Flame and light combined secondary frequency modulation method and device

Abstract

The invention provides a flame and light combined secondary frequency modulation method and device, and belongs to the technical field of electric power. The method comprises the following steps: acquiring a secondary frequency modulation instruction of power grid dispatching, and acquiring thermal power of a thermal power generating unit at the current moment; according to the secondary frequency modulation instruction and the thermal power at the current moment, photovoltaic power station power needing to be borne by the photovoltaic power station at the current moment is determined, and a photovoltaic power station power instruction is obtained based on the photovoltaic power station power; determining a power adjustment value of each photovoltaic unit in the photovoltaic power station and a corresponding power adjustment instruction according to the power instruction of the photovoltaic power station and the number of the photovoltaic units in the photovoltaic power station; converting a power regulation value in the power regulation instruction into a voltage regulation value to obtain a voltage regulation instruction of each photovoltaic unit; and based on the voltage regulation instruction and the operation mode of each photovoltaic unit, respectively determining a voltage control instruction of each photovoltaic unit, and controlling the corresponding photovoltaic unit according to the voltage control instruction. According to the invention, the AGC instruction can be accurately tracked.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a method and device for combined fire and light secondary frequency modulation. Background Art

[0002] It is becoming a trend for new clean energy such as photovoltaic and wind power to replace traditional kerosene. With the increase of new energy penetration in the power system, the increase of photovoltaic and wind power generating units, the decrease of the number of traditional synchronous generating units, the decrease of power system inertia, the decrease of active frequency regulation reserve margin, the decrease of system frequency regulation capability, the decrease of disturbance resistance capability, and the need to improve frequency stability. Therefore, it is very important to study the frequency stability of new power systems with a high proportion of new energy.

[0003] When there is a power difference between the output power on the power generation side of the power system and the power demand on the user side, the system frequency will change. According to the different nature of the frequency change, after the frequency deviates from the normal range, the power grid will perform inertia response, primary frequency regulation and secondary frequency regulation in sequence to correct it in stages. Among them, secondary frequency regulation is to mobilize available power resources for automatic generation control (Automatic Generation Control, AGC), daily peak regulation, power outages and other measures to maintain the balance of power supply, which can achieve zero-difference regulation.

[0004] The AGC instructions of the power grid dispatch change frequently in steps, and the active power of the unit is adjusted according to the AGC instructions. One step of the AGC instruction is one adjustment process (in seconds). In the power system, thermal power units usually bear all the AGC frequency regulation instructions, but due to the response characteristics of the fuel system, the thermal power units participating in the secondary frequency regulation have a slow climbing rate and cannot accurately track the AGC instructions, resulting in a slow frequency recovery speed. Summary of the invention

[0005] The embodiment of the present invention provides a method and device for secondary frequency modulation of fire and light, so as to accurately track AGC instructions and accelerate the speed of frequency recovery.

[0006] In a first aspect, an embodiment of the present invention provides a fire-light combined secondary frequency modulation method, comprising:

[0007] Obtain the secondary frequency regulation instruction of the power grid dispatch and obtain the thermal power of the thermal power unit at the current moment;

[0008] Determine the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power power at the current moment, and obtain the photovoltaic power station power instruction based on the photovoltaic power station power;

[0009] Determining a power adjustment value and a corresponding power adjustment instruction for each photovoltaic unit in the photovoltaic power station according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station;

[0010] Converting the power regulation value in the power regulation instruction into a voltage regulation value to obtain a voltage regulation instruction for each photovoltaic unit;

[0011] Based on the voltage regulation instruction and the operation mode of each photovoltaic unit, the voltage control instruction of each photovoltaic unit is determined respectively, and the corresponding photovoltaic unit is controlled according to the voltage control instruction.

[0012] In a possible implementation, the operation mode of the photovoltaic unit includes maximum power point operation and variable power tracking operation; the photovoltaic unit includes a first photovoltaic unit operating at a maximum power point and a second photovoltaic unit operating at a variable power tracking operation;

[0013] Determining the power adjustment value of each photovoltaic unit in the photovoltaic power station and the corresponding power adjustment instruction according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station includes:

[0014] Determining the adjustment direction of the photovoltaic power station power instruction;

[0015] If the adjustment direction of the photovoltaic power station power instruction is the direction of power reduction, then according to the photovoltaic power station power, the number of the first photovoltaic units and the number of the second photovoltaic units, a first power adjustment value that needs to be reduced for each photovoltaic unit in the photovoltaic power station is calculated; and based on the first power adjustment value, a first power adjustment instruction for each photovoltaic unit is generated;

[0016] If the adjustment direction of the photovoltaic power station power instruction is the direction of power increase, the second power adjustment value that needs to be increased for each photovoltaic unit in the photovoltaic power station is calculated based on the photovoltaic power station power and the number of the second photovoltaic units; and the second power adjustment instruction for each photovoltaic unit is generated based on the second power adjustment value.

[0017] In a possible implementation, converting the power regulation value in the power regulation instruction into a voltage regulation value to obtain the voltage regulation instruction of each photovoltaic unit includes:

[0018] Obtaining the current photovoltaic power and current photovoltaic voltage of each photovoltaic unit in the photovoltaic power station;

[0019] Determining a power-voltage curve of a photovoltaic unit in the photovoltaic power station according to the current photovoltaic power and the current photovoltaic voltage;

[0020] Determining a voltage regulation value of each photovoltaic unit according to the power voltage curve and the power regulation value in the power regulation instruction;

[0021] Based on the voltage regulation value of each photovoltaic unit, a voltage regulation instruction of each photovoltaic unit is generated.

[0022] In a possible implementation, based on the voltage regulation instruction and the operation mode of each photovoltaic unit, the voltage control instruction of each photovoltaic unit is determined respectively, and the corresponding photovoltaic unit is controlled according to the voltage control instruction, including:

[0023] Obtaining a voltage control value of each photovoltaic unit in the photovoltaic power station at the current moment;

[0024] For each photovoltaic unit, determining an operation mode of the photovoltaic unit;

[0025] If the operation mode of the photovoltaic unit is variable power tracking operation, a corrected voltage control value of the photovoltaic unit is determined according to the voltage control value of the photovoltaic unit and the voltage regulation value in the voltage regulation instruction;

[0026] If the operation mode of the photovoltaic unit is the maximum power point operation, then determine whether the adjustment direction of the voltage adjustment instruction is the direction of voltage increase; if the adjustment direction of the voltage adjustment instruction is the direction of voltage increase, then determine the corrected voltage control value of the photovoltaic unit according to the voltage control value of the photovoltaic unit and the voltage adjustment value in the voltage adjustment instruction; if the adjustment direction of the voltage adjustment instruction is the direction of voltage decrease, then use the voltage control value of the photovoltaic unit as the corrected voltage control value of the photovoltaic unit;

[0027] Determining a voltage control instruction for the photovoltaic unit based on the modified voltage control value;

[0028] The voltage control instruction of the photovoltaic unit is used as an input signal of the inverter voltage outer loop of the photovoltaic unit to control the photovoltaic unit.

[0029] In a possible implementation, after determining the voltage control instructions of each photovoltaic unit based on the voltage regulation instruction and the operation mode of each photovoltaic unit, and controlling the corresponding photovoltaic unit according to the voltage control instruction, the method further includes:

[0030] Re-acquire the thermal power of the thermal power unit at the current moment, and re-execute the steps of determining the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power at the current moment, and obtaining the photovoltaic power station power instruction based on the photovoltaic power station power and subsequent steps, until the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment is zero.

[0031] In a possible implementation, before determining the modified voltage control value of the photovoltaic unit according to the voltage control value of the photovoltaic unit and the voltage regulation value in the voltage regulation instruction, the method further includes:

[0032] A first-order filtering is performed on the voltage regulation value in the voltage regulation command of the photovoltaic unit.

[0033] In a possible implementation, the first-order filtering of the voltage regulation value in the voltage regulation instruction of the photovoltaic unit includes:

[0034] Obtaining a total inertia parameter of a thermal photovoltaic power generation system composed of the thermal power generation unit and the photovoltaic power station, and a historical photovoltaic power station power instruction at a moment before the current moment;

[0035] Determine the filtering time parameter according to the total inertia parameter, the historical photovoltaic power station power command at the previous moment and the preset frequency change rate action threshold;

[0036] Based on the filtering time parameter and a preset first-order filtering transfer function, the voltage regulation value in the voltage regulation instruction of the photovoltaic unit is filtered.

[0037] In a possible implementation, the secondary frequency modulation instruction includes a secondary frequency modulation power;

[0038] According to the secondary frequency modulation instruction and the thermal power at the current moment, the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment is determined, including:

[0039] Calculating the difference between the secondary frequency modulation power and the thermal power at the current moment;

[0040] The difference is determined as the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment.

[0041] In a possible implementation, the filtering time parameter is determined according to the total inertia parameter, the historical photovoltaic power station power command at the previous moment, and a preset frequency change rate action threshold, including:

[0042] According to the expression: Determine the filter time parameters;

[0043] Where, T AGC represents the filtering time parameter, ΔP represents the power difference between the photovoltaic power station power instruction and the historical photovoltaic power station power instruction at the previous moment, ω N represents the rated angular frequency of the system, J represents the total inertia parameter, F def Indicates the frequency change rate action threshold.

[0044] In a second aspect, an embodiment of the present invention provides a fire-light combined secondary frequency modulation device, comprising:

[0045] An acquisition module is used to obtain the secondary frequency modulation instruction of the power grid dispatch and obtain the thermal power of the thermal power unit at the current moment;

[0046] A first determination module is used to determine the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power power at the current moment, and obtain the photovoltaic power station power instruction based on the photovoltaic power station power;

[0047] A second determination module is used to determine the power adjustment value and the corresponding power adjustment instruction of each photovoltaic unit in the photovoltaic power station according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station;

[0048] A conversion module, used to convert the power adjustment value in the power adjustment instruction into a voltage adjustment value to obtain a voltage adjustment instruction for each photovoltaic unit;

[0049] The control module is used to determine the voltage control instructions of each photovoltaic unit based on the voltage regulation instructions and the operation mode of each photovoltaic unit, and control the corresponding photovoltaic unit according to the voltage control instructions.

[0050] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0051] The embodiment of the present invention determines the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment through the secondary frequency regulation instruction dispatched by the power grid and the thermal power of the thermal power unit at the current moment, and can hand over the part that the thermal power unit fails to respond in time to the photovoltaic power station, so that the photovoltaic power station can make up for the power difference between the thermal power output of the thermal power unit and the secondary frequency regulation instruction in a short time by using its own advantages of fast power control, and effectively improve the frequency regulation capability of the generator set; and then by decomposing the photovoltaic power station power instruction into power regulation values ​​of each photovoltaic unit, and converting the power regulation value into a voltage regulation value, the photovoltaic power station power instruction can be converted into a voltage regulation instruction that each photovoltaic unit can receive and respond to, thereby realizing voltage regulation and control of the photovoltaic unit, so that each photovoltaic unit in the photovoltaic power station can quickly bear the power difference between the output of the thermal power unit and the secondary frequency regulation instruction, and accelerate the speed of frequency recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be 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 paying creative work.

[0053] Figure 1 is a flow chart of the implementation of the fire-light combined secondary frequency modulation method provided in an embodiment of the present invention;

[0054] Figure 2 is a first flow chart of the fire-light combined secondary frequency modulation method provided by an embodiment of the present invention;

[0055] Figure 3 is a second flow chart of the fire-light combined secondary frequency modulation method provided in an embodiment of the present invention;

[0056] Figure 4 Effect diagram of secondary frequency modulation response under three working conditions provided by the embodiment of the present invention;

[0057] Figure 5 Schematic diagram of the impact of system frequency under three working conditions provided by an embodiment of the present invention;

[0058] Figure 6 A schematic structural diagram of a fire-light combined secondary frequency modulation device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0060] The AGC instructions of the power grid dispatch change frequently in steps, and the active power of the unit is adjusted according to the AGC instructions. One step of the AGC instruction is an adjustment process (seconds). The inventors found that in the process of secondary frequency regulation, the thermal power unit usually bears all the AGC frequency regulation instructions, but the thermal power unit has a slow climbing rate and cannot accurately track the AGC instructions, resulting in a slow frequency recovery speed.

[0061] In the new power system, the scale of photovoltaic grid connection is getting larger and larger. Considering that the inverter, a key equipment in the photovoltaic power generation system, is an IGBT-based power electronic device, its power tracking step is 0.4s to 3s; the communication network between the photovoltaic power station end fast power control device and the inverter can reach the millisecond level, and the photovoltaic unit has the ability of millisecond-level fast power control. Therefore, if the photovoltaic power station and the thermal power unit are jointly frequency-regulated, the photovoltaic power station can use its own advantages of fast power control to make up for the power difference between the AGC command and the thermal power unit in a short period of time, effectively improve the frequency regulation capability of the generator set, and play a huge role in the frequency stability of the power grid.

[0062] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0063] Figure 1 The implementation flow chart of the fire-light combined secondary frequency modulation method provided in the embodiment of the present invention is described in detail as follows:

[0064] Step 101, obtaining the secondary frequency modulation instruction of the power grid dispatching, and obtaining the thermal power of the thermal power unit at the current moment.

[0065] When there is a power difference between the output power on the power generation side of the power system and the demand power on the user side, the system frequency will change. When the power system performs secondary frequency regulation, the power system will send secondary frequency regulation instructions from the power grid dispatch to the thermal power units to mobilize the thermal power units to perform automatic power generation control.

[0066] In this embodiment, the photovoltaic power station can also simultaneously obtain the secondary frequency modulation instruction of the power grid dispatching so as to respond during the secondary frequency modulation.

[0067] In this embodiment, the photovoltaic power station is mainly used to make up for the power difference between the secondary frequency modulation instruction and the thermal power unit in a short period of time. Therefore, the thermal power of the thermal power unit at the current moment can also be obtained here.

[0068] Step 102, determining the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power power at the current moment, and obtaining the photovoltaic power station power instruction based on the photovoltaic power station power.

[0069] Optionally, the secondary frequency modulation instruction includes secondary frequency modulation power.

[0070] This embodiment determines the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power at the current moment, and can be to calculate the difference between the secondary frequency modulation power and the thermal power at the current moment; and determines the difference as the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment.

[0071] In this embodiment, the power difference between the secondary frequency modulation instruction and the thermal power unit can be calculated through the secondary frequency modulation power in the secondary frequency modulation instruction and the thermal power power at the current moment, that is, the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment.

[0072] In addition, a photovoltaic power station power instruction of the photovoltaic power station can be generated according to the photovoltaic power station power and the adjustment direction that the photovoltaic power station needs to be adjusted.

[0073] Step 103 : determining the power adjustment value and the corresponding power adjustment instruction of each photovoltaic unit in the photovoltaic power station according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station.

[0074] In this embodiment, a plurality of photovoltaic units are provided in the photovoltaic power station, and the power of the photovoltaic power station can be adjusted by adjusting the power of the photovoltaic units. Therefore, the power command of the photovoltaic power station can be decomposed to determine the power adjustment command of each photovoltaic unit respectively.

[0075] The power adjustment instruction may include a power adjustment value and an adjustment direction of the photovoltaic unit.

[0076] Step 104: convert the power regulation value in the power regulation instruction into a voltage regulation value to obtain the voltage regulation instruction of each photovoltaic unit.

[0077] In this embodiment, the power adjustment value may be converted into a voltage adjustment value according to the power-voltage curve of the photovoltaic unit, so as to perform voltage control on the photovoltaic unit.

[0078] Step 105 , based on the voltage regulation instruction and the operation mode of each photovoltaic unit, respectively determine the voltage control instruction of each photovoltaic unit, and control the corresponding photovoltaic unit according to the voltage control instruction.

[0079] In this embodiment, the voltage regulation instruction and the voltage control value of each photovoltaic unit itself can be superimposed to accurately control the photovoltaic unit.

[0080] Here, steps 101 to 104 may be performed at the coordination controller of the photovoltaic power station. Before step 105, the voltage regulation instruction may be sent to the controller of the photovoltaic inverter of each photovoltaic unit, and step 105 may be implemented in the controller of the photovoltaic inverter of each photovoltaic unit. Figure 2 and Figure 3 .

[0081] The embodiment of the present invention determines the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment through the secondary frequency regulation instruction dispatched by the power grid and the thermal power of the thermal power unit at the current moment, and can hand over the part that the thermal power unit fails to respond in time to the photovoltaic power station, so that the photovoltaic power station can make up for the power difference between the thermal power output of the thermal power unit and the secondary frequency regulation instruction in a short time by using its own advantages of fast power control, and effectively improve the frequency regulation capability of the generator set; and then by decomposing the photovoltaic power station power instruction into power regulation values ​​of each photovoltaic unit, and converting the power regulation value into a voltage regulation value, the photovoltaic power station power instruction can be converted into a voltage regulation instruction that each photovoltaic unit can receive and respond to, thereby realizing voltage regulation and control of the photovoltaic unit, so that each photovoltaic unit in the photovoltaic power station can quickly bear the power difference between the output of the thermal power unit and the secondary frequency regulation instruction, and accelerate the speed of frequency recovery.

[0082] In some embodiments, after determining the voltage control instructions of each photovoltaic unit based on the voltage regulation instructions and the operating mode of each photovoltaic unit, and controlling the corresponding photovoltaic unit according to the voltage control instructions, the thermal power of the thermal power unit at the current moment can be re-acquired, and the steps of determining the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instructions and the thermal power at the current moment, and obtaining the photovoltaic power station power instruction based on the photovoltaic power station power and subsequent steps are re-executed until the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment is zero.

[0083] In this embodiment, the thermal power of the thermal power generation unit at the current moment can be obtained in real time, and the photovoltaic power station power that the photovoltaic power station needs to bear can be determined and adjusted in real time.

[0084] When the secondary frequency modulation command is just received, the thermal power unit has not yet responded, and the photovoltaic power station bears all the secondary frequency modulation commands, which is the rapid power response stage; after the thermal power unit starts to respond, the thermal power unit begins to track the secondary frequency modulation command, and the photovoltaic power station bears part of the secondary frequency modulation command, which is the slow power regulation stage; after the thermal power unit bears all the secondary frequency modulation commands, the photovoltaic power station can exit the secondary frequency modulation process and no longer bear the secondary frequency modulation commands, which is the power recovery stage.

[0085] In some embodiments, the operation mode of the photovoltaic unit includes maximum power point operation and variable power tracking operation; the photovoltaic unit includes a first photovoltaic unit operating at the maximum power point and a second photovoltaic unit operating at the variable power tracking operation.

[0086] The photovoltaic power station includes at least one first photovoltaic unit operating at the maximum power point, so as to accurately determine the power voltage curve later. The photovoltaic power station also includes a plurality of second photovoltaic units operating with variable power tracking, and all the second photovoltaic units have the same power.

[0087] Here, since the first photovoltaic unit operates at the maximum power point, the power of the first photovoltaic unit cannot be further increased, and therefore, only the adjustment direction can be adjusted to reduce power. The second photovoltaic unit can be adjusted to reduce power or increase power.

[0088] In this embodiment, the power adjustment value of each photovoltaic unit in the photovoltaic power station and the corresponding power adjustment instruction are determined according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station. The adjustment direction of the photovoltaic power station power instruction can be determined first.

[0089] If the adjustment direction of the power instruction of the photovoltaic power station is the direction of power reduction, the first power adjustment value that needs to be reduced for each photovoltaic unit in the photovoltaic power station is calculated according to the power of the photovoltaic power station, the number of the first photovoltaic units and the number of the second photovoltaic units; and the first power adjustment instruction for each photovoltaic unit is generated based on the first power adjustment value.

[0090] Here, since the adjustment direction is power reduction, all photovoltaic units in the photovoltaic power station can be adjusted accordingly. Therefore, the obtained photovoltaic power station power can be divided into each photovoltaic unit, and each photovoltaic unit bears the corresponding part of the power adjustment.

[0091] If the adjustment direction of the photovoltaic power station power instruction is the direction of power increase, the second power adjustment value that needs to be increased for each photovoltaic unit in the photovoltaic power station is calculated according to the photovoltaic power station power and the number of second photovoltaic units; and the second power adjustment instruction for each photovoltaic unit is generated based on the second power adjustment value.

[0092] Here, since the adjustment direction is power increase, the first photovoltaic unit in the photovoltaic power station cannot be adjusted accordingly, and only the second photovoltaic unit can be adjusted accordingly. Therefore, the obtained photovoltaic power station power can be divided into each second photovoltaic unit, and each second photovoltaic unit bears the corresponding part of the power adjustment.

[0093] In some embodiments, the power regulation value in the power regulation instruction is converted into a voltage regulation value to obtain the voltage regulation instruction of each photovoltaic unit, which can be to obtain the current photovoltaic power and the current photovoltaic voltage of each photovoltaic unit in the photovoltaic power station; determine the power-voltage curve of the photovoltaic unit in the photovoltaic power station according to the current photovoltaic power and the current photovoltaic voltage; determine the voltage regulation value of each photovoltaic unit according to the power-voltage curve and the power regulation value in the power regulation instruction; and generate the voltage regulation instruction of each photovoltaic unit based on the voltage regulation value of each photovoltaic unit.

[0094] In this embodiment, based on the classic photovoltaic power-voltage curve formula, combined with the current photovoltaic power and DC bus voltage value corresponding to the maximum power point of the first photovoltaic unit of the photovoltaic power station, and the current power and DC bus voltage value of the second photovoltaic unit, a dynamic power-voltage (PV) curve can be fed back and estimated in real time.

[0095] Here, the voltage adjustment value corresponding to the power adjustment value can be calculated based on the current power of the second photovoltaic unit to obtain a voltage adjustment instruction. For example, the obtained voltage adjustment instruction can be reduced by 1V, increased by 1V, increased by 5%, reduced by 5%, etc.

[0096] Considering that the right side of the PV curve is generally used for regulation in photovoltaic power stations, the power increase in the regulation direction corresponds to the voltage decrease, and the power decrease corresponds to the voltage increase. The left and right sides are distinguished by the maximum power point. Since the left side has a larger jitter, the left side is generally not used for regulation.

[0097] In some embodiments, see Figure 3 As shown, based on the voltage regulation instruction and the operation mode of each photovoltaic unit, the voltage control instruction of each photovoltaic unit is determined respectively, and the corresponding photovoltaic unit is controlled according to the voltage control instruction, which can be:

[0098] Step 1: Obtain the voltage control value of each photovoltaic unit in the photovoltaic power station at the current moment. The voltage control value here is the voltage control value when the photovoltaic unit itself is in maximum power point operation or variable power tracking operation, and the voltage control value is the voltage control value when the photovoltaic unit is controlled. The voltage control value can be calculated by the controller of the photovoltaic inverter of the photovoltaic unit.

[0099] Step 2: for each photovoltaic unit, determine the operation mode of the photovoltaic unit.

[0100] Step three: if the operation mode of the photovoltaic unit is variable power tracking operation, then determine the corrected voltage control value of the photovoltaic unit according to the voltage control value of the photovoltaic unit and the voltage regulation value in the voltage regulation instruction.

[0101] In this embodiment, if the operation mode of the photovoltaic unit is variable power tracking operation, the photovoltaic unit can respond to a power increase instruction or a power decrease instruction. Therefore, the corrected voltage control value can be determined directly based on the voltage control value and voltage adjustment value of the photovoltaic unit.

[0102] Step four, if the operation mode of the photovoltaic unit is maximum power point operation, determine whether the adjustment direction of the voltage regulation instruction is the direction of voltage increase; if the adjustment direction of the voltage regulation instruction is the direction of voltage increase, determine the corrected voltage control value of the photovoltaic unit according to the voltage control value of the photovoltaic unit and the voltage regulation value in the voltage regulation instruction; if the adjustment direction of the voltage regulation instruction is the direction of voltage decrease, use the voltage control value of the photovoltaic unit as the corrected voltage control value of the photovoltaic unit.

[0103] In this embodiment, if the operation mode of the photovoltaic unit is the maximum power point operation, the photovoltaic unit can only respond to the power reduction instruction, that is, in the case of right standby, it can only respond to the voltage regulation instruction with the regulation direction of voltage increase. Therefore, the voltage regulation instruction can be judged first.

[0104] When the adjustment direction is the direction of voltage increase, consistent with the second photovoltaic unit, the voltage adjustment value can be superimposed on the voltage control value to determine the corrected voltage control value. When the adjustment direction is the direction of voltage decrease, the first photovoltaic unit does not respond, and therefore, is controlled only with the voltage control value.

[0105] Step five: determining the voltage control instruction of the photovoltaic unit based on the corrected voltage control value.

[0106] Step six: using the voltage control instruction of the photovoltaic unit as an input signal of the inverter voltage outer loop of the photovoltaic unit to control the photovoltaic unit.

[0107] Since the power operating points of the first photovoltaic unit and the second photovoltaic unit are different, the corresponding slopes are different. Therefore, for the same power regulation value, the calculated voltage regulation value may be different.

[0108] In this embodiment, considering that the difference between the first photovoltaic unit calculating and regulating the voltage according to the maximum power operating point and regulating according to the voltage regulation instruction of the second photovoltaic unit is small and will not affect the secondary frequency modulation process, a step of determining the adjustment direction is added to the voltage regulation process of the first photovoltaic unit, and regulation is performed according to the voltage regulation instruction of the second photovoltaic unit.

[0109] In addition, in order to ensure the accuracy of the secondary frequency regulation, the voltage regulation value may also be calculated for the first photovoltaic unit.

[0110] When the adjustment direction of the power adjustment instruction is power increase, the voltage adjustment instruction of the first photovoltaic unit is not calculated, and the voltage adjustment instruction is not sent to the first photovoltaic unit, so as to ensure that the first photovoltaic unit operates at the maximum power point.

[0111] When the adjustment direction of the power adjustment instruction is power reduction, the voltage adjustment value of the first photovoltaic unit is determined according to the power voltage curve and the power adjustment value in the power adjustment instruction, thereby obtaining the voltage adjustment instruction of the first photovoltaic unit. Afterwards, the voltage adjustment value in the voltage adjustment instruction can be directly superimposed on the voltage control value to obtain a corrected voltage control value, without the need to determine the adjustment direction of the voltage adjustment instruction.

[0112] In some embodiments, before determining the corrected voltage control value of the photovoltaic unit based on the voltage control value of the photovoltaic unit and the voltage regulation value in the voltage regulation instruction, the voltage regulation value in the voltage regulation instruction of the photovoltaic unit may be first-order filtered.

[0113] In order to prevent the PV unit from responding too quickly in the initial stage of AGC regulation, causing rapid frequency fluctuations and unnecessary primary frequency modulation or inertia response, the voltage regulation value can be filtered in the first order.

[0114] Optionally, this embodiment performs first-order filtering on the voltage regulation value in the voltage regulation instruction of the photovoltaic unit, which can be done by first obtaining the total inertia parameter of the thermal-photovoltaic power generation system composed of the thermal power unit and the photovoltaic power station, and the historical photovoltaic power station power instruction at the previous moment before the current moment; then determining the filtering time parameter based on the total inertia parameter, the historical photovoltaic power station power instruction at the previous moment and a preset frequency change rate action threshold; finally, filtering the voltage regulation value in the voltage regulation instruction of the photovoltaic unit based on the filtering time parameter and a preset first-order filtering transfer function.

[0115] Here, the first-order filter transfer function can be Among them, T AGC represents the filtering time parameter, and s represents the differential operator in the frequency domain.

[0116] Optionally, this embodiment determines the filtering time parameter according to the total inertia parameter, the historical photovoltaic power station power command at the previous moment and the preset frequency change rate action threshold, which can be based on the expression: Determine the filter time parameter; where T AGC represents the filtering time parameter, ΔP represents the power difference between the PV power station power command and the historical PV power station power command at the previous moment, ω N represents the rated angular frequency of the system, J represents the total inertia parameter, F def Indicates the frequency change rate action threshold.

[0117] Here, ω N The value of can be 314.15926.

[0118] In some embodiments, a combined thermal-solar secondary frequency modulation system is constructed, and three different simulation conditions are set. Condition 1 is that the thermal power unit responds to secondary frequency modulation alone, Condition 2 is that the thermal power unit and the photovoltaic power station jointly respond to secondary frequency modulation, which does not contain a first-order filtering link, and Condition 3 is that the thermal power unit and the photovoltaic power station jointly respond to secondary frequency modulation, which is the combined thermal-solar secondary frequency modulation method containing a first-order filtering link proposed in the above embodiment.

[0119] Figure 4 The effect diagram of the secondary frequency modulation response under the above three working conditions is shown in FIG. Figure 5 The following figure shows the influence of system frequency under three working conditions. Figure 4 and Figure 5It can be seen that in working condition 1, due to the too fast response of the photovoltaic power source, the system power is in excess, which leads to a frequency rise, and the frequency may exceed 50Hz, which may trigger a frequency modulation action of the thermal power unit or the photovoltaic power source, causing unnecessary frequency fluctuation events and frequency modulation costs. In working condition 2, by optimizing the dynamic response time constant of the AGC command of the photovoltaic power station, the power command tracking effect of the thermal power photovoltaic combination can be significantly improved, and the redundant action of the primary frequency modulation can be avoided, while the speed of frequency recovery to the frequency modulation dead zone can be increased.

[0120] The embodiment of the present invention determines the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment through the secondary frequency modulation instruction of the power grid dispatch and the thermal power of the thermal power unit at the current moment, and can hand over the part that the thermal power unit fails to respond in time to the photovoltaic power station, so that the photovoltaic power station can make up for the power difference between the thermal power output of the thermal power unit and the secondary frequency modulation instruction in a short time by using its own advantages of fast power control, and effectively improve the frequency modulation capability of the generator set; and then by decomposing the photovoltaic power station power instruction into the power adjustment value of each photovoltaic unit, and converting the power adjustment value into the voltage adjustment value, the photovoltaic power station power instruction can be converted into a voltage adjustment instruction that each photovoltaic unit can receive and respond to, thereby realizing the voltage regulation and control of the photovoltaic unit, so that each photovoltaic unit in the photovoltaic power station can quickly bear the power difference between the output of the thermal power unit and the secondary frequency modulation instruction, and accelerate the speed of frequency recovery. Among them, the voltage adjustment instruction is also first-order filtered to prevent the photovoltaic unit from causing rapid frequency fluctuations due to excessive power response in the initial stage of secondary frequency modulation, causing unnecessary primary frequency modulation or inertia response.

[0121] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0122] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0123] Figure 6 The structural diagram of the fire-light combined secondary frequency modulation device provided by an embodiment of the present invention is shown. For the convenience of description, only the part related to the embodiment of the present invention is shown, which is described in detail as follows:

[0124] like Figure 6 As shown, the fire-light combined secondary frequency modulation device 60 includes:

[0125] The acquisition module 61 is used to acquire the secondary frequency modulation instruction of the power grid dispatching and acquire the thermal power of the thermal power unit at the current moment;

[0126] The first determination module 62 is used to determine the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power power at the current moment, and obtain the photovoltaic power station power instruction based on the photovoltaic power station power;

[0127] A second determination module 63 is used to determine the power adjustment value of each photovoltaic unit in the photovoltaic power station and the corresponding power adjustment instruction according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station;

[0128] A conversion module 64, used to convert the power regulation value in the power regulation instruction into a voltage regulation value to obtain a voltage regulation instruction for each photovoltaic unit;

[0129] The control module 65 is used to determine the voltage control instructions of each photovoltaic unit based on the voltage regulation instructions and the operation mode of each photovoltaic unit, and control the corresponding photovoltaic unit according to the voltage control instructions.

[0130] In a possible implementation, the operation mode of the photovoltaic unit includes maximum power point operation and variable power tracking operation; the photovoltaic unit includes a first photovoltaic unit operating at the maximum power point and a second photovoltaic unit operating at the variable power tracking operation;

[0131] The second determining module 63 is specifically used for:

[0132] Determine the adjustment direction of the photovoltaic power station power command;

[0133] If the adjustment direction of the power instruction of the photovoltaic power station is the direction of power reduction, a first power adjustment value that needs to be reduced for each photovoltaic unit in the photovoltaic power station is calculated according to the power of the photovoltaic power station, the number of the first photovoltaic units, and the number of the second photovoltaic units; and a first power adjustment instruction for each photovoltaic unit is generated based on the first power adjustment value;

[0134] If the adjustment direction of the photovoltaic power station power instruction is the direction of power increase, the second power adjustment value that needs to be increased for each photovoltaic unit in the photovoltaic power station is calculated according to the photovoltaic power station power and the number of second photovoltaic units; and the second power adjustment instruction for each photovoltaic unit is generated based on the second power adjustment value.

[0135] In a possible implementation, the conversion module 64 is specifically configured to:

[0136] Obtain the current photovoltaic power and current photovoltaic voltage of each photovoltaic unit in the photovoltaic power station;

[0137] Determine the power-voltage curve of the photovoltaic unit in the photovoltaic power station according to the current photovoltaic power and the current photovoltaic voltage;

[0138] Determine the voltage regulation value of each photovoltaic unit according to the power voltage curve and the power regulation value in the power regulation instruction;

[0139] Based on the voltage regulation value of each photovoltaic unit, a voltage regulation instruction of each photovoltaic unit is generated.

[0140] In a possible implementation, the control module 65 is specifically configured to:

[0141] Obtain the voltage control value of each photovoltaic unit in the photovoltaic power station at the current moment;

[0142] For each photovoltaic unit, determining an operation mode of the photovoltaic unit;

[0143] If the operation mode of the photovoltaic unit is variable power tracking operation, a corrected voltage control value of the photovoltaic unit is determined according to the voltage control value of the photovoltaic unit and the voltage regulation value in the voltage regulation instruction;

[0144] If the operation mode of the photovoltaic unit is the maximum power point operation, then determine whether the adjustment direction of the voltage adjustment instruction is the direction of voltage increase; if the adjustment direction of the voltage adjustment instruction is the direction of voltage increase, then determine the corrected voltage control value of the photovoltaic unit according to the voltage control value of the photovoltaic unit and the voltage adjustment value in the voltage adjustment instruction; if the adjustment direction of the voltage adjustment instruction is the direction of voltage decrease, then use the voltage control value of the photovoltaic unit as the corrected voltage control value of the photovoltaic unit;

[0145] Determining a voltage control instruction for the photovoltaic unit based on the modified voltage control value;

[0146] The voltage control instruction of the photovoltaic unit is used as an input signal of the inverter voltage outer loop of the photovoltaic unit to control the photovoltaic unit.

[0147] In a possible implementation, the control module 65 is further configured to:

[0148] Re-acquire the thermal power of the thermal power unit at the current moment, and re-execute the steps of determining the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power at the current moment, and obtaining the photovoltaic power station power instruction based on the photovoltaic power station power and subsequent steps, until the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment is zero.

[0149] In a possible implementation, the control module 65 is specifically configured to:

[0150] A first-order filtering is performed on the voltage regulation value in the voltage regulation command of the photovoltaic unit.

[0151] In a possible implementation, the control module 65 is specifically configured to:

[0152] Obtain the total inertia parameters of the thermal-solar power generation system composed of the thermal power unit and the photovoltaic power station, as well as the historical photovoltaic power station power command at the moment before the current moment;

[0153] Determine the filtering time parameter according to the total inertia parameter, the historical photovoltaic power station power command at the previous moment and the preset frequency change rate action threshold;

[0154] Based on the filtering time parameter and a preset first-order filtering transfer function, the voltage regulation value in the voltage regulation instruction of the photovoltaic unit is filtered.

[0155] In a possible implementation, the secondary frequency modulation instruction includes a secondary frequency modulation power;

[0156] The first determining module 62 is specifically used for:

[0157] Calculate the difference between the secondary frequency modulation power and the thermal power power at the current moment;

[0158] The difference is determined as the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment.

[0159] In a possible implementation, the control module 65 is specifically configured to:

[0160] According to the expression: Determine the filter time parameters;

[0161] Where, T AGC represents the filtering time parameter, ΔP represents the power difference between the PV power station power command and the historical PV power station power command at the previous moment, ω N represents the rated angular frequency of the system, J represents the total inertia parameter, F def Indicates the frequency change rate action threshold.

[0162] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0163] Those of ordinary skill in the art will appreciate that the templates, units, and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can 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.

[0164] If the module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. Computer-readable media may include: any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0165] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. A fire-light combined secondary frequency modulation method, characterized in that: include: Obtain the secondary frequency regulation instruction of the power grid dispatch and obtain the thermal power of the thermal power unit at the current moment; Determine the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power power at the current moment, and obtain the photovoltaic power station power instruction based on the photovoltaic power station power; Determining a power adjustment value and a corresponding power adjustment instruction for each photovoltaic unit in the photovoltaic power station according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station; Converting the power regulation value in the power regulation instruction into a voltage regulation value to obtain a voltage regulation instruction for each photovoltaic unit; Based on the voltage regulation instruction and the operation mode of each photovoltaic unit, the voltage control instruction of each photovoltaic unit is determined respectively, and the corresponding photovoltaic unit is controlled according to the voltage control instruction.

2. The fire-light combined secondary frequency modulation method according to claim 1 is characterized in that: The operation modes of the photovoltaic unit include maximum power point operation and variable power tracking operation; the photovoltaic unit includes a first photovoltaic unit operating at the maximum power point and a second photovoltaic unit operating at the variable power tracking operation; Determining the power adjustment value of each photovoltaic unit in the photovoltaic power station and the corresponding power adjustment instruction according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station includes: Determining the adjustment direction of the photovoltaic power station power instruction; If the adjustment direction of the photovoltaic power station power instruction is the direction of power reduction, then according to the photovoltaic power station power, the number of the first photovoltaic units and the number of the second photovoltaic units, a first power adjustment value that needs to be reduced for each photovoltaic unit in the photovoltaic power station is calculated; and based on the first power adjustment value, a first power adjustment instruction for each photovoltaic unit is generated; If the adjustment direction of the photovoltaic power station power instruction is the direction of power increase, the second power adjustment value that needs to be increased for each photovoltaic unit in the photovoltaic power station is calculated based on the photovoltaic power station power and the number of the second photovoltaic units; and the second power adjustment instruction for each photovoltaic unit is generated based on the second power adjustment value.

3. The fire-light combined secondary frequency modulation method according to claim 1 is characterized in that: Converting the power regulation value in the power regulation instruction into a voltage regulation value to obtain a voltage regulation instruction for each photovoltaic unit includes: Obtaining the current photovoltaic power and current photovoltaic voltage of each photovoltaic unit in the photovoltaic power station; Determining a power-voltage curve of a photovoltaic unit in the photovoltaic power station according to the current photovoltaic power and the current photovoltaic voltage; Determining a voltage regulation value of each photovoltaic unit according to the power voltage curve and the power regulation value in the power regulation instruction; Based on the voltage regulation value of each photovoltaic unit, a voltage regulation instruction of each photovoltaic unit is generated.

4. The fire-light combined secondary frequency modulation method according to claim 1 is characterized in that: Based on the voltage regulation instruction and the operation mode of each photovoltaic unit, the voltage control instruction of each photovoltaic unit is determined respectively, and the corresponding photovoltaic unit is controlled according to the voltage control instruction, including: Obtaining a voltage control value of each photovoltaic unit in the photovoltaic power station at the current moment; For each photovoltaic unit, determining an operation mode of the photovoltaic unit; If the operation mode of the photovoltaic unit is variable power tracking operation, a corrected voltage control value of the photovoltaic unit is determined according to the voltage control value of the photovoltaic unit and the voltage regulation value in the voltage regulation instruction; If the operation mode of the photovoltaic unit is the maximum power point operation, then determine whether the adjustment direction of the voltage adjustment instruction is the direction of voltage increase; if the adjustment direction of the voltage adjustment instruction is the direction of voltage increase, then determine the corrected voltage control value of the photovoltaic unit according to the voltage control value of the photovoltaic unit and the voltage adjustment value in the voltage adjustment instruction; if the adjustment direction of the voltage adjustment instruction is the direction of voltage decrease, then use the voltage control value of the photovoltaic unit as the corrected voltage control value of the photovoltaic unit; Determining a voltage control instruction for the photovoltaic unit based on the modified voltage control value; The voltage control instruction of the photovoltaic unit is used as an input signal of the inverter voltage outer loop of the photovoltaic unit to control the photovoltaic unit.

5. The fire-light combined secondary frequency modulation method according to claim 4 is characterized in that: After determining the voltage control instructions of each photovoltaic unit based on the voltage regulation instruction and the operation mode of each photovoltaic unit, and controlling the corresponding photovoltaic unit according to the voltage control instruction, the method further includes: Re-acquire the thermal power of the thermal power unit at the current moment, and re-execute the steps of determining the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power at the current moment, and obtaining the photovoltaic power station power instruction based on the photovoltaic power station power and subsequent steps, until the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment is zero.

6. The fire-light combined secondary frequency modulation method according to claim 5 is characterized in that: Before determining the modified voltage control value of the photovoltaic unit according to the voltage control value of the photovoltaic unit and the voltage regulation value in the voltage regulation instruction, the method further includes: A first-order filtering is performed on the voltage regulation value in the voltage regulation command of the photovoltaic unit.

7. The fire-light combined secondary frequency modulation method according to claim 6 is characterized in that: The first-order filtering of the voltage regulation value in the voltage regulation instruction of the photovoltaic unit includes: Obtaining a total inertia parameter of a thermal photovoltaic power generation system composed of the thermal power generation unit and the photovoltaic power station, and a historical photovoltaic power station power instruction at a moment before the current moment; Determine the filtering time parameter according to the total inertia parameter, the historical photovoltaic power station power command at the previous moment and the preset frequency change rate action threshold; Based on the filtering time parameter and a preset first-order filtering transfer function, the voltage regulation value in the voltage regulation instruction of the photovoltaic unit is filtered.

8. The fire-light combined secondary frequency modulation method according to any one of claims 1 to 7, characterized in that: The secondary frequency modulation instruction includes a secondary frequency modulation power; According to the secondary frequency modulation instruction and the thermal power at the current moment, the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment is determined, including: Calculating the difference between the secondary frequency modulation power and the thermal power at the current moment; The difference is determined as the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment.

9. The fire-light combined secondary frequency modulation method according to claim 7, characterized in that: According to the total inertia parameter, the historical photovoltaic power station power command at the previous moment and the preset frequency change rate action threshold, the filtering time parameter is determined, including: According to the expression: Determine the filter time parameters; Where, T AGC represents the filtering time parameter, ΔP represents the power difference between the photovoltaic power station power instruction and the historical photovoltaic power station power instruction at the previous moment, ω N represents the rated angular frequency of the system, J represents the total inertia parameter, F def Indicates the frequency change rate action threshold.

10. A fire-light combined secondary frequency modulation device, characterized in that: include: An acquisition module is used to obtain the secondary frequency modulation instruction of the power grid dispatch and obtain the thermal power of the thermal power unit at the current moment; A first determination module is used to determine the photovoltaic power station power that the photovoltaic power station needs to bear at the current moment according to the secondary frequency modulation instruction and the thermal power power at the current moment, and obtain the photovoltaic power station power instruction based on the photovoltaic power station power; A second determination module is used to determine the power adjustment value and the corresponding power adjustment instruction of each photovoltaic unit in the photovoltaic power station according to the photovoltaic power station power instruction and the number of photovoltaic units in the photovoltaic power station; A conversion module, used to convert the power adjustment value in the power adjustment instruction into a voltage adjustment value to obtain a voltage adjustment instruction for each photovoltaic unit; The control module is used to determine the voltage control instructions of each photovoltaic unit based on the voltage regulation instructions and the operation mode of each photovoltaic unit, and control the corresponding photovoltaic unit according to the voltage control instructions.

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