Power grid simulation device control method based on uncertain interference estimator

Abstract

The invention discloses a power grid simulation device control method based on an uncertain interference estimator, and the method comprises the steps: enabling a rectifier to control the DC voltage to be stable through a control system, enabling an inverter to control the AC output of a power grid simulation device through the control system, and simulating various power grid voltages; constructing a mathematical model of the inverter side of the power grid simulation device; standardizing the mathematical model of the inverter side of the power grid simulation device to obtain an uncertain dynamic standardized model controlled by the power grid simulation device; according to the reference model based on the uncertain interference estimation, the error equation and the lumped interference dynamic estimation, a control law of voltage and current double-loop control of the inverter side of the power grid simulation device based on the uncertain interference estimator is obtained; according to the method, an uncertain interference estimator is used for replacing a traditional PI controller, uncertain items and disturbance in double-loop control are estimated and compensated, no-error tracking of a reference signal by a power grid simulation device is guaranteed, and the load disturbance resisting capacity is improved.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a control method for a power grid simulation device based on an uncertain interference estimator. Background Art

[0002] With the large-scale use of new energy power generation equipment such as photovoltaics and wind power, their proportion in the power system continues to increase, and the power industry's standards and requirements for the grid connection of new energy equipment are becoming increasingly stringent. In order to ensure the stability of grid operation and the adaptability of new energy equipment under grid fault conditions, it is necessary to use a grid simulation device to simulate abnormal operating conditions such as voltage mutation, frequency mutation and voltage imbalance of the actual grid, and conduct grid connection performance tests for new energy power generation equipment without affecting the actual grid operation.

[0003] The control strategy of the inverter side of the existing power grid simulation device is mainly the dual-loop control using the synchronous coordinate system PI controller. PI control is relatively mature and has a fast dynamic response. However, in actual operation, the power grid simulation device is difficult to achieve the desired effect when conducting grid-connected performance tests due to parameter changes, system random disturbances and complex load conditions. In addition, it is impossible to achieve error-free tracking of the AC component, and the output voltage quality may not meet the requirements. Summary of the invention

[0004] The technical problem to be solved by the present invention is to propose a control method for a power grid simulation device based on an uncertain interference estimator. The method estimates and compensates for the uncertain terms and disturbances in the dual-loop control by using an uncertain interference estimator instead of a traditional PI controller, thereby ensuring that the power grid simulation device tracks the reference signal without error and improving the ability to resist load disturbances.

[0005] In order to solve the above technical problems, the present invention provides a control method for a power grid simulation device based on an uncertain interference estimator, wherein the power grid simulation device includes a rectifier, an inverter, a control system and a filter; the method includes the following steps:

[0006] The rectifier controls the DC voltage stability through the control system, and the inverter controls the AC output of the power grid simulation device through the control system to simulate various power grid voltages. According to the topological structure of the power grid simulation device, a mathematical model of the inverter side of the power grid simulation device is constructed;

[0007] The mathematical model of the inverter side of the power grid simulation device is standardized to obtain the uncertain dynamic standardized model of the dual-loop control of the power grid simulation device;

[0008] Based on the uncertain dynamic normalization model, a reference model based on uncertain disturbance estimation, an error equation and a lumped disturbance dynamic estimation value of the control system are obtained;

[0009] According to the reference model, error equation and lumped disturbance estimation strategy based on uncertain disturbance estimation, the control law of the voltage and current dual-loop control on the inverter side of the power grid simulation device based on the uncertain disturbance estimator is obtained.

[0010] Preferably, the step of "constructing a mathematical model of the inverter side of the power grid simulation device" is:

[0011]

[0012] Among them, u d 、u q are the d-axis and q-axis components of the inverter output voltage, e d 、e q is the d-axis and q-axis components of the load voltage, i d 、i q are the d-axis and q-axis components of the inverter output current; ω is the angular frequency of the AC system, L and R are the filter inductance and line resistance respectively;

[0013]

[0014] Among them, i od 、i oq are the d and q axis components of the inverter load current.

[0015] Preferably, the uncertain dynamic model of the inverter side of the power grid simulation device is obtained according to the mathematical model of the inverter side of the power grid simulation device:

[0016] The uncertain dynamic model of the current loop is:

[0017]

[0018] Among them, f id 、f iq is the uncertainty term of the current loop control equation on the d and q axes, D id , D iq is the unknown disturbance on the d and q axes;

[0019] The uncertain dynamic model of the voltage loop is:

[0020]

[0021] Among them, f vd 、f vq is the uncertainty term of the voltage loop control equation on the d and q axes, D vd , D vq is the unknown disturbance on the d and q axes.

[0022] Preferably, the uncertain dynamic normalized model of the dual-loop control of the power grid simulation device is:

[0023] The standardized model of the uncertain dynamics of the current loop is:

[0024]

[0025] Among them, x i (t) = [i d ,i q ] T is the state variable of the current loop system, u i (t)=[u d ,u q ] T is the control input of the current loop system, f i (t) = [f id ,f iq ] T , D i (t)=[D id ,D iq ] T , A i , B i is the constant coefficient matrix,

[0026] The standardized model of the voltage loop uncertainty dynamics is:

[0027]

[0028] Among them, x v (t) = [e d ,e q ] T is the state variable of the voltage loop system, u v (t) = [i d ,i q ] T is the control input of the current loop system, f v (t) = [f vd ,f vq ] T , D v (t)=[D vd ,D vq ] T , A v , B v is the constant coefficient matrix,

[0029] Preferably, the reference model based on uncertain disturbance estimation of the control system is:

[0030]

[0031] Among them, x m(t) is the reference vector of the current loop reference model, u m (t) is the input reference signal of the current loop reference model, A m , B m For the corresponding x m (t),u m The coefficient matrix of (t), A m =B m ;

[0032]

[0033] Among them, x n (t) is the reference vector of the voltage loop reference model, u n (t) is the input reference signal of the voltage loop reference model, A n , B n For the corresponding x n (t),u n The coefficient matrix of (t), A n =B n .

[0034] Preferably, the error equation based on the uncertain interference estimation is:

[0035] The error equation of the current loop is:

[0036] e(t)=x m (t)-x i (t)

[0037] The error equation of the voltage loop is:

[0038] e(t)=x n (t)-x v (t)

[0039] Where e(t) is the state error of the control loop at time t.

[0040] Preferably, the aggregate interference value is estimated by a filter, and the aggregate interference estimation value is expressed as:

[0041]

[0042] in, is the estimated value of the total interference of the current loop, g i (t) a filter with a suitable bandwidth for estimating the aggregate interference of the current loop;

[0043]

[0044] in, is the estimated value of the voltage loop lumped interference, g v(t) is a filter with suitable bandwidth for estimating the voltage loop lumped interference.

[0045] Preferably, the lumped disturbance estimation strategy is: the control system current loop input u i (t) is:

[0046] u i (t) = B i -1 [A m x i (t)-A i x i (t)+B m u m (t)-D i (t)];

[0047] The lumped interference is estimated by the estimated value of the lumped interference, and the input of the control system current loop is obtained as:

[0048]

[0049] The control system voltage loop input u v (t) is:

[0050] u v (t) = B v -1 [A n x v (t)-A v x v (t)+B n u n (t)-D v (t)];

[0051] The lumped interference is estimated by the estimated value of the lumped interference, and the input of the control system current loop is obtained as:

[0052]

[0053] Among them, G i (s), G v (s) is a first-order filter, B i , B v is a constant coefficient matrix.

[0054] 9. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 8, characterized in that:

[0055] The control law of the voltage and current dual-loop control on the inverter side of the power grid simulation device is:

[0056] By the first-order filter G iThe frequency domain form of (s) get

[0057] The current inner loop control law is:

[0058]

[0059] Among them, U i (s), X m (s), U m (s), X i (s), D i0 (s) are u i (t), x m (t),u m (t), x i (t), D i0 (t) in frequency domain, I is the identity matrix;

[0060] By the first-order filter G v The frequency domain form of (s) get

[0061] The voltage loop control law is:

[0062]

[0063] Among them, U v (s), X n (s), U n (s), X v (s), D v0 (s) are u v (t), x n (t),u n (t), x v (t), D v0 (t) in the frequency domain, where I is the identity matrix.

[0064] After adopting the above method, a control method for a power grid simulation device based on an uncertain interference estimator is provided, wherein the power grid simulation device includes a rectifier, an inverter, a control system and a filter; the method includes the following steps: the rectifier controls the DC voltage to be stable through the control system, the inverter controls the AC output of the power grid simulation device to simulate various power grid voltages through the control system, and a mathematical model of the inverter side of the power grid simulation device is constructed according to the topological structure of the power grid simulation device;

[0065] The mathematical model of the inverter side of the power grid simulation device is standardized to obtain an uncertain dynamic standardized model of the dual-loop control of the power grid simulation device; based on the uncertain dynamic standardized model, a reference model based on uncertain interference estimation, an error equation and a lumped interference dynamic estimation value of the control system are obtained; according to the reference model based on uncertain interference estimation, the error equation and the lumped interference dynamic estimation strategy, a control law of the voltage and current dual-loop control of the inverter side of the power grid simulation device based on the uncertain interference estimator is obtained; the control method of the power grid simulation device based on the uncertain interference estimator estimates and compensates for the uncertain terms and disturbances in the dual-loop control by using the uncertain interference estimator instead of the traditional PI controller, thereby ensuring the power grid simulation device to track the reference signal without difference and improving the ability to resist load disturbances. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 A circuit diagram of a power grid simulation device according to the present invention;

[0067] Figure 2 A control block diagram of a current loop control law of a power grid simulation device control method based on an uncertain interference estimator according to the present invention;

[0068] Figure 3 A control block diagram of a voltage loop control law of a power grid simulation device control method based on an uncertain interference estimator according to the present invention; DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solution 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 embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0070] Embodiment 1

[0071] See also Figure 1 , Figure 1 A circuit diagram of a power grid simulation device according to the present invention;

[0072] This embodiment discloses a control method for a power grid simulation device based on an uncertain interference estimator, wherein the power grid simulation device includes a rectifier 10, an inverter 20, a control system and a filter; the method includes the following steps:

[0073] The rectifier controls the DC voltage stability through the control system, and the inverter controls the AC output of the power grid simulation device through the control system to simulate various power grid voltages. According to the topological structure of the power grid simulation device, a mathematical model of the inverter side of the power grid simulation device is constructed;

[0074] The mathematical model of the inverter side of the power grid simulation device is standardized to obtain the uncertain dynamic standardized model of the dual-loop control of the power grid simulation device;

[0075] Based on the uncertain dynamic normalization model, a reference model based on uncertain disturbance estimation, an error equation and a lumped disturbance dynamic estimation value of the control system are obtained;

[0076] According to the reference model, error equation and lumped disturbance estimation strategy based on uncertain disturbance estimation, the control law of the voltage and current dual-loop control on the inverter side of the power grid simulation device based on the uncertain disturbance estimator is obtained.

[0077] Embodiment 2

[0078] This embodiment is based on the first embodiment. In this embodiment, the step of "constructing a mathematical model of the inverter side of the power grid simulation device" is:

[0079]

[0080] Among them, u d 、u q are the d-axis and q-axis components of the inverter output voltage, e d 、e q is the d-axis and q-axis components of the load voltage, i d 、i q are the d-axis and q-axis components of the inverter output current; ω is the angular frequency of the AC system, L and R are the filter inductance and line resistance respectively;

[0081]

[0082] Among them, i od 、i oq are the d and q axis components of the inverter load current.

[0083] Embodiment 3

[0084] This embodiment is based on the second embodiment. In this embodiment, an uncertain dynamic model of the inverter side of the power grid simulation device is obtained according to the mathematical model of the inverter side of the power grid simulation device:

[0085] The uncertain dynamic model of the current loop is:

[0086]

[0087] Among them, f id 、f iq is the uncertainty term of the current loop control equation on the d and q axes, D id , D iq is the unknown disturbance on the d and q axes;

[0088] The uncertain dynamic model of the voltage loop is:

[0089]

[0090] Among them, f vd 、f vq is the uncertainty term of the voltage loop control equation on the d and q axes, D vd , D vq is the unknown disturbance on the d and q axes.

[0091] In this embodiment, the uncertain dynamic normalized model of the dual-loop control of the power grid simulation device is:

[0092] The standardized model of the uncertain dynamics of the current loop is:

[0093]

[0094] Among them, x i (t) = [i d ,i q ] T is the state variable of the current loop system, u i (t)=[u d ,u q ] T is the control input of the current loop system, f i (t) = [f id ,f iq ] T , D i (t)=[D id ,D iq ] T , A i , B i is the constant coefficient matrix,

[0095] The standardized model of the voltage loop uncertainty dynamics is:

[0096]

[0097] Among them, x v (t) = [e d ,e q ] T is the state variable of the voltage loop system, u v (t) = [i d ,i q ] T is the control input of the current loop system, f v (t) = [f vd ,f vq ]T , D v (t)=[D vd ,D vq ] T , A v , B v is the constant coefficient matrix,

[0098] Embodiment 4

[0099] This embodiment is based on the third embodiment. In this embodiment,

[0100] The reference model of the control system based on uncertain disturbance estimation is:

[0101]

[0102] Among them, x m (t) is the reference vector of the current loop reference model, u m (t) is the input reference signal of the current loop reference model, A m , B m For the corresponding x m (t),u m The coefficient matrix of (t), A m =B m ;

[0103]

[0104] Among them, x n (t) is the reference vector of the voltage loop reference model, u n (t) is the input reference signal of the voltage loop reference model, A n , B n For the corresponding x n (t),u n The coefficient matrix of (t), A n =B n .

[0105] Embodiment 5

[0106] This embodiment is based on the fourth embodiment. In this embodiment,

[0107] The error equation based on uncertain interference estimation is:

[0108] The error equation of the current loop is:

[0109] e(t)=x m (t)-x i (t)

[0110] The error equation of the voltage loop is:

[0111] e(t)=x n (t)-x v (t)

[0112] Where e(t) is the state error of the control loop at time t.

[0113] Embodiment 6

[0114] This embodiment is based on the fifth embodiment. In this embodiment,

[0115] The aggregate interference value is estimated by a filter, and the aggregate interference estimation value is expressed as:

[0116]

[0117] in, is the estimated value of the total interference of the current loop, g i (t) a filter with a suitable bandwidth for estimating the aggregate interference of the current loop;

[0118]

[0119] in, is the estimated value of the voltage loop lumped interference, g v (t) is a filter with suitable bandwidth for estimating the voltage loop lumped interference.

[0120] The lumped disturbance estimation strategy is: the control system current loop input u i (t) is:

[0121] u i (t) = B i -1 [A m x i (t)-A i x i (t)+B m u m (t)-D i (t)];

[0122] The lumped interference is estimated by the estimated value of the lumped interference, and the input of the control system current loop is obtained as:

[0123]

[0124] The control system voltage loop input u v (t) is:

[0125] u v (t) = B v -1 [A n x v(t)-A v x v (t)+B n u n (t)-D v (t)];

[0126] The lumped interference is estimated by the estimated value of the lumped interference, and the input of the control system current loop is obtained as:

[0127]

[0128] Among them, G i (s), G v (s) is a first-order filter, B i , B v is a constant coefficient matrix.

[0129] Embodiment 7

[0130] This embodiment is based on the sixth embodiment. In this embodiment, the control law of the voltage and current dual-loop control on the inverter side of the power grid simulation device is:

[0131] By the first-order filter G i The frequency domain form of (s) get

[0132] See also Figure 2 , the current inner loop control law is:

[0133]

[0134] Among them, U i (s), X m (s), U m (s), X i (s), D i0 (s) are u i (t), x m (t),u m (t), x i (t), D i0 (t) in frequency domain, I is the identity matrix;

[0135] By the first-order filter G v The frequency domain form of (s) get

[0136] See also Figure 3 , the voltage loop control law is:

[0137]

[0138] Among them, U v (s), X n (s), Un (s), X v (s), D v0 (s) are u v (t), x n (t),u n (t), x v (t), D v0 (t) in the frequency domain, where I is the identity matrix.

[0139] The control method of the power grid simulation device based on the uncertain disturbance estimator uses the uncertain disturbance estimator instead of the traditional PI controller to estimate and compensate for the uncertain terms and disturbances in the dual-loop control, thereby ensuring that the power grid simulation device tracks the reference signal without error and improving the ability to resist load disturbances.

[0140] The preferred embodiments of the present application are described above with reference to the accompanying drawings, but the scope of the present application is not limited thereby. Any modification, equivalent substitution and improvement made by a person skilled in the art without departing from the scope and essence of the present application shall be within the scope of the present application.

Claims

1. A control method for a power grid simulation device based on an uncertain disturbance estimator, characterized in that: The power grid simulation device includes a rectifier, an inverter, a control system and a filter; the method includes the following steps: The rectifier controls the DC voltage stability through the control system, and the inverter controls the AC output of the power grid simulation device through the control system to simulate various power grid voltages. According to the topological structure of the power grid simulation device, a mathematical model of the inverter side of the power grid simulation device is constructed; The mathematical model of the inverter side of the power grid simulation device is standardized to obtain the uncertain dynamic standardized model of the dual-loop control of the power grid simulation device; Based on the uncertain dynamic normalization model, a reference model based on uncertain disturbance estimation, an error equation and a lumped disturbance dynamic estimation value of the control system are obtained; According to the reference model, error equation and lumped disturbance estimation strategy based on uncertain disturbance estimation, the control law of the voltage and current dual-loop control on the inverter side of the power grid simulation device based on the uncertain disturbance estimator is obtained.

2. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 1, characterized in that: The step of "constructing a mathematical model of the inverter side of the power grid simulation device" is: Among them, u d 、u q are the d-axis and q-axis components of the inverter output voltage, e d 、e q is the d-axis and q-axis components of the load voltage, i d 、i q are the d-axis and q-axis components of the inverter output current; ω is the angular frequency of the AC system, L and R are the filter inductance and line resistance respectively; Among them, i od 、i oq are the d and q axis components of the inverter load current, and C is the filter capacitance.

3. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 2, characterized in that: According to the mathematical model of the inverter side of the power grid simulation device, the uncertain dynamic model of the inverter side of the power grid simulation device is obtained: The uncertain dynamic model of the current loop is: Among them, f id 、f iq is the uncertainty term of the current loop control equation on the d and q axes, D id , D iq is the unknown disturbance on the d and q axes; The uncertain dynamic model of the voltage loop is: Among them, f vd 、f vq is the uncertainty term of the voltage loop control equation on the d and q axes, D vd , D vq is the unknown disturbance on the d and q axes.

4. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 3, characterized in that: The uncertain dynamic normalized model of the dual-loop control of the power grid simulation device is: The standardized model of the uncertain dynamics of the current loop is: Among them, x i (t) = [i d ,i q ] T is the state variable of the current loop system, u i (t)=[u d ,u q ] T is the control input of the current loop system, f i (t) = [f id ,f iq ] T , D i (t)=[D id ,D iq ] T , A i , B i is the constant coefficient matrix, The standardized model of the voltage loop uncertainty dynamics is: Among them, x v (t) = [e d ,e q ] T is the state variable of the voltage loop system, u v (t) = [i d ,i q ] T is the control input of the current loop system, f v (t) = [f vd ,f vq ] T , D v (t)=[D vd ,D vq ] T , A v , B v is the constant coefficient matrix, 5. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 4, characterized in that: The reference model of the control system based on uncertain disturbance estimation is: Among them, x m (t) is the reference vector of the current loop reference model, u m (t) is the input reference signal of the current loop reference model, A m , B m For the corresponding x m (t),u m The coefficient matrix of (t), A m =B m ; Among them, x n (t) is the reference vector of the voltage loop reference model, u n (t) is the input reference signal of the voltage loop reference model, A n , B n For the corresponding x n (t),u n The coefficient matrix of (t), A n =B n .

6. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 5, characterized in that: The error equation based on uncertain interference estimation is: The error equation of the current loop is: e(t)=x m (t)-x i (t) The error equation of the voltage loop is: e(t)=x n (t)-x v (t) Where e(t) is the state error of the control loop at time t.

7. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 6, characterized in that: The aggregate interference value is estimated by a filter, and the aggregate interference estimation value is expressed as: in, is the estimated value of the total interference of the current loop, g i (t) a filter with a suitable bandwidth for estimating the aggregate interference of the current loop; in, is the estimated value of the voltage loop lumped interference, g v (t) is a filter with suitable bandwidth for estimating the voltage loop lumped interference.

8. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 7, characterized in that: The lumped disturbance estimation strategy is: the control system current loop input u i (t) is: u i (t)=B i -1 [A m x i (t)-A i x i (t)+B m u m (t)-D i (t)]; The lumped interference is estimated by the estimated value of the lumped interference, and the input of the control system current loop is obtained as: ； The control system voltage loop input u v (t) is: u v (t)=B v -1 [A n x v (t)-A v x v (t)+B n u n (t)-D v (t)]; The lumped interference is estimated by the estimated value of the lumped interference, and the input of the control system current loop is obtained as: Among them, G i (s), G v (s) is a first-order filter, B i , B v is a constant coefficient matrix.

9. The control method of a power grid simulation device based on an uncertain disturbance estimator according to claim 8, characterized in that: The control law of the voltage and current dual-loop control on the inverter side of the power grid simulation device is: By the first-order filter G i The frequency domain form of (s) get The current inner loop control law is: Among them, U i (s), X m (s), U m (s), X i (s), D i0 (s) are u i (t), x m (t),u m (t), x i (t), D i0 (t) in frequency domain, I is the identity matrix; By the first-order filter G v The frequency domain form of (s) get The voltage loop control law is: Among them, U v (s), X n (s), U n (s), X v (s), D v0 (s) are u v (t), x n (t),u n (t), x v (t), D v0 (t) in the frequency domain, where I is the identity matrix.

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