Method and device for compensating net load prediction error and power distribution network

Abstract

The invention discloses a net load prediction error compensation method and device and a power distribution network, and relates to the field of power grid management, and the method comprises the steps: judging whether a net load prediction error is greater than zero or not; if the net load prediction error is larger than zero, it is determined that energy needs to be supplemented for the direct-current power grid, and the working power of the super-capacitor is determined according to the stored energy of the super-capacitor and the lower limit value of the stored energy; controlling the super capacitor to discharge to the direct current bus at the working power; if the net load prediction error is not larger than zero, it is determined that energy needs to be absorbed from the direct-current power grid, and the working power of the super-capacitor is determined according to the stored energy of the super-capacitor and the upper limit value of the stored energy; and controlling the super capacitor to charge from the direct current bus at the working power. The super capacitor is used for compensating the net load prediction error, the charging and discharging functions of the battery are shared, the charging and discharging times of the battery are reduced, and the working stability of a power grid is improved.

Description

Technical Field

[0001] The present invention relates to the field of power grid management, and in particular to a net load forecast error compensation method, device and distribution network. Background Art

[0002] Net load forecasting helps power system operators optimize power generation, reduce the need for backup power, and improve the overall performance of the power system. However, errors associated with net load forecasting are inevitable due to the uncertainty of end-user behavior, weather conditions, and data limitations. Therefore, net load forecasting errors need to be considered in power system planning and operation to ensure grid stability, frequency regulation, and reliability. Net load forecasting errors are mainly due to the volatility and uncertainty of loads and renewable energy sources such as photovoltaic power generation. Volatility refers to the difference between the average power per minute and the average power per hour, and uncertainty refers to the difference between the average predicted power per hour and the average power per hour. Batteries are used in related technologies to compensate for the net load errors caused by photovoltaics and loads, but the battery has a limited number of charge and discharge times, which affects the service life and stability of the power grid. Summary of the invention

[0003] The purpose of the present invention is to provide a net load forecast error compensation method, device and distribution network, which use supercapacitors to compensate for the net load forecast error, share the charging and discharging functions of the battery, reduce the number of battery charging and discharging times, and improve the stability of the power grid.

[0004] To solve the above technical problems, the present invention provides a net load forecast error compensation method, which is applied to a distribution network, wherein the distribution network includes an AC bus, a DC bus, a photovoltaic power generation source, a battery and a super capacitor, wherein the AC bus and the DC bus are connected via a converter, the AC bus is also connected to an AC grid and a load, the DC bus is also respectively connected to the photovoltaic power generation source, the battery and the super capacitor, the AC grid is used to supply power to the AC bus, the photovoltaic power generation source is used to supply power to the DC bus, and the battery is used to discharge the DC grid or charge from the DC grid;

[0005] The net load forecast error compensation method comprises:

[0006] Determining whether a net load prediction error is greater than zero, wherein the net load prediction error is related to the power of the photovoltaic power generation source and the power of the load;

[0007] If the net load prediction error is greater than zero, it is determined that energy needs to be supplemented for the DC grid, and the working power of the supercapacitor is determined according to the storage energy of the supercapacitor and the lower limit of the storage energy;

[0008] Controlling the supercapacitor to discharge to the DC bus at the working power;

[0009] If the net load prediction error is not greater than zero, it is determined that energy needs to be absorbed from the DC power grid, and the working power of the supercapacitor is determined according to the storage energy of the supercapacitor and the upper limit of the storage energy;

[0010] The supercapacitor is controlled to be charged from the DC bus with the working power.

[0011] On the other hand, after judging whether the net load forecast error is greater than zero, it also includes:

[0012] Determine the storage energy of the supercapacitor, the expression of the storage energy is ;

[0013] Among them, E sc is the storage energy of the supercapacitor, C is the capacitance of the supercapacitor, V sc is the open circuit voltage of the supercapacitor, , SoC sc is the state of charge of the supercapacitor, V scr is the rated open circuit voltage of the supercapacitor.

[0014] On the other hand, determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the lower limit of the storage energy includes:

[0015] The predicted working power of the supercapacitor is determined according to the storage energy of the supercapacitor, the lower limit of the storage energy and the predicted working power relationship, and the predicted working power relationship is:

[0016] ;

[0017] in, is the predicted working power at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, E scl is the lower limit of the storage energy of the supercapacitor, P nlfe (t) is the net load forecast error at time t, P scr is the rated power of the supercapacitor, and t is an integer greater than 1;

[0018] Determine the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1;

[0019] The operating power of the supercapacitor at time t is determined according to the predicted stored energy of the supercapacitor at time t.

[0020] On the other hand, determining the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1 includes:

[0021] The predicted storage energy of the supercapacitor at time t is determined according to the predicted working power at time t, the storage energy of the supercapacitor at time t-1 and the predicted storage energy relationship, and the predicted storage energy relationship is: ;

[0022] in, is the predicted storage energy of the supercapacitor at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, T r is the time difference between time t and time t-1.

[0023] On the other hand, determining the working power of the supercapacitor at time t according to the predicted stored energy of the supercapacitor at time t includes:

[0024] The working power of the supercapacitor at time t is determined according to the predicted storage energy of the supercapacitor at time t and the working power relationship, and the working power relationship is:

[0025] ;

[0026] Among them, P sc (t) is the working power of the supercapacitor at time t.

[0027] On the other hand, determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the upper limit of the storage energy includes:

[0028] The predicted working power of the supercapacitor is determined according to the storage energy of the supercapacitor, the upper limit of the storage energy and the predicted working power relationship, and the predicted working power relationship is:

[0029] ;

[0030] in, is the predicted working power at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, E scu is the upper limit of the storage energy of the supercapacitor, P nlfe (t) is the net load forecast error at time t, P scr is the rated power of the supercapacitor, and t is an integer greater than 1;

[0031] Determine the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1;

[0032] The operating power of the supercapacitor at time t is determined according to the predicted stored energy of the supercapacitor at time t.

[0033] On the other hand, determining the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1 includes:

[0034] The predicted storage energy of the supercapacitor at time t is determined according to the predicted working power at time t, the storage energy of the supercapacitor at time t-1 and the predicted storage energy relationship, and the predicted storage energy relationship is: ;

[0035] in, is the predicted storage energy of the supercapacitor at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, T r is the time difference between time t and time t-1.

[0036] On the other hand, determining the working power of the supercapacitor at time t according to the predicted stored energy of the supercapacitor at time t includes:

[0037] The working power of the supercapacitor at time t is determined according to the predicted storage energy of the supercapacitor at time t and the working power relationship, and the working power relationship is:

[0038] ;

[0039] Among them, P sc (t) is the working power of the supercapacitor at time t.

[0040] In order to solve the above technical problems, the present invention also provides a net load forecast error compensation device, comprising:

[0041] Memory for storing computer programs;

[0042] A processor is used to implement the steps of the above-mentioned net load forecast error compensation method when executing the computer program.

[0043] In order to solve the above technical problems, the present invention also provides a distribution network, including the above net load forecast error compensation device, and also including an AC bus, a DC bus, a photovoltaic power generation source, a battery and a super capacitor, wherein the AC bus and the DC bus are connected through a converter, the AC bus is also connected to the AC grid and the load, the DC bus is also respectively connected to the photovoltaic power generation source, the battery and the super capacitor, the AC grid is used to supply power to the AC bus, the photovoltaic power generation source is used to supply power to the DC bus, and the battery is used to discharge the DC grid or charge from the DC grid;

[0044] The super capacitor is used to discharge to the DC bus or charge from the DC bus at the operating frequency obtained by the net load prediction error compensation device.

[0045] The present invention discloses a net load prediction error compensation method, device and distribution network, which relates to the field of power grid management, including: judging whether the net load prediction error is greater than zero; if the net load prediction error is greater than zero, determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the lower limit of the storage energy; controlling the supercapacitor to discharge to the DC bus with the working power; if the net load prediction error is not greater than zero, determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the upper limit of the storage energy; controlling the supercapacitor to charge from the DC bus with the working power. Using a supercapacitor to compensate for the net load prediction error shares the charging and discharging function of the battery, reduces the number of battery charging and discharging times, and improves the stability of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the prior art and the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0047] Figure 1 A flow chart of a net load forecast error compensation method provided by the present invention;

[0048] Figure 2 A schematic diagram of the structure of a power distribution network provided by the present invention;

[0049] Figure 3 A flow chart of another method for compensating net load forecast error provided by the present invention;

[0050] Figure 4 A schematic structural diagram of a net load forecast error compensation device provided by the present invention. DETAILED DESCRIPTION

[0051] The core of the present invention is to provide a net load forecast error compensation method, device and distribution network, which uses supercapacitors to compensate for the net load forecast error, shares the charging and discharging functions of the battery, reduces the number of battery charging and discharging times, and improves the stability of the power grid.

[0052] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Figure 1 A flow chart of a net load forecast error compensation method provided by the present invention, the net load forecast error compensation method is applied to a distribution network, Figure 2 A schematic diagram of the structure of a distribution network provided by the present invention, the distribution network includes an AC bus, a DC bus, a photovoltaic power source, a battery and a supercapacitor, the AC bus and the DC bus are connected through a converter, the AC bus is also connected to an AC grid and a load, the DC bus is also respectively connected to the photovoltaic power source, the battery and the supercapacitor, the AC grid is used to supply power to the AC bus, the photovoltaic power source is used to supply power to the DC bus, and the battery is used to discharge the DC grid or charge from the DC grid;

[0054] Net load forecast error compensation methods include:

[0055] S11: Determine whether the net load prediction error is greater than zero; if so, proceed to step S12; if not, proceed to step S14;

[0056] S12: determining that energy needs to be supplemented for the DC grid, and determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the lower limit of the storage energy;

[0057] S13: Control the supercapacitor to discharge to the DC bus with working power;

[0058] S14: determining that energy needs to be absorbed from the DC grid, and determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the upper limit of the storage energy;

[0059] S15: Control the supercapacitor to charge from the DC bus with working power.

[0060] The load is connected to the AC bus of the system. The photovoltaic power source is connected to the DC bus through a DC / DC converter. The battery is connected to the DC bus through a DC / DC converter. The supercapacitor is connected to the DC bus through a DC / DC converter to compensate for the prediction error of the load and photovoltaic power source power.

[0061] The net load forecast error is mainly due to the volatility and uncertainty of the load and renewable energy sources such as photovoltaic (PV) power generation. The volatility refers to the difference between the average power per minute and the average power per hour, and the uncertainty refers to the difference between the average predicted power per hour and the average power per hour. Due to this volatility and uncertainty, the net load power changes every 5 to 15 minutes during the day. In existing research, there are several techniques for net load forecast error compensation, such as model predictive control and neural networks. In addition, flexible loads and energy storage devices can also be used to compensate for the net load forecast error. However, if the battery is only used as an energy storage device for charging and discharging with small changes relative to the net load power, the battery life will be reduced. Therefore, supercapacitors (SC) are generally used together with batteries to absorb transient ripples during load changes, thereby extending the battery life.

[0062] The power provided by the grid is P G , the power used by the load is P D , the power provided by the photovoltaic source is P PV , the working power of the battery is P B , the working power of the supercapacitor is P SC . PCC is a node.

[0063] The real-time net load power is used to determine the charging and discharging plan of the SC, assuming that the net load changes every 5 minutes. The net load power is expressed as the sum of its average hourly net load forecast power and forecast error. The expression is , P nl (t) is the net load power at time t, is the net load forecast power at time t, P nlfe (t) is the net load forecast error at time t, where t represents the time period [(t-1)×T r , t×T r ], T r Set to 5 minutes. The forecast error is the sum of the volatility and uncertainty of the net load power.

[0064] When the net load forecast power is positive every hour of every day, it is regarded as the net load demand power. At this time, energy needs to be replenished for the grid, and the supercapacitor is discharged at this time. When the net load forecast power is negative every hour of every day, it is regarded as the net load feed-in power. At this time, energy needs to be absorbed from the grid, and the supercapacitor is charged at this time. The net load forecast error is used as input to provide a supercapacitor charging and discharging plan. In order to implement the proposed control method, the DC / DC converter of the supercapacitor operates in current control mode to provide the required charging and discharging power for the DC bus of the system.

[0065] Furthermore, the supercapacitor needs to consider its own stored energy and the upper and lower limits of energy during the charging and discharging process, so when determining the working power, it is necessary to first determine the stored energy and the upper and lower limits.

[0066] The present invention discloses a method for compensating a net load prediction error, which relates to the field of power grid management, including: judging whether the net load prediction error is greater than zero; if the net load prediction error is greater than zero, determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the lower limit of the storage energy; controlling the supercapacitor to discharge to a DC bus with the working power; if the net load prediction error is not greater than zero, determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the upper limit of the storage energy; controlling the supercapacitor to charge from the DC bus with the working power. Using a supercapacitor to compensate for the net load prediction error shares the charging and discharging function of the battery, reduces the number of times the battery is charged and discharged, and improves the stability of the power grid.

[0067] Based on the above embodiments:

[0068] Figure 3 A flow chart of another method for compensating net load forecast error provided by the present invention;

[0069] In some embodiments, after determining whether the net load prediction error is greater than zero, the method further includes:

[0070] Determine the storage energy of the supercapacitor. The expression for storage energy is: ;

[0071] Among them, E sc is the storage energy of the supercapacitor, C is the capacitance of the supercapacitor, V sc is the open circuit voltage of the supercapacitor, , SoC sc is the state of charge of the supercapacitor, V scr is the rated open circuit voltage of the supercapacitor.

[0072] The energy stored in a supercapacitor is proportional to the square of its SoC. This means that the lower and upper limits of the SoC will determine E scThe lower and upper limits. Therefore, in order to meet the constraints of the SoC, the energy stored in the supercapacitor must be within its limits. In addition, the power of the supercapacitor must be within its rated power limit. Considering these constraints, the supercapacitor power can be determined.

[0073] In some embodiments, determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the lower limit of the storage energy includes:

[0074] The predicted working power of the supercapacitor is determined according to the storage energy of the supercapacitor, the lower limit of the storage energy and the predicted working power relationship. The predicted working power relationship is:

[0075] ;

[0076] in, is the predicted working power at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, E scl is the lower limit of the storage energy of the supercapacitor, P nlfe (t) is the net load forecast error at time t, P scr is the rated power of the supercapacitor, and t is an integer greater than 1;

[0077] Determine the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1;

[0078] The working power of the supercapacitor at time t is determined according to the predicted storage energy of the supercapacitor at time t.

[0079] It should be noted that && is a condition that must be met at the same time, which can be understood as "and".

[0080] When the net load forecast error is greater than zero, the SC discharges. First, an initial estimate of the SC power is determined taking into account the energy storage and rated power constraints. This means that if the available energy in the SC is at its lower limit, the SC does not discharge. In addition, if P nlfe (t)> P scr , that is, the net load prediction error is greater than the rated power limit of the SC, the SC cannot output power equal to the net load prediction error and can only discharge at its rated power limit; if P nlfe (t)≤ P scr , that is, the net load prediction error is less than or equal to the rated power limit of the SC, and the SC can output power equal to the net load prediction error and discharge with the net load prediction error.

[0081] The estimated value only satisfies the power constraint. It is necessary to calculate the corresponding energy estimate based on this value to satisfy the energy constraint and obtain the final SC power.

[0082] In some embodiments, determining the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1 includes:

[0083] The predicted storage energy of the supercapacitor at time t is determined based on the predicted working power at time t, the storage energy of the supercapacitor at time t-1, and the predicted storage energy relationship. The predicted storage energy relationship is: ;

[0084] in, is the predicted storage energy of the supercapacitor at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, T r is the time difference between time t and time t-1.

[0085] To determine the final SC power, calculate the SC power The corresponding SC energy estimate , that is, the energy estimate of the current period is equal to the remaining energy of the previous period minus the discharge amount, ensuring that the energy of the SC at this power also meets the constraint conditions. Corresponding SC energy The predicted value needs to be determined based on the energy stored in the supercapacitor at the previous moment.

[0086] In some embodiments, determining the working power of the supercapacitor at time t according to the predicted stored energy of the supercapacitor at time t includes:

[0087] The working power of the supercapacitor at time t is determined based on the predicted storage energy and working power relationship of the supercapacitor at time t. The working power relationship is:

[0088] ;

[0089] Among them, P sc (t) is the working power of the supercapacitor at time t.

[0090] if ≤E scl ,express If the SC energy exceeds the lower limit after discharge, the final SC discharge power should be calculated by subtracting the lower limit value from the residual energy in the previous period and dividing it by the time interval. > E scl ,express Reasonable, the final discharge power of SC is equal to .

[0091] In some embodiments, determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the upper limit of the storage energy includes:

[0092] The predicted working power of the supercapacitor is determined based on the storage energy of the supercapacitor, the upper limit of the storage energy and the predicted working power relationship. The predicted working power relationship is:

[0093] ;

[0094] in, is the predicted working power at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, E scu is the upper limit of the storage energy of the supercapacitor, P nlfe (t) is the net load forecast error at time t, P scr is the rated power of the supercapacitor, and t is an integer greater than 1;

[0095] Determine the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1;

[0096] The working power of the supercapacitor at time t is determined according to the predicted storage energy of the supercapacitor at time t.

[0097] When the net load forecast error is less than or equal to zero, the SC is charged. First, an estimate of the SC power is determined taking into account the energy storage and rated power constraints. If the available energy in the SC is at its upper limit, the SC is not charged. In addition, if -P nlfe (t)> P scr , that is, the net load prediction error is greater than the rated power limit of the SC, the SC cannot input power equal to the net load prediction error and can only charge with its rated power limit; if - P nlfe (t)≤ P scr , that is, the net load prediction error is less than or equal to the rated power limit of the SC, and the SC can input power equal to the net load prediction error and charge with the net load prediction error.

[0098] In some embodiments, determining the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1 includes:

[0099] The predicted storage energy of the supercapacitor at time t is determined based on the predicted working power at time t, the storage energy of the supercapacitor at time t-1, and the predicted storage energy relationship. The predicted storage energy relationship is: ;

[0100] in, is the predicted storage energy of the supercapacitor at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, T ris the time difference between time t and time t-1.

[0101] To determine the final SC power, calculate the SC power The corresponding SC energy estimate , that is, the energy estimate of the current period is equal to the remaining energy of the previous period minus the discharge amount, ensuring that the energy of the SC at this power also meets the constraint conditions. Corresponding SC energy The predicted value needs to be determined based on the energy stored in the supercapacitor at the previous moment.

[0102] In some embodiments, determining the working power of the supercapacitor at time t according to the predicted stored energy of the supercapacitor at time t includes:

[0103] The working power of the supercapacitor at time t is determined based on the predicted storage energy and working power relationship of the supercapacitor at time t. The working power relationship is:

[0104] ;

[0105] Among them, P sc (t) is the working power of the supercapacitor at time t.

[0106] The energy estimate for the current period is equal to the remaining energy in the previous period plus the charge amount. >E scu ,express If the SC energy exceeds the upper limit after charging, the final SC charging power should be calculated by subtracting the upper limit value from the remaining energy in the previous period and dividing it by the time interval. ≤E scu ,express Reasonable, the final charging power of SC is equal to .

[0107] Figure 4 A schematic diagram of the structure of a net load forecast error compensation device provided by the present invention, the net load forecast error compensation device comprising:

[0108] A memory 41, used for storing computer programs;

[0109] The processor 42 is used to implement the steps of the above-mentioned net load forecast error compensation method when executing the computer program.

[0110] For an introduction to the net load prediction error compensation device provided in this application, please refer to the above embodiments and will not be repeated here.

[0111] Figure 2A schematic diagram of the structure of a distribution network provided by the present invention, the distribution network includes the above-mentioned net load prediction error compensation device, and also includes an AC bus, a DC bus, a photovoltaic power generation source, a battery and a super capacitor, the AC bus and the DC bus are connected through a converter, the AC bus is also connected to the AC grid and the load, the DC bus is also connected to the photovoltaic power generation source, the battery and the super capacitor respectively, the AC grid is used to supply power to the AC bus, the photovoltaic power generation source is used to supply power to the DC bus, and the battery is used to discharge the DC grid or charge from the DC grid;

[0112] The supercapacitor is used to discharge to or charge from the DC bus at an operating frequency obtained by the net load prediction error compensation device.

[0113] For the introduction of the distribution network provided in this application, please refer to the above embodiments and will not be repeated here.

[0114] It should also be noted that, in this specification, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the statement "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0115] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0116] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for compensating a net load forecast error, characterized in that: Applied to a power distribution network, the power distribution network includes an AC bus, a DC bus, a photovoltaic power source, a battery and a super capacitor, the AC bus and the DC bus are connected via a converter, the AC bus is also connected to an AC grid and a load, the DC bus is also respectively connected to the photovoltaic power source, the battery and the super capacitor, the AC grid is used to supply power to the AC bus, the photovoltaic power source is used to supply power to the DC bus, and the battery is used to discharge the DC grid or charge from the DC grid; The net load forecast error compensation method comprises: Determining whether a net load prediction error is greater than zero, wherein the net load prediction error is related to the power of the photovoltaic power generation source and the power of the load; If the net load prediction error is greater than zero, it is determined that energy needs to be supplemented for the DC grid, and the working power of the supercapacitor is determined according to the storage energy of the supercapacitor and the lower limit of the storage energy; Controlling the supercapacitor to discharge to the DC bus at the working power; If the net load prediction error is not greater than zero, it is determined that energy needs to be absorbed from the DC power grid, and the working power of the supercapacitor is determined according to the storage energy of the supercapacitor and the upper limit of the storage energy; The supercapacitor is controlled to be charged from the DC bus with the working power.

2. The net load forecast error compensation method according to claim 1, characterized in that: After determining whether the net load forecast error is greater than zero, the following steps are also included: Determine the storage energy of the supercapacitor, the expression of the storage energy is ; Among them, E sc is the storage energy of the supercapacitor, C is the capacitance of the supercapacitor, V sc is the open circuit voltage of the supercapacitor, , SoC sc is the state of charge of the supercapacitor, V scr is the rated open circuit voltage of the supercapacitor.

3. The net load forecast error compensation method according to claim 1, characterized in that: Determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the lower limit of the storage energy includes: The predicted working power of the supercapacitor is determined according to the storage energy of the supercapacitor, the lower limit of the storage energy and the predicted working power relationship, and the predicted working power relationship is: ； in, is the predicted working power at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, E scl is the lower limit of the storage energy of the supercapacitor, P nlfe (t) is the net load forecast error at time t, P scr is the rated power of the supercapacitor, and t is an integer greater than 1; Determine the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1; The operating power of the supercapacitor at time t is determined according to the predicted stored energy of the supercapacitor at time t.

4. The net load forecast error compensation method according to claim 3, characterized in that: Determining the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1 includes: The predicted storage energy of the supercapacitor at time t is determined according to the predicted working power at time t, the storage energy of the supercapacitor at time t-1 and the predicted storage energy relationship, and the predicted storage energy relationship is: ; in, is the predicted storage energy of the supercapacitor at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, T r is the time difference between time t and time t-1.

5. The net load forecast error compensation method according to claim 4, characterized in that: Determining the working power of the supercapacitor at time t according to the predicted stored energy of the supercapacitor at time t includes: The working power of the supercapacitor at time t is determined according to the predicted storage energy of the supercapacitor at time t and the working power relationship, and the working power relationship is: ； Among them, P sc (t) is the working power of the supercapacitor at time t.

6. The net load forecast error compensation method according to claim 1, characterized in that: Determining the working power of the supercapacitor according to the storage energy of the supercapacitor and the upper limit value of the storage energy includes: The predicted working power of the supercapacitor is determined according to the storage energy of the supercapacitor, the upper limit of the storage energy and the predicted working power relationship, and the predicted working power relationship is: ； in, is the predicted working power at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, E scu is the upper limit of the storage energy of the supercapacitor, P nlfe (t) is the net load forecast error at time t, P scr is the rated power of the supercapacitor, and t is an integer greater than 1; Determine the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1; The operating power of the supercapacitor at time t is determined according to the predicted stored energy of the supercapacitor at time t.

7. The net load forecast error compensation method according to claim 6, characterized in that: Determining the predicted storage energy of the supercapacitor at time t according to the predicted working power at time t and the storage energy of the supercapacitor at time t-1 includes: The predicted storage energy of the supercapacitor at time t is determined according to the predicted working power at time t, the storage energy of the supercapacitor at time t-1 and the predicted storage energy relationship, and the predicted storage energy relationship is: ; in, is the predicted storage energy of the supercapacitor at time t, E sc (t-1) is the storage energy of the supercapacitor at time t-1, T r is the time difference between time t and time t-1.

8. The net load forecast error compensation method according to claim 7, characterized in that: Determining the working power of the supercapacitor at time t according to the predicted stored energy of the supercapacitor at time t includes: The working power of the supercapacitor at time t is determined according to the predicted storage energy of the supercapacitor at time t and the working power relationship, and the working power relationship is: ； Among them, P sc (t) is the working power of the supercapacitor at time t.

9. A net load forecast error compensation device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the net load forecast error compensation method as claimed in any one of claims 1 to 8 when executing the computer program.

10. A distribution network, characterized in that: The device comprises the net load forecast error compensation device as claimed in claim 9, and further comprises an AC bus, a DC bus, a photovoltaic power generation source, a battery and a super capacitor, wherein the AC bus and the DC bus are connected via a converter, the AC bus is also connected to an AC grid and a load, the DC bus is also respectively connected to the photovoltaic power generation source, the battery and the super capacitor, the AC grid is used to supply power to the AC bus, the photovoltaic power generation source is used to supply power to the DC bus, and the battery is used to discharge the DC grid or charge from the DC grid; The super capacitor is used to discharge to the DC bus or charge from the DC bus at the operating frequency obtained by the net load prediction error compensation device.

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