PID parameter setting method for inhibiting conflict between primary frequency modulation and secondary frequency modulation of hydroelectric generator set

Abstract

The application discloses a PID parameter setting method for inhibiting the conflict between primary frequency modulation and secondary frequency modulation of a hydroelectric generator set, and belongs to the technical field of hydroelectric generator set regulation. The method comprises the following steps: S1, calculating the initial value of the PID parameter according to the water flow inertia time constant of a water diversion system and the mechanical inertia time constant of the hydroelectric generator set; S2, taking the initial value of the PID parameter of the speed regulator as the PID parameter value, solving the root of the characteristic equation in S1, and calculating the dynamic analytical expression of the unit power under frequency unit step disturbance according to the Ferrari method of the monomial quartic equation; S3, calculating the analytical expression of the integral component of the square error of the unit power of the hydroelectric generator set based on the dynamic analytical expression of the unit power; and S4, calculating the PID parameter formula of the speed regulator for inhibiting the conflict between the primary frequency modulation and the secondary frequency modulation of the hydroelectric generator set through the analytical expression of the integral component of the square error of the unit power and the initial value of the PID parameter of the speed regulator. The method solves the problem that the dynamic processes of the primary frequency modulation and the secondary frequency modulation conflict, and can fully exert the regulation capacity of the hydroelectric generator set.

Description

TECHNICAL FIELD

[0001] The application 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 modulation and secondary frequency modulation of a hydroelectric generator set. BACKGROUND

[0002] The participation of a hydroelectric generator set in primary frequency modulation and secondary frequency modulation is a key to maintaining the safe and stable operation of a power grid and plays a crucial role in the construction of a new power system. The current PID parameter setting methods for a hydroelectric generator set mainly include two categories of test setting method and recommended formula setting method. The test setting method mainly simulates the frequency disturbance of the unit under load conditions to set the PID parameters to obtain better primary frequency modulation performance, or disturbs the power set value of the unit under load conditions to set the PID parameters to obtain better secondary frequency modulation performance. The recommended formula setting method mainly gives an empirical formula of the PID parameters of the governor according to the frequency disturbance dynamic process to meet the requirement that the unit has better primary frequency modulation performance, or gives an empirical formula of the PID parameters according to the power disturbance dynamic process to meet the requirement that the unit has better secondary frequency modulation performance.

[0003] It can be seen that the current PID parameter setting for a hydroelectric generator set is only based on frequency disturbance or power disturbance, without considering the correlation between frequency disturbance and power disturbance. However, the dynamic processes of primary frequency modulation and secondary frequency modulation often conflict in engineering practice, which limits the play of the regulation capacity of the unit and even causes the problem of unqualified dynamic process examination of the unit. SUMMARY

[0004] The purpose of the present application is to solve the problem that the conflict between the dynamic processes of primary frequency modulation and secondary frequency modulation of a unit easily occurs in the operation of the unit in the absence of consideration of frequency disturbance and power disturbance in the setting of PID parameters in the prior art.

[0005] To solve the above technical problems, the present application provides a PID parameter setting method for suppressing the conflict between primary frequency modulation and secondary frequency modulation of a hydroelectric generator set, which comprises the following steps:

[0006] S1. Calculating the initial value of the PID parameters by using the Crivcovenko recommended formula according to the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the hydroelectric generator set;

[0007] S2. Taking the initial value of the PID parameters of the governor as the PID parameter value, solving the roots of the characteristic equation in S1, and calculating the dynamic analytical expression of the unit power under frequency unit step disturbance according to the Ferrari method of the monomial quartic equation;

[0008] S3. Calculating the analytical expression of the integral of the square error of the power of the hydroelectric generator set based on the dynamic analytical expression of the unit power;

[0009] S4, calculate the governor PID parameter formula for suppressing the conflict between the primary frequency modulation and the secondary frequency modulation of the hydroelectric generating set by the analytical expression of the integral of the square error of the unit power and the initial value of the governor PID parameter.

[0010] As preferred, the S1 comprises:

[0011] S11, obtain the transfer function of the hydroelectric generating set power to the grid frequency fluctuation in the power closed loop under the premise of the hydroelectric generating set participating in the primary frequency modulation by considering the feedback process of the hydroelectric generating set power according to the relationship between the parameters of the typical power closed loop hydroelectric generating set regulation system; at the same time, obtain the transfer function of the hydroelectric generating set power to the power given by considering the feedback process of the hydroelectric generating set frequency;

[0012] S12, obtain the transfer function of the hydroelectric generating set power to the grid frequency fluctuation in the opening degree closed loop under the premise of the hydroelectric generating set participating in the primary frequency modulation by considering the feedback process of the hydroelectric generating set opening degree according to the relationship between the parameters of the typical opening degree closed loop hydroelectric generating set regulation system; at the same time, obtain the transfer function of the hydroelectric generating set power to the opening degree given by considering the feedback process of the hydroelectric generating set frequency;

[0013] S13, divide the transfer function of the hydroelectric generating set power to the grid frequency fluctuation in the power closed loop by the transfer function of the hydroelectric generating set power to the power given to obtain G3;

[0014] S14, divide the transfer function of the hydroelectric generating set power to the grid frequency fluctuation in the opening degree closed loop by the transfer function of the hydroelectric generating set power to the opening degree given to obtain G6;

[0015] S15, in the primary frequency modulation dynamic process, ignore the response time of the servo system, use the ideal hydraulic turbine model for the hydraulic turbine and do not consider the influence of the hydroelectric generating set speed on the damping, perform simplified analysis to obtain a 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 generating set, combine the matching of the water flow inertia time constant of the water diversion system and the mechanical inertia time constant of the hydroelectric generating set to be constrained according to the standard provisions and respectively calculate the initial value of the PID parameter by using the Khrivchenko recommended formula.

[0017] As preferred, when the hydroelectric generating set participates in the secondary frequency modulation, the damping state of the transfer function between the secondary frequency modulation given and the equivalent primary frequency modulation given is represented by the relationship between the adjustment parameters of the governor in the damping coefficient of the transfer function;

[0018] When the damping coefficient is <1, the system is under-damped;

[0019] When the damping coefficient is >1, the system is over-damped;

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

[0021]

[0022] The critical damping state is the best quadratic frequency modulation result in which there is no oscillation phenomenon in the dynamic process of the system, the under-damping state causes oscillation phenomenon in the dynamic process of the system, and the over-damping state causes the dynamic response speed of the hydroelectric generating set to be reduced.

[0023] As preferred, the power closed-loop transmission function of the hydroelectric generating set power to the grid frequency fluctuation is specifically represented as:

[0024]

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

[0026] The transmission function of the hydroelectric generating set power to the power given value is specifically represented as:

[0027]

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

[0029] The transmission function of the hydroelectric generating set power to the grid frequency fluctuation when the opening is closed-loop is specifically represented as:

[0030]

[0031] In the formula, A’4, A’3, A’2, A’1, A’0 are coefficients in the opening closed-loop system transmission function;

[0032] The transmission function of the hydroelectric generating set power to the opening given value is specifically represented as:

[0033]

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

[0035] As a preferred, the G3 specific expression is:

[0036]

[0037] The G6 specific expression is:

[0038]

[0039] As a preferred, in the S2, the unit step disturbance of the frequency unit is analyzed and the expression of the unit step disturbance of the frequency unit is specifically expressed as:

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

[0041]

[0042] P3(t) = F3;

[0043] In the formula, t is time, P1 is a monotone decay component corresponding to a real root of the system, P2 is an oscillation decay component corresponding to a conjugate complex root of the system, P3 is a constant component after the system is stabilized, K1, K2, K3, F3, δ, ω, ψ are coefficients in the expression of the system.

[0044] As a preferred, in the S3, the analytic expression of the square error integral of the hydroelectric unit power is specifically expressed as:

[0045]

[0046] In the formula, p1 and p2 are two real roots corresponding to a characteristic equation of the system.

[0047] As a preferred, in the S4, in order to ensure that the integral error is minimum, the integral gain and the differential gain of the governor are Taylor expanded and the first order term is reserved in the Krylov formula, and the PID parameter formula of the governor is obtained.

[0048] As a preferred, in order to ensure that the integral error is minimum, the integral gain and the differential gain of the governor need to satisfy:

[0049]

[0050] As a preferred, the PID parameter formula of the governor is specifically expressed as:

[0051]

[0052] In the formula, each parameter satisfies

[0053] In the formula, K I0 is the initial value of the integral gain of the governor, K D0 is the initial value of the differential gain of the governor, I I0 is the first order change rate of the integral gain of the power square error integral of the hydroelectric generating set near the initial value, I D0 is the first order change rate of the differential gain of the power square error integral of the hydroelectric generating set near the initial value, I II0 is the second order change rate of the integral gain of the power square error integral of the hydroelectric generating set near the initial value, I DD0 is the second order change rate of the differential gain of the power square error integral of the hydroelectric generating set near the initial value, I ID0 is the second order change rate of the integral gain and the differential gain of the power square error integral of the hydroelectric generating set near the initial value.

[0054] Compared with the prior art, the beneficial effects of the present application are:

[0055] The present application obtains the PID parameters by derivation, wherein the PID parameters are optimized on the basis of the formula recommended by Klyavchenko, the transmission relationship between the primary frequency modulation dynamic process and the secondary frequency modulation dynamic process is considered in the optimization process, and the dynamic process damping between two different disturbances is ensured to be critical damping, so as to prevent the oscillation problem between the two disturbances in the under-damping state, and also to ensure that the unit has a faster dynamic process. Thus, the problem that the primary frequency modulation and the secondary frequency modulation dynamic process conflict with each other in the operation process of the unit is solved, and the regulation capacity of the hydroelectric generating set can be fully utilized. BRIEF DESCRIPTION OF DRAWINGS

[0056] Other characteristics, objects and advantages of the present application will become more apparent from the following detailed description of non-restrictive embodiments made with reference to the attached drawings. The drawings are merely intended to illustrate the preferred embodiments and are not considered to be limiting on the present application. Moreover, the same reference signs are used throughout the drawings to denote the same components.

[0057] Figure 1 is a typical structure block diagram of the power closed-loop hydroelectric generating set regulation system in the method of the present application;

[0058] Figure 2 is a typical structure block diagram of the opening closed-loop hydroelectric generating set regulation system in the method of the present application. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific implementation described herein is only one of the best embodiments of the present application, which is used to explain the present application and does not limit the protection scope of the present application. All other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0060] Embodiment 1: PID parameter setting method for inhibiting the conflict between primary frequency modulation and secondary frequency modulation of hydroelectric generating set, according to Figure 1 The relationship between the parameters can be obtained from the typical structure block diagram of power closed-loop hydroelectric generating set regulation system as shown in the figure:

[0061]

[0062] Wherein, x is the actual instantaneous speed value of the unit operation, d x is the frequency deviation value of the unit, K P is the proportional gain of the governor, K I is the integral gain of the governor, K D is the differential gain of the governor, y P is the proportional output of the governor, y I is the integral output of the governor, y D is the differential output of the governor, y PID is the opening degree instruction of the PID governor output, T y is the response time constant of the follow-up 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 transmission coefficient of the water turbine torque to the guide vane opening, e is the water turbine coefficient, e qh is the transmission coefficient of the water turbine flow to the water head, P t is the water turbine power, P e is the generator power, d m is the difference value of the power torque and the resistance torque, T a is the mechanical inertia time constant of the hydroelectric generating set, D is the damping coefficient of the hydroelectric generating set, K is the transmission 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 governor, s is the pull type operator.

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

[0064]

[0065] ​Wherein, each parameter expression is:

[0066]

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

[0068] In deriving the unit primary frequency modulation transfer function formula (2), the feedback process of unit power is considered, which is more suitable for analyzing the situation of primary and secondary frequency modulation of the unit being put into at the same time compared with the traditional method.

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

[0070]

[0071] In deriving the unit secondary frequency modulation transfer function formula (4), the feedback process of unit frequency is considered, which is more suitable for analyzing the situation of primary and secondary frequency modulation of the unit being put into at the same time compared with the traditional method.

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

[0073]

[0074] As can be seen from formula (5), in the speed regulator power closed loop, the frequency given dynamic process of the unit can be regarded as the same size given value after passing through the transfer function (5) and then performing the power given dynamic process.

[0075] The commonly used regulation system structure block diagram of the hydraulic generator unit in the opening degree closed loop is shown in Figure 2 The figure shows that y r is the opening degree given value, d y is the opening degree deviation, b P is the opening degree slip coefficient of the speed regulator.

[0076] According to the typical structure block diagram of the opening degree closed loop hydraulic generator unit regulation system shown in Figure 2 The relationship between the parameters can be obtained as:

[0077]

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

[0079]

[0080] Wherein, the expression of each parameter is:

[0081]

[0082] Wherein, A'4, A'3, A'2, A'1, A'0 are coefficients of denominator polynomial in the opening degree closed loop system transfer function.

[0083] In deriving the unit primary frequency modulation transfer function formula (7), the feedback process of unit opening degree is considered, which is more suitable for analyzing the situation of unit primary frequency modulation and secondary frequency modulation being put in at the same time compared with the traditional method.

[0084] The transfer function of unit power to opening degree is:

[0085]

[0086] In deriving the unit primary frequency modulation transfer function formula (9), the feedback process of unit frequency is considered, which is more suitable for analyzing the situation of unit primary frequency modulation and secondary frequency modulation being put in at the same time compared with the traditional method.

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

[0088]

[0089] It can be seen from formula (10) that when the governor opening degree is closed, the frequency given dynamic process of the unit can be regarded as the same size given value passing through the transfer function (10) and then performing the opening degree given dynamic process.

[0090] It can be seen from formula (5) and formula (10) that whether the unit adopts power closed loop or opening degree closed loop, when participating in secondary frequency modulation, it can be equivalent to giving a value passing through a second-order system and then performing primary frequency modulation, and the damping coefficient of the second-order system is:

[0091]

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

[0093]

[0094] When the damping coefficient ξ of the transfer function is less than 1, the system is under-damped, that is:

[0095]

[0096] In this case, there is an oscillation phenomenon in the dynamic process of the system, and there is a period of time in which the adjustment direction of the dynamic process of the unit primary frequency modulation and the secondary frequency modulation is opposite, causing the phenomenon of conflict between the unit primary frequency modulation and the secondary frequency modulation.

[0097] When the damping coefficient ξ of the transfer function is greater than 1, the system is over-damped, that is:

[0098]

[0099] At this time, there is no oscillation phenomenon in the system dynamic process, the regulation direction between the dynamic process of the unit primary frequency modulation and the secondary frequency modulation is consistent at the moment, the phenomenon of the conflict between the unit primary frequency modulation and the secondary frequency modulation can be inhibited, but at this time, due to the over-damping of the system, the dynamic response speed of the unit secondary frequency modulation is reduced.

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

[0101]

[0102] At this time, there is no oscillation phenomenon in the system dynamic process, the regulation direction between the dynamic process of the unit primary frequency modulation and the secondary frequency modulation is consistent at the moment, the phenomenon of the conflict between the unit primary frequency modulation and the secondary frequency modulation can be inhibited, and at the same time, the unit can have a high dynamic response speed of the secondary frequency modulation, that is, when the constraint of formula (15) is met, the optimal secondary frequency modulation result can be obtained.

[0103] For the dynamic process of the unit primary frequency modulation, the transfer function of the power output to the grid by the unit 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 hydraulic turbine adopts an ideal hydraulic turbine model, that is, e=1, e qh =0.5, e y =1, the influence of the hydro-generator speed on the damping is not considered, that is, the damping coefficient D=1. At this time, formula (2) can be expressed as:

[0104]

[0105] Among them, the parameters satisfy:

[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 the general value range of T w and T a , that is, T w is in the range [0.5, 4], T aIn the range [2.5, 15], while according to the standard "GB9652.1-2019 Water Turbine Speed Regulation System Technical Conditions" T w / T a <1.2 to T w and T a matching constraints, and using the recommended formula of Kryuchkov for PID parameter, its recommended formula is as follows:

[0111]

[0112] Where, K P0 is the initial value of the speed regulator proportional gain, 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] Thus the roots of the characteristic equation (18) are calculated, and the roots of the characteristic equation calculated under different T w and T a matching are shown in Table 1. As can be seen from Table 1, when the system parameters change in the engineering common interval, 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 monomial fourth order equation, and the characteristic root is a pair of conjugate complex roots and two unequal real roots, according to the Ferrari method of monomial fourth order equation, the characteristic equation has the same root as the following two monomial quadratic equations:

[0118]

[0119] Where, H1, H2, H3, H4 are equivalent second order characteristic equation coefficients.

[0120] Where, each parameter satisfies:

[0121]

[0122] Where, D0, D1, D2, D3 are the standardization coefficients of the characteristic equation, p, q, k are the related coefficients in the Ferrari method for solving monomial fourth order equations.

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

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

[0125]

[0126] wherein E1, E2, F1, F2, F3 satisfy:

[0127]

[0128] wherein the expressions of the parameters are:

[0129]

[0130] wherein C0, C1, C2, C3 are standardization coefficients of the transfer function, E1, E2, F1, F2 are equivalent second-order transfer function coefficients, F3 is a steady-state component coefficient, P1 is a monotone decaying component corresponding to a real root of the system, P2 is an oscillating decaying component corresponding to a conjugate complex root of the system, and P3 is a constant component after the system is stabilized.

[0131] It can be obtained that:

[0132]

[0133] The time-domain expression of the unit power is obtained by performing the inverse Laplace transform on equation (22):

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

[0135]

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

[0137] wherein the parameters satisfy:

[0138]

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

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

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

[0142]

[0143] To ensure the minimum integral error, considering formula (15), the governor K I 、K D Must satisfy:

[0144]

[0145] K I , K D The expression is too complex, Taylor expansion is carried out at the recommended point of the formula recommended by Klyuchnikov, and the first order term is retained, and the recommended formula of PID is obtained:

[0146]

[0147] Wherein, each parameter satisfies:

[0148]

[0149] Wherein, I I0 The first order change rate of water turbine power square error integral to integral gain near the initial value, I D0 The first order change rate of water turbine power square error integral to differential gain near the initial value, I II0 The second order change rate of water turbine power square error integral to integral gain near the initial value, I DD0 The second order change rate of water turbine power square error integral to differential gain near the initial value, I ID0 The second order change rate of water turbine power square error integral to integral gain and differential gain near the initial value.

[0150] The PID parameter setting method for inhibiting the conflict between primary frequency modulation and secondary frequency modulation of water turbine unit of the application is implemented according to the following steps:

[0151] Step 1, according to the water flow inertia time constant T w , the mechanical inertia time constant T a The initial value K P0 , K I0 And K D0 Of the governor PID parameter is calculated by using the formula recommended by Klyuchnikov:

[0152]

[0153] Step 2, according to the water flow inertia time constant T w , the mechanical inertia time constant T a , the power slip coefficient e p Of the governor, the dynamic analytical expression of the unit power when the frequency unit step disturbance is calculated:

[0154] The PID parameter initial value of the governor of formula (19) is used as the PID parameter value, and the characteristic equation related parameter expression is obtained:

[0155]

[0156] The equivalent characteristic equation parameters are obtained by combining formula (21) with the related parameter calculation results of formula (17):

[0157]

[0158] According to the calculation results of formula (17), C0-C3 are obtained by combining formula (27):

[0159]

[0160] According to the calculation results of formula (21) and formula (27), is obtained by combining formula (28):

[0161]

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

[0163]

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

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

[0166]

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

[0168] Step 3, the analytical expression of the unit power square error integral I is calculated according to the unit power dynamic analytical expression.

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

[0170]

[0171] Step 4, the governor PID parameters that can suppress the conflict between the primary frequency modulation and the secondary frequency modulation of the unit are calculated according to the analytical expression of the unit power square error integral I and the initial value of the governor PID parameters.

[0172] The integral gain K of the governor is calculated according to the calculation result of formula (37) and formula (36) I and the partial derivative of the derivative gain K of the governor D :

[0173]

[0174] The integral gain K of the governor is calculated according to the calculation result of formula (37) and formula (36) I and the derivative gain K D :

[0175]

[0176] The proportional gain K of the governor is calculated according to the calculation result of formula (36) and formula (15) P :

[0177]

[0178] The PID parameters are derived in the scheme, wherein the PID parameters are optimized on the basis of the formula recommended by Klyuchnikov, the transfer relationship between the primary frequency modulation dynamic process and the secondary frequency modulation dynamic process is considered in the optimization process, the dynamic process damping between two different disturbances is ensured to be critical damping, the oscillation problem between the two disturbances in the under-damping state is prevented, and the unit is ensured to have a faster dynamic process. Therefore, the problem that the primary frequency modulation and the secondary frequency modulation dynamic processes conflict with each other in the operation process of the unit is solved, and the regulation capacity of the hydroelectric unit can be fully utilized.

[0179] The above specific embodiments are the preferred embodiments of the present application, and the specific implementation range of the present application is not limited by the above specific embodiments. The scope of the present application includes but is not limited to the above specific embodiments. Any equivalent changes made according to the shape, structure and method of the present application are within the protection scope of the present application.

Claims

1. A PID parameter setting method for inhibiting the conflict between the primary frequency modulation and the secondary frequency modulation of a hydroelectric generating set, characterized in that, It comprises the following steps: S1, according to the water flow inertia time constant of the water diversion system, the mechanical inertia time constant of the hydroelectric generator set, the initial value of the PID parameter is calculated by using the formula recommended by Klevtchikov; S1 comprises: S11, according to the relationship between the parameters of the typical power closed-loop hydroelectric generator set regulating system, under the premise of the participation of the hydroelectric generator set in primary frequency modulation, considering the feedback process of the power of the hydroelectric generator set, the transfer function of the power of the hydroelectric generator set to the frequency fluctuation of the power grid is obtained when the power is closed loop; At the same time, considering the feedback process of the frequency of the hydroelectric generator set, the transfer function of the power of the hydroelectric generator set to the given power is obtained; S12, according to the relationship between the parameters of the typical opening degree closed-loop hydroelectric generator set regulating system, under the premise of the participation of the hydroelectric generator set in primary frequency modulation, considering the feedback process of the opening degree of the hydroelectric generator set, the transfer function of the power of the hydroelectric generator set to the frequency fluctuation of the power grid is obtained when the opening degree is closed loop; At the same time, considering the feedback process of the frequency of the hydroelectric generator set, the transfer function of the power of the hydroelectric generator set to the given opening degree is obtained; S13, the transfer function of the power of the hydroelectric generator set to the frequency fluctuation of the power grid when the power is closed loop is divided by the transfer function of the power of the hydroelectric generator set to the given power, to obtain G3; S14, the transfer function of the power of the hydroelectric generator set to the frequency fluctuation of the power grid when the opening degree is closed loop is divided by the transfer function of the power of the hydroelectric generator set to the given opening degree, to obtain G6; S15, in the primary frequency modulation dynamic process, the response time of the servo system is ignored, the ideal hydraulic turbine model is used, and the influence of the rotating speed of the hydroelectric generator set on the damping is not considered, the simplified analysis is carried out, and the characteristic equation is obtained; S16, 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 is determined, 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 is constrained in combination with the standard provisions, and the initial value of the PID parameter is calculated by using the formula recommended by Klevtchikov; S2, the initial value of the PID parameter of the governor is taken as the PID parameter value, the root of the characteristic equation in S1 is solved, and the dynamic analytical expression of the unit power at the frequency unit step disturbance is calculated according to the Ferrari method of the monomial quartic equation; S3, the analytical expression of the square error integral of the power of the hydroelectric generator set is calculated based on the dynamic analytical expression of the unit power; S4, the PID parameter formula of the governor for inhibiting the conflict between the primary frequency modulation and the secondary frequency modulation of the hydroelectric generator set is calculated through the analytical expression of the square error integral of the power of the hydroelectric generator set and the initial value of the PID parameter of the governor; The governor PID parameter formula is specifically represented as: ； In the formula, each parameter satisfies ; wherein K I0 is the initial value of the integral gain of the governor, D0 is the initial value of the differential gain of the governor, I0 is the first order rate of change of the integral gain of the governor with respect to the integral component of the power squared error of the hydroelectric generating unit about the initial value, D0 is the first order rate of change of the differential gain of the governor with respect to the integral component of the power squared error of the hydroelectric generating unit about the initial value, II0 is the second order rate of change of the integral gain of the governor with respect to the integral component of the power squared error of the hydroelectric generating unit about the initial value, DD0 is the second order rate of change of the differential gain of the governor with respect to the integral component of the power squared error of the hydroelectric generating unit about the initial value, ID0 is the second order rate of change of the integral gain and the differential gain of the governor with respect to the integral component of the power squared error of the hydroelectric generating unit about the initial value; K I is the integral gain of the governor, D is the differential gain of the governor, and I is the integral component of the power squared error of the hydroelectric generating unit.

2. The method of claim 1, wherein the PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of the hydroelectric generating unit is characterized in that, When the hydroelectric generator set participates in the secondary frequency modulation, the damping state of the transfer function between the given secondary frequency modulation and the equivalent primary frequency modulation is represented by the relationship between the adjusting parameters of the governor in the damping coefficient; When the damping coefficient <1, the system is underdamped; When the damping coefficient >1, the system is overdamped; When the damping coefficient =1, the system is critically damped, which is specifically represented as: ； wherein K P is the proportional gain of the governor, K I is the integral gain of the governor, K D is the differential gain of the governor; the critical damping state is the best quadratic frequency modulation result without oscillation phenomenon in the system dynamic process, the under-damped state will cause oscillation phenomenon in the system dynamic process, and the over-damped state will cause the dynamic response speed of the hydroelectric generating set quadratic frequency modulation to decrease.

3. The method of claim 1, wherein the PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of the hydroelectric generating unit is characterized by, The transfer function of the power of the hydroelectric generator set to the frequency fluctuation of the power grid when the power is closed loop is specifically represented as: ； In the formula, p e is the generator power, x r is the unit frequency given value, which is the grid frequency measured value when the unit is connected to the grid, e y is the water turbine torque to guide vane opening transfer coefficient, K is the generator electromagnetic torque and power angle between the transfer coefficient, e is the water turbine coefficient, T w is the water flow inertia time constant of the water diversion system, K D is the differential gain of the governor, K I is the integral gain of the governor, K P is the proportional gain of the governor, s is the Laplace operator, A5, A4, A3, A2, A1, A0 are the coefficients in the power closed loop system transfer function; The transfer function of the power of the hydroelectric generator set to the given power is specifically represented as: ； where p r is the power setpoint, e p is the power slip of the governor; The transfer function of the power of the hydroelectric generating set to the frequency fluctuation of the power grid in the opening closed loop is specifically expressed as: ； In the formula, A'4, A'3, A'2, A'1 and A'0 are coefficients in the transfer function of the opening closed loop system; The transfer function of the power of the hydroelectric generating set to the opening given is specifically expressed as: ； where y r is the opening degree given value; b p is the opening degree slip factor of the governor.

4. The PID parameter setting method for inhibiting the conflict between the primary frequency modulation and the secondary frequency modulation of a hydroelectric generating unit according to claim 3, characterized in that, The specific expression of G3 is: ； The specific expression of G6 is: 。 5. The method of claim 1, wherein the PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of the hydroelectric generating unit is characterized by, In S2, the dynamic analytic expression of the power of the hydroelectric generating set when the frequency unit step disturbance is specifically expressed as: ； ； ； ； In the formula, t is time, P1 is a monotone decay component corresponding to a real root of the system, P2 is an oscillation decay component corresponding to a conjugate complex root of the system, P3 is a constant component after the system is stabilized, K1, K2, K3, F3, δ, ω and ψ are coefficients in the expression of the system.

6. The method of claim 1, wherein the PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of the hydroelectric generating unit is characterized by, In S3, the analytic expression of the power square error integral of the hydroelectric generating set is specifically expressed as: ； In the formula, p1, p2 are two real roots corresponding to the system characteristic equation; p e K1, K2, K3, F3, δ, ω, ψ are coefficients in the system expression.

7. The method of claim 1, wherein the PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of the hydroelectric generating unit is characterized by, In S4, in order to ensure that the integral error is minimum, the integral gain and the differential gain of the governor are Taylor expanded and the first order term is reserved in the Krylov formula to obtain a PID parameter formula of the governor.

8. The method of claim 7, wherein the PID parameter setting method for suppressing the conflict between the primary frequency regulation and the secondary frequency regulation of the hydroelectric generating unit is characterized in that, In order to ensure that the integral error is minimum, the integral gain and the differential gain of the governor need to satisfy: In order to ensure that the integral error is minimum, the integral gain and the differential gain of the governor need to satisfy: 。

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