PID (Proportion Integration Differentiation) parameter setting method for inhibiting conflict between primary frequency modulation and secondary frequency modulation of hydroelectric generating set

Abstract

The invention discloses a PID parameter setting method for suppressing conflict between primary frequency modulation and secondary frequency modulation of a hydroelectric generating set, and belongs to the technical field of hydroelectric generating set adjustment. Comprising the following steps: S1, calculating an initial value of a PID (Proportion Integration Differentiation) parameter according to a water diversion system water flow inertia time constant and a hydroelectric generating set mechanical inertia time constant; s2, taking the PID parameter initial value of the speed regulator as a PID parameter value, solving the root of the characteristic equation in the S1, and calculating a unit power dynamic analytical expression during frequency unit step disturbance according to a Fisher method of a quartic equation; s3, calculating an analytic expression of the hydroelectric generating set power square error integral quantity based on the unit power dynamic analytic expression; and S4, calculating a speed regulator PID parameter formula for suppressing the conflict between the primary frequency modulation and the secondary frequency modulation of the hydroelectric generating set according to the analytic expression of the unit power square error integral quantity and the initial value of the speed regulator PID parameter. The problem that the dynamic process of primary frequency modulation and the dynamic process of secondary frequency modulation conflict is solved, and the adjusting capacity of the hydroelectric generating set can be brought into full play.

Description

Technical Field

[0001] The invention belongs to the technical field of hydroelectric generator set regulation, and particularly relates to a PID parameter setting method for suppressing the conflict between primary frequency regulation and secondary frequency regulation of a hydroelectric generator set. Background Art

[0002] The participation of hydropower units in primary and secondary frequency regulation is the key to maintaining safe and stable operation of the power grid, and plays a vital role in building a new power system. At present, there are two main methods for setting the PID parameters of hydropower units: experimental setting method and recommended formula setting method. The experimental setting method mainly simulates the unit frequency disturbance under load conditions to set the PID parameters to obtain better primary frequency regulation performance, or sets the PID parameters by disturbing the unit power given value under load conditions to obtain better secondary frequency regulation performance; the recommended formula setting method mainly gives the governor PID parameter empirical formula based on the frequency disturbance dynamic process to meet the unit's better primary frequency regulation performance, or gives the PID parameter empirical formula based on the power disturbance dynamic process to meet the unit's better secondary frequency regulation performance.

[0003] It can be seen that at present, the PID parameters of hydropower units are adjusted only based on frequency disturbance or only based on power disturbance, without considering the relationship between frequency disturbance and power disturbance. However, in actual engineering projects, the dynamic processes of primary frequency regulation and secondary frequency regulation of units often conflict, which limits the regulation ability of the unit and even causes the unit to fail the dynamic process assessment. Summary of the invention

[0004] The purpose of the present invention is to address the problem in the prior art that frequency disturbance and power disturbance are not considered in PID parameter setting, which easily causes a conflict between the dynamic processes of primary frequency regulation and secondary frequency regulation during unit operation.

[0005] In order to solve the above technical problems, the present invention provides a PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of a hydropower unit, comprising the following steps:

[0006] S1. Calculate the initial values ​​of PID parameters using the formula recommended by Krivchenko based on the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the hydroelectric generator set;

[0007] S2, the initial value of the governor PID parameter is used as the PID parameter value, the root of the characteristic equation in S1 is solved and the dynamic analytical expression of the unit power when the frequency unit step disturbance is calculated according to the Ferrari method of the quartic equation;

[0008] S3, calculating the analytical formula of the square error integral of the hydropower unit power based on the unit power dynamic analytical expression;

[0009] S4. Calculate the PID parameter formula of the speed regulator for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of the hydropower unit through the analytical expression of the integral of the square error of the unit power and the initial value of the PID parameter of the speed regulator.

[0010] Preferably, the S1 comprises:

[0011] S11. Based on the relationship between various parameters of a typical power closed-loop hydroelectric generator unit regulation system, taking the participation of the hydroelectric generator unit in primary frequency regulation as a premise, the feedback process of the hydroelectric generator unit power is considered to obtain the transfer function of the hydroelectric generator unit power to the grid frequency fluctuation when the power is closed; at the same time, the feedback process of the hydroelectric generator unit frequency is considered to obtain the transfer function of the hydroelectric generator unit power to the given power;

[0012] S12. Based on the relationship between various parameters of a typical closed-loop hydroelectric generator unit regulation system, the feedback process of the hydroelectric generator unit opening is taken into account, and the transfer function of the hydroelectric generator unit power to the grid frequency fluctuation when the opening is closed-loop is obtained. At the same time, the feedback process of the hydroelectric generator unit frequency is taken into account, and the transfer function of the hydroelectric generator unit power to the given opening is obtained.

[0013] S13, dividing the transfer function of the hydropower unit power to the grid frequency fluctuation during the power closed loop by the transfer function of the hydropower unit power to the given power, to obtain G3;

[0014] S14, dividing the transfer function of the hydropower unit power to the grid frequency fluctuation when the opening is closed by the transfer function of the hydropower unit power to the given opening to obtain G6;

[0015] S15. In the primary frequency modulation dynamic process, the response time of the follow-up system is ignored, the turbine adopts an ideal turbine model, and the influence of the speed of the hydroelectric generator set on the damping is not considered. A simplified analysis is performed to obtain the characteristic equation;

[0016] S16. Determine the range of the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the hydroelectric generator set, constrain the matching of the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the hydroelectric generator set in accordance with the standard provisions, and use the Krivchenko recommended formula to calculate the initial values ​​of the PID parameters.

[0017] Preferably, when the hydropower unit participates in the secondary frequency regulation, the damping state of the transfer function between the secondary frequency regulation setting and the equivalent primary frequency regulation setting is represented by the relationship between the speed regulator adjustment parameters in the damping coefficient of the transfer function;

[0018] When the damping coefficient is <1, the system is underdamped;

[0019] When the damping coefficient > 1, the system is in an overdamped state;

[0020] When the damping coefficient = 1, the system is in a critical damping state, which is specifically expressed as:

[0021]

[0022] Among them, the critical damping state is the best secondary frequency regulation result when there is no oscillation phenomenon in the dynamic process of the system. The under-damping state will cause oscillation phenomenon in the dynamic process of the system, and the over-damping state will cause the dynamic response speed of the secondary frequency regulation of the hydropower unit to decrease.

[0023] Preferably, the transfer function of the hydropower unit power to the grid frequency fluctuation during the power closed loop is specifically expressed as:

[0024]

[0025] In the formula, p e is the generator power, x r is the set frequency value of the unit. When the unit is connected to the grid, this value is the measured value of the grid frequency. y is the transfer coefficient of turbine torque to guide vane opening, K is the transfer coefficient between generator electromagnetic torque and power angle, e is turbine coefficient, T w K is the inertia time constant of water flow in the water diversion system, D is the differential gain of the speed regulator, K I is the integral gain of the speed regulator, K P is the proportional gain of the speed regulator, s is the pull operator, A5, A4, A3, A2, A1, A0 are the coefficients in the transfer function of the power closed-loop system;

[0026] The transfer function of the hydropower unit power to the given power is specifically expressed as:

[0027]

[0028] In the formula, p r is the power given value, e p is the power slip coefficient of the speed regulator;

[0029] The transfer function of the hydropower unit power to the grid frequency fluctuation when the opening is closed is specifically expressed as:

[0030]

[0031] Where A'4, A'3, A'2, A'1, and A'0 are the coefficients in the transfer function of the opening closed-loop system;

[0032] The transfer function of the power of the hydropower unit with a given opening degree is specifically expressed as:

[0033]

[0034] In the formula, yr is the given value of opening; b p is the opening slip coefficient of the speed regulator.

[0035] Preferably, the specific expression of G3 is:

[0036]

[0037] The specific expression of G6 is:

[0038]

[0039] Preferably, in S2, the dynamic analytical expression of the unit power during the frequency unit step disturbance is specifically expressed as:

[0040] P e (t) = P1(t) + P2(t) + P3(t);

[0041]

[0042] P3(t) = F3;

[0043] Where t is time, P1 is the monotonic attenuation component corresponding to the real root of the system, P2 is the oscillatory attenuation component corresponding to the conjugate complex root of the system, P3 is the constant component after the system is stabilized, and K1, K2, K3, F3, δ, ω, and ψ are the coefficients in the system expression.

[0044] Preferably, in S3, the analytical expression of the integral of the square error of the hydropower unit power is specifically expressed as:

[0045]

[0046] Where p1 and p2 are the two real roots corresponding to the system characteristic equation.

[0047] Preferably, in S4, in order to ensure that the integral error is minimized and the critical damping state is taken into consideration, the integral gain and differential gain of the speed regulator are Taylor expanded in the formula recommended by Krivchenko and the first-order terms are retained to obtain the PID parameter formula of the speed regulator.

[0048] As a preferred method, in order to ensure the minimum integral error and take into account the critical damping state, the integral gain and differential gain of the speed regulator need to meet the following requirements:

[0049]

[0050] Preferably, the speed regulator PID parameter formula is specifically expressed as:

[0051]

[0052] In the formula, each parameter satisfies

[0053] In the formula, K I0 is the initial value of the speed regulator integral gain, K D0 is the initial value of the speed regulator differential gain, I I0 is the first-order change rate of the integral gain of the square error of the hydropower unit power near the initial value, I D0 is the first-order change rate of the integral of the square error of the hydropower unit to the differential gain near the initial value, I II0 is the second-order change rate of the integral gain of the square error of the hydropower unit power near the initial value, I DD0 is the second-order change rate of the integral of the square error of the hydropower unit to the differential gain near the initial value, I ID0 It is the second-order change rate of the integral gain and differential gain of the square error integral of the hydropower unit near the initial value.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] This scheme deduces PID parameters, where the PID parameters are optimized based on the formula recommended by Krivchenko. During the optimization process, the transfer relationship between the primary frequency modulation dynamic process and the secondary frequency modulation dynamic process is considered, and the dynamic process damping between the two different disturbances is guaranteed to be critical damping, which prevents the oscillation problem between the two disturbances in the underdamped state, and also ensures that the unit has a faster dynamic process. Thus, the problem of conflict between the primary frequency modulation and the secondary frequency modulation dynamic process during the operation of the unit is suppressed, and the regulation capacity of the hydropower unit can be fully utilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Other features, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings. The drawings are only for the purpose of illustrating preferred embodiments and are not to be considered as limiting the present invention. Also, the same reference symbols are used throughout the drawings to represent the same parts.

[0057] Figure 1 It is a typical structural block diagram of the power closed-loop hydroelectric generator set regulation system in the method of the present invention;

[0058] Figure 2 It is a typical structural block diagram of the opening closed-loop hydraulic generator set regulation system in the method of the present invention. DETAILED DESCRIPTION

[0059] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific implementation method described herein is only an optimal embodiment of the present invention, which is only used to explain the present invention and does not limit the scope of protection of the present invention. All other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0060] Embodiment 1: PID parameter setting method for suppressing the conflict between primary frequency regulation and secondary frequency regulation of hydropower units, according to Figure 1 The typical structure block diagram of the power closed-loop hydroelectric generator regulation system shown in the figure shows the relationship between the various parameters:

[0061]

[0062] Among them, x is the instantaneous speed value of the unit during actual operation, d x is the unit frequency deviation value, K P is the proportional gain of the speed regulator, K I is the integral gain of the speed regulator, K D is the differential gain of the speed regulator, y P is the proportional output of the speed regulator, y I is the integral output of the speed regulator, y D is the differential output of the speed regulator, y PID is the opening command output by the PID speed regulator, T y is the response time constant of the servo system, y is the guide vane opening value, T w is the water flow inertia time constant of the water diversion system, e y is the transfer coefficient of turbine torque to guide vane opening, e is the turbine coefficient, e qh is the transfer coefficient of turbine flow to water head, P t is the turbine power, P e is the generator power, d m is the difference between the dynamic torque and the resistance torque, T a is the mechanical inertia time constant of the hydroelectric generator set, D is the damping coefficient of the hydroelectric generator set, K is the transfer coefficient between the electromagnetic torque of the generator and the power angle, P r is the power given value, d P is the power deviation, e p is the power slip coefficient of the speed regulator, and s is the pull operator.

[0063] According to formula (1), when the unit participates in primary frequency regulation, the transfer function of the unit power to the grid frequency fluctuation is:

[0064]

[0065] Among them, the expressions of each parameter are:

[0066]

[0067] Among them, A5, A4, A3, A2, A1, and A0 are coefficients of the denominator polynomial in the transfer function of the power closed-loop system.

[0068] When deriving the unit primary frequency regulation transfer function formula (2), the feedback process of the unit power is taken into account. Compared with the traditional method, it is more suitable for analyzing the situation where the unit primary frequency regulation and secondary frequency regulation are put into operation at the same time.

[0069] The transfer function of unit power to given power is:

[0070]

[0071] When deriving the unit secondary frequency regulation transfer function formula (4), the feedback process of the unit frequency is taken into account. Compared with the traditional method, it is more suitable for analyzing the situation where the unit primary frequency regulation and secondary frequency regulation are put into operation at the same time.

[0072] According to formula (2) and formula (4), we can get:

[0073]

[0074] It can be seen from formula (5) that when the speed regulator power is closed, the frequency setting dynamic process of the unit can be regarded as a given value of the same size passing through the transfer function (5) and then performing the power setting dynamic process.

[0075] The commonly used regulation system structure diagram of a closed-loop hydroelectric generator set is as follows: Figure 2 As shown in the figure. r is the given value of opening, d y is the opening deviation, b P is the opening slip coefficient of the speed regulator.

[0076] according to Figure 2 The typical structure block diagram of the closed-loop hydraulic generator unit opening regulation system shown in the figure shows the relationship between the various parameters:

[0077]

[0078] According to formula (6), when the unit participates in primary frequency regulation, the transfer function of the unit power to the grid frequency fluctuation is:

[0079]

[0080] The expressions of each parameter are:

[0081]

[0082] Among them, A′4, A′3, A′2, A′1, and A′0 are the coefficients of the denominator polynomial in the transfer function of the open closed-loop system.

[0083] When deriving the unit primary frequency regulation transfer function formula (7), the feedback process of the unit opening is taken into account. Compared with the traditional method, it is more suitable for analyzing the situation where the unit primary frequency regulation and secondary frequency regulation are put into operation at the same time.

[0084] The transfer function of the unit power opening is given by:

[0085]

[0086] When deriving the unit primary frequency regulation transfer function formula (9), the feedback process of the unit frequency is taken into account. Compared with the traditional method, it is more suitable for analyzing the situation where the unit primary frequency regulation and secondary frequency regulation are put into operation at the same time.

[0087] According to formula (7) and formula (9), we can get:

[0088]

[0089] It can be seen from formula (10) that when the speed regulator is closed-loop, the frequency setting dynamic process of the unit can be regarded as a given value of the same size passing through the transfer function (10) and then undergoing the opening setting dynamic process.

[0090] It can be seen from equations (5) and (10) that no matter whether the unit adopts power closed loop or opening closed loop, when participating in secondary frequency regulation, it is equivalent to the given value passing through the second-order system and then performing a frequency regulation, and the damping coefficient of the second-order system is:

[0091]

[0092] The steady-state gain of a second-order system is:

[0093]

[0094] When the damping coefficient ξ of the transfer function is less than 1, the system is in an underdamped state, that is:

[0095]

[0096] In this case, there is oscillation in the system dynamic process, and there is a time period with opposite adjustment directions between the dynamic processes of the primary frequency regulation and the secondary frequency regulation of the unit, resulting in a conflict between the primary frequency regulation and the secondary frequency regulation of the unit.

[0097] When the damping coefficient ξ of the transfer function is greater than 1, the system is in an overdamped state, that is:

[0098]

[0099] At this time, there is no oscillation in the dynamic process of the system, and the adjustment direction between the dynamic processes of the primary frequency regulation and the secondary frequency regulation of the unit is always consistent, which can suppress the conflict between the primary frequency regulation and the secondary frequency regulation of the unit. However, due to the over-damping of the system, the dynamic response speed of the secondary frequency regulation of the unit is easily reduced.

[0100] When the damping coefficient of the transfer function ξ=1, the system is in a critical damping state, that is:

[0101]

[0102] At this time, there is no oscillation in the system dynamic process, and the adjustment direction between the primary frequency regulation and the secondary frequency regulation of the unit is always consistent, which can suppress the conflict between the primary frequency regulation and the secondary frequency regulation of the unit. At the same time, it can ensure that the unit has a high dynamic response speed of the secondary frequency regulation, that is, the best secondary frequency regulation result can be obtained when the constraint (15) is met.

[0103] For the primary frequency regulation dynamic process of the unit, the transfer function of the power output from the unit to the grid and the grid frequency is formula (2). For the convenience of analysis, the response time of the servo system is ignored, that is, T y ≈0, the turbine adopts the ideal turbine model, that is, e=1, e qh =0.5,e y =1, and the influence of the speed of the hydroelectric generator set on the damping is not considered, that is, the damping coefficient D = 1. At this time, equation (2) can be expressed as:

[0104]

[0105] Among them, each parameter satisfies:

[0106]

[0107] Among them, A″4, A″3, A″2, A″1, A″0 are the coefficients of the denominator polynomial in the transfer function G1, and B″3, B″2, B″1, B″0 are the coefficients of the numerator polynomial in the transfer function G1.

[0108] At this time, the characteristic equation of the system is:

[0109] A4″s 4 +A3″s 3 +A2″s 2 +A1″s+A0″=0 (18)

[0110] For engineering w With T a The general value range of T w In the range [0.5, 4], T aIn the range [2.5, 15], according to the standard "GB9652.1-2019 Technical Conditions for Hydro-Turbine Speed ​​Control System" T w / T a <1.2 to T w With T a The matching of is constrained, and the Krivchenko recommended formula is used to formulate the PID parameters. The recommended formula is as follows:

[0111]

[0112] Among them, K P0 is the initial value of the proportional gain of the speed regulator, K I0 is the initial value of the speed regulator integral gain, K D0 is the initial value of the speed regulator differential gain.

[0113] The roots of the characteristic equation (18) are calculated for different T w With T a The roots of the characteristic equation calculated under matching are shown in Table 1. It can be seen from Table 1 that when the system parameters change within the common engineering range, the characteristic equation (18) always has a pair of conjugate complex roots and two unequal real roots.

[0114] Table 1 Distribution of roots of system characteristic equation

[0115]

[0116]

[0117] Since the characteristic equation is a quartic equation, and the characteristic roots are a pair of conjugate complex roots and two unequal real roots, according to the Ferrari method for quartic equations, the characteristic equation has the same roots as the following two quadratic equations:

[0118]

[0119] Among them, H1, H2, H3, and H4 are the coefficients of the equivalent second-order characteristic equation.

[0120] Among them, each parameter satisfies:

[0121]

[0122] Among them, D0, D1, D2, and D3 are the standardized coefficients of the characteristic equation, and p, q, and k are the correlation coefficients in solving the quartic equation using the Ferrari method.

[0123] For a unit step disturbance in the grid frequency, the unit power can be expressed as:

[0124] P e(s)=P1(s)+P2(s)+P3(s) (22)

[0125]

[0126] Where E1, E2, F1, F2, and F3 satisfy:

[0127]

[0128] The expressions of each parameter are:

[0129]

[0130] Among them, C0, C1, C2, and C3 are the standardized coefficients of the transfer function, E1, E2, F1, and F2 are the equivalent second-order transfer function coefficients, F3 is the steady-state component coefficient, P1 is the monotonic attenuation component corresponding to the real root of the system, P2 is the oscillatory attenuation component corresponding to the conjugate complex root of the system, and P3 is the constant component after the system is stabilized.

[0131] We can get:

[0132]

[0133] By performing a Lapse inverse transformation on equation (22), the time domain expression of the unit power is obtained as follows:

[0134] P e (t) = P1(t) + P2(t) + P3(t) (29)

[0135]

[0136] P3(t)=F3 (32)

[0137] Among them, each parameter satisfies:

[0138]

[0139] Among them, t is time, K1, K2, K3, δ, ω, ψ are coefficients in the system expression.

[0140] When time tends to infinity, the stable value of the system tends to F3 according to formula (29).

[0141] In order to ensure that the system has good regulation quality and avoid the inconvenience caused by multiple targets in the traditional regulation quality evaluation system, the square error integral method with more comprehensive evaluation ability is used to evaluate the regulation quality of the system. The square error integral of the unit power is:

[0142]

[0143] In order to ensure the minimum integral error, considering equation (15), the speed regulator K I , K D Need to meet:

[0144]

[0145] K obtained from formula (35) I , K D The expression is too complicated. Taylor expansion is performed on it at the recommended points of Krivchenko's recommended formula, and the first-order terms are retained. The recommended formula for PID is:

[0146]

[0147] Among them, each parameter satisfies:

[0148]

[0149] Among them, I I0 is the first-order change rate of the integral gain of the square error of the hydropower unit power near the initial value, I D0 is the first-order change rate of the integral of the square error of the hydropower unit to the differential gain near the initial value, I II0 is the second-order change rate of the integral gain of the square error of the hydropower unit power near the initial value, I DD0 is the second-order change rate of the integral of the square error of the hydropower unit to the differential gain near the initial value, I ID0 It is the second-order change rate of the integral gain and differential gain of the square error integral of the hydropower unit near the initial value.

[0150] A PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of a hydropower unit of the present invention is specifically implemented according to the following steps:

[0151] Step 1: According to the water flow inertia time constant T of the water diversion system w , Unit mechanical inertia time constant T a The initial value K of the speed regulator PID parameter is calculated using the formula recommended by Krivchenko P0 , K I0 and K D0 :

[0152]

[0153] Step 2: According to the water flow inertia time constant T of the water diversion system w , Unit mechanical inertia time constant T a , power slip coefficient e of the speed regulator p , calculate the unit power dynamic analytical expression when the frequency unit step disturbance occurs;

[0154] The initial value of the speed regulator PID parameter of formula (19) is used as the PID parameter value to obtain the parameter expression related to the characteristic equation:

[0155]

[0156] The calculation results of the relevant parameters of formula (17) are used and combined with formula (21) to obtain the equivalent characteristic equation parameters:

[0157]

[0158] According to the calculation results of formula (17), combined with formula (27), C0~C3 are obtained:

[0159]

[0160] According to the calculation results of formula (21) and formula (27), combined with formula (28), we can obtain:

[0161]

[0162] According to the calculation results of formula (28), combined with formula (33), the parameters in the dynamic analytical expression of the unit power when the frequency unit step disturbance occurs are calculated:

[0163]

[0164] According to the calculation results of formula (33), combined with formula (29) to formula (32), the dynamic analytical expression of the unit power when the frequency unit step disturbance occurs is calculated:

[0165] P e (t) = P1(t) + P2(t) + P3(t) (29)

[0166]

[0167] P3(t)=F3 (32)

[0168] Step 3, calculating the analytical expression of the square error integral of the power of the computer unit I according to the dynamic analytical expression of the power of the unit;

[0169] According to the dynamic analytical expression of the unit power, the analytical expression of the square error integral I of the computer unit power is calculated by equation (34).

[0170]

[0171] Step 4, based on the analytical expression of the unit power square error integral I and the initial value of the speed regulator PID parameter, the speed regulator PID parameter that can suppress the conflict between the primary frequency regulation and the secondary frequency regulation of the unit is calculated.

[0172] According to formula (37), the square error integral of the computer group power I is calculated near the initial value of the speed regulator to calculate the speed regulator integral gain K I and the speed regulator differential gain K D The partial derivative of :

[0173]

[0174] According to the calculation result of formula (37), combined with formula (36), the integral gain K of the speed regulator is calculated: I With differential gain K D :

[0175]

[0176] According to the calculation result of formula (36), combined with formula (15), the proportional gain K of the speed regulator is calculated: P :

[0177]

[0178] This scheme deduces PID parameters, where the PID parameters are optimized based on the formula recommended by Krivchenko. During the optimization process, the transfer relationship between the primary frequency modulation dynamic process and the secondary frequency modulation dynamic process is considered, and the dynamic process damping between the two different disturbances is guaranteed to be critical damping, which prevents the oscillation problem between the two disturbances in the underdamped state, and also ensures that the unit has a faster dynamic process. Thus, the problem of conflict between the primary frequency modulation and the secondary frequency modulation dynamic process during the operation of the unit is suppressed, and the regulation capacity of the hydropower unit can be fully utilized.

[0179] The above specific embodiments are preferred embodiments of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the present specific embodiments. All equivalent changes made in accordance with the shape, structure, and method of the present invention are within the protection scope of the present invention.

Claims

1. A PID parameter setting method for suppressing the conflict between primary frequency regulation and secondary frequency regulation of a hydropower unit, characterized in that: The steps include: S1. Calculate the initial values ​​of PID parameters using the formula recommended by Krivchenko based on the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the hydroelectric generator set; S2, the initial value of the governor PID parameter is used as the PID parameter value, the root of the characteristic equation in S1 is solved and the dynamic analytical expression of the unit power when the frequency unit step disturbance is calculated according to the Ferrari method of the quartic equation; S3, calculating the analytical formula of the square error integral of the hydropower unit power based on the unit power dynamic analytical expression; S4. Calculate the PID parameter formula of the speed regulator for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of the hydropower unit through the analytical expression of the integral of the square error of the unit power and the initial value of the PID parameter of the speed regulator.

2. The PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of a hydropower unit according to claim 1 is characterized in that: The S1 includes: S11. Based on the relationship between various parameters of a typical power closed-loop hydroelectric generator unit regulation system, taking the participation of the hydroelectric generator unit in primary frequency regulation as a premise, the feedback process of the hydroelectric generator unit power is considered to obtain the transfer function of the hydroelectric generator unit power to the grid frequency fluctuation when the power is closed; at the same time, the feedback process of the hydroelectric generator unit frequency is considered to obtain the transfer function of the hydroelectric generator unit power to the given power; S12. Based on the relationship between various parameters of a typical closed-loop hydroelectric generator unit regulation system, the feedback process of the hydroelectric generator unit opening is taken into account, and the transfer function of the hydroelectric generator unit power to the grid frequency fluctuation when the opening is closed-loop is obtained. At the same time, the feedback process of the hydroelectric generator unit frequency is taken into account, and the transfer function of the hydroelectric generator unit power to the given opening is obtained. S13, dividing the transfer function of the hydropower unit power to the grid frequency fluctuation during the power closed loop by the transfer function of the hydropower unit power to the given power, to obtain G3; S14, dividing the transfer function of the hydropower unit power to the grid frequency fluctuation when the opening is closed by the transfer function of the hydropower unit power to the given opening to obtain G6; S15. In the primary frequency modulation dynamic process, the response time of the follow-up system is ignored, the turbine adopts an ideal turbine model, and the influence of the speed of the hydroelectric generator set on the damping is not considered. A simplified analysis is performed to obtain the characteristic equation; S16. Determine the range of the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the hydroelectric generator set, constrain the matching of the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the hydroelectric generator set in accordance with the standard provisions, and use the Krivchenko recommended formula to calculate the initial values ​​of the PID parameters.

3. The PID parameter setting method for suppressing the conflict between primary frequency regulation and secondary frequency regulation of a hydropower unit according to claim 1 is characterized in that: When the hydropower unit participates in the secondary frequency regulation, the damping state of the transfer function between the secondary frequency regulation setting and the equivalent primary frequency regulation setting is represented by the relationship between the various regulating parameters of the speed regulator in the damping coefficient of the transfer function; When the damping coefficient is <1, the system is underdamped; When the damping coefficient > 1, the system is in an overdamped state; When the damping coefficient = 1, the system is in a critical damping state, which is specifically expressed as: Among them, the critical damping state is the best secondary frequency regulation result when there is no oscillation phenomenon in the dynamic process of the system. The under-damping state will cause oscillation phenomenon in the dynamic process of the system, and the over-damping state will cause the dynamic response speed of the secondary frequency regulation of the hydropower unit to decrease.

4. The PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of a hydropower unit according to claim 2 is characterized in that: The transfer function of the hydropower unit power to the grid frequency fluctuation during the power closed loop is specifically expressed as: In the formula, p e is the generator power, x r is the set frequency value of the unit. When the unit is connected to the grid, this value is the measured value of the grid frequency. y is the transfer coefficient of turbine torque to guide vane opening, K is the transfer coefficient between generator electromagnetic torque and power angle, e is turbine coefficient, T w K is the inertia time constant of water flow in the water diversion system, D is the differential gain of the speed regulator, K I is the integral gain of the speed regulator, K P is the proportional gain of the speed regulator, s is the Lagrangian operator, A5, A4, A3, A2, A1, A0 are the coefficients in the transfer function of the power closed-loop system; The transfer function of the hydropower unit power to the given power is specifically expressed as: In the formula, p r is the power given value, e p is the power slip coefficient of the speed regulator; The transfer function of the hydropower unit power to the grid frequency fluctuation when the opening is closed is specifically expressed as: Where A'4, A'3, A'2, A'1, and A'0 are the coefficients in the transfer function of the opening closed-loop system; The transfer function of the power of the hydropower unit with a given opening degree is specifically expressed as: In the formula, y r is the given value of opening; b p is the opening slip coefficient of the speed regulator.

5. The PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of a hydropower unit according to claim 4 is characterized in that: The specific expression of G3 is: The specific expression of G6 is:

6. The PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of a hydropower unit according to claim 1 is characterized in that: In S2, the dynamic analytical expression of the unit power during the frequency unit step disturbance is specifically expressed as: P e (t)=P1(t)+P2(t)+P3(t); P3(t) = F3; Where t is time, P1 is the monotonic attenuation component corresponding to the real root of the system, P2 is the oscillatory attenuation component corresponding to the conjugate complex root of the system, P3 is the constant component after the system is stabilized, and K1, K2, K3, F3, δ, ω, and ψ are the coefficients in the system expression.

7. The PID parameter setting method for suppressing the conflict between primary frequency regulation and secondary frequency regulation of a hydropower unit according to claim 1 is characterized in that: In S3, the analytical expression of the integral of the square error of the hydropower unit power is specifically expressed as: Where p1 and p2 are the two real roots corresponding to the system characteristic equation.

8. The PID parameter setting method for suppressing the conflict between primary frequency regulation and secondary frequency regulation of a hydropower unit according to claim 1 is characterized in that: In S4, in order to ensure that the integral error is minimized and the critical damping state is considered, the integral gain and differential gain of the speed regulator are Taylor expanded in the formula recommended by Krivchenko and the first-order terms are retained to obtain the PID parameter formula of the speed regulator.

9. The PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of a hydropower unit according to claim 8 is characterized in that: In order to ensure the minimum integral error and take into account the critical damping state, the integral gain and differential gain of the speed regulator need to meet the following requirements:

10. The PID parameter setting method for suppressing the conflict between primary frequency regulation and secondary frequency regulation of a hydropower unit according to claim 8, characterized in that: The speed regulator PID parameter formula is specifically expressed as: In the formula, each parameter satisfies In the formula, K I0 is the initial value of the speed regulator integral gain, K D0 is the initial value of the speed regulator differential gain, I I0 is the first-order change rate of the integral gain of the square error of the hydropower unit power near the initial value, I D0 is the first-order change rate of the integral of the square error of the hydropower unit to the differential gain near the initial value, I II0 is the second-order change rate of the integral gain of the square error of the hydropower unit near the initial value, I DD0 is the second-order change rate of the integral of the square error of the hydropower unit to the differential gain near the initial value, I ID0 It is the second-order change rate of the integral gain and differential gain of the square error of the hydropower unit power near the initial value.

Images