Compressed air energy storage unit auxiliary photovoltaic power station frequency modulation control method and system

Abstract

The invention discloses a compressed air energy storage unit auxiliary photovoltaic power station frequency modulation control method and system, and relates to the technical field of photovoltaic power station frequency modulation control, and the method comprises the following steps: collecting the real-time frequency information of a power grid, and calculating the frequency difference and the frequency change rate; dividing a response interval based on the frequency difference change amplitude and the frequency change rate amplitude, and adjusting a response strategy of the compressed air energy storage expansion machine; and through a response strategy, controlling the power output of the compressed air energy storage expansion generator to be matched with the power output of the photovoltaic power station so as to jointly adjust the power grid frequency. According to the method, the compressed air energy storage expansion generator quickly responds, the system frequency difference is caused under the condition of dry load disturbance in advance, the response speed is higher than that of a traditional mode, the large frequency difference possibly occurring in the system is eliminated in advance, and the influence of power disturbance is prevented from being further increased.

Description

Technical Field

[0001] The present invention relates to the technical field of photovoltaic power station frequency modulation control, and in particular to a method and system for frequency modulation control of a photovoltaic power station assisted by a compressed air energy storage unit. Background Art

[0002] The "new power system" with new energy as its main feature is gradually taking shape, but the high proportion of new energy grid connection reduces the inertia level and frequency support capacity of the power system, and has strong intermittent and volatile power generation. The frequency stability problem has become one of the core issues of the current power grid security and stability and the efficient consumption of new energy. In order to improve the solution to the problem of grid frequency stability and increase the technical means and methods to solve the frequency stability, the requirements for various grid-connected entities to participate in power auxiliary services are getting higher and higher. More and more compressed air energy storage projects with large capacity, flexible start and stop, long operating life and high safety have been put into operation, and their technology has also been rapidly developed. The new version of the "Regulations on the Management of Power Grid Operation" and "Measures for the Management of Power Auxiliary Services" of the National Energy Administration in 2021 clearly include compressed air energy storage as a grid-connected entity in the scope of auxiliary services, but domestic research on compressed air energy storage still focuses on the improvement of single-unit capacity, and there is still a blank in the field of auxiliary services. Mastering the performance of compressed air energy storage power generation systems in participating in auxiliary services is the only way for power grid companies to participate in the formulation of rules and achieve flexible and effective regulation.

[0003] With the development and progress of technology, the state has issued corresponding standards and made corresponding regulations for the frequency monitoring and control of photovoltaic power stations. New photovoltaic units are generally equipped with primary frequency regulation devices and participate in the frequency adjustment of the power grid. Since the power generation capacity of photovoltaic unit inverters in different time periods is greatly affected by light conditions, the upper limit of active power output of large inverters is difficult to determine. At the same time, affected by the differences in power generation characteristics, location and inverter characteristics of photovoltaic panels, the power generation capacity of each inverter is different, and the inverter cannot fully exert its power generation capacity, especially when the entire station needs to increase active power output, resulting in insufficient active power generation and insufficient control accuracy.

[0004] At present, in the research on frequency regulation of compressed air energy storage units, there is little research data on the coupled frequency regulation of compressed air energy storage and photovoltaic power stations, and the research field is mainly concentrated in the field of energy storage configuration supporting planning. The actual impact assessment on the grid frequency may have certain uncertainties and deviations. In addition, the current technical means, as a means of energy storage for photovoltaic power generation configuration, are mostly concentrated on the configuration of electrochemical energy storage, and its research is also concentrated in this field. Since electrochemical energy storage belongs to the short-time scale energy storage type, it does not have the advantages of compressed air energy storage, such as large storage energy, long regulation time, and high conversion efficiency. Due to the lack of relevant research on the coupled operation of compressed air energy storage and photovoltaic power stations, the operation and control methods of related equipment are also yet to be studied. Summary of the invention

[0005] In view of the problems existing in the existing compressed air energy storage unit auxiliary photovoltaic power station frequency modulation control and system, the present invention is proposed.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a method for frequency modulation control of a compressed air energy storage unit assisted photovoltaic power station, which comprises the following steps:

[0008] Collect real-time frequency information of the power grid and calculate the frequency difference and frequency change rate;

[0009] The response interval is divided based on the frequency difference change amplitude and the frequency change rate amplitude, and the response strategy of the compressed air energy storage expander is adjusted;

[0010] Through the response strategy, the power output of the compressed air energy storage expansion generator is controlled to coordinate with the power output of the photovoltaic power station to jointly adjust the grid frequency.

[0011] As a preferred solution of the frequency modulation control method of the compressed air energy storage unit assisted photovoltaic power station described in the present invention, wherein: after the grid frequency acquisition obtains the real-time frequency of the grid, the frequency signal is sent to the frequency difference and frequency change rate calculation module to calculate the frequency difference Δf and the frequency change rate. The relationship between the frequency difference and the frequency change rate is:

[0012]

[0013] Where σ(t) is the function of the frequency change rate over time, is the frequency change rate.

[0014] As a preferred solution of the method for frequency modulation control of a photovoltaic power station assisted by a compressed air energy storage unit according to the present invention, the method for generating a response strategy includes:

[0015] Considering the range and amplitude of the frequency change rate under different frequency difference ranges, the amplitude of the frequency change rate is used as a constraint limit to quickly respond to load adjustment needs and ensure that the output frequency of the photovoltaic power station meets the needs of the power grid.

[0016] As a preferred solution of the frequency regulation control method of the compressed air energy storage unit assisted photovoltaic power station of the present invention, the step of adjusting the grid frequency includes:

[0017] The photovoltaic power station adopts the active power-frequency droop characteristic control mode, and the simplified characteristics of the single response to primary frequency modulation are:

[0018]

[0019] Where ΔP is the power that the photovoltaic power station responds to when it responds to frequency modulation, P N and f N is the rated active capacity of the PV power station and the rated frequency of the system, δ% is the regulation rate of the PV unit, and Δf is the frequency deviation;

[0020] When a photovoltaic power station undertakes a frequency regulation task alone, it needs to reserve some spare capacity to cope with insufficient active output due to weather changes or when the power grid has a frequency regulation demand.

[0021] As a preferred solution of the frequency modulation control method of the compressed air energy storage unit assisted photovoltaic power station of the present invention, the method for generating the response strategy also includes:

[0022] After adding the compressed air energy storage expansion generator regulation, the compressed air energy storage device takes advantage of its rapid action and undertakes the frequency regulation task in the initial stage. The primary frequency regulation characteristic equation of the combined system is:

[0023] ΔP u =ΔP+ΔP r ;

[0024] Where ΔP u is the total active output of the combined system, ΔP is the active response of photovoltaic power in the combined system due to the frequency difference, and ΔP r is the active response of the compressed air energy storage expander in the combined system, and its expression is:

[0025]

[0026] R r H is the differential coefficient when the compressed air energy storage expander participates in frequency regulation, ca is the inertia time constant of the compressed air energy storage expansion generator;

[0027] By adding the calculation formula of the power response of the photovoltaic power station when responding to frequency modulation and the calculation formula of the differential coefficient when the compressed air energy storage expander participates in frequency modulation, the active response of the combined system is obtained as follows:

[0028]

[0029] Then the transformation is performed, and the formula is expressed as:

[0030]

[0031] As a preferred solution of the frequency modulation control method of the compressed air energy storage unit assisted photovoltaic power station described in the present invention, wherein: considering the external load disturbance deviation, the system dynamic response equation is expressed as:

[0032]

[0033] And sort it out, the formula is:

[0034]

[0035] The power imbalance is defined as:

[0036] ΔP v =ΔP-ΔP L ;

[0037] Combining the power imbalance formula, the rearranged system dynamic response equation, and the relationship between frequency difference and frequency change rate, we get:

[0038]

[0039] And sort out the changes, expressed as:

[0040]

[0041] At this time, the power imbalance caused by the disturbing load that causes the frequency difference is a function related to the frequency change rate.

[0042] As a preferred solution of the frequency modulation control method of the compressed air energy storage unit assisted photovoltaic power station of the present invention, the expression of the system response at time t2 is:

[0043]

[0044] The active response formula of the combined system, the sorted system dynamic response equation, and the expression of the system response at time t2 are incorporated into the formula for defining the power imbalance to obtain:

[0045]

[0046] Due to the large deviation in the inverse order of magnitude of the system load damping coefficient, the energy storage expansion generator regulation coefficient, and the photovoltaic power station regulation rate, the formula is simplified to:

[0047]

[0048] Combining the simplified formula and the calculation formula of the power imbalance caused by the disturbance load that causes the frequency difference after the arrangement, we get:

[0049]

[0050] Arrange it and get:

[0051]

[0052] σ1 is the threshold value of the frequency change rate, from which the interval of the frequency change rate is obtained:

[0053] Interval I: 0≤|σ|≤|σ1|;

[0054] Interval II: |σ1|≤|σ|;

[0055] If the system fluctuation causes the frequency change rate to fall within interval I, and the change amplitude is small, the frequency difference change is small, and the energy storage expansion generator takes the lead in action according to the frequency change rate, adjusting its own operation to respond to load fluctuations; if the frequency change rate falls within interval II, after the energy storage expansion generator responds, a large frequency difference will appear in the system. At this time, the photovoltaic power station responds to the active power fluctuation according to the frequency difference and jointly adjusts the system disturbance.

[0056] In a second aspect, an embodiment of the present invention provides a compressed air energy storage unit assisted photovoltaic power station frequency regulation control system, which includes a collection module, a calculation module, and an adjustment module;

[0057] The acquisition module is used to monitor the grid frequency in real time and obtain grid frequency deviation information;

[0058] The calculation module is used to calculate the collected information and formulate a response strategy;

[0059] The adjustment module cooperates with the power output of the compressed air energy storage expansion generator to jointly adjust the grid frequency.

[0060] In a third aspect, an embodiment of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the processor executes the computer program, any step of the above-mentioned compressed air energy storage unit assisted photovoltaic power station frequency regulation control method is implemented.

[0061] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the above-mentioned compressed air energy storage unit assisted photovoltaic power station frequency regulation control method is implemented.

[0062] The beneficial effects of the present invention are as follows: utilizing the system frequency difference and the response relationship of the photovoltaic-compressed air energy storage combined system to derive the expression of the system frequency change rate, and then obtain the fluctuation range of the frequency change rate, and propose a combined system according to the grid frequency change rate, in which the compressed air energy storage expansion generator first responds, and then the combined system is jointly controlled according to the fluctuation range of the frequency change rate, so that the compressed air energy storage expansion generator responds quickly, and the system frequency difference caused by the dry load disturbance is eliminated in advance. The response speed is faster than the traditional method, and the large frequency difference that may occur in the system is eliminated in advance to prevent the influence of the power disturbance from further increasing. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0064] Figure 1 The figure is a flow chart of the frequency regulation control method of a compressed air energy storage unit assisting a photovoltaic power station.

[0065] Figure 2 Energy storage-photovoltaic power station active power control strategy diagram for compressed air energy storage unit auxiliary photovoltaic power station frequency regulation control method DETAILED DESCRIPTION

[0066] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0067] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0068] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0069] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0070] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0071] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0072] Example 1

[0073] Reference Figure 1 and Figure 2 , which is the first embodiment of the present invention, and provides a method for frequency modulation control of a photovoltaic power station assisted by a compressed air energy storage unit, comprising the following steps:

[0074] S1. Collect real-time frequency information of the power grid and calculate the frequency difference and frequency change rate.

[0075] The control system is provided with a power grid frequency acquisition module, a frequency difference and frequency change rate calculation module, a frequency response interval partition judgment module, and a compressed air energy storage expansion generator operating power adjustment module;

[0076] After the grid frequency acquisition obtains the real-time frequency of the grid, the frequency signal is sent to the frequency difference and frequency change rate calculation module to calculate the frequency difference Δf and the frequency change rate. The relationship between the frequency difference and the frequency change rate is:

[0077]

[0078] Where σ(t) is the function of the frequency change rate over time, is the frequency change rate.

[0079] The frequency response interval discrimination module is set to discriminate the amplitude of the frequency difference change. According to the requirements of GB / T15945-2008: Under normal operating conditions of the power system, the absolute value of the frequency deviation should be within 0.2Hz, and it can be relaxed to 0.5Hz when the system capacity is small. Take 0.2Hz as the frequency response adjustment deviation threshold β, and set 2 intervals: 0≤∣Δf∣≤β, β≤∣Δf∣. According to the different intervals of the frequency difference, adjust the active output of the units within the regional power grid, and control the compressed air energy storage expansion generator to adjust the active power.

[0080] S2. Divide the response interval based on the frequency difference change amplitude and the frequency change rate amplitude, and adjust the response strategy of the compressed air energy storage expander.

[0081] The generation method of response strategy includes:

[0082] Considering the range and amplitude of the frequency change rate under different frequency difference ranges, the amplitude of the frequency change rate is used as a constraint limit to quickly respond to load adjustment needs and ensure that the output frequency of the photovoltaic power station meets the needs of the power grid.

[0083] S3. Through the response strategy, the power output of the compressed air energy storage expansion generator is controlled to coordinate with the power output of the photovoltaic power station to jointly adjust the grid frequency.

[0084] The steps to adjust the grid frequency include,

[0085] The photovoltaic power station adopts the active power-frequency droop characteristic control mode, and the simplified characteristics of the single response to primary frequency modulation are:

[0086]

[0087] Where ΔP is the power that the photovoltaic power station responds to when it responds to frequency modulation, P N and f N is the rated active capacity of the PV power station and the rated frequency of the system, δ% is the regulation rate of the PV unit, and Δf is the frequency deviation;

[0088] When a photovoltaic power station undertakes a frequency regulation task alone, it is necessary to reserve some spare capacity to cope with insufficient active output when the weather changes or when the grid has a frequency regulation demand. When operating in this way, part of the capacity is idle at ordinary times, which affects the economic efficiency. Therefore, the advantages and disadvantages of the reserved capacity method are more prominent;

[0089] When a photovoltaic power station undertakes a frequency regulation task alone, it needs to reserve some spare capacity to cope with insufficient active output due to weather changes or when the power grid has a frequency regulation demand.

[0090] The generation method of the response strategy also includes:

[0091] After adding the compressed air energy storage expansion generator regulation, the compressed air energy storage device takes advantage of its rapid action and undertakes the frequency regulation task in the initial stage. The primary frequency regulation characteristic equation of the combined system is:

[0092] ΔP u =ΔP+ΔP r ;

[0093] Where ΔP u is the total active output of the combined system, ΔP is the active response of photovoltaic power in the combined system due to the frequency difference, and ΔP r is the active response of the compressed air energy storage expander in the combined system, and its expression is:

[0094]

[0095] R r H is the differential coefficient when the compressed air energy storage expander participates in frequency regulation, ca is the inertia time constant of the compressed air energy storage expansion generator;

[0096] By adding the calculation formula of the power response of the photovoltaic power station when responding to frequency modulation and the calculation formula of the differential coefficient when the compressed air energy storage expander participates in frequency modulation, the active response of the combined system is obtained as follows:

[0097]

[0098] Then the transformation is performed, and the formula is expressed as:

[0099]

[0100] Reference Figure 2 As shown, ΔP L is the external power disturbance deviation, T r is the energy storage expansion generator frequency modulation delay response time constant, including the time delay of intake valve command transmission, valve opening and closing, etc., T tran T is the delay in issuing and transmitting commands of the photovoltaic control system. ctr is the time delay of inverter action and control output, H is the system moment of inertia, and D is the load damping coefficient;

[0101] Considering the external load disturbance deviation, the system dynamic response equation is expressed as:

[0102]

[0103] And sort it out, the formula is:

[0104]

[0105] The power imbalance is defined as:

[0106] ΔP v =ΔP-ΔP L ;

[0107] Combining the power imbalance formula, the rearranged system dynamic response equation, and the relationship between frequency difference and frequency change rate, we get:

[0108]

[0109] At the beginning of the disturbance, due to the influence of inertia, the change is small, and the spare capacity of the photovoltaic power station is not adjusted, but the frequency change rate will have a large response. Therefore, it is approximately considered that Δf = 0, as a quick response of primary frequency modulation. And the changes are sorted out and expressed as:

[0110]

[0111] At this time, the power imbalance caused by the disturbing load that causes the frequency difference is a function related to the frequency change rate.

[0112] The system is disturbed at time t1, at which time the system has inertia Δf = 0; at time t2, the frequency difference reaches a stable value Δf st ,σ(t)=0| t＝t2 During the adjustment process, the frequency change rate is expressed in intervals to limit the frequency change rate to fall within different intervals when the disturbance amplitude is different.

[0113] The expression of the system response at time t2 is:

[0114]

[0115] The active response formula of the combined system, the sorted system dynamic response equation, and the expression of the system response at time t2 are incorporated into the formula for defining the power imbalance to obtain:

[0116]

[0117] Due to the large deviation in the inverse order of magnitude of the system load damping coefficient, the energy storage expansion generator regulation coefficient, and the photovoltaic power station regulation rate, the formula is simplified to:

[0118]

[0119] Combining the simplified formula and the calculation formula of the power imbalance caused by the disturbance load that causes the frequency difference after the arrangement, we get:

[0120]

[0121] Arrange it and get:

[0122]

[0123] σ1 is the threshold value of the frequency change rate, from which the interval of the frequency change rate is obtained:

[0124] Interval I: 0≤|σ|≤|σ1|;

[0125] Interval II: |σ1|≤|σ|;

[0126] If the system fluctuation causes the frequency change rate to fall within interval I, and the change amplitude is small, the frequency difference change is small, and the energy storage expansion generator takes the lead in action according to the frequency change rate, adjusting its own operation to respond to load fluctuations; if the frequency change rate falls within interval II, after the energy storage expansion generator responds, a large frequency difference will appear in the system. At this time, the photovoltaic power station responds to the active power fluctuation according to the frequency difference and jointly adjusts the system disturbance.

[0127] Design energy storage-photovoltaic combined operation unit, the energy storage corresponding to the system frequency change when the adjustment coefficient is R r , the corresponding adjustment rate of the photovoltaic power station is δ%, and the photovoltaic power station adjusts the frequency according to a certain capacity. When the moment of inertia is H, the threshold value σ1 of the frequency change rate is calculated, and then the frequency change rate interval is obtained. The system calculates and judges the frequency difference and frequency change rate through a fixed time Δt, and uses this as a basis to determine whether it is necessary to start the frequency modulation module to balance the system disturbance.

[0128] When the system has power ΔP L When there is a disturbance, a frequency difference Δf1 appears, and the frequency change rate σ is obtained by calculation:

[0129] When σ is in interval I: 0≤|σ|≤|σ1|, the frequency change rate fluctuates slightly, and the frequency difference is within the primary frequency regulation dead zone of the photovoltaic power station. At this time, the primary frequency regulation of the photovoltaic power station does not operate, and the system is controlled as follows:

[0130]

[0131]

[0132] The frequency difference is eliminated by adjusting the active power consumed by the expansion generator in response to system disturbances.

[0133] When σ is in interval I: 0≤|σ|≤|σ1|, the frequency difference Δf'2 is outside the primary frequency regulation dead zone of the photovoltaic power station, and the primary frequency regulation of the photovoltaic power station starts to act. Since the energy storage response acts in advance, after the action, the system frequency difference is Δf2, and |Δf2|<|Δf'2|. The system is controlled as follows:

[0134]

[0135] The energy storage system and photovoltaic power station are controlled as follows:

[0136]

[0137] The part of the ramp rate that is insufficient for active adjustment of energy storage will be responded to by primary frequency regulation of the photovoltaic power station's backup capacity.

[0138] When δ is in interval II: |σ1|≤|σ|, the frequency change rate is very large, the frequency difference changes very quickly, and the probability of a large frequency difference is very high, which quickly exceeds the primary frequency regulation dead zone of the photovoltaic power station. Let the frequency difference appear at this time be Δf3, which has the risk of exceeding safety. At this time, the system responds simultaneously with the energy storage expansion generator and the primary frequency regulation of the photovoltaic power station, and the system is controlled as follows:

[0139]

[0140] The energy storage system and photovoltaic power station are controlled as follows:

[0141]

[0142] When σ is in interval II: |σ1|≤|σ|, the frequency change rate is very large, the frequency difference changes very quickly, and the probability of a large frequency difference is very high, which quickly exceeds the primary frequency regulation dead zone of the photovoltaic power station. Let the frequency difference appear at this time be Δf4', which has the risk of exceeding safety. At this time, due to weather reasons, the reserved spare capacity of photovoltaic power generation cannot meet the frequency regulation demand. The system is independently regulated by compressed air energy storage in the initial stage, and is controlled as follows:

[0143]

[0144] The energy storage system is controlled as follows:

[0145]

[0146] When the frequency difference drops to △f4, and |△f4|<|△f'4|, the spare capacity of the photovoltaic power station meets the frequency regulation demand, then the system is controlled as follows:

[0147]

[0148] The energy storage system and photovoltaic power station are controlled as follows:

[0149]

[0150] In summary, the expression of the system frequency change rate is derived by utilizing the response relationship between the system frequency difference and the photovoltaic-compressed air energy storage combined system, and then the fluctuation range of the frequency change rate is obtained. It is proposed that the combined system responds first according to the grid frequency change rate, and then the combined system is jointly controlled according to the fluctuation range of the frequency change rate. The compressed air energy storage expansion generator responds quickly, and the system frequency difference caused by the dry load disturbance is eliminated in advance. The response speed is faster than the traditional method, and the large frequency difference that may occur in the system is eliminated in advance to prevent the impact of the power disturbance from further increasing.

[0151] Example 2

[0152] On the basis of the first embodiment, this embodiment further provides a compressed air energy storage unit auxiliary photovoltaic power station frequency regulation control system, including a collection module, a calculation module, and an adjustment module;

[0153] The acquisition module is used to monitor the grid frequency in real time and obtain grid frequency deviation information;

[0154] The calculation module is used to calculate the collected information and formulate a response strategy;

[0155] The adjustment module cooperates with the power output of the compressed air energy storage expansion generator to jointly adjust the grid frequency.

[0156] This embodiment also provides a computer device, which is suitable for the case where a compressed air energy storage unit assists a photovoltaic power station frequency modulation control method, and includes a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the compressed air energy storage unit assists a photovoltaic power station frequency modulation control method as proposed in the above embodiment.

[0157] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0158] This embodiment also provides a storage medium on which a computer program is stored. When the program is executed by a processor, the method for implementing the frequency regulation control of a compressed air energy storage unit assisting a photovoltaic power station as proposed in the above embodiment is implemented.

[0159] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be found in the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0160] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for frequency modulation control of a compressed air energy storage unit assisted photovoltaic power station, characterized in that: The following steps are included: Collect real-time frequency information of the power grid and calculate the frequency difference and frequency change rate; The response interval is divided based on the frequency difference change amplitude and the frequency change rate amplitude, and the response strategy of the compressed air energy storage expander is adjusted; Through the response strategy, the power output of the compressed air energy storage expansion generator is controlled to coordinate with the power output of the photovoltaic power station to jointly adjust the grid frequency.

2. The method for frequency modulation control of a compressed air energy storage unit assisted photovoltaic power station according to claim 1, characterized in that: After the grid frequency acquisition obtains the real-time frequency of the grid, the frequency signal is sent to the frequency difference and frequency change rate calculation module to calculate the frequency difference Δf and the frequency change rate. The relationship between the frequency difference and the frequency change rate is: Where σ(t) is the function of the frequency change rate over time, is the frequency change rate.

3. The method for controlling frequency modulation of a photovoltaic power station assisted by a compressed air energy storage unit according to claim 2, characterized in that: The generation method of response strategy includes: Considering the range and amplitude of the frequency change rate under different frequency difference ranges, the amplitude of the frequency change rate is used as a constraint limit to quickly respond to load adjustment needs and ensure that the output frequency of the photovoltaic power station meets the needs of the power grid.

4. The method for frequency modulation control of a compressed air energy storage unit assisted photovoltaic power station according to claim 3, characterized in that: The steps to adjust the grid frequency include, The photovoltaic power station adopts the active power-frequency droop characteristic control mode, and the simplified characteristics of the single response to primary frequency modulation are: Where ΔP is the power that the photovoltaic power station responds to when it responds to frequency modulation, P N and f N is the rated active capacity of the PV power station and the rated frequency of the system, δ% is the regulation rate of the PV unit, and Δf is the frequency deviation; When a photovoltaic power station undertakes a frequency regulation task alone, it needs to reserve some spare capacity to cope with insufficient active output due to weather changes or when the power grid has a frequency regulation demand.

5. The method for controlling frequency modulation of a photovoltaic power station assisted by a compressed air energy storage unit according to claim 4, characterized in that: The generation method of the response strategy also includes: After adding the compressed air energy storage expansion generator regulation, the compressed air energy storage device takes advantage of its rapid action and undertakes the frequency regulation task in the initial stage. The primary frequency regulation characteristic equation of the combined system is: ΔP u =ΔP+ΔP r ; Where ΔP u is the total active output of the combined system, ΔP is the active response of photovoltaic power in the combined system due to the frequency difference, and ΔP r is the active response of the compressed air energy storage expander in the combined system, and its expression is: R r H is the differential coefficient when the compressed air energy storage expander participates in frequency regulation, ca is the inertia time constant of the compressed air energy storage expansion generator; By adding the calculation formula of the power response of the photovoltaic power station when responding to frequency modulation and the calculation formula of the differential coefficient when the compressed air energy storage expander participates in frequency modulation, the active response of the combined system is obtained as follows: Then the transformation is performed, and the formula is expressed as:

6. The method for frequency modulation control of a compressed air energy storage unit assisted photovoltaic power station according to claim 5, characterized in that: Considering the external load disturbance deviation, the system dynamic response equation is expressed as: And sort it out, the formula is: The power imbalance is defined as: ΔP v =ΔP-ΔP L ; Combining the power imbalance formula, the rearranged system dynamic response equation, and the relationship between frequency difference and frequency change rate, we get: And sort out the changes, expressed as: At this time, the power imbalance caused by the disturbing load that causes the frequency difference is a function related to the frequency change rate.

7. The method for frequency modulation control of a compressed air energy storage unit assisted photovoltaic power station according to claim 6, characterized in that: The expression of the system response at time t2 is: The active response formula of the combined system, the sorted system dynamic response equation, and the expression of the system response at time t2 are incorporated into the formula for defining the power imbalance to obtain: Due to the large deviation in the inverse order of magnitude of the system load damping coefficient, the energy storage expansion generator regulation coefficient, and the photovoltaic power station regulation rate, the formula is simplified to: Combining the simplified formula and the calculation formula of the power imbalance caused by the disturbance load that causes the frequency difference after the arrangement, we get: Arrange it and get: σ1 is the threshold value of the frequency change rate, from which the interval of the frequency change rate is obtained: Interval I: 0≤|σ|≤|σ1|; Interval II: |σ1|≤|σ|; If the system fluctuation causes the frequency change rate to fall within interval I, and the change amplitude is small, the frequency difference change is small, and the energy storage expansion generator takes the lead in action according to the frequency change rate, adjusting its own operation to respond to load fluctuations; if the frequency change rate falls within interval II, after the energy storage expansion generator responds, a large frequency difference will appear in the system. At this time, the photovoltaic power station responds to the active power fluctuation according to the frequency difference and jointly adjusts the system disturbance.

8. A compressed air energy storage unit assisted photovoltaic power station frequency modulation control system, based on the compressed air energy storage unit assisted photovoltaic power station frequency modulation control method according to any one of claims 1 to 7, characterized in that: It includes a collection module, a calculation module, and an adjustment module; The acquisition module is used to monitor the grid frequency in real time and obtain grid frequency deviation information; The calculation module is used to calculate the collected information and formulate a response strategy; The adjustment module cooperates with the power output of the compressed air energy storage expansion generator to jointly adjust the grid frequency.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the frequency regulation control method of a compressed air energy storage unit assisting a photovoltaic power station as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the frequency regulation control method of a compressed air energy storage unit assisting a photovoltaic power station as described in any one of claims 1 to 7 are implemented.

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