A control method and control device for a commercial and industrial energy storage system

Abstract

The application provides a control method and a control device for a commercial and industrial energy storage system. The control method comprises the following steps: collecting real-time output power of the energy storage system, real-time output power of a photovoltaic system, real-time absorption power of a load branch and real-time power of a grid-connected point; judging the validity of the real-time power of the grid-connected point according to the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch, the real-time power of the grid-connected point and a pre-set power calculation error threshold of the grid-connected point; if the real-time power of the grid-connected point is valid, performing PID control on the output of the energy storage system and the output of the photovoltaic system so that the real-time power of the grid-connected point is near a power control target value of the grid-connected point. The method applies a PID control algorithm to control the output of the energy storage system and the output of the photovoltaic system, controls the real-time power of the grid-connected point to be near a set value and realizes the purpose of self-generation and self-use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power energy storage, and more particularly to a control method and a control device of an industrial and commercial energy storage system. BACKGROUND

[0002] With the increasing demand for renewable energy worldwide, the role of energy storage systems in power systems is becoming increasingly important. Among them, the optimization operation of industrial and commercial energy storage system as an important part has important significance for improving the level of new energy power generation consumption and realizing self-generation and self-use. However, due to the intermittency and randomness of photovoltaic power generation and the change of load, the optimization operation of energy storage system becomes complex. Therefore, how to effectively control the output of energy storage system and photovoltaic system to meet the principle of "self-generation and self-use, prohibition of surplus power on the grid" is an important technical challenge.

[0003] The existing solution mainly collects the grid-connected point power and compares it with the set value. When the grid-connected point power is less than the set value, the reverse flow protection starts timing. When the reverse flow protection timing time is less than the set time, the difference between the collected grid-connected point power and the set value is added to the active target instruction to control the output of the energy storage system and the photovoltaic system to eliminate the generation of reverse power, otherwise, the protection action is taken to trip the grid-connected point switch.

[0004] Although the existing technology solves the problem of optimization operation of energy storage system to some extent, there are still some problems and shortcomings. When reverse power appears at the grid-connected point, the difference between the collected grid-connected point power and the set value is added to the active target instruction. Due to the asynchronous data sampling, the power of the grid-connected point will fluctuate frequently, the control effect is not good, and the system is easy to be unstable, which leads to the reverse power protection action to trip the grid-connected point switch. In addition, the existing technical solution often issues shutdown instructions to all photovoltaic inverters with normal communication and startup when reverse power occurs, and sets the inverter power of the shutdown inverter to the minimum, which limits the level of new energy power generation consumption to some extent. SUMMARY

[0005] The present application provides a control method and a control device of an industrial and commercial energy storage system to solve the technical problems in the prior art.

[0006] According to a first aspect of the present application, a control method of an industrial and commercial energy storage system is provided, comprising:

[0007] connecting the energy storage system and the photovoltaic system to the power grid;

[0008] collecting the branch power data under the grid-connected point through an external protocol access mode, including the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch and the real-time power of the grid-connected point;

[0009] According to the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch, the real-time power of the grid-connected point and the pre-set grid-connected point power calculation error threshold, the validity of the real-time power of the grid-connected point is judged.

[0010] If the real-time power of the grid-connected point has validity, PID control is performed on the output of the energy storage system and the output of the photovoltaic system respectively, so that the real-time power of the grid-connected point is near the grid-connected point power control target value.

[0011] According to the second aspect of the present application, a control device of an industrial and commercial energy storage system is provided, comprising an energy storage system, a photovoltaic system and a local controller, the local controller comprising:

[0012] The acquisition module is used to acquire the power data of each branch under the grid-connected point through an external protocol access mode, including the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch and the real-time power of the grid-connected point.

[0013] The judgment module is used to judge the validity of the real-time power of the grid-connected point according to the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch, the real-time power of the grid-connected point and the pre-set grid-connected point power calculation error threshold.

[0014] The control module is used to perform PID control on the output of the energy storage system and the output of the photovoltaic system respectively if the real-time power of the grid-connected point has validity, so that the real-time power of the grid-connected point is near the grid-connected point power control target value.

[0015] The control method and control device of the industrial and commercial energy storage system provided by the present application apply PID control algorithm to the output control of the energy storage system and the output control of the photovoltaic system respectively, so that the real-time power of the grid-connected point does not exceed the target value or is controlled within the safety value within the action time of the anti-flow controller, preventing the anti-flow controller from acting and ensuring the stable operation of the system, which is beneficial to improve the new energy power generation consumption level of the industrial and commercial energy storage system and realize the purpose of self-generation and self-use. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a schematic diagram of the application scenario of the multi-energy system of the present application;

[0017] Figure 2 It is a flowchart of the control method of the industrial and commercial energy storage system provided by the present application;

[0018] Figure 3 It is a schematic diagram of the overall flow of the control method of the industrial and commercial energy storage system;

[0019] Figure 4 A structural schematic diagram of a control device of a commercial and industrial energy storage system is provided. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application. In addition, the technical features in each of the embodiments or in a single embodiment provided by the present application can be combined with each other at will to form a feasible technical solution, and such combination is not restricted by the order of steps and / or structure mode, but should be based on the fact that a person of ordinary skill in the art can realize it. When the combination of technical solutions appears contradictory or unfeasible, it should be considered that the combination of technical solutions does not exist and is not within the protection scope of the present application.

[0021] Referring to Figure 1 , a schematic diagram of an application scenario of the present application is shown, and a commercial and industrial energy storage system based on a PID control algorithm is constructed, which includes an energy storage system, a photovoltaic system, an anti-backflow controller, a local load and a local controller. The energy storage system adopts lithium battery energy storage, the capacity is 100 kWh, and the charging and discharging efficiency is 95%; the photovoltaic system adopts a polycrystalline silicon solar cell panel, the rated power is 100 kW; the anti-backflow controller adopts a CGS7003T anti-backflow controller of Shanghai Changgaojibao Company; the local load is a commercial office building, the peak power is 100 kW; and the local controller adopts an LC100 of SunGrow, and the communication protocol adopts a Modbus TCP protocol.

[0022] Figure 2 A control method flowchart of a commercial and industrial energy storage system is provided by the present application, as shown in Figure 2 and Figure 3 , the method includes:

[0023] Step 1, through an external protocol access mode, collecting power data of each branch under a grid-connected point, including real-time output power of the energy storage system, real-time output power of the photovoltaic system, real-time absorption power of the load branch and real-time power of the grid-connected point.

[0024] It can be understood that the power data of each branch under the grid-connected point is collected in real time, each branch includes the energy storage system, the photovoltaic system, the load branch and the like, and the collected power data includes real-time output power of the energy storage system, real-time output power of the photovoltaic system, real-time absorption function of the load branch and real-time power of the grid-connected point and the like.

[0025] Step 2, according to the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch, the real-time power of the grid-connected point and the pre-set grid-connected point power calculation error threshold, judging the validity of the real-time power of the grid-connected point.

[0026] Wherein, judging the validity of the real-time power of the grid-connected point includes:

[0027] Step 21, according to the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch and the real-time power of the grid-connected point, calculating the grid-connected point power calculation error.

[0028] Wherein, calculating the grid-connected point power calculation error is:

[0029] ΔP=Ppv+Pbess-Pload-Ppcc;

[0030] Wherein, Ppv is the real-time output power of the photovoltaic system, Pbess is the real-time output power of the energy storage system, Pload is the real-time absorption power of the load branch, Ppcc is the real-time power of the grid-connected point, and ΔP is the grid-connected point power calculation error.

[0031] Step 22, according to the size relationship between the grid-connected point power calculation error and the grid-connected point power calculation error threshold, determining whether the real-time power of the grid-connected point is valid.

[0032] Wherein, after calculating the grid-connected point power calculation error ΔP, if abs(ΔP)≤Perr, the real-time power of the grid-connected point is valid, Preal=Ppcc, if abs(ΔP)>Perr, the real-time power of the grid-connected point is invalid, then discarding the real-time power of the grid-connected point, abs(·) represents taking absolute value, Perr is the grid-connected point power calculation error threshold, and Preal is the grid-connected point power valid value.

[0033] When the real-time power of the grid-connected point is valid, the real-time power of the grid-connected point is recorded as the grid-connected point power valid value, and the subsequent PID control is performed; if the real-time power of the grid-connected point is invalid, the process is ended and no subsequent control step is performed.

[0034] Step 3, if the real-time power of the grid-connected point has validity, PID control is performed on the output of the energy storage system and the output of the photovoltaic system respectively, so that the real-time power of the grid-connected point is near the grid-connected point power control target value.

[0035] It can be understood that when the real-time power of the grid-connected point is valid, PID control algorithm is used to control the output of the energy storage system and the output of the photovoltaic system respectively. Wherein, controlling the output of the energy storage system and the output of the photovoltaic system includes:

[0036] Step 31, set control parameters, the control parameters include grid-connected point power control target value, control parameters of energy storage system and control parameters of photovoltaic system, the control parameters of energy storage system include proportional coefficient, integral time constant and differential time constant of PID control algorithm of energy storage system, the control parameters of photovoltaic system include proportional coefficient, integral time constant and differential time constant of PID control algorithm of photovoltaic system.

[0037] It can be understood that before controlling the output of the energy storage system and the output of the photovoltaic system, some control parameters are set first. First, the control target, that is, the grid-connected point power target, is set. When controlling the output of the energy storage system, some control parameters of the energy storage system need to be set, including proportional coefficient, integral time constant and differential time constant of the PID control algorithm of the energy storage system. Similarly, when controlling the output of the photovoltaic system, some control parameters of the photovoltaic system need to be set, including proportional coefficient, integral time constant and differential time constant of the PID control algorithm of the photovoltaic system.

[0038] Step 32, based on the PID algorithm, the output of the energy storage system and the output of the photovoltaic system are calculated respectively according to the difference between the current power effective value of the grid-connected point and the grid-connected point power control target value as feedback.

[0039] Wherein, after setting the control parameters, the output of the energy storage system and the output of the photovoltaic system are calculated according to the PID control algorithm, and the calculation formula can be expressed as follows:

[0040]

[0041] Wherein, U1(t) is the output of the energy storage system, U2(t) is the output of the photovoltaic system, err(t) is the difference between the current power effective value of the grid-connected point and the grid-connected point power control target value, And Proportional coefficient, integral time constant and differential time constant of the PID control algorithm of the energy storage system, respectively.

[0042] Wherein, it should be noted that the energy storage system has maximum charging power and maximum discharging power of energy storage, therefore, when the output of the energy storage system exceeds the maximum charging power and the maximum discharging power of energy storage, the output can only be carried out with the maximum charging power and the maximum discharging power of energy storage.

[0043] Then, assuming that the maximum charging power of energy storage is c max And the maximum discharging power of energy storage is d maxFirstly, according to the sign of U1(t), it is judged whether the energy storage system needs to be discharged or needs to be charged. Specifically, when the sign of U1(t) is negative, the energy storage system needs to be charged; when the sign of U1(t) is positive, the energy storage system needs to be discharged.

[0044] When the energy storage system needs to be charged, if abs(U1(t))>c max , then U1(t)=-c max ; if abs(U1(t))≤c max , then U1(t)=U1(t).

[0045] If the energy storage system needs to be discharged, if U1(t)>d max , then U1(t)=d max ; if U1(t)≤d max , then U1(t)=U1(t).

[0046] Similarly, the photovoltaic system has a minimum photovoltaic power generation g min , a maximum photovoltaic power generation g max , and the output of the photovoltaic system can only be between the minimum photovoltaic power generation and the maximum photovoltaic power generation. Specifically, if U2(t)<g min , then U2(t)=g min .

[0047] If U2(t)>g max , then U2(t)=g max .

[0048] If g min ≤U2(t)≤g max , then U2(t)=U2(t).

[0049] In the process of controlling the output of the energy storage system and the output of the photovoltaic system, the voltage and current of the grid-connected point and the real-time power of the grid-connected point are monitored in real time. When the voltage and current of the grid-connected point are in opposite directions and the current of the grid-connected point is less than the set power threshold, a timer is started and a delay time is set. If the reverse current phenomenon disappears within the set delay time, the timer is cleared and the voltage and current of the grid-connected point are continuously monitored. If the reverse current phenomenon still exists beyond the set delay time, the connection between the photovoltaic system, the energy storage system and the power grid is cut off to prevent reverse current energy from entering the power grid.

[0050] It can be understood that, for example, Figure 1In the commercial and industrial energy storage system, the anti-backflow controller starts to work, monitors the voltage and current of the grid-connected point, and sets the power threshold value as -2kW. When the power is sent back to the grid, that is, the voltage and current directions of the grid-connected point are reversed, and the power of the grid-connected point is less than the set power threshold value, the timer is started, and the delay time is 2s. If the reverse flow phenomenon disappears within the delay time, it means that the output control of the energy storage system and the photovoltaic system has a certain effect, and the energy storage system and the photovoltaic system can be connected to the grid, and then the timer is cleared. If the reverse flow phenomenon still exists when the delay time is up, it means that the output of the energy storage system and the photovoltaic system connected to the grid is controlled by PID, but the phenomenon of power being sent back to the grid still exists, and the anti-backflow controller can only perform a protection action to cut off the connection between the photovoltaic system, the energy storage system and the grid to prevent reverse flow of electric energy into the grid.

[0051] By the above technical means, the problem of frequent protection action of the anti-backflow controller is effectively solved; the control effect of the energy storage system based on the PID control algorithm in processing nonlinear and time-varying energy storage systems is improved, and the technical problem of system instability is avoided; at the same time, through the control of the output of the photovoltaic system, the consumption level of new energy power generation is improved, and the purpose of self-generation and self-use is realized.

[0052] Referring to Figure 4 The application further provides a control device of a commercial and industrial energy storage system, which comprises an energy storage system 10, a photovoltaic system 20 and a local controller 30, and the local controller 30 comprises:

[0053] The acquisition module 31 is configured to acquire the power data of each branch under the grid-connected point by an external protocol access mode, including the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch and the real-time power of the grid-connected point.

[0054] The judgment module 32 is configured to judge the validity of the real-time power of the grid-connected point according to the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch, the real-time power of the grid-connected point and the pre-set power calculation error threshold value of the grid-connected point.

[0055] The control module 33 is configured to perform PID control on the output of the energy storage system and the output of the photovoltaic system if the real-time power of the grid-connected point has validity, so that the real-time power of the grid-connected point is near the grid-connected point power control target value.

[0056] The control device of the commercial and industrial energy storage system further comprises an anti-backflow controller 40.

[0057] The anti-reverse flow controller 40 is used for monitoring the voltage, current and real-time power of the grid-connected point in the process of PID control of the local controller on the energy storage system and the photovoltaic system, and when the voltage and current of the grid-connected point are reversed and the current power of the grid-connected point is less than the set power threshold, a timer is started and a delay time is set;

[0058] If the reverse current phenomenon disappears within the set delay time, the timer is cleared and the voltage and current of the grid-connected point are continuously monitored;

[0059] If the reverse current phenomenon still exists beyond the set delay time, the connection between the photovoltaic system, the energy storage system and the power grid is cut off to prevent reverse current from entering the power grid.

[0060] The related technical features of the working processes of the judging module 32 and the control module 33 in the local controller 30 can refer to the related technical features of steps 2 and 3 in the control method of the industrial and commercial energy storage system, and will not be described here.

[0061] Compared with the prior art, the control method and the control device of the multi-energy system provided by the embodiments of the present application have the following beneficial effects:

[0062] (1) The PID control algorithm is applied to control the output of the energy storage system and the output of the photovoltaic system, respectively, to control the power of the grid-connected point near the set value in real time, and to realize the purpose of self-generation and self-use;

[0063] (2) The real-time power of the grid-connected point is controlled to be less than the target value or within the safe value within the action time of the anti-reverse flow controller to prevent the action of the anti-reverse flow controller.

[0064] It should be noted that in the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0065] Although the preferred embodiments of the present application have been described, those skilled in the art can make further changes and modifications to the embodiments once they know the basic inventive concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0066] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A control method of an industrial and commercial energy storage system, characterized by, The application relates to a power grid access method and device of a power storage system and a photovoltaic system. The power grid access method comprises the following steps: The power grid access device comprises the following parts: The power grid access device comprises the following parts: The power grid access device comprises the following parts: The power grid access device comprises the following parts: The power grid access device comprises the following parts: The power grid access device comprises the following parts: The power grid access device comprises the following parts: ； ； wherein, is the output of the energy storage system, is the output of the photovoltaic system, is the difference between the current power effective value of the point of common coupling and the target value of the point of common coupling power control, , and are the proportional coefficient, the integral time constant and the derivative time constant of the PID control algorithm of the energy storage system, respectively.

2. The control method of a commercial and industrial energy storage system according to claim 1, characterized in that, The power grid access device comprises the following parts: The power grid access device comprises the following parts: The power grid access device comprises the following parts:

3. The control method of a commercial and industrial energy storage system according to claim 2, characterized in that, The power grid access device comprises the following parts: ； wherein, Ppv(t) is the real-time output power of the photovoltaic system, Pess(t) is the real-time output power of the energy storage system, Ph(t) is the real-time absorption power of the load branch, Pgrid(t) is the real-time power of the grid point, Perror(t) is the grid point power calculation error. The size relationship between the grid-connected point power calculation error and the grid-connected point power calculation error threshold value is used to determine whether the real-time power of the grid-connected point is valid, including: If , the real-time power of the grid-connected point is valid, If , the real-time power of the grid-connected point is invalid, and the real-time power of the grid-connected point is discarded, abs(·) represents taking the absolute value, is the grid-connected point power calculation error threshold value, is the grid-connected point power valid value.

4. The control method of a commercial energy storage system according to claim 1, characterized by, The control parameters of the energy storage system further include an energy storage maximum charging power c max and an energy storage maximum discharging power d max The control method further includes: When is negative, the energy storage system needs to be charged; when is positive, the energy storage system needs to be discharged; If the energy storage system needs to be charged, if abs ( ) > c max , then = -c max ; if abs ( ) ≤ c max , then = ; If the energy storage system needs to be discharged, if d max then d max ; if d max then d .

5. The control method of a commercial and industrial energy storage system according to claim 1, characterized by, The control parameters of the photovoltaic system also comprise a photovoltaic minimum power generation g min , a photovoltaic maximum power generation g max The control method also comprises: If < g min then = g min ; If > g max , then = g max ; if g min ≤ ≤ g max then = .

6. 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7. A control device of an industrial and commercial energy storage system for implementing the control method of the industrial and commercial energy storage system according to claim 1, characterized by, The commercial energy storage system comprises an energy storage system, a photovoltaic system and a local controller, and the local controller comprises: a collection module, configured to collect power data of each branch under a grid-connected point through an external protocol access mode, including real-time output power of the energy storage system, real-time output power of the photovoltaic system, real-time absorption power of a load branch and real-time power of the grid-connected point; a judgment module, configured to judge validity of the real-time power of the grid-connected point according to the real-time output power of the energy storage system, the real-time output power of the photovoltaic system, the real-time absorption power of the load branch, the real-time power of the grid-connected point and a pre-set power calculation error threshold of the grid-connected point; a control module, configured to perform PID control on output of the energy storage system and output of the photovoltaic system if the real-time power of the grid-connected point has validity, so that the real-time power of the grid-connected point is near a power control target value of the grid-connected point.

8. Control device for a commercial and industrial energy storage system according to claim 7, characterized in that, The anti-reverse flow controller is further configured to monitor voltage and current of the grid-connected point and the real-time power of the grid-connected point in real time during the PID control of the local controller on the energy storage system and the photovoltaic system, start a timer when the voltage and the current of the grid-connected point are in reverse directions and the current power of the grid-connected point is less than a set power threshold, and set a delay time; if the reverse flow phenomenon disappears within the set delay time, the timer is cleared and the voltage and the current of the grid-connected point are continuously monitored; if the reverse flow phenomenon still exists beyond the set delay time, the connection between the photovoltaic system, the energy storage system and the power grid is cut off to prevent reverse flow of electric energy into the power grid. ​

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