Frequency Security-Constrained Dispatching Method and Analysis Device with Wind Power Frequency Response Support

Abstract

The present invention discloses a frequency security-constrained dispatching method and a dispatching analysis device with wind power frequency response support. By setting a maximum frequency change rate constraint, a quasi-steady state constraint, and a frequency nadir constraint, wherein the maximum frequency change rate constraint is used to constrain the frequency change rate of the power system at t = 0<supgt;+< / supgt; not to exceed the allowable value of the set maximum frequency change rate of the system, the quasi-steady state constraint is used to constrain the frequency change rate of the power system to be zero at t = ∞, and the frequency nadir constraint is used to constrain the frequency deviation of the power system to be less than the allowable value of the set maximum frequency deviation of the system and the frequency change rate of the power system at the frequency nadir to be zero; The present invention takes into account the dynamic process of wind power providing frequency response support in the power system, comprehensively considers the inertia and primary frequency regulation capacity differences between synchronous units and wind farms, constructs frequency security constraints, and ensures the frequency security of the system after being disturbed in each time period.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrical engineering, and more specifically, relates to a frequency security-constrained dispatch method and analysis device with wind power frequency response support. Background Art

[0002] Under the development trend of new energy power sources gradually replacing traditional conventional power sources, the development of the power system gradually presents the characteristics of "high proportion of new energy and high proportion of power electronic devices". Different from the traditional power system dominated by synchronous units in the past, the frequency stability characteristics of the "dual-high" power system will change, and the frequency change after system faults will be more obvious, and even problems such as system frequency collapse may be caused, which puts forward new requirements for the safe and stable operation of the power system, and sufficient frequency response support resources need to be deployed at the operation level. To ensure the dynamic frequency security after the system is disturbed, on the one hand, new energy needs to provide frequency response support for the power system; on the other hand, frequency security constraints need to be considered in the unit commitment model of the power system. Existing studies have not comprehensively considered the differences in inertia and primary frequency regulation capabilities of each synchronous unit and wind farm, resulting in potential safety hazards of exceeding the frequency index limits in the system. How to ensure the frequency security after the system is disturbed at each time period has become a difficult problem that dispatchers urgently need to solve. Summary of the Invention

[0003] In view of the above defects or improvement requirements of the prior art, the present invention provides a frequency security-constrained dispatch method and analysis device with wind power frequency response support, aiming to consider the differences in inertia and primary frequency regulation capabilities of each synchronous unit and wind farm and ensure the frequency security after the system is disturbed at each time period.

[0004] To achieve the above object, according to one aspect of the present invention, a frequency security-constrained dispatch method with wind power frequency response support is provided, including:

[0005] Obtain the parameters of each component in the power system, where the components of the power system include synchronous units, wind farms, power grids, and electrical loads;

[0006] Construct the frequency security constraints of the frequency security unit commitment model, where the frequency security constraints include the maximum frequency change rate constraint, the quasi-steady state constraint, and the frequency minimum point constraint. Among them, the maximum frequency change rate constraint is used to constrain that the frequency change rate of the power system at t = 0 + does not exceed the allowable value of the set maximum frequency change rate of the system, the quasi-steady state constraint is used to constrain that the frequency change rate of the power system at t = ∞ is zero and the frequency deviation does not exceed the allowable value of the maximum frequency deviation in the quasi-steady state, and the frequency minimum point constraint is used to constrain that the frequency deviation of the power system is less than the allowable value of the set maximum frequency deviation of the system and the frequency change rate of the power system at the frequency minimum point is zero;

[0007] Construct the objective function of the frequency-secure unit commitment model, where the objective function is to minimize the operating cost of the power system;

[0008] Solve the frequency-secure unit commitment model to obtain the frequency response strategy of the power system after being subjected to active power disturbances.

[0009] In one embodiment, the specific form of the objective function is:

[0010]

[0011] where k is the time period number, i is the synchronous unit number, are respectively the fuel cost, start-up cost, and shut-down cost of synchronous unit i in the k-th time period, c cur is the penalty coefficient for wind curtailment, is the wind curtailment rate of wind farm j in the k-th time period, is the maximum output of the wind farm in the k-th time period, and Δk is the duration of a single time period.

[0012] In one embodiment, the specific form of the maximum frequency change rate constraint is:

[0013]

[0014] where i is the synchronous unit number, j is the wind farm number, ΔP0 is the response active power of the system under disturbance, is the allowable value of the maximum system frequency change rate, U Gi represents the start-stop state of synchronous unit i, with a value of 0 indicating shutdown and 1 indicating startup, H Gi is the inertia time constant of synchronous unit i, H Wj is the virtual inertia time constant of wind farm j.

[0015] In one embodiment, the specific form of the quasi-steady state constraint is:

[0016]

[0017] where i is the synchronous unit number, j is the wind farm number, ΔP0 is the response active power of the system under disturbance, represents the allowable value of the maximum quasi-steady state frequency deviation, U Gi represents the start-stop state of synchronous unit i, with a value of 0 indicating shutdown and 1 indicating startup, K Gi represents the primary frequency regulation power gain coefficient of synchronous unit i, K Wj represents the virtual primary frequency regulation power gain coefficient of wind farm j, K D is the system load damping coefficient.

[0018] In one embodiment, the specific form of the lowest frequency point constraint is as follows:

[0019]

[0020] where i is the number of the synchronous unit, j is the number of the wind farm, ΔP0 is the active power response of the system to the disturbance, and the moment t m is the moment when the system frequency drops to the lowest, is the primary frequency regulation response of the synchronous unit i when the system frequency drops to the lowest, and K Wj represents the virtual primary frequency regulation power gain coefficient of the wind farm j, and Δf max is the allowable value of the maximum system frequency deviation, and K D is the system load damping coefficient.

[0021] In one embodiment, linearization is performed on the primary frequency regulation response and the specific form of the lowest frequency point constraint is optimized as:

[0022]

[0023]

[0024] where is the lower bound of , represents the linearization result of the primary frequency regulation response , U Gi represents the start-stop state of the synchronous unit i, with the value of 0 indicating shutdown and 1 indicating startup, and K Gi represents the primary frequency regulation power gain coefficient of the synchronous unit i, is the lower bound of the system inertia H sys , H Gi is the inertia time constant of the synchronous unit i, and T Gi is the primary frequency regulation response time constant of the synchronous unit i.

[0025] In one embodiment, it is obtained by relaxing the feasible region and solving with the goal of minimizing the system inertia.

[0026] In one embodiment, the frequency safety constraint of the frequency safety unit commitment model further includes that during the process of the synchronous unit and the wind farm providing the primary frequency regulation response, the primary frequency regulation response support power cannot exceed the corresponding reserve capacity.

[0027] In one embodiment, the frequency security unit combination model further includes power balance constraints, upper / lower limits of unit output constraints, wind farm curtailment constraints, spinning reserve constraints, upper / lower ramp capacity constraints of units, minimum start / stop time constraints of units, and line capacity constraints.

[0028] According to another aspect of the present invention, there is provided a frequency security constraint dispatching analysis device with wind power frequency response support, including:

[0029] A parameter acquisition unit for acquiring parameters of each component in the power system, and the components of the power system include synchronous units, wind farms, power grids, and electrical loads;

[0030] A constraint condition construction unit for constructing frequency security constraints of the frequency security unit combination model, and the frequency security constraints include maximum frequency change rate constraints, quasi-steady state constraints, and frequency minimum point constraints. Among them, the maximum frequency change rate constraint is used to constrain that the frequency change rate of the power system at t = 0 + does not exceed the set allowable value of the maximum frequency change rate of the system, the quasi-steady state constraint is used to constrain that the frequency change rate of the power system at t = ∞ is zero and the frequency deviation does not exceed the allowable value of the maximum frequency deviation in the quasi-steady state, and the frequency minimum point constraint is used to constrain that the frequency deviation of the power system is less than the set allowable value of the maximum frequency deviation of the system and the frequency change rate of the power system at the frequency minimum point is zero;

[0031] An objective function construction unit for constructing an objective function of the frequency security unit combination model, and the objective function is to minimize the operation cost of the power system;

[0032] A solving unit for solving the frequency security unit combination model to obtain the frequency response strategy of the power system after being subjected to active power disturbances.

[0033] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following beneficial effects can be achieved:

[0034] The frequency security constraint dispatching method and dispatching analysis device with wind power frequency response support provided by the present invention, by constructing a frequency security unit combination model, setting an objective function and constraint conditions, among which the constraint conditions include maximum frequency change rate constraints, quasi-steady state constraints, and frequency minimum point constraints. These three constraints are set on the basis of the equivalent model of the system frequency response with wind power frequency response support, considering the differences in the inertia and primary frequency regulation capabilities of each synchronous unit. By adding these three constraints, the start / stop modes of each unit can be reasonably arranged and the working states of each synchronous unit and wind farm can be deployed, ensuring the dynamic frequency security of the system after being disturbed in each time period. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flowchart of steps of a frequency security-constrained dispatch method with wind power frequency response support for an embodiment;

[0036] Figure 2 It is a system frequency response equivalent model with wind power frequency response support provided for an embodiment;

[0037] Figure 3 It is a schematic diagram of a modified IEEE 14-node system provided for an embodiment;

[0038] Figure 4 It is a schematic diagram of the optimal start-up mode of synchronous units for an embodiment, where (a) corresponds to the conventional unit commitment model; (b) corresponds to the frequency security-constrained unit commitment model of the present invention;

[0039] Figure 5(a) is a schematic diagram of the comparison of the maximum RoCoF for an embodiment;

[0040] Figure 5(b) is a schematic diagram of the comparison of the maximum frequency deviation for an embodiment;

[0041] Figure 5(c) is a schematic diagram of the comparison of the quasi-steady-state frequency deviation for an embodiment. Detailed implementation manners

[0042] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0043] As Figure 1 shown is a flowchart of steps of a frequency security-constrained dispatch method with wind power frequency response support in an embodiment. The dispatch method at least includes:

[0044] Step S100: Obtain the parameters of each component in the power system. The components of the power system include synchronous units, wind farms, power grids, and electrical loads.

[0045] Specifically, collect the conventional parameters of synchronous units, wind farms, and power grids in the power system where it is located, as well as the electrical load and wind farm output curves.

[0046] The conventional parameters of synchronous units include: minimum technical output maximum technical output maximum up-ramp rate maximum down-ramp rate maximum start-up ramp rate maximum outage ramp rate minimum on-time Minimum downtime Inertia time constant H Gi , Primary frequency regulation power gain coefficient K Gi and primary frequency regulation response time constant T Gi . Wherein, the subscript i is the synchronous generator set index.

[0047] The conventional parameters of the wind farm include: wind farm capacity Virtual inertia time constant H Wj and virtual primary frequency regulation power gain coefficient K Wj . Wherein, j is the wind farm index.

[0048] The conventional parameters of the power grid include: power flow sensitivity matrix S and line maximum capacity

[0049] The electric load and wind farm output curve are: the electric load prediction curve D m (k) at bus m and the maximum active power output curve of the wind farm k is the time period index.

[0050] Step S200: Construct the frequency security constraints of the frequency security unit commitment model. The frequency security constraints include the maximum frequency change rate constraint, quasi-steady state constraint and frequency minimum point constraint.

[0051] Among them, the maximum frequency change rate (RoCoF) constraint is used to constrain that the frequency change rate of the power system at t = 0 + does not exceed the set allowable value of the system maximum frequency change rate. The quasi-steady state constraint is used to constrain that the frequency change rate of the power system at t = ∞ is zero and the frequency deviation does not exceed the allowable value of the quasi-steady state maximum frequency deviation. The frequency minimum point constraint is used to constrain that the frequency deviation of the power system is less than the set allowable value of the system maximum frequency deviation and the frequency change rate of the power system at the frequency minimum point is zero.

[0052] Before constructing the frequency security constraints, a system frequency response equivalent model with wind power frequency response support in the power system can be established, and the frequency response equation after the system is subjected to active power disturbance can be written. Each constraint condition is written based on the frequency response equation.

[0053] In one embodiment, the process of deriving the frequency response equation after the system is subjected to active power disturbance is as follows:

[0054] After the system is subjected to active power disturbance, the inertial response of the synchronous generator set Primary frequency regulation response As shown in formulas (1)-(2):

[0055]

[0056]

[0057] Among them, Δf(t) is the system frequency deviation at time t.

[0058] The active power ΔP of the load damping characteristic D (t) is calculated as shown in (3):

[0059] ΔP D (t) = K D Δf(t) (3)

[0060] Among them, K D is the load damping coefficient.

[0061] The inertial response of the wind farm The primary frequency regulation response are respectively expressed as:

[0062]

[0063]

[0064] Among them, j is the wind farm index.

[0065] According to (1)-(5), the equivalent model of the system frequency response is as Figure 2 shown, and H sys represents the total system inertia time constant, which is expressed as:

[0066]

[0067] Among them, U Gi represents the start / stop state of the synchronous machine i, and the value of 0 means shutdown and 1 means startup.

[0068] Based on the above formulas (1)-(6), the frequency response equation of the system after being disturbed can be written:

[0069]

[0070] Among them, ΔP0 is the active power of the system after being disturbed.

[0071] Based on the frequency response equation of the above formula (7), various constraint conditions can be written.

[0072] 1. The construction process of the system maximum RoCoF constraint is as follows:

[0073] The system maximum RoCoF appears at t = 0 + when. At t = 0 +At this moment, the system frequency deviation Δf = 0, and the primary frequency regulation response powers of the synchronous units and the wind farm and the active load damping response ΔP D are both 0. At this time, only the inertial responses of the synchronous units and the wind farm provide power support for the active disturbance, and the system RoCoF reaches the maximum value. The maximum RoCoF constraint is expressed as:

[0074]

[0075] where is the allowable value of the maximum system RoCoF. By formula (8), the system frequency change rate is made lower than the safety threshold, otherwise, the relay protection will be triggered, resulting in more units being cut off, thus triggering more serious frequency safety problems.

[0076] Formula (8) can be equivalently converted into a linear constraint, that is, the maximum RoCoF constraint, as shown in (9):

[0077]

[0078] 2. The construction process of the system quasi-steady state constraint is as follows:

[0079] When the primary frequency regulation response of the system enters the quasi-steady state (t = ∞), the system frequency deviation is stabilized at Δf ss , and at this time, the RoCoF of the system is expressed as:

[0080]

[0081] When the system enters the quasi-steady state, the primary frequency regulation response powers of the synchronous units and the wind farm and are respectively expressed as:

[0082]

[0083] ss represents the steady state, is the primary frequency regulation response of the synchronous units under the steady state, is the primary frequency regulation response of the wind farm under the steady state, and Δf ss is the system frequency deviation under the steady state.

[0084] Substituting formulas (10) and (11) into (7), the system quasi-steady state frequency safety constraint can be obtained as:

[0085]

[0086] where represents the allowable value of the maximum frequency deviation in the quasi-steady state.

[0087] (12) can be equivalently converted into linear constraints, as shown in (13):

[0088]

[0089] 3. The construction process for the lowest frequency point constraint is as follows:

[0090] Let the allowable value of the maximum system frequency deviation be Δf max . Considering the case of critical safety at the lowest frequency point, assume that at time t m the system frequency exactly drops to the lowest allowable value (f0 - Δf max ), where f0 is the rated frequency, generally 50 Hz. At this moment, there is:

[0091]

[0092] Substituting (14) into (7) gives:

[0093]

[0094] Equation (15) represents the case of critical safety at the lowest system frequency point. Replacing the equal sign in it with a less than or equal sign, the safety constraint for the lowest frequency point can be expressed as:

[0095]

[0096] In equation (16), the active power of the primary frequency regulation response of synchronous unit i has an unknown analytical expression and cannot be directly incorporated into the unit commitment model. Moreover, the frequency response equation (7) is a high-order differential equation with respect to the frequency difference Δf(t), making it difficult to solve for the analytical expression of the frequency.

[0097] Therefore, in one embodiment, a linearized frequency method is adopted to obtain an approximate analytical expression. The linearized frequency is used to approximate the system frequency and serve as the input to the speed control systems of each unit.

[0098] First, construct the system linearized frequency difference Δf line as:

[0099]

[0100] The time taken for the linearized frequency difference Δf line to reach the allowable value Δf max at the lowest frequency point is:

[0101]

[0102] Using Δf line as the input signal to the speed control system, the primary frequency regulation response of the synchronous unit Decoupled from the actual frequency difference Δf(t), the frequency response equivalent model still retains the transfer functions of each speed control system, so it can take into account the performance differences of different speed control systems participating in the primary frequency regulation response.

[0103] Then, the linearized frequency difference Δf line (t) in the time domain is converted into the linearized frequency difference Δf line (s) in the frequency domain.

[0104] Subsequently, based on the linearized frequency difference Δf line (s) in the frequency domain, the primary frequency regulation response power of the synchronous generator unit in the frequency domain is constructed, and its expression is:

[0105]

[0106] Among them, is the linearized primary frequency regulation response of the synchronous generator unit in the frequency domain.

[0107] Finally, taking the inverse Laplace transform of Equation (19), the time-domain expression of the frequency regulation response of synchronous generator unit i can be obtained, expressed as:

[0108]

[0109] Among them, is the linearized primary frequency regulation response of the synchronous generator unit in the time domain.

[0110] Substituting Equation (18) into Equation (20), when Δf line reaches the allowable value Δf max of the lowest frequency point, that is, at time t m , the primary frequency regulation response power of the thermal power unit:

[0111] ]>

[0112] Substituting Equation (21) into (16), the analytical lowest frequency point constraint can be obtained:

[0113]

[0114] Derivation Taking the derivative of the system inertia H sys as shown in Equation (23), it can be seen that increases monotonically with H sys .

[0115]

[0116] Therefore, the sufficient conditions for the lowest frequency point constraints (21)-(22) can be given, as shown in (24)-(25):

[0117]

[0118]

[0119] Among them, is the lower bound of the system inertia H sys of; is of the lower bound; (24) is a linear constraint condition.

[0120] In one embodiment, in addition to the three constraints of the above (9), (13), (24)-(25), it may further include constraint conditions of conventional unit commitment such as power balance constraint, upper / lower limit constraint of unit output, wind farm curtailment constraint, spinning reserve constraint, upper / lower ramping capacity constraint of unit, minimum start / stop time constraint of unit, and line capacity constraint.

[0121] In one embodiment, during the primary frequency regulation response process provided by synchronous units and wind farms, the primary frequency regulation response support power cannot exceed its reserve capacity. In the constraint conditions, when the primary frequency regulation response support power exceeds its reserve capacity, the reserve capacity is used to replace the primary frequency regulation response support power in the constraint.

[0122] Specifically, for the quasi-steady state constraint condition of Equation (13):

[0123]

[0124] Among them, the primary frequency regulation response support power of synchronous units in the steady state involved in the quasi-steady state constraint condition and the primary frequency regulation response support power of the wind farm Considering the limitation of the reserve capacity, when the primary frequency regulation response support power exceeds its reserve capacity, the reserve capacity is used to replace the primary frequency regulation response support power, that is, the constraint of Equation (13) can be converted into the constraints of Equations (26)-(28), specifically

[0125]

[0126]

[0127]

[0128] Among them, P base is the base power, is the maximum output of synchronous unit i, P Gi (k) is the actual output of synchronous unit i in the k-th period; is the curtailment rate of wind farm j in the k-th period, is the maximum output of the wind farm in the k-th period.

[0129] Specifically, for the lowest frequency constraint condition of Equation (25):

[0130]

[0131] Among them, the lowest frequency constraint condition involves the primary frequency regulation response support power of the synchronous generator set at the lowest frequency and the primary frequency regulation response support power of the wind farm Considering the limitation of the reserve capacity, when the primary frequency regulation response support power exceeds its reserve capacity, the reserve capacity is used to replace the primary frequency regulation response support power. That is, the constraint of Equation (23) can be converted into the constraints of Equations (29)-(31), specifically

[0132]

[0133]

[0134]

[0135] In an embodiment, the in Constraint (24) can be obtained by relaxing the feasible region of the original problem and solving it with the goal of minimizing the system inertia. The objective function is as shown in (32):

[0136]

[0137] Its constraint conditions are all the constraints in the original problem except for the lowest frequency constraints (24), (29)-(31).

[0138] Step S300: Construct the objective function of the frequency-secure unit commitment model, and the objective function is to minimize the operating cost of the power system.

[0139] The objective function of the unit commitment model is to minimize the operating cost of the power system, including the fuel cost, start-stop cost, and wind curtailment cost of the units. Its specific expression can be

[0140]

[0141] Among them, are respectively the fuel cost, start-up cost, and shut-down cost of unit i in the k-th period; c cur is the wind curtailment penalty coefficient, with the unit of $ / (MW·h); j is the wind farm station number; is the wind curtailment rate of wind farm j; Δk is the duration of a single period.

[0142] Step S400: Solve the frequency-secure unit commitment model to obtain the frequency response strategy of the power system after being subjected to active power disturbances.

[0143] Calling an existing solver can solve the economic dispatch strategy of a high - proportion wind - power power system and output the frequency response strategy after receiving a disturbance, including determining the start - stop status, output, and wind curtailment of wind farms at each time period.

[0144] Correspondingly, the present invention also claims to protect a frequency - security - constraint dispatch analysis device with wind - power frequency response support, which includes:

[0145] A parameter acquisition unit for acquiring the parameters of each component in the power system. The components of the power system include synchronous units, wind farms, power grids, and electrical loads;

[0146] A constraint condition construction unit for constructing the frequency - security constraints of the frequency - security unit commitment model. The frequency - security constraints include the maximum frequency change rate constraint, the quasi - steady - state constraint, and the minimum - frequency point constraint. Among them, the maximum frequency change rate constraint is used to constrain that the frequency change rate of the power system at t = 0 + does not exceed the allowable value of the set maximum frequency change rate of the system. The quasi - steady - state constraint is used to constrain that the frequency change rate of the power system at t = ∞ is zero and the frequency deviation does not exceed the allowable value of the quasi - steady - state maximum frequency deviation. The minimum - frequency point constraint is used to constrain that the frequency deviation of the power system is less than the allowable value of the set maximum frequency deviation of the system and the frequency change rate of the power system at the minimum - frequency point is zero;

[0147] An objective - function construction unit for constructing the objective function of the frequency - security unit commitment model. The objective function is to minimize the operation cost of the power system;

[0148] A solution unit for solving the frequency - security unit commitment model to obtain the frequency response strategy of the power system after receiving an active - power disturbance.

[0149] This frequency - security - constraint dispatch analysis device is used to execute the frequency - security - constraint dispatch method introduced above. The functions of its units correspond to the relevant steps above. For specific reference, please refer to the above introduction and will not be elaborated here.

[0150] Taking the Figure 3 power system as an example, using the frequency - security - constraint unit commitment with wind - power frequency response support provided by the present invention, compared with the conventional unit commitment model without (9), (13), (24) - (25) constraints, in the obtained operation results, the start - up modes are compared as Figure 4 shown. The black dots indicate that the unit is in the on - state, and the white dots indicate that the unit is in the off - state. Among them, (a) corresponds to the operation result under the conventional constraints, and (b) corresponds to the operation result under the constraints of the present invention. The different start - stop states indicate that the system operation mode is affected by the frequency - security constraints, and the system operation mode needs to change. Sufficient inertia and primary frequency - regulation resources need to be deployed to ensure the frequency security of the system after being disturbed. The frequency - security indicators of the system after being disturbed at each time period are asFigures 5(a) to 5(c) As shown, among which, Fig. 5(a) is the comparison result of the maximum RoCoF. It can be seen from this that when subjected to the same active power disturbance, by adopting the frequency security-constrained unit commitment of the present invention, the fluctuation of the maximum frequency change rate slightly decreases and does not exceed the allowable value of the maximum RoCoF. Fig. 5(b) is the comparison diagram of the maximum frequency difference of the system. When subjected to the same active power disturbance, by adopting the frequency security-constrained unit commitment of the present invention, the fluctuation amplitude of its maximum frequency difference significantly decreases and does not exceed the allowable value of the maximum frequency difference. Fig. 5(c) is the comparison diagram of the quasi-steady-state frequency difference. When subjected to the same active power disturbance, by adopting the frequency security-constrained unit commitment of the present invention, the fluctuation amplitude of its quasi-steady-state frequency difference significantly decreases and does not exceed the allowable value of the maximum quasi-steady-state frequency difference; thus, it can be seen that the present invention can improve the frequency security of the system after being disturbed.

[0151] Those skilled in the art can easily understand that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A frequency security-constrained dispatch method with wind power frequency response support, characterized in that Including: Obtain the parameters of each component in the power system, where the components of the power system include synchronous units, wind farms, power grids, and electrical loads; Construct the frequency security constraints of the unit commitment model with frequency security, where the frequency security constraints include the maximum frequency change rate constraint, the quasi-steady state constraint, and the minimum frequency point constraint. Among them, the maximum frequency change rate constraint is used to constrain that the frequency change rate of the power system at t = 0 + does not exceed the allowable value of the maximum frequency change rate of the set system. The quasi-steady state constraint is used to constrain that the frequency change rate of the power system at t = ∞ is zero and the frequency deviation does not exceed the allowable value of the maximum frequency deviation in the quasi-steady state. The minimum frequency point constraint is used to constrain that the frequency deviation of the power system is less than the allowable value of the maximum frequency deviation of the set system and the frequency change rate of the power system at the minimum frequency point is zero; Construct the objective function of the frequency-secure unit commitment model, where the objective function is to minimize the operating cost of the power system; Solve the frequency-secure unit commitment model to obtain the frequency response strategy of the power system after being subjected to active power disturbances; Among them, the specific form of the objective function is: Among them, C is the operating cost of the power system, k is the time period number, and i is the number of synchronous units. They are respectively the fuel cost, start-up cost, and shutdown cost of synchronous unit i in the k-th time period. c cur is the penalty coefficient for curtailed wind, is the curtailed wind rate of wind farm j in the k-th time period, is the maximum output of wind farm j in the k-th time period, and Δk is the duration of a single time period.

2. The frequency security-constrained dispatch method with wind power frequency response support according to claim 1, wherein The specific form of the maximum frequency change rate constraint is: Among them, i is the synchronous unit number, j is the wind farm number, ΔP0 is the response active power of the system under disturbance, is the allowable value of the maximum system frequency change rate, U Gi represents the start-stop state of synchronous unit i, with the value of 0 indicating shutdown and 1 indicating startup, H Gi is the inertia time constant of synchronous unit i, H wj is the virtual inertia time constant of wind farm j.

3. The frequency security-constrained dispatch method with wind power frequency response support according to claim 1, characterized in that The specific form of the quasi-steady state constraint is: Among them, i is the synchronous unit number, j is the wind farm number, ΔP0 is the response active power when the system is disturbed, represents the allowable value of the quasi-steady-state maximum frequency deviation, U Gi represents the start-stop state of synchronous unit i, with the value of 0 indicating shutdown and 1 indicating startup, K Gi represents the primary frequency regulation power gain coefficient of synchronous unit i, K Wj represents the virtual primary frequency regulation power gain coefficient of wind farm j, K D is the system load damping coefficient.

4. The frequency security-constrained dispatch method with wind power frequency response support according to claim 1, wherein The specific form of the lowest frequency point constraint is: Among them, i is the synchronous unit number, j is the wind farm number, ΔP0 is the active power response of the system to disturbances, and t m is the moment when the system frequency drops to the lowest, is the primary frequency regulation response of synchronous unit i when the system frequency drops to the lowest, K Wj represents the virtual primary frequency regulation power gain coefficient of wind farm j, Δf max is the allowable value of the maximum system frequency deviation, K D is the system load damping coefficient.

5. The frequency security-constrained dispatch method with wind power frequency response support according to claim 4, characterized in that Response to primary frequency regulation Perform linearization processing and optimize the specific form of the constraint of the lowest frequency point to: Among them, is the lower bound of indicating the linearized result of the primary frequency regulation response , U Gi represents the start-stop state of the synchronous unit i, with the value of 0 indicating shutdown and 1 indicating startup. K Gi represents the primary frequency regulation power gain coefficient of the synchronous unit i. is the lower bound of the system inertia H sys of H Gi is the inertia time constant of the synchronous unit i, and T Gi is the primary frequency regulation response time constant of the synchronous unit i.

6. The frequency security-constrained dispatch method with wind power frequency response support according to claim 5, wherein Obtained by relaxing the feasible region and solving with the goal of minimizing the system inertia.

7. The frequency security-constrained dispatch method with wind power frequency response support as claimed in claim 1, wherein The frequency security constraints of the frequency-secure unit commitment model also include that during the process of synchronous units and wind farms providing primary frequency regulation responses, the primary frequency regulation response support power cannot exceed the corresponding reserve capacity.

8. The frequency security-constrained dispatch method with wind power frequency response support according to claim 1, wherein The frequency-secure unit commitment model also includes power balance constraints, unit output upper / lower limit constraints, wind farm curtailment constraints, spinning reserve constraints, unit up / down ramp capacity constraints, unit minimum start / stop time constraints, and line capacity constraints.

9. A frequency security constraint dispatching analysis device with wind power frequency response support, characterized in that Including: A parameter acquisition unit for acquiring the parameters of each component in the power system, where the components of the power system include synchronous units, wind farms, power grids, and electrical loads; A constraint construction unit is used to construct frequency security constraints of a frequency security unit commitment model. The frequency security constraints include a maximum frequency change rate constraint, a quasi-steady state constraint, and a minimum frequency point constraint. Among them, the maximum frequency change rate constraint is used to constrain that the frequency change rate of the power system at t = 0 + does not exceed the allowed value of the set maximum frequency change rate of the system. The quasi-steady state constraint is used to constrain that the frequency change rate of the power system at t = ∞ is zero and the frequency deviation does not exceed the allowed value of the maximum frequency deviation in the quasi-steady state. The minimum frequency point constraint is used to constrain that the frequency deviation of the power system is less than the allowed value of the set maximum frequency deviation of the system and the frequency change rate of the power system at the minimum frequency point is zero; An objective function construction unit for constructing the objective function of the frequency-secure unit commitment model, where the objective function is to minimize the operating cost of the power system; A solving unit for solving the frequency-secure unit commitment model to obtain the frequency response strategy of the power system after being subjected to active power disturbances; Among them, the specific form of the objective function is: Among them, C is the operating cost of the power system, k is the time period number, i is the synchronous generator unit number, are respectively the fuel cost, start-up cost and shut-down cost of the synchronous generator unit i in the k-th time period, c cur is the penalty coefficient for wind curtailment, is the wind curtailment rate of wind farm j in the k-th time period, is the maximum output of wind farm j in the k-th time period, and Δk is the duration of a single time period.

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