Energy storage system grid-connected point power cooperative control method and system

Abstract

The invention discloses an energy storage system grid-connected point power cooperative control method and system, and relates to the technical field of energy storage systems, and the method comprises the steps: collecting the secondary voltage and current of a grid-connected point, and calculating the active power P of the grid-connected point; based on the active power P of the grid-connected point, judging whether to trigger an anti-countercurrent control or demand control condition; when anti-reflux control is triggered, an anti-reflux instruction is calculated according to the anti-reflux set value, the anti-reflux return difference and the anti-reflux adjustment multiple; when demand control is triggered, a demand instruction is calculated according to a demand set value, a demand return difference and a demand adjustment multiple; generating a charging and discharging instruction based on the plan curve instruction, the anti-reflux instruction and the demand instruction; according to the invention, on countercurrent prevention and demand instruction calculation, limiting conditions such as the regulation quantity reduction multiple, the regulation quantity amplification multiple and the return difference are introduced, and the power of the grid-connected point can be quickly responded and dynamically regulated under the complex working condition that the load power of the grid-connected point fluctuates severely.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage systems, in particular to a power coordination control method and control system for a grid-connected point of an energy storage system. BACKGROUND

[0002] In the electricity billing mechanism for industrial and commercial enterprises, electricity charges are mainly composed of two parts: electricity quantity charges and demand charges. Electricity quantity charges are calculated based on the electricity consumption of the enterprise, i.e., the total amount of electricity consumed by the enterprise within a certain period multiplied by the corresponding electricity price. Demand charges are calculated based on the maximum power consumption of the enterprise, and the calculation of demand charges aims to reflect the enterprise's occupation of the power grid capacity during electricity consumption. For enterprises with significant load fluctuations, demand charges usually account for a high proportion of the total electricity charges. Through energy storage system demand management, the energy storage system can discharge during peak electricity consumption. When the enterprise's power consumption is about to reach the demand peak, the energy storage system releases the stored electricity in time to supplement the enterprise's electricity demand, reduces the peak power obtained from the power grid, and effectively reduces the demand charge expenditure.

[0003] The reverse flow phenomenon refers to the situation where electric energy flows back into the power grid from the user side, such as an energy storage system or a distributed photovoltaic power generation facility. Reverse flow can cause fluctuations in the voltage of the power grid, threatening the stable operation of the power system. Anti-reverse flow control monitors the power flow direction of the grid-connected point in real time and accurately. Once a reverse flow trend is detected, the control system immediately takes measures such as adjusting the charge and discharge state of the energy storage system and controlling the output power of the distributed power source to ensure that electric energy does not flow back into the power grid, thereby effectively ensuring the safe and stable operation of the power grid.

[0004] The demand and anti-reverse flow control strategies have high real-time requirements for load fluctuations, and the charge and discharge power needs to be changed in time to maintain the stability of the power obtained from the power grid. However, there are limitations to the adjustment of the charge and discharge power of the energy storage system, which cannot instantly meet the rapidly changing electricity demand of the enterprise, resulting in difficulty in ensuring control accuracy. Moreover, there is an unavoidable time delay from the detection of load changes to the adjustment of the charge and discharge state of the energy storage system, which further affects the demand and anti-reverse flow control effect, making it difficult to accurately control during severe load fluctuations. SUMMARY

[0005] In view of the deficiencies in the prior art, the present application provides a power coordination control method for a grid-connected point of an energy storage system.

[0006] To achieve the above-mentioned purpose, the technical solution of the present application is as follows: A power coordination control method for a grid-connected point of an energy storage system, comprising the following steps: Collecting the secondary voltage and current of the grid-connected point incoming line, calculating the active power P of the grid-connected point; Based on the active power P at the grid connection point, determine whether the backflow prevention control or demand control conditions are triggered. When the anti-backflow control is triggered, it is based on the anti-backflow setpoint P. _set_rpp Anti-backflow hysteresis P _set_rpp_err And calculation of anti-backflow adjustment ratio, anti-backflow command P _out_rpp ; When demand control is triggered, it is based on the demand setpoint P. _set_demd Demand feedback P _set_demd_err And the calculation of demand adjustment multiple and demand instruction P _out_demd ; Based on the plan curve instruction P _set Anti-backflow command P _out_rpp and demand instruction P _out_demd Generate charge / discharge command P _out .

[0007] Preferably, the method for determining whether to trigger anti-backflow control is as follows: When the active power P at the grid connection point is first less than the anti-backflow setting value P _set_rpp Record and determine the subsequent time t. _set Is the active power P at the internal grid connection point consistently less than the backflow prevention setting value P? _set_rpp If so, the anti-backflow control will be triggered; otherwise, it will not be triggered.

[0008] Preferably, when anti-backflow control is triggered, the anti-backflow adjustment amount is calculated as follows: When P>P _set_rpp +P _set_rpp_err At that time, the adjustment amount △P1=(PP) _set_rpp )×P _set_rpp_reduce , where P _set_rpp_reduce To prevent reverse flow and reversion, the factor should be reduced. When P _set_rpp <P≤P _set_rpp +P _set_rpp_err At that time, the adjustment amount ΔP1 = 0; When P≤ P _set_rpp At that time, the initial trigger adjustment amount ΔP1 = (PP) _set_rpp )×P _set_rpp_enlarge Non-first-time trigger adjustment amount ΔP = PP _set_rpp , where P _set_rpp_enlarge To prevent backflow, the amplification factor is increased; Anti-backflow command P _out_rpp =P _out_old +△P1, where P _out_old This is the last charge / discharge command.

[0009] The preferred method for determining whether to trigger demand control is as follows: When the active power P at the grid connection point first exceeds the demand setpoint P _set_demd Record and determine the subsequent time t. _set Does the active power P at the internal grid connection point continuously exceed the demand setpoint P? _set_demd If so, demand control will be triggered; otherwise, it will not be triggered.

[0010] Preferably, when demand control is triggered, the method for calculating the demand adjustment is as follows: When P <P _set_demd -P _set_demd_err At that time, the adjustment amount △P2=(PP) _set_demd )×P _set_demd_reduce , where P _set_demd_reduce This is the factor by which demand is reduced. When P _set_demd -P _set_demd_err ≤P <P _set_demd At that time, the adjustment amount ΔP2 = 0; When P≥P _set_demd At that time, the initial trigger adjustment amount ΔP2 = (PP) _set_demd )×P _set_demd_enlarge Non-first-time trigger adjustment amount ΔP2=PP _set_demd ; Demand instruction P _out_demd =P _out_old +△P2, where P _out_old This is the last charge / discharge command.

[0011] Preferably, when demand control is triggered, the demand command is calculated as follows: Active power at grid-connected points is collected at time intervals, and the average active power P at grid-connected points within the time period T is calculated. _average , When P _average <P _set_demd -P _set_demd_err At that time, the demand instruction P _out_demd =Planned Curve Instruction P _set ; When P _set_demd -P _set_demd_err ≤P _average <P _set_demd At that time, the demand instruction P _out_demd =P _set ×P _set_demd_reduce , where P _set_demd_reduce This is the factor by which demand is reduced. When P _average ≥P _set_demd At that time, the demand instruction P _out_demd =0.

[0012] Preferably, the method for generating charge / discharge commands is as follows: Initial charge-discharge instruction P _out = Plan curve instruction P _set , If the charge-discharge instruction P _out > Anti-flow instruction P _out_rpp , P _out = P _out_rpp ; If the charge-discharge instruction P _out < Demand instruction P _out_demd , P _out = P _out_demd .

[0013] Preferably, based on the SOC of the BMS in the energy storage system, the maximum power of the PCS charge-discharge, the rated power of the PCS, etc., the controller distributes the charge-discharge instruction P_out to each PCS.

[0014] A power coordination control system for a grid-connected point of an energy storage system adopts the power coordination control method for the grid-connected point of the energy storage system.

[0015] Compared with the prior art, the present application has the following advantages: 1. The present application has grid-connected point demand and anti-flow control functions, and through real-time monitoring of the grid-connected point power, without distinguishing between charging or discharging modes, anti-flow and demand are directly judged, so that the adjustment capacity of the energy storage system is fully utilized. The system controls the energy storage charge-discharge to dynamically adjust the grid-connected point power in real time, realizing more efficient power management.

[0016] 2. In the anti-flow and demand instruction calculation, the present application introduces limiting conditions such as adjustment amount reduction multiple, adjustment amount amplification multiple, power fluctuation time, and hysteresis, which can quickly respond to and dynamically adjust the grid-connected point power under complex working conditions of severe fluctuations of the grid-connected point load power, thereby effectively improving the grid-connected point power stability during energy storage operation. BRIEF DESCRIPTION OF DRAWINGS

[0017] The disclosure of the present application will be described with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present application, in which the same reference numerals are used to refer to the same components, and wherein: Figure 1 is a flow chart of the power coordination control method for the grid-connected point of the energy storage system of the present application; Figure 2 is a flow chart of the anti-flow instruction calculation of the present application; Figure 3 is a flow chart of the demand instruction calculation method one of the present application; Figure 4 is a flow chart of the demand instruction calculation method two of the present application. DETAILED DESCRIPTION

[0018] It is easy to understand that, according to the technical solutions of the present application, those skilled in the art can propose various structures and implementation modes that can be replaced with each other without changing the essential spirit of the present application. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solutions of the present application, and should not be regarded as the whole or as a limitation or restriction on the technical solutions of the present application.

[0019] Embodiment As Figure 1 shown, a grid-connected point power coordination control method of an energy storage system comprises the following steps: S1: collecting the line-in secondary voltage and current of the grid-connected point, and calculating the active power P of the grid-connected point; The active power of the grid-connected point refers to the power actually participating in energy conversion and transmission at the public connection point of the energy storage system connected with the power grid in the power system, which reflects the instantaneous or average active energy exchange at the point; In this embodiment, the controller directly collects the line-in secondary voltage and current of the grid-connected point. The controller first converts it from the three-phase stationary coordinate system to the synchronous rotating coordinate system, usually the d-q coordinate system, to obtain the d-axis voltage component and the q-axis voltage component of the grid-connected point voltage, and the d-axis current component and the q-axis current component of the grid-connected point current. Then, according to the power calculation formula, the active power P = ud x id + uq x iq is calculated.

[0020] S2: judging whether the anti-flow control or demand control condition is triggered based on the active power P of the grid-connected point; The controller judges the active power of the grid-connected point and the time since the last control of the PCS, whether the set adjustment period is reached or the anti-flow and demand control is triggered, and if the conditions are met, the control is triggered, and a new PCS charge and discharge power instruction is issued. If not, it continues to wait until the conditions are met. When the control is triggered, the anti-flow instruction and the demand instruction are calculated to obtain the energy storage charge and discharge instruction.

[0021] S3: when the anti-flow control is triggered, the anti-flow instruction P _set_rpp is calculated according to the anti-flow set value P _set_rpp_err , the anti-flow hysteresis P _out_rpp and the anti-flow adjustment multiple.

[0022] The anti-flow set value P _set_rpp needs to consider a certain threshold in the setting process; The anti-reverse flow return difference is set according to the actual situation. Positive discharge and negative charging, for example, the anti-reverse flow set value is 1000, when the grid connection point power fluctuation is small, the return difference can be set to 300, when the grid connection point power is between 1000 and 1300, at this time, the instruction value of the pcs issued will not be increased, that is, the discharge power will not be increased or the charging power will not be reduced, preventing the instruction from increasing and superimposing the downward fluctuation of the grid connection point power, so that the grid connection point power suddenly decreases a lot. When the grid connection point power fluctuation is large, the return difference can be set larger, for example, 600, and the instruction will not be increased again in advance.

[0023] The anti-reverse flow regulation multiple is also set according to the actual situation. Positive discharge and negative charging, small grid connection point power fluctuation, small amplification multiple, for example, 1.2 times, the anti-reverse flow regulation amount is multiplied by 1.2 when it is negative, and the anti-reverse flow calculation instruction is reduced a little; small reduction multiple, for example, 0.8, the anti-reverse flow regulation amount is multiplied by 0.8 when it is positive, and the anti-reverse flow calculation instruction is increased a little. Large grid connection point power fluctuation, large amplification multiple, for example, 1.4 times, the anti-reverse flow regulation amount is multiplied by 1.4 when it is negative, and the anti-reverse flow calculation instruction is reduced a lot; small reduction multiple, for example, 0.6, the anti-reverse flow regulation amount is multiplied by 0.6 when it is positive, and the anti-reverse flow calculation instruction is increased a little. Preventing the grid connection point power from suddenly decreasing.

[0024] S4: When the demand control is triggered, the demand instruction P is calculated according to the demand set value P _set_demd , the demand return difference P _set_demd_err , and the demand regulation multiple. _out_demd .

[0025] The demand set value P _set_demd During the setting process, a certain threshold value needs to be considered; The demand return difference P _set_demd_err is set according to the actual situation. Positive discharge and negative charging, for example, the demand set value is 3000, when the grid connection point power fluctuation is small, the return difference can be set to 300, when the grid connection point power is between 2700 and 3000, at this time, the instruction value of the pcs issued will not be reduced, that is, the charging power will not be increased or the discharge power will not be reduced, preventing the instruction from reducing and superimposing the upward fluctuation of the grid connection point power, so that the grid connection point power suddenly increases a lot. When the grid connection point power fluctuation is large, the return difference can be set larger, for example, 600, and the instruction will not be reduced again in advance.

[0026] The demand regulation multiple is also set according to the actual situation on site. When the power fluctuation at the grid connection point is small, the amplification multiple is set to be small, for example, 1.2 times, and the demand regulation amount is multiplied by 1.2 when the demand regulation amount is positive, so that the demand calculation instruction is increased; the reduction multiple is set to be large, for example, 0.8, and the demand regulation amount is multiplied by 0.8 when the demand regulation amount is negative, so that the demand calculation instruction is decreased. When the power fluctuation at the grid connection point is large, the amplification multiple is set to be large, for example, 1.4 times, and the demand regulation amount is multiplied by 1.4 when the demand regulation amount is positive, so that the demand calculation instruction is increased; the reduction multiple is set to be small, for example, 0.6, and the demand regulation amount is multiplied by 0.6 when the demand regulation amount is negative, so that the demand calculation instruction is decreased. The sudden increase of the power at the grid connection point is prevented.

[0027] S5: generating the charge-discharge instruction P based on the planned curve instruction P _set , the anti-reverse flow instruction P _out_rpp , and the demand instruction P _out_demd ; _out ; Specifically, the charge-discharge instruction generation method is, initial charge-discharge instruction P _out = planned curve instruction P _set , if the charge-discharge instruction P _out > anti-reverse flow instruction P _out_rpp , then P _out = P _out_rpp ; if the charge-discharge instruction P _out < demand instruction P _out_demd , then P _out = P _out_demd ; The anti-reverse flow instruction is to prevent the power at the grid connection point from being lower than the anti-reverse flow setting value, the demand instruction is to prevent the power at the grid connection point from being higher than the demand setting value, and the planned curve charge-discharge instruction is the instruction from the upper computer; First, the charge-discharge instruction P out = planned curve charge-discharge instruction P set , and then the charge-discharge instruction P out undergoes the following two judgments. (1) the charge-discharge instruction is greater than the anti-reverse flow instruction P _out > P _out_rpp , and the actual charge-discharge instruction is executed according to the anti-reverse flow instruction, and the charge-discharge instruction P _out = P _out_rpp ; (2) the charge-discharge instruction is less than the demand instruction P _out < P _out_demd, the execution of the charge-discharge instruction will cause the grid-connected point to have excess demand, the actual charge-discharge instruction is executed according to the demand instruction, and the charge-discharge instruction P _out =P _out_demd .

[0028] Specifically, the judgment method for triggering the anti-reverse flow control is, When the grid-connected point active power P is less than the anti-reverse flow setting value P _set_rpp for the first time, the time t _set afterwards is recorded and whether the grid-connected point active power P is continuously less than the anti-reverse flow setting value P _set_rpp is judged, if yes, the anti-reverse flow control is triggered, otherwise, the anti-reverse flow control is not triggered; In this embodiment, the anti-reverse flow setting value P _set_rpp is set to leave a certain margin from the actual reverse flow occurrence point, and when the grid-connected point power is lower than the anti-reverse flow setting value, it is considered that reverse flow occurs. When the grid-connected point active power P is less than the anti-reverse flow setting value P _set_rpp for the first time, after the power fluctuation time t _set , it is judged whether the grid-connected point power fluctuates around the anti-reverse flow setting value or continuously occurs reverse flow.

[0029] If the grid-connected point power fluctuates around the anti-reverse flow setting value P _set_rpp , no actual reverse flow occurs or a short-term actual reverse flow occurs, the PCS does not need to be controlled immediately, but the PCS is controlled frequently, and the discharge is reduced multiple times, which can cause the grid-connected point power to suddenly increase, affect the stability of the grid-connected point, and due to communication time, PCS response time and other problems, the short-term sudden reverse flow is quickly restored to normal, and the previous reverse flow period is not controlled in time, at this time, the anti-reverse flow setting value P _set_rpp or the anti-reverse flow return difference P _set_demd_err should be increased.

[0030] If it is judged that the reverse flow continuously occurs, the anti-reverse flow control is triggered.

[0031] As shown in Figure 2 , when the anti-reverse flow control is triggered, the anti-reverse flow adjustment amount calculation method is, (1) When the grid-connected point power is greater than the anti-reverse flow setting value plus the anti-reverse flow return difference , P>P _set_rpp +P _set_rpp_err , the adjustment amount △P1=(P-P _set_rpp )×P _set_rpp_reduce , wherein P _set_rpp_reduce is the anti-reverse flow return reduction multiple; P _set_rpp +P _set_rpp_err , the discharge needs to be increased, and the increased discharge power is △P1=(P-P _set_rpp )×P_set_rpp_reduce The discharge power that should be increased is (P-P _set_rpp ), but if the grid-connected point power is directly controlled to the anti-flow setting value, load fluctuations can cause the grid-connected point power to drop below the anti-flow setting value, resulting in an anti-flow phenomenon. The adjustment amount is multiplied by the anti-flow reset reduction factor to reduce the discharge adjustment amount, and the grid-connected point power is gradually controlled to approach the anti-flow setting value.

[0032] (2) The grid-connected point power is greater than the anti-flow setting value and less than or equal to the anti-flow setting value plus the anti-flow hysteresis When P _set_rpp <P≤P _set_rpp +P _set_rpp_err , the adjustment amount ΔP1=0; P _set_rpp <P≤P _set_rpp +P _set_rpp_err , the discharge should be increased, but the grid-connected point power is not too high above the anti-flow setting value, and considering load power fluctuations, increasing the discharge will have the risk of reducing the grid-connected point power below the anti-flow setting value or even below 0, so this time the PCS charge and discharge power is not adjusted, and ΔP1=0.

[0033] (3) The grid-connected point power is less than or equal to the anti-flow setting value When P≤P _set_rpp , the first trigger adjustment amount ΔP1=(P-P _set_rpp )×P _set_rpp_enlarge , and the non-first trigger adjustment amount ΔP=P-P _set_rpp , where P _set_rpp_enlarge is the anti-flow action amplification factor; The current adjustment that triggers the anti-flow control reduces the discharge power ΔP1=(P-P _set_rpp )×P _set_rpp_enlarge . The discharge power that should be reduced is (P-P _set_rpp ), but since it cannot be determined whether the drop in grid-connected point power has reached the lowest point, if the subsequent grid-connected point power continues to drop, the grid-connected point will still continue to have an anti-flow after this adjustment, and it will not be possible to return above the anti-flow setting value until the next adjustment after a regulation period. The first trigger anti-flow adjustment increases the adjustment amount, and the grid-connected point power can return above the anti-flow setting value in most cases; For the current adjustment that does not trigger the anti-flow control, i.e., the case where the grid-connected point power is still continuously lower than the anti-flow setting value after the first adjustment, the second adjustment reduces the discharge power ΔP1=P-P _set_rpp, the second adjustment is adjusted according to the actual need adjustment amount. When the first adjustment does not adjust the grid-connected point power to above the anti-backflow setting value, after a period of time, it is not likely that the grid-connected point power remains to be decreased, if the adjustment amount is increased again, after superimposing the load fluctuation, it is possible to make the grid-connected point power rise more, and the next adjustment needs to increase the discharge to make the grid-connected point power decrease, which is not conducive to maintaining the stability of the grid-connected point power.

[0034] Anti-backflow instruction Anti-backflow instruction P _out_rpp = P _out_old +△P1, wherein P _out_old is the last charge and discharge instruction.

[0035] When the real-time power uploading interval of the PCS is long, the real-time power of the PCS at the time of calculating the charge and discharge instruction does not conform to the actual situation, and the calculated charge and discharge instruction cannot correctly control the grid-connected point power, so the last adjustment charge and discharge instruction P _out_old is superimposed with the anti-backflow adjustment amount△P1 of this time, and△P1 is△P1 in the above case, and the anti-backflow instruction of this time is calculated. When the real-time power uploading interval of the PCS is short, the real-time power of the PCS at the time of calculating the charge and discharge instruction is basically consistent with the actual situation, and the real-time power P _pcs of the PCS can be used for superimposed calculation.

[0036] Specifically, the judgment method for triggering the demand control is that, When the grid-connected point active power P is greater than the demand setting value P _set_demd for the first time, the grid-connected point active power P in the subsequent time t _set is judged whether it is continuously greater than the demand setting value P _set_demd or not, if yes, the demand control is triggered, otherwise, the demand control is not triggered. When setting the demand setting value, a certain margin is left from the actual over-demand occurrence point, and the grid-connected point power is higher than the demand setting value, that is, it is considered that the over-demand occurs. When the grid-connected point active power P is greater than the demand setting value P _set_demd for the first time, after the power fluctuation time t _set , it is judged whether the grid-connected point power fluctuates around the demand setting value or the over-demand continuously occurs.

[0037] If the grid-connected point power fluctuates around the demand setting value P _set_demd , and the actual over-demand does not occur or occurs temporarily, the PCS does not need to be controlled immediately, but frequent control of the PCS will reduce the charge many times, which will cause the grid-connected point power to suddenly decrease, affecting the stability of the grid-connected point, and due to the communication time, the response time of the PCS and other problems, the sudden backflow in a short time is not controlled in time.

[0038] If it is judged that the over-demand occurs continuously, the demand control is triggered.

[0039] As shown in Figure 3 , when the demand control is triggered, the demand instruction calculation method one is, (1) the grid-connected point power is less than the demand setting value plus the demand back difference When P _set_demd -P _set_demd_err , the adjustment amount ΔP2=(P-P _set_demd )×P _set_demd_reduce , wherein P _set_demd_reduce is the demand return reduction multiple; P _set_demd -P _set_demd_err , the charging needs to be increased, and the increased charging power is ΔP2=(P-P _set_demd )×P _set_demd_reduce . The actual charging power that should be increased is (P-P _set_demd ), but if the grid-connected point power is controlled to the demand setting value line, the load fluctuation may cause the grid-connected point power to rise above the demand setting value, and the over-demand phenomenon occurs. The adjustment amount is multiplied by the demand return reduction multiple, the charging adjustment amount is reduced, and the grid-connected point power is slowly forced to approach the demand setting value.

[0040] (2) the grid-connected point power is less than the demand setting value and greater than or equal to the demand setting value plus the demand back difference When P _set_demd -P _set_demd_err ≤P<P _set_demd , the adjustment amount ΔP2=0; P _set_demd -P _set_demd_err ≤P<P _set_demd , the charging should be increased, but the grid-connected point power is not too low below the demand setting value, and considering that the load power fluctuation is frequent, increasing the charging has the risk of causing the grid-connected point power to rise above the demand setting value, so the PCS charging and discharging power is not adjusted this time, and ΔP2=0.

[0041] (3) the grid-connected point power is greater than or equal to the demand setting value When P≥P _set_demd , the first triggered adjustment amount ΔP2=(P-P _set_demd )×P _set_demd_enlarge , and the non-first triggered adjustment amount ΔP2=P-P _set_demd ; P≥P _set_demd , the charging needs to be reduced, the charging power ΔP2=(P-P _set_demd )×P _set_demd_enlarge that should be reduced is (P-P _set_demd), but since it is not possible to determine whether the increase in grid-connected point power has reached the maximum, if the subsequent grid-connected point power continues to increase, the grid-connected point will continue to exceed the demand after this adjustment, and it will not be possible to return below the demand set value until the next adjustment after a regulation period. For the first time, the demand adjustment is increased, and in most cases, the grid-connected point power can be returned below the demand set value; For the next adjustment that does not trigger the demand control, i.e. the grid-connected point power is still higher than the demand set value after the first adjustment, the second adjustment reduces the charging power △P2 = P - P _set_demd , and the second adjustment is adjusted according to the actual demand adjustment. When the first adjustment does not adjust the grid-connected point power below the demand set value, after a period of time, it is not possible for the grid-connected point power to remain rising, and if the adjustment is increased, it may cause the grid-connected point power to decrease significantly after the load fluctuation, and the next adjustment needs to increase the charging to increase the grid-connected point power, which is not conducive to maintaining the stability of the grid-connected point power.

[0042] Demand instruction Demand instruction P _out_demd = P _out_old + △P2, where P _out_old is the last charging and discharging instruction; When the PCS real-time power uploading interval is long, the PCS real-time power at the time of charging and discharging instruction calculation does not match the actual value, and the calculated charging and discharging instruction cannot correctly control the grid-connected point power, so the last adjustment charging and discharging instruction P _out_old is added to this time demand adjustment amount △P2 to calculate the current demand instruction. When the PCS real-time power uploading interval is short, the PCS real-time power at the time of charging and discharging instruction calculation is basically consistent with the actual value, and the PCS real-time power P _pcs can be used for superposition calculation.

[0043] As Figure 4 shown, when the demand control is triggered, the second method for calculating the demand instruction is, According to the time interval, the grid-connected point active power is collected, and the average value of the grid-connected point active power in the time period T is calculated. _average ; This embodiment records the real-time grid-connected point power P, and the recording interval is every 0.5 seconds or less. The average value of the grid-connected point active power P _average is obtained by taking the average value of the recorded grid-connected point power in the last 5 minutes or more. When setting the demand set value, a certain margin is left from the actual excess demand point.

[0044] (1) The average value of the grid-connected point power is less than the demand set value minus the demand margin When P _average < P _set_demd - P_set_demd_err At that time, the demand instruction P _out_demd =Planned Curve Instruction P _set ; P _average <P _set_demd -P _set_demd_err At this point, there is no risk of exceeding demand at the grid connection point, and the energy storage system charges and discharges according to the planned curve P. _set Charging is initiated; demand command P _out_demd =P _set .

[0045] (2) The average power at the grid connection point is greater than or equal to the demand setpoint minus the demand margin, and less than the demand setpoint. When P _set_demd -P _set_demd_err ≤P _average <P _set_demd At that time, the demand instruction P _out_demd =P _set ×P _set_demd_reduce , where P _set_demd_reduce This is the demand recovery reduction factor; P _set_demd -P _set_demd_err ≤P _average <P _set_demd At this time, there is a risk of exceeding the demand at the grid connection point, and the energy storage system charges and discharges according to the planned curve P. _set Charge by reducing the value by a certain factor, demand instruction P _out_demd =P _set *P _set_demd_reduce .

[0046] (3) The average power at the grid connection point is greater than or equal to the demand setting value. When P _average ≥P _set_demd At that time, the demand instruction P _out_demd =0; P _average ≥P _set_demd At this point, the grid connection point has already experienced excess demand, the energy storage system stops charging, and the demand command P... _out_demd =0.

[0047] Specifically, based on the BMS's SOC, PCS's maximum charging and discharging power, and PCS's rated power within the energy storage system, the controller will send charging and discharging commands P... _out Assigned to each PCS.

[0048] Among them, whether charging or discharging can be carried out needs to be judged according to the SOC, for example, when the SOC of the energy storage device is set to be lower than or equal to 5%, discharging is prohibited, when the SOC of the energy storage device is 5%, only charging instruction is allowed to be executed, charging power can be distributed to the energy storage device, and discharging power cannot be distributed to the energy storage device.

[0049] At the same time, the instruction issued to the PCS should not be greater than the charge-discharge range of the PCS. Positive discharge and negative charge, assuming that the maximum discharge power is 1000 and the maximum charge power is -1000, the instruction issued to the PCS should be between -1000 and 1000. The rated power is another indicator of the charge-discharge capacity of the PCS, and the absolute value of the charge-discharge instruction issued should not exceed the rated power of the PCS.

[0050] A kind of energy storage system grid-connected point power coordination control system adopts the energy storage system grid-connected point power coordination control method described above.

[0051] The technical scope of the present application is not limited to the content in the above description, and those skilled in the art can make various modifications and changes to the above embodiments without departing from the technical idea of the present application, and these modifications and changes should be within the protection scope of the present application.

Claims

1. A method for coordinated power control at the grid connection point of an energy storage system, characterized in that: The method comprises the following steps, Collecting the secondary voltage and current of the grid-connected point, and calculating the active power P of the grid-connected point; Based on the active power P of the grid-connected point, judging whether the anti-reverse flow control or the demand control condition is triggered; When the anti-backflow control is triggered, the anti-backflow command P is calculated according to the anti-backflow setting value P _set_rpp , the anti-backflow hysteresis P _set_rpp_err , and the anti-backflow adjustment multiple _out_rpp ; When the demand control is triggered, the demand instruction P _set_demd is calculated based on the demand set value P _set_demd_err , the demand back difference P _out_demd and the demand adjustment multiple. Based on the planned curve instruction P _set , the anti-backflow instruction P _out_rpp , and the demand instruction P _out_demd , the charge-discharge instruction P _out is generated.

2. The grid point power coordination control method of an energy storage system according to claim 1, characterized in that: The judgment method for triggering the anti-reverse flow control is, When the grid-connected point active power P first becomes less than the anti-flow setting value P _set_rpp , record and determine whether the grid-connected point active power P is continuously less than the anti-flow setting value P _set for a subsequent time t _set_rpp . If yes, trigger the anti-flow control, otherwise, do not trigger.

3. The grid point power coordination control method of an energy storage system according to claim 2, characterized in that: When the anti-reverse flow control is triggered, the anti-reverse flow regulation amount calculation method is, When P > P _set_rpp + P _set_rpp_err , the adjustment amount ΔP1 = (P - P _set_rpp ) × P _set_rpp_reduce , wherein P _set_rpp_reduce is the anti-backflow reset reduction factor; When P _set_rpp When P _set_rpp + P _set_rpp_err , the adjustment amount ΔP1=0. When P≤P _set_rpp , the first triggered adjustment amount ΔP1=(P-P _set_rpp )×P _set_rpp_enlarge , and the non-first triggered adjustment amount ΔP=P-P _set_rpp , wherein P _set_rpp_enlarge is the anti-flow prevention action amplification factor. P _out_rpp = P _out_old + ΔP1, where P _out_old is the last charge-discharge command.

4. The grid point power coordination control method of an energy storage system according to claim 1, characterized in that: The judgment method for triggering the demand control is, When the grid-connected point active power P first becomes greater than the demand setting value P _set_demd , record and determine whether the grid-connected point active power P is continuously greater than the demand setting value P _set after time t _set_demd , if yes, trigger the demand control, otherwise, do not trigger.

5. The grid point power coordinated control method of an energy storage system according to claim 4, characterized in that: When the demand control is triggered, the demand regulation amount calculation method is, When P <P _set_demd -P _set_demd_err At that time, the adjustment amount ΔP2 = (PP) _set_demd )×P _set_demd_reduce , where P _set_demd_reduce This is the factor by which demand is reduced. When P _set_demd - P _set_demd_err ≤ P < P _set_demd , the adjustment amount ΔP2 = 0; When P≥P _set_demd , the first triggered adjustment amount ΔP2=(P-P _set_demd )×P _set_demd_enlarge , and the non-first triggered adjustment amount ΔP2=P-P _set_demd ; demand command P _out_demd = P _out_old + ΔP2, where P _out_old is the last charge or discharge command.

6. The grid point power coordinated control method of an energy storage system according to claim 4, characterized in that: When the demand control is triggered, the demand instruction calculation method is, The grid-connected point active power is collected according to time intervals, and the grid-connected point active power average value P in a time period T is calculated _average , When P _average < P _set_demd < P _set_demd_err , the demand command P _out_demd = the planned curve command P _set ; When P _set_demd - P _set_demd_err ≤ P _average - P _set_demd , the demand command P _out_demd = P _set × P _set_demd_reduce , where P _set_demd_reduce is the demand reset reduction factor; When P _average ≥ P _set_demd , the demand P _out_demd = 0.

7. The grid point power coordinated control method of an energy storage system according to claim 1, characterized in that: The charge-discharge instruction generation method is, Initial charge and discharge command P _out = planned curve command P _set , If the charge-discharge command P _out > is the anti-flow prevention command P _out_rpp , then P _out = P _out_rpp ; If the charge-discharge command P _out <demand command P _out_demd , then P _out = P _out_demd .

8. The grid point power coordination control method of an energy storage system according to claim 1, characterized in that: Based on the SOC of the BMS in the energy storage system, the maximum power of the PCS charging and discharging, and the rated power of the PCS, the controller distributes the charging and discharging instructions P out to each PCS.

9. A grid point power coordination control system for an energy storage system, characterized in that: The energy storage system grid-connected point power coordination control method in any one of claims 1-8 is adopted.

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