 cycles, the regulatory target was restored to ± X%, one cycle for 15 minutes.

Power generation control of the photovoltaic power generation apparatus:

obtaining FCS set target power value P_F1、P_F2、... ... 、P_FnAnd FCS actual output power value Ps₁、Ps₂、... ... 、Ps_n；

Step 6, judging an adjustment target, if the adjustment target =0%, the photovoltaic power generation equipment basically outputs no power, executing step 6.1, otherwise, executing step 6.2;

step 6.1, adjusting the target =0%, limiting reverse power supply, and calculating the total power value to be adjusted by the FCS with the transformer load factor of 0% as the target:

P_FCS=ΔP_FCS1 +ΔP_FCS2+ ... ... +ΔP_FCSnwherein, Δ P_FCS1=（0%―D_i%）*S_iThe power value to be adjusted for the ith FCS;

calculating the remaining total power of the energy storage system: p_{Store up}=ΔP_{Store 1} +ΔP_{Store 2} + ... ... +ΔP_{Store n}，

Wherein, the residual power Delta P of the energy storage system of the ith station area_{Store i} =Sa_i―Pa_i，

if-P_{Store up}│≥│P_FCSThe energy storage system can meet the load requirement of the distribution area, and each FCS is according to delta P_FCSiMake an adjustment, otherwise, i.e. | P_{Store up}│<│P_FCSAnd l, considering that the stored energy cannot meet the load requirement of the distribution area, and distributing P to each FCS according to the principle that the load rate of each distribution area is the same after adjustment_{Store up}。

And 6.2, at the moment, the photovoltaic power generation equipment basically works normally, the electric energy output of the photovoltaic power generation equipment is used as much as possible according to the regulation and control strategy of the invention, and the purpose is realized through the following steps.

All transformer load ratios are checked and if all negative values are present step 6.2.1 is performed, if all positive values are present step 6.2.2 is performed, if both positive and negative values are present step 6.2.3 is performed.

And 6.2.1, comparing the target power value set by all the FCSs with the actual output power value, and if the set target power value is larger than the actual output power value (larger than 5% of the rated power and the absolute value difference is larger than 10 kW), determining that the direct current side supplies power to the alternating current side completely at the moment, wherein the FCSs do not need to be adjusted.

If the power is basically the same (the difference is less than 5%), the direct current side may not supply full power to the alternating current side, the rated power of all the photovoltaic power generation devices is evenly distributed according to the number of the non-power-outage transformer areas, the distributed power is compared with the capacity of the FCS, and the output power value of the FCS is adjusted to be the smaller value of the two.

Step 6.2.2, the load factor of the transformer is all positive values, the target power value set by all FCS is compared with the actual output power value,

if the set target power value is larger than the actual output power value, the direct current side is considered to be supplied with power to the alternating current side fully, and the FCS does not need to be adjusted (power is supplied to the power grid in a forward direction under the non-heavy load condition, and forced energy storage and discharge are not needed).

If the difference is substantially the same (less than 5%), it is considered that the dc side may not be fully supplied with power to the ac side, and the value Δ P after each FCS adjustment when the station area is adjusted to-X% is calculated_Si=（―X%―D_i%）*S_iComparing | P_Si+ΔP_SiAnd FCS capacity, the output power value of the FCS is adjusted to the smaller value of the two.

And 6.2.3, comparing the target power value set by all the FCS with the actual output power value, if the target power value set by the FCS is larger than the actual output power value, executing step 6.2.3.1, and if the target power value set by the FCS is basically the same (the difference is less than 5%), executing step 6.2.3.2.

The target power value set in step 6.2.3.1 and FCS is larger than the actual output power value, and it is considered that the dc side has fully supplied power to the ac side at this time. Calculating P by taking the load factor of the transformer as 0 percent_FCS=ΔP_FCS1 +ΔP_FCS2+ ... ... +ΔP_FCSnWherein each FCS requires a regulated power value Δ P_FCS1=（0%―D_i%）*S_i，P_FCSCalculating the total power P of the forward power supply for the value after the forward and reverse demand is offset_{Is just}And total power P of reverse power supply_{Inverse direction}；

If P is_{Inverse direction}>P_{Is just for}Excess power P after forward and reverse cancellation_FCSThe power station can be reserved in the original reverse power supply station area, and the station area for forward power supply is according to delta P_FCS1Adjusting, and distributing P according to logic with same load rate after distribution in reverse power supply area_{Is just}；

If P is_{Is just}>P_{Inverse direction}Excess power P after forward and reverse cancellation_FCSThe power supply station can be reserved in the original forward power supply station area, and the station area for reverse power supply is according to delta P_FCS1Adjusting, and distributing P according to logic with same load rate after distribution in forward power supply area_{Inverse direction}。

Step 6.2.3.2, the target power value set by the FCS is basically the same as the actual output power value, and at this time, the dc side may not fully supply power to the ac side. Calculate the value Δ P after each FCS adjustment if the station area is adjusted to-X%_Si=（―X%―D_i%）*S_iComparing | P_Si+ΔP_SiAnd FCS capacity, the output power value of the FCS is adjusted to the smaller value of the two.

The invention also provides a regulation and control device based on the soft and straight interconnection of the low-voltage distribution transformer area, and the regulation and control method based on the soft and straight interconnection of the low-voltage distribution transformer area is realized.

The device is a platform area intelligent fusion terminal which comprises a communication module, a parameter storage module, a heavy load regulation and control module, an equipment judgment module, an energy storage system control module and a photovoltaic power generation equipment regulation and control module.

The communication module completes the communication function with each area device.

The parameter storage module stores parameters read in the regulation and control process, and the parameters comprise:

capacity S of transformer₁、S₂、... ... 、S_nAs a result of the setting of the parameters,

adjusting the target to +/-X percent as parameter setting, setting the default value to +/-70 percent,

the overload threshold value of the transformer load factor is +/-Y percent, the default value is +/-80 percent,

real-time power P of transformer₁、P₂、... ... 、P_nNamely, the station area data of the alternate acquisition,

load factor D of transformer₁%、D₂%、... ... 、D_n%，

Target power value P currently set by FCS_F1、P_F2、... ... 、P_Fn，

Actual output power value P of FCS_S1、P_S2、... ... 、P_Sn，

Default set percentage M% of the FCS when no regulation strategy is executed (default is 50% of the total rated power of the pv inverter),

capacity S of FCS_fcs(the fixed value is 200 kW),

current output power Pa of energy storage₁、Pa₂、... ... 、Pa_n，

Rated output power Sa of energy storage₁、Sa₂、... ... 、Sa_n，

The residual electric quantity Z percent of the energy storage battery,

energy storage system battery protection threshold Z₁% (lower limit of protection, default 45%),

energy storage system battery recovery threshold Z₂% recovery lower limit, default 60%),

power Pb of photovoltaic summary meter on direct current side₁、Pb₂、... ... 、Pb_n，

Rated capacity Pc of direct current side photovoltaic₁、Pc₂、... ... 、Pc_n。

And the heavy load regulation and control module is used for finishing the judgment of the platform area state and the regulation and control of the heavy load state.

And the equipment judgment module is used for finishing the judgment of the working state and the communication state of the transformer area.

And the energy storage system control module completes the state control of the energy storage system according to the state and the residual electric quantity of the energy storage system.

And the photovoltaic power generation equipment regulation and control module completes parameter setting of the FCS according to the power generation and platform area operation conditions of the equipment.

Claims

1. A regulation and control method based on low-voltage distribution transformer area flexible-direct interconnection is realized based on n transformer areas connected through a switch and a direct-current bus, the direct-current bus is connected with a transformer area alternating-current power supply circuit through an FCS, direct-current equipment is connected to the transformer area side of the switch on the direct-current bus, the direct-current equipment comprises photovoltaic power generation equipment and an energy storage system, and the regulation and control method is characterized by comprising the following steps:

step 1, obtaining operation data of each distribution area, including:

capacity S of transformer₁、S₂、... ... 、S_n；

Adjusting the target + -X%;

the heavy load threshold value of the transformer load rate is +/-Y%;

rated output power Sa of energy storage system₁、Sa₂、... ... 、Sa_n；

Capacity S of FCS_fcs；

real-time power P of transformer₁、P₂、... ... 、P_n；

Load factor D of transformer₁%、D₂%、... ... 、D_n%；

Current output power Pa of energy storage system₁、Pa₂、... ... 、Pa_n；

wherein i is more than or equal to 1 and less than or equal to n;

if the platform area is the heavy load mark or the reverse heavy load mark, executing the step 4;

step 4, calculating the total power to be adjusted when the heavy load platform area is adjusted to the adjustment target X percent:

A=ΔP₁+ΔP₂+ ... ... +ΔP_n，

wherein the power Δ P to be adjusted for the ith cell_i=（S_i*X%）―P_iIf the ith station zone does not have a reload flag, Δ P_i=0；

B=ΔQ₁+ΔQ₂+ ... ... +ΔQ_n，

If a ≠ 0 and B =0, perform step 4.1;

if a =0 and B ≠ 0, perform step 4.2;

if A ≠ 0 and B ≠ 0, execute step 4.3;

step 4.1, calculating the remaining total power of the energy storage system: p_{Store up}=ΔP_{1 store up}+ΔP_{2 store up}+ ... ... +ΔP_{n store}，

if-P_{Store up}| ≧ A |, allocating A to the energy storage system of each district; otherwise, P is added_{Store up}Energy storage system allocated to each zone, unregulated power P_Surplus=│A│―│P_{Store up}Executing step 5;

step 4.2, calculating the load rate of the normal distribution area, and adjusting the load rate to X% of adjustable total power Px = delta Px₁+ΔPx₂+ ... ... +ΔPx_n，

otherwise, distributing B to the normal distribution area according to the principle that the load rates of the distribution background areas are equal;

4.3, if the | A | is less than or equal to the | B |, adjusting the load rate of the transformer to X% by the heavy load area, and adjusting the load rate of the transformer to-X% by the reverse heavy load area;

If | A ≦ B + P_{Store up}Adjusting the load rate of the transformer to-X% by the reverse overloading area, and distributing the-A-B-to the energy storage systems of the areas;

if-A-l>│B+ P_{Store up}Forced discharge of the energy storage system at rated power, unregulated power P_Surplus=│A│―│B+ P_{Store up}Executing step 5;

step 5, adding P_SurplusAnd allocating to a normal station area, including:

C=ΔPc₁+ΔPc₂+ ... ... +ΔPc_n，

wherein, the power Δ Pc that the ith station zone can release_i=（S_i*X%）―P_iIf the ith station zone is not the positive station zone, Δ Pc_i=0；

2. The method of claim 1,

and if a certain area is in a power failure state or a communication failure state or the communication of the photovoltaic power generation equipment fails, the equipment of the area is removed in the regulation and control process.

3. The method of claim 1,

obtaining a battery protection threshold value Z of an energy storage system₁% and energy storage system battery recovery threshold Z₂%；

Acquiring the residual electric quantity Zi% of the energy storage system in real time, and if the residual electric quantity Zi% of the energy storage system is lower than a protection threshold value Z₁% and in a forced discharge mode, modifying the working mode of the energy storage system into an automatic mode, canceling regulation qualification and not participating in regulation;

if the energy storage system in the automatic mode exists and the residual electric quantity Zi% is greater than the recovery threshold value Z₂% recovers regulation qualification and participates in regulation.

4. The method of claim 1,

the regulation and control method further comprises the following steps:

if the energy storage system in the forced discharge state exists, calculating the power difference delta Pq of each region converted from the current state to the heavy load state_i=（Y%―D_i%）*S_iAnd taking the minimum value, and if the output power of the energy storage system in the forced discharge state is smaller than the minimum value, stopping the output of the energy storage system and setting the energy storage system in an automatic mode.

5. The method for controlling the soft and straight interconnection of low-voltage distribution substations according to claim 1 or 4,

the regulation and control method further comprises the following steps:

obtaining the actual output power Ps of each FCS₁、Ps₂、... ... 、Ps_nJudging whether FCS for supplying power from AC side to DC side exists, if FCS exists, calculating power difference delta Pq for converting station area receiving station area mutual aid from normal state to overload state_i=（Y%―D_i%）*S_iThe minimum value is obtained, and the FCS output is stopped if the FCS output power supplied from the AC side to the DC side is smaller than the minimum value.

6. The method of claim 1,

the regulation and control method further comprises the following steps:

obtaining power Pb of direct current side photovoltaic power generation equipment in real time₁、Pb₂、... ... 、Pb_n；

If the output power value Pb of photovoltaic power generation equipment in a certain area_iLess than Sa_iAfter 5% and this state lasts 2 cycles, the adjustment target is corrected from ± X% to 0%;

if the output power value Pb of the photovoltaic power generation equipment of all the transformer areas_iGreater than Sa_i10% and this state lasts 2 cycles, the regulatory objective is restored to ± X%;

the period was 15 minutes.

7. The method of claim 6, wherein the low voltage distribution substation flexible-direct interconnection is performed,

The regulation and control method further comprises the following steps:

step 6, judging an adjustment target, if the adjustment target =0%, executing step 6.1, otherwise, executing step 6.2;

step 6.1, calculating the total power value to be adjusted by the FCS by taking the load factor of the transformer as 0 percent as a target:

if-P_{Store up}│≥│P_FCSPer, FCS is expressed as Δ P_FCSiAdjusting, otherwise, distributing P to each FCS according to the principle that the load rate of each district is the same after adjustment_{Store up}；

Step 6.2, checking the load rates of all transformers,

if all are negative, step 6.2.1 is performed,

if all are positive values, step 6.2.2 is performed,

if both positive and negative values are present, step 6.2.3 is performed,

step 6.2.1, comparing the target power value set by all FCSs with the actual output power value, if the difference between the target power value and the actual output power value is less than 5%, distributing the rated power of all photovoltaics averagely, comparing the distributed power with the FCS capacity, and adjusting the output power value of the FCS to be the smaller value of the target power value and the actual output power value;

step 6.2.2, comparing the target power value set by all FCS with the actual output power value, if the difference between the target power value and the actual output power value is less than 5%, calculating the adjusting value delta P of each FCS when the station area is adjusted to-X%_Si=（―X%―D_i%）*S_iComparing | P_Si+ΔP_SiAdjusting the output power value of the FCS to be the smaller value of the two values;

step 6.2.3, comparing all the target power values set by the FCS with the actual output power value, if the target power value set by the FCS is greater than the actual output power value, executing step 6.2.3.1, and if the difference between the target power value set by the FCS and the actual output power value is less than 5%, executing step 6.2.3.2;

step 6.2.3.1, calculating P with the transformer load factor of 0% as the target_FCS=ΔP_FCS1 +ΔP_FCS2+ ... ... +ΔP_FCSnWherein, Δ P_FCS1=（0%―D_i%）*S_i(ii) a Calculating the total power P of the forward power supply_{Is just for}And total power P of reverse power supply_{Inverse direction}；

If P_{Inverse direction}>P_{Is just}Forward power supply area according to delta P_FCS1Adjusting, and distributing P according to logic with same load rate after distribution in reverse power supply area_{Is just for}；

If P_{Is just for}>P_{Inverse direction}The counter-supplied area is according to delta P_FCS1Adjusting, and distributing P according to logic with same load rate after distribution in the forward power supply area_{Inverse direction}；

Step 6.2.3.2, calculate the value Δ P adjusted for each FCS if the station area is adjusted to-X%_Si=（―X%―D_i%）*S_iComparing | P_Si+ΔP_SiAnd FCS capacity, adjusting the output power value of the FCS to the smaller value of the two.

8. A regulation and control device based on low-voltage distribution area flexible-direct interconnection is characterized in that the device is an intelligent platform area fusion terminal and comprises a communication module, a parameter storage module, a heavy-load regulation and control module, an equipment judgment module, an energy storage system control module and a photovoltaic power generation equipment regulation and control module, and the regulation and control method based on low-voltage distribution area flexible-direct interconnection in any one of claims 1 to 7 is achieved.