A frequency active support method and power control device suitable for new energy and energy storage stations

Abstract

The present invention discloses an active frequency support method and a power control device suitable for new energy and energy storage stations. By simulating the inertia response and primary adjustment of conventional thermal and hydroelectric generating units to the grid frequency, the corresponding active output is coordinated with the AGC output already possessed by the original station, thereby realizing the response of the new energy and energy storage stations to the grid frequency changes at multiple time scales. The present invention provides a solution to the problem of missing inertia support and primary frequency regulation on the power supply side under the background of increased penetration of new energy. By utilizing the advantage of fast dynamic response speed of power electronic equipment in the station, a faster frequency response capability than conventional thermal and hydroelectric generating units can be obtained, and the grid can be better supported in practical applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric power automation new energy secondary system, and specifically relates to an active frequency support method and a power control device suitable for new energy and energy storage stations. Background Art

[0002] In recent years, with the large-scale access to the power grid of new energy power stations such as wind power, photovoltaic power stations and battery energy storage power stations, the proportion of new energy and energy storage in the power grid has continued to increase. However, new energy and energy storage also have their inherent defects. Traditional thermal power and hydropower units have the ability to change output and suppress frequency changes through their own inertia and speed regulators when the grid frequency changes, that is, inertia support and primary frequency regulation capabilities; while the power components of new energy and energy storage power electronic devices are static devices, which do not have inertia support and primary frequency regulation capabilities, and can only passively accept frequency changes, and cannot actively respond to frequency changes.

[0003] In recent years, the penetration rate of new energy and energy storage in the power grid has continued to increase, and the inertia and primary frequency regulation response capabilities of the source end have continued to decline, resulting in a decrease in the stability of the power grid. The frequency of the power grid has changed more and faster due to insufficient response support. This situation increases the possibility of power grid frequency failure or even collapse. In the face of changes in power grid frequency, simply cutting off new energy and energy storage will not only cause a waste of new energy and energy storage resources, but also greatly reduce their utilization rate. Due to the high construction costs of new energy (wind farms and photovoltaic power stations occupy livestock land) and energy storage (high power density batteries are expensive) stations, low utilization will greatly increase the green premium of the electricity they generate, which is not conducive to the sustainable development of new energy and energy storage.

[0004] Most new energy and energy storage stations now have AGC functions. By receiving active power instructions from dispatch, they can achieve secondary adjustment of the grid frequency similar to the synchronizers (frequency regulators) of thermal power and hydropower units to achieve zero-difference frequency regulation, but the response to the grid frequency is still slightly single. Some wind power converters, photovoltaic inverters, and energy storage PCS manufacturers use virtual synchronization technology to simulate the inertia characteristics and active power-frequency droop curves of thermal power and hydropower units to achieve the inertia support and primary frequency regulation functions of a single machine. However, the capacity of new energy and energy storage units is one thousandth of that of traditional large-scale thermal power and hydropower units, and the support effect on the grid frequency is minimal. Therefore, most new energy and energy storage stations have not invested in the virtual synchronization function of a single machine as expected. Therefore, the active frequency support of new energy and energy storage stations is still an urgent problem to be solved. Summary of the invention

[0005] Purpose of the invention: In order to solve the problem that the virtual synchronization of a single machine cannot well reflect the frequency support effect of new energy and energy storage stations, the present invention proposes a frequency active support method suitable for new energy and energy storage stations, and realizes frequency response through the total capacity of the whole station unit. The whole station capacity of new energy and energy storage stations is generally tens of MVA to hundreds of MVA, which is close to the unit capacity of a medium-sized thermal power plant. Multiple stations in parallel perform frequency response at the same time, which can improve the frequency support effect on the power grid.

[0006] Technical solution: A frequency active support method applicable to new energy and energy storage stations, comprising the following steps:

[0007] Step 1: Based on the grid connection point frequency f, grid connection point frequency change rate df / dt, grid connection point real-time active power P pcc Determine whether the inertia response conditions are met; if the inertia response conditions are met, calculate the simulated inertia response active power command ΔP iner , execute step 2; otherwise, simulate the inertia response active power command ΔP iner =0, go to step 2;

[0008] Step 2: According to the frequency change of the grid connection point, determine whether the conditions for a primary frequency modulation response are met. If so, calculate the primary frequency modulation response instruction ΔP gov , execute step 3, otherwise no frequency modulation response is performed;

[0009] Step 3: During a frequency modulation period, determine whether a new AGC command is received. If no new AGC command is received, obtain the total active power command P=P′ agc +ΔP gov +ΔP iner ; If a new AGC instruction P is received agc , then the new AGC instruction P agc and the previous AGC instruction P′ agc For comparison, when the frequency is disturbed (f<f L ), if P agc >P′ agc , then the total active power command P = P agc +ΔP gov +ΔP iner Otherwise, the total active power command P = P' agc +ΔP gov +ΔP iner , when disturbed in frequency (f>f H ), if P agc <P′ agc , then the total active power command P = P agc +ΔP gov +ΔP inerOtherwise, the total active power command P = P' agc +ΔP gov +ΔP iner ;

[0010] Step 4: Issue the total active power command.

[0011] Furthermore, in step 1, the inertia response condition is:

[0012]

[0013] And when the absolute value of the frequency change rate |df / dt| is greater than the dead zone R of the frequency change rate fd And the real-time active power P of the grid-connected point pcc Greater than C act P e , where C act is the minimum inertia response threshold of the real-time active power at the grid-connected point, P e is the rated active power of the entire station.

[0014] Furthermore, in step 1, if the inertia response condition is met, the simulated inertia response active power command ΔP is calculated according to the following formula: iner ;

[0015]

[0016] In the formula, f e is the rated frequency, T j is the inertia time constant.

[0017] Furthermore, in step 2, the condition for the primary frequency modulation response is: the frequency change at the grid connection point exceeds the dead zone f of the regulation characteristic curve d .

[0018] Furthermore, in step 2, if the primary frequency modulation response condition is met, the primary frequency modulation response instruction ΔP is calculated according to the following formula: gov :

[0019]

[0020]

[0021] In the formula, f L is the interference threshold at frequency, f H is the frequency interference threshold.

[0022] Furthermore, when facing new energy stations, the coefficient C is used in and coefficient C out The response command ΔP to the primary frequency modulation gov Constraints are made, where C in >Cout ; Specifically:

[0023] Only when the grid frequency f>f H And the real-time active power P of the grid-connected point pcc <C out P e When ΔP gov =0;

[0024] Only when the grid frequency f>f H And the real-time active power P of the grid-connected point pcc ≥C out P e And P pcc <C in P e hour:

[0025] ΔP gov =C out P e -P Pcc (ΔP gov <0) (9).

[0026] The present invention also discloses a power control device, which is used to be deployed in a secondary grid structure of a station having an AGC function, and comprises:

[0027] The inertia response unit is used to calculate the inertia response according to the grid connection point frequency f, the grid connection point frequency change rate df / dt and the grid connection point real-time active power P pcc Determine whether the inertia response conditions are met; if the inertia response conditions are met, calculate the simulated inertia response active power command ΔP iner ; If the inertia response condition is not met, the simulated inertia response active power command ΔP iner =0;

[0028] The primary frequency modulation response unit is used to determine whether the conditions for primary frequency modulation response are met according to the frequency change of the grid connection point. If so, the primary frequency modulation response instruction ΔP is calculated. gov , otherwise no frequency modulation response is performed.

[0029] Furthermore, they are deployed serially or in parallel in the secondary grid structure of the station that already has the AGC function.

[0030] Furthermore, the inertia response condition is:

[0031]

[0032] And when the absolute value of the frequency change rate |df / dt| is greater than the dead zone R of the frequency change rate fd And the real-time active power P of the grid-connected point pcc Greater than C act Pe , where C ac t is the minimum inertia response threshold of the real-time active power at the grid connection point, P e is the rated active power of the entire station.

[0033] If the inertia response conditions are met, the simulated inertia response active power command ΔP can be calculated according to the following formula: iner ;

[0034]

[0035] In the formula, f e is the rated frequency, T j is the inertia time constant.

[0036] Furthermore, the frequency change at the grid connection point exceeds the dead zone f of the regulation characteristic curve. d ;

[0037] If available, the primary frequency modulation response command ΔP can be calculated according to the following formula: gov :

[0038]

[0039]

[0040] In the formula, f L is the interference threshold at frequency, f H is the frequency interference threshold.

[0041] Furthermore, when deployed in a secondary grid structure of a wind farm / photovoltaic power station that already has an AGC function, the coefficient C in and coefficient C out The response command ΔP to the primary frequency modulation gov Constraints are made, where C in >C out ; Specifically:

[0042] Only when the grid frequency f>f H And the real-time active power P of the grid-connected point pcc <C out P e When ΔP gov =0;

[0043] Only when the grid frequency f>f H And the real-time active power P of the grid-connected point pcc ≥C out P e And P pcc <C in P e hour:

[0044] ΔPgov =C out P e -P Pcc (ΔP gov <0) (9).

[0045] The present invention also discloses a wind farm grid structure, including a fast power control device, an EMS for sending AGC instructions, a wind turbine energy management system and various wind turbine sets;

[0046] The fast power control device is serially deployed between the EMS and the wind turbine energy management system, and is used to implement inertia response and primary frequency modulation by adopting the above-disclosed active frequency support method applicable to new energy and energy storage stations, and forwarding the AGC command sent by the EMS to the wind turbine energy management system;

[0047] The wind turbine energy management system is used to issue detailed instructions to each wind turbine set.

[0048] The present invention discloses a wind farm grid structure, including a fast power control device, an EMS for issuing AGC instructions to a wind turbine energy management system and the fast power control device, a wind turbine energy management system and each wind turbine set;

[0049] The fast power control device is deployed in parallel with the EMS, and is used to implement inertia response and primary frequency modulation by adopting the above-disclosed frequency active support method applicable to new energy and energy storage stations; and when it is detected that the frequency of the grid connection point enters the inertia response or primary frequency modulation range, a signal is sent to lock the EMS, and at the same time, a simulated inertia response active power instruction or a primary frequency modulation response instruction is sent and superimposed with an AGC instruction and sent to the wind turbine energy management system; and when the inertia response or primary frequency modulation ends, a release signal is sent to the EMS;

[0050] The wind turbine energy management system is used to issue detailed instructions to each wind turbine set.

[0051] The invention discloses a photovoltaic power station grid structure, including a fast power control device, an AGC and a photovoltaic communication management unit;

[0052] The fast power control device is deployed in series with the AGC, and is used to adopt the above-disclosed frequency active support method applicable to new energy and energy storage stations to perform inertia response or primary frequency modulation. When the grid connection point frequency enters the inertia response or primary frequency modulation range, the simulated inertia response active power instruction and the primary frequency modulation response instruction are sent to the AGC, and then the AGC performs instruction superposition and sends them to the photovoltaic communication management unit;

[0053] The photovoltaic communication management unit is used to send subdivision instructions to the corresponding photovoltaic inverter.

[0054] The invention discloses a photovoltaic power station grid structure, including a fast power control device, an AGC and a photovoltaic communication management unit;

[0055] The AGC is used to send steady-state instructions to the photovoltaic communication management unit and the fast power control device simultaneously when the frequency of the grid connection point is within the normal range;

[0056] The fast power control device is deployed in parallel with the AGC, and is used to adopt the above-disclosed frequency active support method applicable to new energy and energy storage stations to perform inertia response or primary frequency modulation, and when the grid connection point frequency enters the inertia response or primary frequency modulation range, send a signal to the AGC to lock its steady-state instruction, and at the same time superimpose the AGC instruction and send it to the photovoltaic communication management unit; and when the inertia response or primary frequency modulation ends, send a signal to the AGC to release the steady-state instruction lock, and at the same time lock the instruction issued by itself;

[0057] The photovoltaic communication management unit is used to send subdivision instructions to the corresponding photovoltaic inverter.

[0058] The present invention discloses a grid structure of an energy storage power station, including an energy storage coordination controller, an EMS for issuing AGC instructions, and an energy storage PCS;

[0059] The energy storage coordination controller is deployed in series between the EMS and the energy storage PCS, and is used to adopt the above-disclosed active frequency support method applicable to new energy and energy storage stations to perform inertia response or primary frequency modulation, and forward the AGC instructions of the EMS to the energy storage PCS.

[0060] The present invention also discloses a grid structure of an energy storage power station, including an energy storage coordination controller, an EMS and an energy storage PCS;

[0061] The EMS is used to send AGC to the PCS and the energy storage coordination controller when the frequency of the grid connection point is within the normal range;

[0062] The energy storage coordination controller and the EMS are deployed in parallel, and are used to block the instructions issued by themselves when the frequency of the grid connection point is within the normal range, and adopt the above-disclosed frequency active support method applicable to new energy and energy storage stations to perform inertia response or primary frequency modulation, and when the frequency of the grid connection point enters the inertia response or primary frequency modulation range, send a signal to the EMS to block its AGC instruction, and superimpose the AGC instruction on the simulated inertia response active instruction or the primary frequency modulation response instruction and send it to the energy storage PCS; and when the inertia response or the primary frequency modulation is completed, send a release signal to the EMS to allow it to continue to issue the AGC instruction, and lock the instructions issued by itself.

[0063] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0064] (1) The present invention utilizes the millisecond-level rapid response characteristics of power electronic devices to rapidly increase or decrease active output when the grid frequency changes significantly, thereby realizing inertia support and primary frequency regulation functions similar to those of thermal power and hydropower units, and obtaining faster frequency response capabilities than conventional thermal power and hydropower units, which can better support the grid in practical applications;

[0065] (2) The present invention enables new energy and energy storage stations to increase inertia response and primary adjustment capabilities based on the secondary adjustment capabilities of the grid frequency. The all-round response at multiple time scales enhances their support capabilities for the grid frequency, and provides a solution to the problems of power supply side inertia support and primary frequency regulation deficiency in the context of increasing new energy penetration. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 Active power-frequency droop curve diagram for new energy and energy storage station grid connection points;

[0067] Figure 2 Active support algorithm flow chart for new energy and energy storage station frequency;

[0068] Figure 3 It is a frequency response curve diagram of the wind farm grid connection point; wherein, sub-figure (1) is the frequency response curve diagram of the wind farm grid connection point under the frequency of 50Hz→49.8Hz+AGC minus 6%Pe; sub-figure (2) is the frequency response curve diagram of the wind farm grid connection point under the frequency of 50Hz→49.8Hz+AGC plus 6%Pe; sub-figure (3) is the frequency response curve diagram of the wind farm grid connection point under the frequency of 50Hz→50.2Hz+AGC minus 6%Pe; sub-figure (4) is the frequency response curve diagram of the wind farm grid connection point under the frequency of 50Hz→50.2Hz+AGC plus 6%Pe;

[0069] Figure 4 The figure is a deployment scenario of a new energy station rapid power control device in a wind farm; wherein sub-figure (1) is deployment scenario 1, and sub-figure (2) is deployment scenario 2;

[0070] Figure 5 The figure is a deployment scenario of a new energy station rapid power control device in a photovoltaic power station; wherein sub-figure (1) is deployment scenario 1, and sub-figure (2) is deployment scenario 2;

[0071] Figure 6 The following are deployment scenarios of the energy storage coordination controller in the energy storage power station; among them, sub-graph (1) is deployment scenario 1, and sub-graph (2) is deployment scenario 2. DETAILED DESCRIPTION

[0072] The technical solution of the present invention is now further described in conjunction with the accompanying drawings and embodiments.

[0073] In the scenario of traditional thermal power and hydropower units with rotational inertia, grid disturbances will cause frequency changes, which can be expressed as the following rotor motion equation:

[0074]

[0075] In the above formula, P gen is the generator output, P load is the active power consumed by the load, and J is the generator moment of inertia, which is a constant value.

[0076] The inertia constant H of the generator can be defined as the ratio of the rotor stored kinetic energy to the rated power of the unit. It is a time value and can be expressed as follows:

[0077]

[0078] Substituting equation (2) into equation (1) and replacing the generator moment of inertia J, the rotor motion equation with inertia constant H can be obtained:

[0079]

[0080] The inertia time constant T j =2H Substituting the inertia constant, we can get:

[0081]

[0082] The impact of grid disturbance on frequency can be seen from equation (4).

[0083] When the load increases, the grid frequency will decrease because the generator output has no time to change; when the load decreases, the grid frequency will increase.

[0084] New energy and energy storage stations can simulate the inertia characteristics of thermal power and hydropower units. When faced with grid connection point disturbances, they can apply an output in the opposite direction of the frequency change to the grid connection point to prevent frequency changes.

[0085] According to formula (5), the active power command of the simulated inertia response of the station can be directly obtained:

[0086]

[0087] The station should provide the simulated inertia response of the frequency under the condition that the following formula is satisfied:

[0088]

[0089] There are two other practical situations that need to be considered. First, to prevent the system from being too sensitive to frequency changes, a dead zone R of the frequency change rate needs to be set. fd ; Second, to prevent the unit from shutting down during the response process, a minimum inertia response threshold C of the station's real-time active power needs to be setact That is, when the absolute value of the frequency change rate |df / dt| is greater than R fd And the real-time active power of the station is greater than C act P e The station only provides simulated inertia response when the

[0090] Figure 1 It is the active power-frequency droop curve of the grid connection point of the new energy and energy storage station. This curve is a static regulation characteristic simulated according to the local load characteristics. d To adjust the dead zone of the characteristic curve, that is, if the frequency change at the grid connection point does not exceed this value, no frequency modulation response will be performed; kP e (k<1) is the spare capacity reserved by the station for primary frequency regulation.

[0091] According to the definition of per unit value of the adjustment coefficient, we can get:

[0092]

[0093] Among them, when the grid connection point frequency f<f L And in the linear regulation area, Δf=f L -f; when the frequency of the grid connection point f>f H And in the linear regulation area, Δf=f H -f. From the above formula, we can get the primary frequency modulation active power instruction ΔP when the change of the grid connection point frequency exceeds the rated frequency and exceeds the dead zone. gov for:

[0094]

[0095] In order to avoid the generator set or converter in the station from being disconnected or shut down due to primary frequency regulation, it is necessary to give ΔP gov Adding constraints, two coefficients C are given here in and C out , and C in >C out When the power of the station is connected to the grid, P pcc <C out P e , and when the frequency is disturbed (f>f H ), it is forbidden to adjust the output downward, that is, ΔP gov =0; when the grid power P pcc ≥C out P e At the same time pcc <C in P e , and when the frequency is disturbed, the total active output cannot be lower than C out P e , at this time, the frequency modulation active power instruction cannot exceed:

[0096] ΔP gov =C out P e -P Pcc (ΔP gov <0) (9)

[0097] The above constraints apply to wind farms and photovoltaic power plants. The converter of the energy storage power plant does not need to be constrained by ΔP because power can flow in both directions. gov Make the above constraints.

[0098] Inertia response and primary frequency modulation need to be coordinated with AGC to ensure the continuity of frequency response at multiple time scales. Inertia response and primary frequency modulation have a time interval in which they act simultaneously, but they can be independent of each other in current theoretical analysis.

[0099] First, determine whether to enter inertia response based on the frequency and its change rate of the station grid connection point and the real-time active power of the grid connection point. If the inertia response conditions are met, the inertia response command value can be calculated by formula (5). Then make a judgment on the primary frequency modulation. Whether to enter the primary frequency modulation only involves the judgment of the grid connection point frequency, but the primary frequency modulation stage needs to cooperate with AGC. The primary frequency modulation response command can be calculated according to formulas (8) and (9), and then the coordination logic with AGC is performed. If a new AGC command is received during the primary frequency modulation, the new AGC command P agc and the previous AGC instruction P′ agc For comparison. When disturbed at frequency (f<f L ), such as P agc >P′ agc , total active power command P = P agc +ΔP gov +ΔP iner ; such as P agc ≤P′ agc , total active power command P = P' agc +ΔP gov +ΔP iner ; When disturbed in frequency (f>f H ), such as P agc <P′ agc , total active power command P = P agc +ΔP gov +ΔP iner ; such as P agc ≥P′ agc , total active power command P = P' agc +ΔP gov +ΔP iner .

[0100] The process of the proposed new energy and energy storage station frequency active support algorithm is shown in Figure 2 .

[0101] In order to achieve multi-time scale response of grid frequency in new energy and energy storage stations, it is necessary to improve the existing secondary communication architecture and add inertia response and primary frequency modulation on the basis of AGC. The algorithm of the present invention is implemented on the developed new energy station fast power control device and energy storage coordination controller, and the device is deployed in the secondary grid structure of the station that already has AGC function. The deployment mode is generally divided into two modes: serial and parallel.

[0102] The EMS of the wind farm is deployed at the station control layer. It receives dispatch instructions through the remote motor and sends AGC instructions to the wind turbine energy management system. The wind turbine energy management system then sends detailed instructions to each wind turbine. Figure 4 son Figure 1 ) The new energy station rapid power control device is deployed serially between the EMS and the wind turbine energy management system. In addition to realizing the inertia response and primary frequency regulation functions, the device also needs to forward the AGC instructions sent by the EMS. Figure 4 son Figure 2 ) The device and EMS are deployed in parallel. When the EMS sends an AGC instruction to the fan energy management system, the device receives the AGC instruction and locks the instruction. When it is detected that the grid connection point frequency enters the inertia response or primary frequency modulation range, the device sends a signal to lock the EMS, and at the same time sends an inertia response or primary frequency modulation instruction and superimposes the AGC and sends it to the fan energy management system. When the inertia response or primary frequency modulation ends, the device sends a release signal to the EMS, and the EMS continues to send AGC instructions to the fan energy management system. At this time, the device locks the instructions issued by itself.

[0103] The AGC of the photovoltaic power station is deployed at the station control layer, receives dispatching instructions through the remote motor, and sends them to each communication management unit of the photovoltaic array. Figure 5 son Figure 1 ), when the new energy station rapid power control device is in inertia response or primary frequency regulation, it sends the inertia response and primary frequency regulation adjustment instructions to the AGC, and then the AGC superimposes the instructions and sends them to the photovoltaic communication management unit. Figure 5 son Figure 2 ) The device and AGC are deployed in parallel. When the frequency of the grid-connected point is within the normal range, the AGC sends steady-state instructions to the photovoltaic communication management unit and the fast power control device at the same time, and the device locks the instructions issued by itself; when the frequency of the grid-connected point enters the inertia response or primary frequency modulation range, the fast power control device sends a signal to the AGC to lock its steady-state instructions, and at the same time superimposes the AGC instructions and sends them to the photovoltaic communication management unit; when the inertia response or primary frequency modulation ends, the device sends a signal to the AGC to release the steady-state instruction block, and at the same time locks the instructions issued by itself.

[0104] The EMS of the energy storage power station is deployed at the station control layer, receives dispatch instructions through the remote motor, and sends them to each PCS. Figure 6 son Figure 1 ), the energy storage coordination controller is deployed serially between the EMS and PCS. In addition to inertia response and primary frequency modulation, the coordination controller also needs to forward the AGC instructions of the EMS. The coordination control of the GOOSE fast response channel to the PCS can greatly enhance the active support effect of the frequency of the grid connection point. Figure 6 son Figure 2 ), the energy storage cooperative control and EMS are deployed in parallel. When the frequency at the grid-connected point is within the normal range, the EMS sends AGC to the PCS and cooperative control, and the cooperative control blocks the instructions issued by itself; when the frequency enters the inertia response or primary frequency modulation range, the cooperative control sends a signal to the EMS to block its AGC instructions. At this time, the cooperative control superimposes the AGC instructions on the inertia response or primary frequency modulation adjustment instructions and sends them to the PCS; when the inertia response or primary frequency modulation ends, the cooperative control sends a release signal to the EMS to allow it to continue to issue AGC instructions, and at the same time blocks the instructions issued by itself.

[0105] The algorithm of the present invention is implemented on the developed new energy station fast power control device and energy storage coordination controller, and has begun to be applied to wind farms and energy storage power stations respectively.

[0106] The test waveform of the wind farm in Pizhou, Jiangsu Province, which has been put into operation, is analyzed. This wind farm has put into operation the primary frequency regulation function, but not the inertia response function. The total capacity of the wind farm is 90MVA; the primary frequency regulation reserve active power is 6%, i.e. 5.4MW; the differential coefficient is 0.05; and the frequency dead zone is 0.1Hz.

[0107] 1) Frequency 50Hz→49.8Hz+AGC minus 6%P e

[0108] like Figure 3 son Figure 1 ), when the grid-connected point frequency is 50Hz, the active power command is 30MW, following the AGC command; after the frequency drops to 49.8Hz, it enters the primary frequency modulation. At this time, the active power command is superimposed with the primary frequency modulation active power command of 3.6MW on the basis of the real-time output of the grid-connected point, and the active power command rises to 33.6MW; during the primary frequency modulation, the AGC command is reduced to 25MW, and the AGC change direction is opposite to the primary frequency modulation active power command direction. At this time, the AGC command change is ignored and the previous active power command value is maintained; after the frequency returns to 50Hz, the active power command follows the latest AGC command value and becomes 25MW.

[0109] 2) Frequency 50Hz→49.8Hz+AGC increase 6%P e

[0110] like Figure 3 son Figure 2), when the grid-connected point frequency is 50Hz, the active power command is 30MW, following the AGC command; after the frequency drops to 49.8Hz, it enters the primary frequency modulation. At this time, the active power command is superimposed with the primary frequency modulation active power command of 3.6MW on the basis of the real-time output of the grid-connected point, and the active power command rises to 33.6MW; during the primary frequency modulation, the AGC command rises to 35.4MW, and the AGC change direction is the same as the primary frequency modulation active power command direction. At this time, the new AGC command is superimposed with the primary frequency modulation active power command, and the active power command rises to 39MW; after the frequency returns to 50Hz, the active power command follows the latest AGC command value and becomes 35.4MW.

[0111] 3) Frequency 50Hz→50.2Hz+AGC minus 6%P e

[0112] like Figure 3 son Figure 3 ), when the grid-connected point frequency is 50Hz, the active power command is 40MW, following the AGC command; after the frequency rises to 50.2Hz, it enters the primary frequency modulation. At this time, the active power command is superimposed with the primary frequency modulation active power command -3.6MW on the basis of the real-time output of the grid-connected point, and the active power command drops to 36.4MW; during the primary frequency modulation, the AGC command drops to 35MW, and the AGC change direction is the same as the primary frequency modulation active power command direction. At this time, the new AGC command is superimposed with the primary frequency modulation active power command, and the active power command drops to 31.4MW; after the frequency recovers to 50Hz, the active power command follows the latest AGC command value and becomes 35MW.

[0113] 4) Frequency 50Hz→50.2Hz+AGC increase 6%P e

[0114] like Figure 3 son Figure 4 ), when the grid-connected point frequency is 50Hz, the active power command is 30MW, following the AGC command; after the frequency rises to 50.2Hz, it enters the primary frequency modulation. At this time, the active power command is superimposed with the primary frequency modulation active power command -3.6MW on the basis of the real-time output of the grid-connected point, and the active power command drops to 26.4MW; during the primary frequency modulation, the AGC command rises to 35.4MW, and the AGC change direction is opposite to the primary frequency modulation active power command direction. At this time, the AGC command change is ignored and the previous active power command value is maintained; after the frequency returns to 50Hz, the active power command follows the latest AGC command value and becomes 35.4MW.

[0115] In addition, from the two curves of active power command and real-time output of the grid-connected point in each figure, it can be seen that the response lag time of the wind farm is 2.2s, the response time is 5.5s, and the regulation time is 11.5s, which meets the requirements of Jiangsu power grid for the primary frequency regulation response time of 3s, response time of 12s, and regulation time of 15s for the wind farm.

Claims

1. A frequency active support method applicable to new energy and energy storage stations, characterized in that: The following steps are involved: Step 1: Based on the grid connection point frequency f, grid connection point frequency change rate df / dt, grid connection point real-time active power P pcc Determine whether the inertia response conditions are met; if the inertia response conditions are met, calculate the simulated inertia response active power command ΔP iner , execute step 2; otherwise, simulate the inertia response active power command ΔP iner =0, go to step 2; Step 2: According to the frequency change of the grid connection point, determine whether the conditions for a primary frequency modulation response are met. If so, calculate the primary frequency modulation response instruction ΔP gov , execute step 3, otherwise no frequency modulation response is performed; Step 3: During a frequency modulation period, determine whether a new AGC command is received. If no new AGC command is received, obtain the total active power command P=P′ agc +ΔP gov +ΔP iner ; If a new AGC instruction P is received agc , then the new AGC instruction P agc and the previous AGC instruction P′ agc For comparison, when the frequency is disturbed, f<f L , if P agc >P′ agc , then the total active power command P = P agc +ΔP gov +ΔP iner Otherwise, the total active power command P = P' agc +ΔP gov +ΔP iner , when the frequency is disturbed, f>f L , if P agc <P′ agc , then the total active power command P = P agc +ΔP gov +ΔP iner Otherwise, the total active power command P = P' agc +ΔP gov +ΔP iner ; Step 4: Issue total active power command; In step 1, the inertia response condition is: And when the absolute value of the frequency change rate |df / dt| is greater than the dead zone R of the frequency change rate fd And the real-time active power P of the grid-connected point pcc Greater than C act P e , where C act is the minimum inertia response threshold of the real-time active power at the grid-connected point, P e is the rated active power of the entire station; In step 2, the condition for the primary frequency modulation response is: the frequency change at the grid connection point exceeds the dead zone f of the regulation characteristic curve d ; In step 2, if the primary frequency modulation response conditions are met, the primary frequency modulation response instruction ΔP is calculated according to the following formula: gov : In the formula, f L is the interference threshold at frequency, f H is the frequency interference threshold; When facing new energy stations, the coefficient C is used in and coefficient C out The response command ΔP to the primary frequency modulation gov Constraints are made, where C in >C out ; Specifically: Only when the grid frequency f>f H And the real-time active power P of the grid-connected point pcc <C out P e When ΔP gov =0; Only when the grid frequency f>f H And the real-time active power P of the grid-connected point pcc ≥C out P e And P pcc <C in P e hour: ΔP gov =C out P e -P Pcc (ΔP gov <0) (9)。 2. According to claim 1, a frequency active support method applicable to new energy and energy storage stations is characterized in that: In step 1, if the inertia response condition is met, the simulated inertia response active power command ΔP is calculated according to the following formula: iner ; In the formula, f e is the rated frequency, T j is the inertia time constant.

3. A power control device, used for deployment in a secondary grid structure of a station that has an AGC function, characterized in that: include: The inertia response unit is used to calculate the inertia response according to the grid connection point frequency f, the grid connection point frequency change rate df / dt and the grid connection point real-time active power P pcc Determine whether the inertia response conditions are met; if the inertia response conditions are met, calculate the simulated inertia response active power command ΔP iner ; If the inertia response condition is not met, the simulated inertia response active power command ΔP iner =0; The primary frequency modulation response unit is used to determine whether the conditions for primary frequency modulation response are met according to the frequency change of the grid connection point. If so, the primary frequency modulation response instruction ΔP is calculated. gov , otherwise no frequency modulation response is performed; The inertia response condition is: And when the absolute value of the frequency change rate |df / dt| is greater than the dead zone R of the frequency change rate fd And the real-time active power P of the grid-connected point pcc Greater than C act P e , where C act is the minimum inertia response threshold of the real-time active power of the grid-connected point, P e is the rated active power of the entire station; If the inertia response conditions are met, the simulated inertia response active power command ΔP can be calculated according to the following formula: iner ; In the formula, f e is the rated frequency, T j is the inertia time constant; The condition for primary frequency modulation response is: the frequency change at the grid point exceeds the dead zone f of the regulation characteristic curve. d ; If available, the primary frequency modulation response command ΔP can be calculated according to the following formula: gov : In the formula, f L is the interference threshold at frequency, f H is the frequency interference threshold; When deployed in a secondary grid structure of a wind farm / photovoltaic power station that already has AGC function, the coefficient C is used. in and coefficient C out The response command ΔP to the primary frequency modulation gov Constraints are made, where C in >C out ; Specifically: Only when the grid frequency f>f H And the real-time active power P of the grid-connected point pcc <C out P e When ΔP gov =0; Only when the grid frequency f>f H And the real-time active power P of the grid-connected point pcc ≥C out P e And P pcc <C in P e hour: ΔP gov =C out P e -P Pcc (ΔP gov <0) (9)。 4. A power control device according to claim 3, characterized in that: Deployed in series or parallel in the secondary grid structure of the station that already has AGC function.

5. A wind farm grid structure, characterized in that: It includes fast power control device, EMS for sending AGC commands, wind turbine energy management system and each wind turbine set; The fast power control device is serially deployed between the EMS and the wind turbine energy management system, and is used to implement inertia response and primary frequency modulation by adopting a frequency active support method applicable to new energy and energy storage stations as described in claim 1 or 2, and forwarding the AGC command sent by the EMS to the wind turbine energy management system; The wind turbine energy management system is used to issue detailed instructions to each wind turbine set.

6. A wind farm grid structure, characterized in that: It includes a fast power control device, an EMS for issuing AGC instructions to the wind turbine energy management system and the fast power control device, a wind turbine energy management system and each wind turbine set; The fast power control device is deployed in parallel with the EMS, and is used to implement inertia response and primary frequency modulation by adopting a frequency active support method applicable to new energy and energy storage stations as described in claim 1 or 2; and when it is detected that the grid connection point frequency enters the inertia response or primary frequency modulation range, a signal is sent to lock the EMS, and at the same time, a simulated inertia response active power instruction or a primary frequency modulation response instruction is issued and superimposed with an AGC instruction and issued to the wind turbine energy management system; And when the inertia response or the primary frequency modulation ends, a release signal is sent to the EMS; The wind turbine energy management system is used to issue detailed instructions to each wind turbine set.

7. A photovoltaic power station grid structure, characterized in that: Includes fast power control device, AGC and photovoltaic communication management unit; The fast power control device is deployed in series with the AGC, and is used to adopt the frequency active support method applicable to new energy and energy storage stations as described in claim 1 or 2 to perform inertia response or primary frequency modulation. When the frequency of the grid connection point enters the inertia response or primary frequency modulation range, the simulated inertia response active power instruction and the primary frequency modulation response instruction are sent to the AGC, and then the AGC performs instruction superposition and sends them to the photovoltaic communication management unit; The photovoltaic communication management unit is used to send subdivision instructions to the corresponding photovoltaic inverter.

8. A photovoltaic power station grid structure, characterized in that: Includes fast power control device, AGC and photovoltaic communication management unit; The AGC is used to send steady-state instructions to the photovoltaic communication management unit and the fast power control device simultaneously when the frequency of the grid connection point is within the normal range; The fast power control device is deployed in parallel with the AGC, and is used to adopt the frequency active support method applicable to new energy and energy storage stations as described in claim 1 or 2 to perform inertia response or primary frequency modulation, and when the grid connection point frequency enters the inertia response or primary frequency modulation range, send a signal to the AGC to lock its steady-state instruction, and at the same time superimpose the AGC instruction and send it to the photovoltaic communication management unit; and when the inertia response or primary frequency modulation ends, send a signal to the AGC to release the steady-state instruction lock, and at the same time lock the instruction issued by itself; The photovoltaic communication management unit is used to send subdivision instructions to the corresponding photovoltaic inverter.

9. A grid structure of an energy storage power station, characterized in that: It includes energy storage coordination controller, EMS for issuing AGC instructions and energy storage PCS; The energy storage coordination controller is deployed in series between the EMS and the energy storage PCS, and is used to adopt the frequency active support method suitable for new energy and energy storage stations as described in claim 1 or 2 to perform inertia response or primary frequency modulation, and forward the AGC instructions of the EMS to the energy storage PCS.

10. A grid structure of an energy storage power station, characterized in that: Including energy storage coordination controller, EMS and energy storage PCS; The EMS is used to send AGC to the PCS and the energy storage coordination controller when the frequency of the grid connection point is within the normal range; The energy storage coordination controller and EMS are deployed in parallel, and are used to lock the instructions issued by themselves when the frequency of the grid connection point is within the normal range, and adopt the frequency active support method suitable for new energy and energy storage stations as described in claim 1 or 2 to perform inertia response or primary frequency modulation, and when the frequency of the grid connection point enters the inertia response or primary frequency modulation range, send a signal to the EMS to lock its AGC instruction, and superimpose the AGC instruction on the simulated inertia response active instruction or the primary frequency modulation response instruction and send it to the energy storage PCS; and when the inertia response or the primary frequency modulation is completed, send a release signal to the EMS to allow it to continue to issue the AGC instruction, and lock the instructions issued by itself.

Images