Wind and light storage adjustment inertia and frequency coordination control method

Abstract

The invention discloses a wind and light storage adjustment inertia and frequency coordination control method, and belongs to the technical field of new energy grid-connected power generation. The method is used for inertia support and frequency cooperative control of a new energy power station containing wind power generation, photovoltaic power generation, energy storage and a phase modifier, and comprises the steps of system minimum inertia demand evaluation, wind and light storage and adjustment inertia time constant evaluation, calculation of minimum inertia support time needed by the system and a wind and light storage and adjustment inertia distribution strategy. According to the wind and light storage and adjustment inertia and frequency coordination control method, the inertia supporting capacity of a new energy grid-connected system is effectively improved, wind, storage, photovoltaic and phase modifier inertia supporting tasks are effectively distributed, and the system frequency safety setting requirement is flexibly met. By calculating the minimum inertial supporting time, inertial supporting and exiting are carried out in time, power back-filling in the frequency recovery stage is avoided, and the frequency modulation burden of the system is relieved.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy grid-connected power generation, and particularly relates to a coordinated control method for inertia and frequency of wind-solar-storage regulation. Technical Background

[0002] With the rapid development of clean energy in recent years, the continuous increase in the installed capacity and penetration rate of new energy sources such as photovoltaic and wind power has brought many challenges to the safe and stable operation of the power grid while alleviating the energy crisis. On the one hand, most new energy sources are connected to the grid through power electronic devices and lack the inertia support of rotating machines. The inertia level of the power system continues to decrease, and inertia plays a key role in the frequency safety and stability of the power system. Low-inertia operation will lead to a decline in the anti-interference ability of the power system. On the other hand, due to the random and volatile characteristics of new energy sources such as wind power and photovoltaic power, and the maximum power tracking control strategy is mostly adopted when connecting to the grid without participating in the frequency and voltage regulation of the system, so it has weak anti-interference ability. Therefore, how to ensure the stable operation of the new energy grid-connected system is an important issue.

[0003] The literature titled "Online Inertia Assessment Method of Power System Considering Real-Time Partitioning of Frequency Dynamic Response" ([Cao Bin, Yuan Shuai, Liu Jiahao, etc. Online Inertia Assessment Method of Power System Considering Real-Time Partitioning of Frequency Dynamic Response [J]. Power System Technology, 2023, 47(03): 930-941) proposes an online inertia assessment method of power system considering real-time partitioning of frequency dynamic response, which divides regions in real time according to the real-time frequency response curve to ensure the correctness of the partitioning results under various operating conditions and improve the regional inertia estimation accuracy. However, for evaluating the system inertia demand and the coordinated control of the inertia support of wind-solar-storage regulation, it is necessary to complete the assessment of the system inertia demand during and even before the disturbance.

[0004] The literature titled "Primary Frequency Regulation Strategy of Doubly Fed Induction Generator Based on Virtual Inertia and Frequency Droop Control" (Zhang Guanfeng, Yang Junyou, Sun Feng, etc. Primary Frequency Regulation Strategy of Doubly Fed Induction Generator Based on Virtual Inertia and Frequency Droop Control [J]. Transactions of China Electrotechnical Society, 2017, 32(22): 225-232.) proposes to use the frequency drop depth Δf and the frequency change rate df / dt as the active power control signal of the doubly fed induction generator to suppress the frequency drop depth and the frequency change rate. However, it does not consider the phenomenon of active power reverse absorption of the doubly fed induction generator caused by df / dt during the frequency recovery stage, which leads to the secondary frequency drop.

[0005] Titled "Research on the Modeling and Control Scheme of a Flywheel Energy Storage Synchronous Condenser Based on Permanent Magnet Variable Frequency Speed Regulation" (Zhang Jiancheng, Hu Yuan, Hua Wen, etc. Research on the Modeling and Control Scheme of a Flywheel Energy Storage Synchronous Condenser Based on Permanent Magnet Variable Frequency Speed Regulation [J]. Zhejiang Electric Power, 2024, 43(10): 27-34.) constructs a flywheel energy storage synchronous condenser model based on permanent magnet variable frequency speed regulation, which uses the kinetic energy of the flywheel to improve the inertia power response ability of the synchronous condenser without changing the grid connection method and fast excitation ability of the synchronous condenser. However, it only considers the synchronous condenser providing inertia support alone and fails to coordinate with new energy units and synchronous generator sets for control.

[0006] In summary, the following problems still exist in the existing technologies:

[0007] 1. When the grid frequency drops due to insufficient inertia support in the power system, the excellent voltage support and inertia support potential of the synchronous condenser are not considered.

[0008] 2. It is not considered that the wind-solar-storage system draws power from the grid during the system frequency recovery stage due to differential control, which is not conducive to the system frequency recovery. The time for the wind-solar-storage system to provide inertia support for the system is not considered.

[0009] 3. When the synchronous condenser participates in the system inertia support, the output sequence of the wind-solar-storage system and the coordinated control method are not considered. Summary of the Invention

[0010] The technical problem to be solved by the present invention is the limitations of the above various technical solutions. When the system inertia support is insufficient, the synchronous condenser is preferentially considered to provide inertia support for the system to tap the inertia support potential of the synchronous condenser; calculate the time for the wind-solar-storage system to provide inertia support for the system and lock the differential control in a timely manner to avoid the wind-solar-storage system absorbing power from the system during the frequency recovery stage; consider the rotational speed safety constraint and power constraint of the wind turbine, consider the upper limit of the power output of the energy storage system, and consider the inertia response characteristics of the synchronous condenser, and propose a coordinated control method for the inertia and frequency of the wind-solar-storage system.

[0011] The object of the present invention is achieved as follows. The present invention provides a coordinated control method for the inertia and frequency of the wind-solar-storage system, and the control process is as follows:

[0012] On the premise of meeting the safety requirements of the grid frequency change, calculate the minimum inertia time constant requirement H of the power system at the initial stage of the frequency disturbance according to the minimum inertia time constant requirement formula smin ;

[0013] Calculate the inertia time constant, including the inherent inertia time constant H g1 of the synchronous generator set, the virtual inertia time constant H VW of the wind turbine, and the virtual inertia time constant H VB of the energy storage station, the virtual inertia time constant H of the photovoltaic power station PV and the inertia time constant H of the synchronous condenser G ;

[0014] Calculate the inertia support time t required when the grid frequency drops to the lowest value h ;

[0015] According to the wind power penetration rate ρ and the inertia time constant, calculate the equivalent inertia time constant under different support conditions, and obtain the disturbance power under different support conditions according to the minimum inertia time constant requirement formula;

[0016] According to the disturbance power and the inertia support time t required when the grid frequency drops to the lowest value h Carry out the participation and withdrawal of the inertia support of the wind-solar-storage-regulating system.

[0017] Preferably, the minimum inertia time constant requirement formula is:

[0018]

[0019] In the formula, ΔP d is the disturbance power, is the maximum allowable value of the frequency change rate.

[0020] Preferably, the expression of the inherent inertia time constant H of the synchronous generator set g1 is:

[0021]

[0022] In the formula, J g is the rotational kinetic energy inertia of the synchronous generator set, ω e is the synchronous angular velocity, S NG is the rated capacity of the synchronous generator set;

[0023] The virtual inertia time constant H of the wind turbine VW is expressed as:

[0024]

[0025] In the formula, P n is the number of pole pairs of the wind turbine, N t is the gearbox speed ratio of the wind turbine, Δω r is the change in the wind turbine speed, H w is the inherent inertia time constant of the wind turbine, λ opt is the optimal tip speed ratio of the wind turbine, v is the real-time wind speed captured by the wind turbine, Δω e is the change in the synchronous angular velocity, R t is the blade radius of the wind turbine, V min is the cut-in wind speed of the maximum power tracking area of the wind turbine, Vmax is the rated wind speed, ω max is the maximum rotational speed during stable operation of the wind turbine;

[0026] The virtual inertia time constant H of the energy storage station VB has the following expression:

[0027]

[0028] In the formula, H g2 is the inertia time constant of an equivalent-capacity synchronous machine, Δγ soc is the change in the state of charge of the energy storage station, γ soc is the state of charge of the energy storage station, E g is the rotational kinetic energy stored in the equivalent-capacity synchronous machine, W B is the energy stored in the energy storage system station, W B = u B Q N γ soc_0 where u B is the voltage of the battery, Q N is the rated capacity of the battery, γ soc_0 is the initial state of charge of the battery;

[0029] The virtual inertia time constant H of the photovoltaic power station PV has the following expression:

[0030]

[0031] In the formula, C is the equivalent capacitance, U dc is the input voltage of the photovoltaic power station, k1 is the virtual inertia control coefficient, and S is the Laplace operator;

[0032] The inertia time constant H of the synchronous condenser when it participates in operation G has the following expression:

[0033]

[0034] In the formula, E k is the mechanical energy of the entire power system when the synchronous condenser participates in operation, S N is the apparent capacity of the synchronous condenser, J G is the moment of inertia of the synchronous condenser, ω n is the rated mechanical angular velocity.

[0035] Preferably, the inertia support time t required when the grid frequency drops to the lowest value h has the following expression:

[0036]

[0037] In the formula, b is the oscillation frequency, Ts Let \(H\) be the inertia time constant of the steam turbine in the synchronous generator set, \(\xi\) be the damping ratio, and \(a\) be the natural frequency parameter;

[0038] The expressions for the oscillation frequency \(b\), damping ratio \(\xi\), and natural frequency parameter \(a\) are as follows:

[0039]

[0040] In the formula, \(F\) s is the characteristic coefficient of the steam turbine, \(D\) sys is the damping coefficient of the power system, \(K\) L is the load regulation coefficient, \(R\) is the droop coefficient, \(\rho\) is the wind power penetration rate, \(H\) s is the inertia support time constant required by the power system, \(H\) s \(=H\) G \(+H\) g \(+H\) VW \(\rho + H\) VB \(\rho n_1 + H\) PV \(\rho n_2\). In the formula, \(H\) g is the equivalent inertia time constant of the synchronous generator set corresponding to the wind power penetration rate \(\rho\), \(n_1\) is the ratio of the rated power of the energy storage station to the rated capacity of the wind turbine, and \(n_2\) is the ratio of the rated power of the photovoltaic power station to the rated capacity of the wind turbine.

[0041] Preferably, the calculation method of the disturbance power under different support conditions is as follows:

[0042] Define the equivalent inertia time constant when the synchronous generator set supports alone as the first equivalent time constant \(H\) s1 , \(H\) s1 \(=H\) g1 (1 - \(\rho\)), \(\rho\) is the wind power penetration rate. When the synchronous generator set supports alone, let \(H\) smin \(=H\) s1 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the first disturbance power \(\Delta P\) d1 ;

[0043] Define the equivalent inertia time constant when the synchronous generator set and the synchronous condenser support together as the second equivalent time constant \(H\) s2 , \(H\) s2 \(=H\) G \(+H\) g , \(H\) g is the equivalent inertia time constant of the synchronous generator set corresponding to the wind power penetration rate \(\rho\). When the synchronous generator set and the synchronous condenser support together, let \(H\) smin \(=H\) s2 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the second disturbance power \(\Delta P\) d2 ;

[0044] Define the equivalent inertia time constant when the synchronous generator set, synchronous condenser and wind farm support together as the third equivalent time constant H s3 , H s3 =H G +H g +H VW ρ. When the synchronous generator set, synchronous condenser and wind farm support together, let H smin =H s3 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the third disturbance power ΔP d3 ;

[0045] Define the equivalent inertia time constant when the synchronous generator set, synchronous condenser, wind farm and energy storage station support together as the fourth equivalent time constant H s4 , H s4 =H G +H g +H VW ρ+H VB ρn1, where n1 is the ratio of the rated power of the energy storage station to the rated capacity of the fan. When the synchronous generator set, synchronous condenser, wind farm and energy storage station support together, let H smin =H s4 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the fourth disturbance power ΔP d4 ;

[0046] Define the equivalent inertia time constant when the synchronous generator set, synchronous condenser, wind farm, energy storage station and photovoltaic power station support together as the fifth equivalent time constant H s5 , H s5 =H G +H g +H VW ρ+H VB ρn1+H PV ρn2, where n2 is the ratio of the rated power of the photovoltaic power station to the rated capacity of the fan. When the synchronous generator set, synchronous condenser, wind farm, energy storage station and photovoltaic power station support together, let H smin =H s5 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the fifth disturbance power ΔP d5 .

[0047] Preferably, the implementation process of the participation and withdrawal of the inertia support of the wind-solar-storage-synchronous condenser is as follows:

[0048] When the power grid has a frequency disturbance, perform inertia support according to the following settings:

[0049] When ΔP d ≤ΔP d1When a frequency disturbance starts, the synchronous generator set provides inertia support at the beginning of the frequency disturbance;

[0050] When ΔP d1 <ΔP d ≤ΔP d2 When, the synchronous wind turbine generator set and the synchronous condenser jointly provide inertia support at the beginning of the frequency disturbance. After the minimum inertia support time t h elapses, the synchronous condenser withdraws from the inertia support;

[0051] When ΔP d2 <ΔP d ≤ΔP d3 When, the synchronous generator set, the synchronous condenser and the wind farm jointly provide inertia support at the beginning of the frequency disturbance. After the minimum inertia support time t h elapses, the synchronous condenser and the wind farm withdraw from the inertia support;

[0052] When ΔP d3 <ΔP d ≤ΔP d4 When, the synchronous generator set, the synchronous condenser, the wind farm and the energy storage station jointly provide inertia support at the beginning of the frequency disturbance. After the minimum inertia support time t h elapses, the synchronous condenser, the wind farm and the energy storage station withdraw from the inertia support;

[0053] When ΔP d4 <ΔP d ≤ΔP d5 When, the synchronous generator set, the synchronous condenser, the wind farm, the energy storage station and the photovoltaic power station jointly provide inertia support at the beginning of the frequency disturbance. After the inertia support time t h elapses, the synchronous condenser, the wind farm, the energy storage station and the photovoltaic power station withdraw from the inertia support.

[0054] The present invention also provides a coordinated control system for inertia and frequency of wind power, photovoltaics, energy storage and regulation, including a controller and a power system. When a frequency disturbance occurs in the power grid, the controller adopts the above-mentioned coordinated control method for inertia and frequency of wind power, photovoltaics, energy storage and regulation to provide inertia support for the power system and ensure the stability of the power grid frequency.

[0055] Preferably, the power system includes a new energy power station and a synchronous generator set. The new energy power station includes a wind farm, a photovoltaic power station, an energy storage station and a synchronous condenser. The wind farm, the photovoltaic power station, the energy storage station and the synchronous condenser are connected in parallel and can all be connected to the power grid independently or in combination or jointly.

[0056] The present invention also provides a readable storage medium, on which a computer program is stored. When the computer program is executed, the above-mentioned coordinated control method for inertia and frequency of wind power, photovoltaics, energy storage and regulation is realized.

[0057] The present invention also provides a device, which includes a processor, a memory, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the above-mentioned coordinated control method for inertia and frequency of wind-solar-storage is implemented.

[0058] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0059] 1. In the coordinated control method for inertia and frequency of wind-solar-storage of the present invention, when providing inertia support for the system, the inertia support capabilities of the synchronous condenser and new energy units are comprehensively considered, improving the stability of the power system.

[0060] 2. In the coordinated control method for inertia and frequency of wind-solar-storage of the present invention, the required inertia support time of the synchronous condenser and new energy units is calculated, and they can participate and withdraw in a timely manner, preventing the increase of the frequency modulation burden due to power reverse absorption during the frequency recovery stage.

[0061] 3. In the coordinated control method for inertia and frequency of wind-solar-storage of the present invention, considering the constraint conditions of new energy units, a coordinated control strategy for inertia and frequency of wind-solar-storage is formulated, releasing the inertia support potential of the wind-solar-storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 is a flowchart of the coordinated control method for inertia and frequency of wind-solar-storage of the present invention;

[0063] Figure 2 is a frequency response model of the wind-solar-storage system of the present invention;

[0064] Figure 3 is an evaluation diagram of the system inertia demand under the frequency change constraint of the present invention;

[0065] Figure 4 is a simulation waveform diagram when the synchronous generator set provides inertia support alone in the present invention;

[0066] Figure 5 is a simulation waveform diagram when the synchronous generator set and the synchronous condenser provide inertia support in the present invention;

[0067] Figure 6 is a simulation waveform diagram when the synchronous generator set, the synchronous condenser and the wind farm provide inertia support in the present invention;

[0068] Figure 7 is a simulation waveform diagram when the synchronous generator set, the synchronous condenser, the wind farm and the energy storage station provide inertia support in the present invention;

[0069] Figure 8 is a simulation waveform diagram when the synchronous generator set, the synchronous condenser, the wind farm, the energy storage station and the photovoltaic power station provide inertia support in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0070] The present invention will be further described below with reference to the accompanying drawings.

[0071] Embodiment 1

[0072] Figure 2 is the frequency response model of the wind-solar-storage-regulating system provided by the present invention, which consists of Figure 2 It can be seen that the wind-solar-storage-regulating system, i.e., the new energy power station, includes a wind farm, a photovoltaic power station, a energy storage station, and a synchronous condenser. The wind farm, the photovoltaic power station, the energy storage station, and the synchronous condenser are connected in parallel and can all be independently or combinedly or jointly connected to the power grid.

[0073] At Figure 2 , ΔP G , ΔP W , ΔP B , ΔP PV are the power outputs of the synchronous condenser, the wind turbine generator set, the energy storage, and the photovoltaic respectively, ΔP m is the power output of the synchronous generator, ΔP GWBV is the power output of the synchronous condenser, the wind turbine generator set, the photovoltaic, and the energy storage, ΔP L is the load regulation signal, K L is the load regulation coefficient, R is the droop coefficient, T s is the inertia time constant of the steam turbine, and F s is the characteristic coefficient of the steam turbine.

[0074] In this embodiment, D sys = 0.7, K L = 1.5, R = 0.04, T s = 8s, F s = 0.5.

[0075] Figure 1 is the flowchart of the inertia and frequency coordinated control method for the wind-solar-storage-regulating system of the present invention. It can be seen from this figure that the regulation process of the inertia and frequency coordinated control method for the wind-solar-storage-regulating system provided by the present invention is as follows:

[0076] Step 1, on the premise of meeting the safety requirements of the power grid frequency change, calculate the minimum inertia time constant demand H smin of the power system at the initial stage of the frequency disturbance according to the minimum inertia time constant demand formula.

[0077] In this embodiment, the minimum inertia time constant demand formula is:

[0078]

[0079] In the formula, ΔP d is the disturbance power, is the maximum allowable value of the frequency change rate.

[0080] Step 2, calculate the inertia time constant, including the inherent inertia time constant H of the synchronous generator set g1 , the virtual inertia time constant H of the fan VW , the virtual inertia time constant H of the energy storage station VB , the virtual inertia time constant H of the photovoltaic power station PV and the inertia time constant H of the synchronous condenser G .

[0081] In this embodiment, the expression of the inherent inertia time constant H of the synchronous generator set g1 is:

[0082]

[0083] In the formula, J g is the rotational kinetic energy inertia of the synchronous generator set, ω e is the synchronous angular velocity, S NG is the rated capacity of the synchronous generator set;

[0084] The expression of the virtual inertia time constant H of the fan VW is:

[0085]

[0086] In the formula, P n is the number of pole pairs of the fan, N t is the gearbox speed ratio of the fan, Δω r is the change in fan speed, H w is the inherent inertia time constant of the fan, λ opt is the optimal tip speed ratio of the fan, v is the real-time wind speed captured by the fan, Δω e is the change in synchronous angular velocity, R t is the blade radius of the fan, V min is the cut-in wind speed of the maximum power tracking area of the fan, V max is the rated wind speed, ω max is the maximum speed when the fan operates stably;

[0087] The expression of the virtual inertia time constant H of the energy storage station VB is:

[0088]

[0089] In the formula, H g2 is the inertia time constant of the equal-capacity synchronous machine, Δγ soc is the change in the state of charge of the energy storage station, γ soc is the state of charge of the energy storage station, E gThe rotational kinetic energy stored in an equal-capacity synchronous machine, W B The energy stored in the energy storage system station, W B = u B Q N γ soc_0 ,u B is the voltage of the storage battery, Q N is the rated capacity of the storage battery, γ soc_0 is the initial state of charge of the storage battery;

[0090] The virtual inertia time constant H of the photovoltaic power station PV The expression is:

[0091]

[0092] In the formula, C is the equivalent capacitance, U dc is the input voltage of the photovoltaic power station, k1 is the virtual inertia control coefficient, and S is the Laplace operator;

[0093] The inertia time constant H of the synchronous condenser when it participates in operation G The expression is:

[0094]

[0095] In the formula, E k is the mechanical energy of the entire power system when the synchronous condenser participates in operation, S N is the apparent capacity of the synchronous condenser, J G is the moment of inertia of the synchronous condenser, ω n is the rated mechanical angular velocity.

[0096] In this embodiment, H g1 = 4s, H VW = 4s, H VB = 2.4s, H PV = 2.5s, H G = 3s, s is seconds.

[0097] Step 3, calculate the inertia support time t required when the grid frequency drops to the lowest value h .

[0098] In this embodiment, the inertia support time t required when the grid frequency drops to the lowest value h The expression is:

[0099]

[0100] In the formula, b is the oscillation frequency, T s is the inertia time constant of the steam turbine in the synchronous generator set, ξ is the damping ratio, and a is the natural frequency parameter;

[0101] The expressions for the oscillation frequency b, damping ratio ξ, and natural frequency parameter a are as follows:

[0102]

[0103] where F s is the characteristic coefficient of the steam turbine, D sys is the damping coefficient of the power system, K L is the load regulation coefficient, R is the droop coefficient, ρ is the wind power penetration rate, H s is the inertia support time constant required by the power system, H s = H G + H g + H VW ρ + H VB ρn1 + H PV ρn2. Here, H g is the equivalent inertia time constant of the synchronous generator corresponding to the wind power penetration rate ρ, n1 is the ratio of the rated power of the energy storage station to the rated capacity of the wind turbine, and n2 is the ratio of the rated power of the photovoltaic power station to the rated capacity of the wind turbine.

[0104] In this embodiment, J g = 1947.3 kg·m 2 , ω e = 78.5 rad / s, S NG = 6 MW, p n = 2, N t = 45, Δω r = 10%, H W = 4 s, λ opt = 9, v = 8 m / s, R t = 49 m, v max = 1.2 pu, v min = 0.8 pu, Δω e = 10%, H g2 = 3 s, Δγ soc = -5%, γ soc = 55%, E g = 64.88 MJ, W B = 30.64 MJ, u B = 540 V, k1 = 5, Q N = 100 KW, γ soc_0 = 60%, C = 1250 uf, U dc = 800 V, E k = 1.5 MJ, S N = 0.55 Mvar, J G = 1217 kg·m 2 , ωn = 3000 r·min -1 , ρ = 20%, t h = 1.93 s, n1 = 0.17, n2 = 0.1, H s = 7.22 s.

[0105] Step 4: According to the wind power penetration rate ρ and the inertia time constant obtained in Step 2, calculate the equivalent inertia time constants under different support conditions, and obtain the disturbance powers under different support conditions according to the minimum inertia time constant requirement formula.

[0106] In this embodiment, the calculation methods of the disturbance powers under different support conditions are as follows:

[0107] Define the equivalent inertia time constant when the synchronous generator unit supports alone as the first equivalent time constant H s1 , H s1 = H g1 (1 - ρ), where ρ is the wind power penetration rate. When the synchronous generator unit supports alone, let H smin = H s1 , substitute it into the minimum inertia time constant requirement formula in S1 to calculate the disturbance power at this time, and denote it as the first disturbance power ΔP d1 ;

[0108] Define the equivalent inertia time constant when the synchronous generator unit and the synchronous condenser support together as the second equivalent time constant H s2 , H s2 = H G + H g , H g is the equivalent inertia time constant of the synchronous generator unit corresponding to the wind power penetration rate ρ. When the synchronous generator unit and the synchronous condenser support together, let H smin = H s2 , substitute it into the minimum inertia time constant requirement formula in S1 to calculate the disturbance power at this time, and denote it as the second disturbance power ΔP d2 ;

[0109] Define the equivalent inertia time constant when the synchronous generator unit, the synchronous condenser and the wind farm support together as the third equivalent time constant H s3 , H s3 = H G + H g + H VW ρ. When the synchronous generator unit, the synchronous condenser and the wind farm support together, let H smin = H s3 , substitute it into the minimum inertia time constant requirement formula in S1 to calculate the disturbance power at this time, and denote it as the third disturbance power ΔP d3 ;

[0110] Define the equivalent inertia time constant when the synchronous generator set, synchronous condenser, wind farm, and energy storage station support together as the fourth equivalent time constant H s4 , H s4 = H G + H g + H VW ρ + H VB ρn1, where n1 is the ratio of the rated power of the energy storage station to the rated capacity of the wind turbine. When the synchronous generator set, synchronous condenser, wind farm, and energy storage station support together, let H smin = H s4 , substitute it into the minimum inertia time constant requirement formula in S1 to calculate the disturbance power at this time, and denote it as the fourth disturbance power ΔP d4 ;

[0111] Define the equivalent inertia time constant when the synchronous generator set, synchronous condenser, wind farm, energy storage station, and photovoltaic power station support together as the fifth equivalent time constant H s5 , H s5 = H G + H g + H VW ρ + H VB ρn1 + H PV ρn2, where n2 is the ratio of the rated power of the photovoltaic power station to the rated capacity of the wind turbine. When the synchronous generator set, synchronous condenser, wind farm, energy storage station, and photovoltaic power station support together, let H smin = H s5 , substitute it into the minimum inertia time constant requirement formula in S1 to calculate the disturbance power at this time, and denote it as the fifth disturbance power ΔP d5 .

[0112] In this embodiment, the first equivalent time constant H s1 = 3.2 s, the second equivalent time constant H s2 = 6.2 s, the third equivalent time constant H s3 = 7 s, the fourth equivalent time constant H s4 = 7.1 s, the fifth equivalent time constant H s5 = 7.22 s, s represents seconds.

[0113] Step 5, according to the disturbance power obtained in step 4 and the inertia support time t required when the grid frequency drops to the lowest value obtained in step 3 h Carry out the participation and withdrawal of the inertia support of the wind-solar-storage-synchronous condenser.

[0114] In this embodiment, the implementation process of the participation and withdrawal of the inertia support of the wind-solar-storage-synchronous condenser is as follows:

[0115] When the grid has a frequency disturbance, carry out inertia support according to the following settings:

[0116] When ΔP d ≤ΔP d1 synchronous generator sets provide inertia support at the beginning of frequency disturbance;

[0117] When ΔP d1 <ΔP d ≤ΔP d2 synchronous wind turbine generators and synchronous condensers jointly provide inertia support at the beginning of frequency disturbance. After the minimum inertia support time t h the synchronous condenser withdraws from inertia support;

[0118] When ΔP d2 <ΔP d ≤ΔP d3 synchronous generator sets, synchronous condensers and wind farms jointly provide inertia support at the beginning of frequency disturbance. After the minimum inertia support time t h the synchronous condenser and the wind farm withdraw from inertia support;

[0119] When ΔP d3 <ΔP d ≤ΔP d4 synchronous generator sets, synchronous condensers, wind farms and energy storage stations jointly provide inertia support at the beginning of frequency disturbance. After the minimum inertia support time t h the synchronous condenser, the wind farm and the energy storage station withdraw from inertia support;

[0120] When ΔP d4 <ΔP d ≤ΔP d5 synchronous generator sets, synchronous condensers, wind farms, energy storage stations and photovoltaic power stations jointly provide inertia support at the beginning of frequency disturbance. After the inertia support time t h the synchronous condenser, the wind farm, the energy storage station and the photovoltaic power station withdraw from inertia support.

[0121] To verify the beneficial effects of the control method of the present invention, simulations were carried out.

[0122] Figure 1 is the flowchart of the inertia and frequency coordinated control method for wind power, energy storage and regulation of the present invention. When a frequency disturbance occurs in the power grid, the inertia demand of the power system is evaluated, the inertia support capabilities of wind power, energy storage and regulation are evaluated, the power generation systems for providing inertia support under this frequency disturbance condition are obtained, the inertia support time is calculated, and inertia support is participated in and withdrawn in a timely manner.

[0123] Figure 2It is the frequency response model of the wind-solar-storage-regulation system of the present invention. This model includes new energy power stations, traditional thermal power plants, and the power grid; the new energy power stations include synchronous condensers, wind farms, energy storage stations, and photovoltaic power stations; the traditional thermal power plants are synchronous generator sets. When the power grid is subject to frequency disturbances, the synchronous condensers, wind farms, energy storage stations, and photovoltaic power stations in the new energy power stations can independently or jointly participate in providing inertia support for the power grid.

[0124] Figure 3 It is the evaluation diagram of the system inertia demand under the constraint of frequency change of the present invention, where the horizontal axis is the maximum frequency change rate, with the unit of Hz / s, the vertical axis is the power disturbance amount, with the unit of pu, and the vertical axis is the minimum system inertia demand, with the unit of s. Figure 3 The intersections on the vertical axis from bottom to top are the first equivalent time constant H s1 = 3.2 s, the second equivalent time constant H s2 = 6.2 s, the third equivalent time constant H s3 = 7 s, the fourth equivalent time constant H s4 = 7.1 s, the fifth equivalent time constant H s5 = 7.22 s.

[0125] Figure 4 It is the simulation waveform diagram when the synchronous generator set of the present invention provides inertia support alone. From top to bottom, they are the system frequency, the output power of the photovoltaic power station, the output power of the wind farm, the output power of the energy storage station, the output power of the synchronous generator set, and the output power of the synchronous condenser. As can be seen from Figure 4 When the power grid undergoes frequency disturbances, the synchronous generator set provides inertia support for the system and increases the active power output. The lowest point f of the system frequency drop min is increased by 0.043 Hz compared with the situation without inertia support, and the system frequency change rate is decreased by 0.022 Hz / s.

[0126] Figure 5 It is the simulation waveform diagram when the synchronous generator set and the synchronous condenser of the present invention provide inertia support. From top to bottom, they are the system frequency, the output power of the photovoltaic power station, the output power of the wind farm, the output power of the energy storage station, the output power of the synchronous generator set, and the output power of the synchronous condenser. As can be seen from Figure 5 When the power grid undergoes frequency disturbances, the synchronous generator set and the synchronous condenser provide inertia support for the system and increase the active power output. The lowest point f of the system frequency drop min is increased by 0.066 Hz compared with the situation without inertia support, and the system frequency change rate is decreased by 0.034 Hz / s.

[0127] Figure 6It is the simulation waveform diagram when the synchronous generator set, synchronous condenser, and wind farm of the present invention provide inertia support. From top to bottom, they are system frequency, output power of the photovoltaic power station, output power of the wind farm, output power of the energy storage station, output power of the synchronous generator set, and output power of the synchronous condenser. From Figure 6 It can be seen that when the power grid has a frequency disturbance, the synchronous generator set, synchronous condenser, and wind farm provide inertia support for the system and increase the active power output. The lowest point f of the system frequency drop min increases by 0.189 Hz compared with the situation without inertia support, and the system frequency change rate decreases by 0.098 Hz / s.

[0128] Figure 7 It is the simulation waveform diagram when the synchronous generator set, synchronous condenser, wind farm, and energy storage station of the present invention provide inertia support. From top to bottom, they are system frequency, output power of the photovoltaic power station, output power of the wind farm, output power of the energy storage station, output power of the synchronous generator set, and output power of the synchronous condenser. From Figure 7 It can be seen that when the power grid has a frequency disturbance, the synchronous generator set, synchronous condenser, wind farm, and energy storage station provide inertia support for the system and increase the active power output. The lowest point f of the system frequency drop min increases by 0.197 Hz compared with the situation without inertia support

[0129] and the system frequency change rate decreases by 0.102 Hz / s.

[0130] Figure 8 It is the simulation waveform diagram when the synchronous generator set, synchronous condenser, wind farm, energy storage station, and photovoltaic power station of the present invention provide inertia support. From top to bottom, they are system frequency, output power of the photovoltaic power station, output power of the wind farm, output power of the energy storage station, output power of the synchronous generator set, and output power of the synchronous condenser. When the power grid has a frequency disturbance, the synchronous generator set, synchronous condenser, wind farm, energy storage station, and photovoltaic power station provide inertia support for the system and increase the active power output. From Figure 8 It can be seen that when the lowest point f of the system frequency drop min increases by 0.204 Hz compared with the situation without inertia support, and the system frequency change rate decreases by 0.106 Hz / s.

[0131] Embodiment 2

[0132] A wind-solar-storage-regulation inertia and frequency coordinated control system includes a controller and a power system. When the power grid has a frequency disturbance, the controller adopts the above-mentioned wind-solar-storage-regulation inertia and frequency coordinated control method to provide inertia support for the power system and ensure the stability of the power grid frequency.

[0133] In this embodiment, the power system includes a new energy power station and a synchronous generator set. The new energy power station includes a wind farm, a photovoltaic power station, an energy storage station, and a synchronous condenser. The wind farm, the photovoltaic power station, the energy storage station, and the synchronous condenser are connected in parallel and can all be independently or combinedly or jointly connected to the power grid.

[0134] Embodiment 3

[0135] An embodiment of the present application may also be a readable storage medium, on which a computer program is stored. When the computer program is executed, the above-mentioned method for coordinated control of inertia and frequency of wind, light, and energy storage is implemented. Specifically, the steps in the decision-making method of decision-making behavior according to various embodiments of the present application described in the above method of this specification are executed.

[0136] The computer-readable storage medium may adopt any combination of one or more readable media. The readable medium may be a readable signal medium or a readable storage medium. The readable storage medium may include, for example, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination of the above. More specific examples (non-exhaustive list) of the readable storage medium include: an electrical connection having one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0137] Embodiment 4

[0138] An embodiment of the present application may also be a device, which includes a processor, a memory, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the above-mentioned method for coordinated control of inertia and frequency of wind, light, and energy storage is implemented. Specifically, when the processor executes the computer program, the steps in the decision-making method of decision-making behavior according to various embodiments of the present application described in the above method of this specification are implemented.

[0139] The above circuit topology and elimination method of the present invention can be regarded as a hardware embodiment of the circuit topology alone, or as a software embodiment with only the elimination method, or as a combination of software and hardware in the form of an elimination method based on the circuit topology and modules. Moreover, the elimination method part of the present invention can be implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program codes, and appears in the form of a computer program product; and can be implemented in various computer languages, for example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript.

[0140] Furthermore, the embodiments of the present invention are described in conjunction with flowcharts and / or block diagrams. It should be understood that each process and / or block in the flowcharts and / or block diagrams of the present invention, as well as the combination of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate a means for implementing the functions specified in one or more processes and / or blocks in the processes of the present invention Figure 1 one or more processes and / or blocks Figure 1 a means for implementing the functions specified in one or more processes and / or blocks in the processes of the present invention. These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing devices to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including an instruction means that implements the functions specified in one or more processes and / or blocks in the processes of the present invention Figure 1 one or more processes and / or blocks Figure 1 a means for implementing the functions specified in one or more processes and / or blocks in the processes of the present invention. These computer program instructions can also be loaded onto a computer or other programmable data processing devices, such that a series of operation steps are executed on the computer or other programmable devices to generate a computer-implemented process. Thus, the instructions executed on the computer or other programmable devices provide steps for implementing the functions specified in one or more processes and / or blocks in the processes of the present invention Figure 1 one or more processes and / or blocks Figure 1 a means for implementing the functions specified in one or more processes and / or blocks in the processes of the present invention.

[0141] Therefore, the above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Changes and modifications made by those of ordinary skill in the art based on the specific implementation manners of the present invention and the above circumstances should be regarded as equivalent solutions of this application and should all fall within the protection scope of the present invention.

Claims

1. A coordinated control method for inertia and frequency of wind-solar-storage regulation, characterized in that, The control process is as follows: On the premise of meeting the safety requirements for power grid frequency changes, the minimum inertia time constant demand H of the power system at the initial stage of frequency disturbance is calculated according to the minimum inertia time constant demand formula smin ; Calculate the inertia time constant, including the inherent inertia time constant H of the synchronous generator set g1 , the virtual inertia time constant H of the wind turbine VW , the virtual inertia time constant H of the energy storage station VB , the virtual inertia time constant H of the photovoltaic power station PV and the inertia time constant H of the synchronous condenser G ; Calculate the inertia support time t required when the grid frequency drops to the lowest value h ; According to the wind power penetration rate ρ and the inertia time constant, the equivalent inertia time constant under different support conditions is calculated, and the disturbance power under different support conditions is obtained according to the minimum inertia time constant requirement formula; Based on the disturbance power and the inertia support time t required when the grid frequency drops to the lowest value h Carry out the participation and withdrawal of the inertial support of the wind-solar-storage regulation 2. The method for coordinated control of inertia and frequency of wind-solar-storage according to claim 1, characterized in that The minimum inertia time constant requirement formula is: where ΔP d is the disturbance power, is the maximum allowable value of the frequency change rate.

3. The method for coordinated control of inertia and frequency of a wind-solar-storage system according to claim 1, wherein The inherent inertia time constant H of the synchronous generator set g1 is expressed as: Wherein, J g is the rotational kinetic energy inertia of the synchronous generator set, ω e is the synchronous angular velocity, and S NG is the rated capacity of the synchronous generator set; The virtual inertia time constant H of the fan VW has the following expression: Where, P n is the number of pole pairs of the fan, N t is the gearbox speed ratio of the fan, Δω r is the change in the fan speed, H w is the inherent inertia time constant of the fan, λ opt is the optimal tip speed ratio of the fan, v is the real-time wind speed captured by the fan, Δω e is the change in the synchronous angular velocity, R t is the blade radius of the fan, V min is the cut-in wind speed of the maximum power tracking area of the fan, V max is the rated wind speed, ω max is the maximum speed during stable operation of the fan; The virtual inertia time constant H of the energy storage station VB has the following expression: In the formula, H g2 is the inertia time constant of the equal-capacity synchronous machine, and Δγ soc is the change in the state of charge of the energy storage station, and γ soc is the state of charge of the energy storage station, and E g is the rotational kinetic energy stored in the equal-capacity synchronous machine, and W B is the energy stored in the energy storage system station, and W B = u B Q N γ soc_0 , where u B is the voltage of the battery, and Q N is the rated capacity of the battery, and γ soc_0 is the initial state of charge of the battery; The virtual inertia time constant H of the photovoltaic power station PV is expressed as: where C is the equivalent capacitance, U dc is the input voltage of the PV power station, k1 is the virtual inertia control coefficient, and S is the Laplace operator; The inertia time constant H of the synchronous condenser when it participates in operation G is expressed as: Where, E k is the mechanical energy of the entire power system when the synchronous condenser participates in operation, S N is the apparent capacity of the synchronous condenser, J G is the moment of inertia of the synchronous condenser, ω n is the rated mechanical angular velocity.

4. The coordinated control method of wind-solar-storage inertia and frequency according to claim 1, characterized in that The inertia support time t required when the grid frequency drops to the lowest value h The expression is as follows: where b is the oscillation frequency, T s is the inertia time constant of the steam turbine in the synchronous generator set, ξ is the damping ratio, and a is the natural frequency parameter; The expressions of the oscillation frequency b, damping ratio ξ and natural frequency parameter a are: Wherein, F s is the characteristic coefficient of the steam turbine, D sys is the damping coefficient of the power system, K L is the load regulation coefficient, R is the droop coefficient, ρ is the wind power penetration rate, H s is the inertia support time constant required by the power system, H s = H G + H g + H VW ρ + H VB ρn1 + H PV ρn2. Wherein, H g is the equivalent inertia time constant of the synchronous generator set corresponding to the wind power penetration rate ρ, n1 is the ratio of the rated power of the energy storage station to the rated capacity of the wind turbine, and n2 is the ratio of the rated power of the photovoltaic power station to the rated capacity of the wind turbine.

5. A coordinated control method for wind-solar-storage inertia and frequency according to any one of claims 1-4, characterized in that The calculation method of the disturbance power under different support conditions is as follows: Define the equivalent inertia time constant when the synchronous generator unit is independently supported as the first equivalent time constant H s1 , H s1 = H g1 (1 - ρ), where ρ is the wind power penetration rate. When the synchronous generator unit is independently supported, let H smin = H s1 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the first disturbance power ΔP d1 ; Define the equivalent inertia time constant when the synchronous generator set and the synchronous condenser support together as the second equivalent time constant H s2 , H s2 = H G + H g , H g is the equivalent inertia time constant of the synchronous generator set corresponding to the wind power penetration rate ρ. When the synchronous generator set and the synchronous condenser support together, let H smin = H s2 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the second disturbance power ΔP d2 ; Define the equivalent inertia time constant when the synchronous generator set, synchronous condenser and wind farm support together as the third equivalent time constant H s3 , H s3 =H G +H g +H VW ρ. When the synchronous generator set, synchronous condenser and wind farm support together, let H smin =H s3 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the third disturbance power ΔP d3 ; Define the equivalent inertia time constant when the synchronous generator set, synchronous condenser, wind farm, and energy storage station jointly support as the fourth equivalent time constant H s4 , H s4 = H G + H g + H VW ρ + H VB ρn1, where n1 is the ratio of the rated power of the energy storage station to the rated capacity of the wind turbine. When the synchronous generator set, synchronous condenser, wind farm, and energy storage station jointly support, let H smin = H s4 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the fourth disturbance power ΔP d4 ; Define the equivalent inertia time constant when synchronous generator sets, synchronous condensers, wind farms, energy storage stations, and photovoltaic power stations jointly support as the fifth equivalent time constant H s5 , H s5 = H G + H g + H VW ρ + H VB ρn1 + H PV ρn2, where n2 is the ratio of the rated power of the photovoltaic power station to the rated capacity of the wind turbine. When synchronous generator sets, synchronous condensers, wind farms, energy storage stations, and photovoltaic power stations jointly support, let H smin = H s5 , substitute it into the minimum inertia time constant requirement formula to calculate the disturbance power at this time, and denote it as the fifth disturbance power ΔP d5 .

6. The method for coordinated control of inertia and frequency of wind-solar-storage according to claim 5, characterized in that The implementation process of the participation and withdrawal of the inertia support of the wind-solar-storage-regulation is as follows: When a frequency disturbance occurs in the power grid, the inertia support is carried out according to the following settings: When ΔP d ≤ ΔP d1 , the synchronous generator set provides inertia support at the beginning of the frequency disturbance; When ΔP d1 < ΔP d ≤ ΔP d2 When, the synchronous wind turbine and the synchronous condenser jointly provide inertia support at the beginning of the frequency disturbance. After the minimum inertia support time t h elapses, the synchronous condenser withdraws from the inertia support; When ΔP d2 <ΔP d ≤ΔP d3 At this time, the synchronous generator set, synchronous condenser and wind farm jointly provide inertia support at the beginning of the frequency disturbance. After the minimum inertia support time t h the synchronous condenser and wind farm withdraw from inertia support; When ΔP d3 <ΔP d ≤ΔP d4 At this time, the synchronous generator set, synchronous condenser, wind farm and energy storage station jointly provide inertia support at the beginning of the frequency disturbance. After the minimum inertia support time t h elapses, the synchronous condenser, wind farm and energy storage station withdraw from the inertia support; When ΔP d4 < ΔP d ≤ ΔP d5 When, at the beginning of the frequency disturbance, the synchronous generator set, synchronous condenser, wind farm, energy storage station, and photovoltaic power station jointly provide inertia support. After the inertia support time t h elapses, the synchronous condenser, wind farm, energy storage station, and photovoltaic power station withdraw from the inertia support.

7. A coordinated control system for wind-solar-storage inertia and frequency, characterized in that, It includes a controller and a power system. When a frequency disturbance occurs in the power grid, the controller adopts a wind-solar-storage-regulation inertia and frequency coordinated control method as described in any one of claims 1 to 6 to provide inertia support for the power system and ensure the stability of the power grid frequency.

8. A wind-solar-storage inertia and frequency coordinated control system according to claim 7, characterized in that, The power system includes a new energy power station and a synchronous generator set. The new energy power station includes a wind farm, a photovoltaic power station, an energy storage station and a synchronous condenser. The wind farm, the photovoltaic power station, the energy storage station and the synchronous condenser are connected in parallel and can all be independently or combined or jointly connected to the power grid.

9. A readable storage medium, characterized in that, It stores a computer program, and when the computer program is executed, it realizes a wind-solar-storage-regulation inertia and frequency coordinated control method as described in any one of claims 1 to 6.

10. A device, characterized in that, It includes a processor, a memory and a computer program stored on the memory and operable on the processor. When the processor executes the computer program, it realizes a wind-solar-storage-regulation inertia and frequency coordinated control method as described in any one of claims 1 to 6.

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