A power grid simulator control method based on an uncertain disturbance estimator

Abstract

The application discloses a grid simulation device control method based on an uncertain interference estimator, a rectifier controls the stability of a direct-current voltage through a control system, an inverter controls an alternating-current output of a grid simulation device to simulate various grid voltages through the control system, a mathematical model of an inverter side of the grid simulation device is constructed according to a topological structure of the grid simulation device; the mathematical model of the inverter side of the grid simulation device is subjected to standardization processing to obtain an uncertain dynamic standardization model of the grid simulation device control; a control law of the voltage and current double-loop control of the inverter side of the grid simulation device based on the uncertain interference estimator is obtained according to a reference model based on uncertain interference estimation, an error equation and lumped interference dynamic estimation; the method uses the uncertain interference estimator to replace a traditional PI controller, estimates and compensates uncertain items and disturbances in the double-loop control, ensures errorless tracking of a reference signal of the grid simulation device and improves the anti-load disturbance capability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, in particular to a grid simulation device control method based on an uncertain disturbance estimator. BACKGROUND

[0002] With the large-scale use of new energy power generation equipment such as photovoltaic and wind power, the proportion in the power system is increasing, and the standards and requirements of the power industry for new energy equipment grid connection are becoming increasingly stringent. In order to ensure the stability of the power grid operation and the adaptability of new energy equipment under grid fault conditions, a grid simulation device is needed to simulate the voltage mutation, frequency mutation and voltage imbalance of the actual power grid and other abnormal operating states, so as to perform grid performance testing for new energy power generation equipment without affecting the actual power grid operation.

[0003] The existing control strategy of the grid simulation device inverter side is mainly the double-loop control using the synchronous coordinate system PI controller. The PI control is relatively mature and has a fast dynamic response. However, in actual operation, the grid simulation device will be affected by parameter changes, system random disturbances and complex load conditions during grid performance testing, and it is difficult to obtain the desired effect. Moreover, the output voltage quality may not meet the requirements. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a grid simulation device control method based on an uncertain disturbance estimator. The method uses an uncertain disturbance estimator instead of a traditional PI controller to estimate and compensate the uncertain terms and disturbances in the double-loop control, ensuring the grid simulation device to track the reference signal without error and improving the ability to resist load disturbances.

[0005] To solve the above technical problems, the present application provides a grid simulation device control method based on an uncertain disturbance estimator. The grid simulation device includes a rectifier, an inverter, a control system and a filter. The method comprises the following steps:

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

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

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

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

[0010] Preferably, the step of "building a mathematical model of the grid simulation device inverse side" is:

[0011]

[0012] Wherein, u d , u q are the d, q axis components of the inverter output voltage, e d , e q are the d, q axis components of the load voltage, i d , i q are the d, 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] Wherein, i od , i oq are the d, q axis components of the inverter load current.

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

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

[0017]

[0018] Wherein, f id , f iq are the uncertain terms of the current loop control equation on the d, q axis, D id , D iq are unknown disturbances on the d, q axis.

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

[0020]

[0021] Wherein, f vd , f vq are the uncertain terms of the voltage loop control equation on the d, q axis, D vd , D vq are unknown disturbances on the d, q axis.

[0022] Preferably, the uncertain dynamic standardization model of the grid simulation device double-loop control is:

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

[0024]

[0025] where 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 are constant coefficient matrices,

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

[0027]

[0028] where 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 voltage loop system, f v (t) = [f vd ,f vq ] T , D v (t) = [D vd ,D vq ] T , A v , B v are constant coefficient matrices,

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

[0030]

[0031] where x m(t) is the input reference signal of the current loop reference model, A m (t) is the input reference signal of the current loop reference model, A m , B m are the coefficient matrices corresponding to x m (t), u m (t) m = B m .

[0032]

[0033] where x n (t) is the input reference signal of the voltage loop reference model, A n (t) is the input reference signal of the voltage loop reference model, A n , B n are the coefficient matrices corresponding to x n (t), u n (t) n = B n .

[0034] Preferably, the error equation based on the uncertain disturbance 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 lumped disturbance value is estimated by a filter, and the lumped disturbance estimation value is represented as:

[0041]

[0042] where, is the estimation value of the lumped disturbance of the current loop, g i (t) is a filter with a suitable bandwidth for estimating the lumped disturbance of the current loop;

[0043]

[0044] where, is the estimation value of the lumped disturbance of the voltage loop, g v(t) is a filter suitable for the bandwidth of the estimation of the aggregated disturbance of the voltage loop.

[0045] Preferably, the aggregated disturbance estimation strategy is that 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 aggregated disturbance is estimated with the estimated value of the aggregated disturbance, and the control system current loop input is:

[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 aggregated disturbance is estimated with the estimated value of the aggregated disturbance, and the control system voltage loop input is:

[0052]

[0053] Wherein, G i (s), G v (s) are first-order filters, B i , B v are constant coefficient matrices.

[0054] Preferably, the control law of the voltage and current double-loop control of the inverter side of the grid simulation device is:

[0055] The frequency domain form of the first-order filter G i (s) is

[0056] The current inner loop control law is: ​

[0057]

[0058] wherein U i (s), X m (s), U m (s), X i (s), D i0 (s) are the frequency domain forms of u i (t), x m (t), u m (t), x i (t), D i0 (t) respectively, and I is an identity matrix.

[0059] The frequency domain form of the first-order filter G v (s) is obtained

[0060] The voltage loop control law is:

[0061]

[0062] wherein U v (s), X n (s), U n (s), X v (s), D v0 (s) are the frequency domain forms of u v (t), x n (t), u n (t), x v (t), D v0 (t) respectively, and I is an identity matrix.

[0063] After the above method, the power grid simulation device control method based on the uncertain disturbance estimator, the power grid simulation device includes a rectifier, an inverter, a control system and a filter; the method comprises the following steps: the rectifier controls the direct current voltage to be stable through the control system, the inverter controls the power grid simulation device alternating current output to simulate various types of power grid voltage through the control system, according to the topology structure of the power grid simulation device, the mathematical model of the inverter side of the power grid simulation device is constructed;

[0064] ​The mathematical model of the inverter side of the power grid simulation device is standardized to obtain an uncertain dynamic standardized model of the double-loop control of the power grid simulation device; based on the uncertain dynamic standardized model, a reference model based on uncertain disturbance estimation, an error equation and a lumped disturbance estimation value of the control system are obtained; according to the reference model based on uncertain disturbance estimation, the error equation and the lumped disturbance estimation strategy, a control law of the voltage and current double-loop control of the inverter side of the power grid simulation device based on the uncertain disturbance estimator is obtained; the power grid simulation device control method based on the uncertain disturbance estimator replaces the traditional PI controller with the uncertain disturbance estimator to estimate and compensate the uncertain terms and disturbances in the double-loop control, thereby ensuring the error-free tracking of the reference signal of the power grid simulation device and improving the ability to resist load disturbances. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 The circuit diagram of the power grid simulation device of the present application is shown in FIG. 1.

[0066] Figure 2 The control block diagram of the current loop control law of the power grid simulation device control method based on the uncertain disturbance estimator of the present application is shown in FIG. 2.

[0067] Figure 3 The control block diagram of the voltage loop control law of the power grid simulation device control method based on the uncertain disturbance estimator of the present application is shown in FIG. 3. DETAILED DESCRIPTION

[0068] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0069] Example 1

[0070] Please refer to Figure 1 , Figure 1 The circuit diagram of the power grid simulation device of the present application is shown in FIG. 1.

[0071] The present embodiment discloses a power grid simulation device control method based on an uncertain disturbance estimator, the power grid simulation device comprising a rectifier 10, an inverter 20, a control system and a filter; the method comprising the following steps:

[0072] The rectifier controls the DC voltage stability through the control system, and the inverter controls the AC output of the power grid simulation device to simulate various grid voltages through the control system; according to the topology structure of the power grid simulation device, a mathematical model of the inverter side of the power grid simulation device is constructed;

[0073] The mathematical model of the inverter side of the power grid simulation device is standardized to obtain an uncertain dynamic standardized model of the double-loop control of the power grid simulation device.

[0074] Based on the uncertain dynamic standardized model, a reference model of the control system based on uncertain disturbance estimation, an error equation and a lumped disturbance estimation value are obtained.

[0075] According to the reference model based on uncertain disturbance estimation, the error equation and the lumped disturbance estimation strategy, a control law of the voltage and current double-loop control of the inverter side of the power grid simulation device based on the uncertain disturbance estimator is obtained.

[0076] Embodiment Two

[0077] This embodiment is based on Embodiment One. In this embodiment, the step of "constructing a mathematical model of the inverter side of the power grid simulation device" is:

[0078]

[0079] wherein u d and u q are the d and q axis components of the inverter output voltage, e d and e q are the d and q axis components of the load voltage, i d and i q are the d and q axis components of the inverter output current; and ω is the angular frequency of the AC system, and L and R are the filter inductance and line resistance, respectively.

[0080]

[0081] wherein i od and i oq are the d and q axis components of the inverter load current.

[0082] Embodiment Three

[0083] This embodiment is based on Embodiment Two. 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:

[0084] The uncertain dynamic model of the current loop is:

[0085]

[0086] wherein f id and f iq are the uncertain terms of the current loop control equation on the d and q axes, D id and D iq are unknown disturbances on the d and q axes.

[0087] The uncertain dynamic model of the voltage loop is:

[0088]

[0089] where f vd , f vq are the uncertain terms of the voltage loop control equation on the d, q axes, D vd , D vq are unknown disturbances on the d, q axes.

[0090] In the present embodiment, the uncertain dynamic standardized model of the power grid simulation device double-loop control is:

[0091] The standardized model of the uncertain dynamics of the current loop is:

[0092]

[0093] where 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 are constant coefficient matrices,

[0094] The standardized model of the uncertain dynamics of the voltage loop is:

[0095]

[0096] where 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 voltage loop system, f v (t) = [f vd , f vq ]T , D v (t) = [D vd , D vq ] T , A v , B v are constant coefficient matrices,

[0097] Embodiment Four

[0098] This embodiment is based on Embodiment Three, in this embodiment,

[0099] The reference model of the control system based on uncertain disturbance estimation is:

[0100]

[0101] where 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 are the coefficient matrices corresponding to x m (t), u m (t), and A m = B m .

[0102]

[0103] where 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 are the coefficient matrices corresponding to x n (t), u n (t), and A n = B n .

[0104] Embodiment Five

[0105] This embodiment is based on Embodiment Four, in this embodiment,

[0106] The error equation based on uncertain disturbance estimation is:

[0107] The error equation of the current loop is:

[0108] e(t) = x m (t) - x i (t)

[0109] The error equation of the voltage loop is:

[0110] e(t) = x n (t) - x v (t)

[0111] wherein e(t) is the state error of the control loop at time t.

[0112] Embodiment Six

[0113] This embodiment is based on Embodiment Five, in this embodiment,

[0114] The lumped disturbance value is estimated by a filter, and the lumped disturbance estimation value is represented as:

[0115]

[0116] wherein, is the estimation value of the lumped disturbance of the current loop, g i (t) is a filter with suitable bandwidth for estimating the lumped disturbance of the current loop;

[0117]

[0118] wherein, is the estimation value of the lumped disturbance of the voltage loop, g v (t) is a filter with suitable bandwidth for estimating the lumped disturbance of the voltage loop.

[0119] The lumped disturbance estimation strategy is that the control system current loop input u i (t) is:

[0120] u i (t) = B i -1 [A m x i (t) - A i x i (t) + B m u m (t) - D i (t)].

[0121] The lumped disturbance is estimated by the estimation value of the lumped disturbance, and the control system current loop input is obtained as:

[0122]

[0123] The control system voltage loop input u v (t) is:

[0124] u v (t) = B v -1 [A n x v(t)-A v x v (t)+B n u n (t)-D v (t)];

[0125] The estimation of the lumped interference is obtained by using the estimated value of the lumped interference, and the input of the voltage loop of the control system is:

[0126]

[0127] wherein, G i (s) is a first-order filter, B v (s) is a first-order filter, B i , B v are constant coefficient matrices.

[0128] Example Seven

[0129] This example is based on Example Six. In this example, the control law of the voltage and current double-loop control of the inverter side of the grid simulation device is:

[0130] The frequency domain form of the first-order filter G i (s) is obtained

[0131] Please refer to Figure 2 , and the current inner loop control law is:

[0132]

[0133] wherein, U i (s), X m (s), U m (s), X i (s), D i0 (s) are the frequency domain forms of u i (t), x m (t), u m (t), x i (t), D i0 (t) respectively, and I is an identity matrix.

[0134] The frequency domain form of the first-order filter G v (s) is obtained

[0135] Please refer to Figure 3 , and the voltage loop control law is:

[0136]

[0137] wherein, U v (s), X n (s), U​​n (s), X v (s), D v0 (s) are respectively u v (t), x n (t), u n (t), x v (t), D v0 (t) in the frequency domain, I is a unit matrix.

[0138] The power grid simulation device control method based on the uncertain disturbance estimator replaces the traditional PI controller with the uncertain disturbance estimator, estimates and compensates the uncertain terms and disturbances in the double-loop control, ensures errorless tracking of the reference signal by the power grid simulation device, and improves the anti-load disturbance capability.

[0139] The preferred embodiments of the present application are described above with reference to the accompanying drawings, and are not intended to limit the scope of the present application. Any modifications, equivalent replacements and improvements made by those 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 power system simulator control method based on an uncertain disturbance estimator, characterized by, The power grid simulation device comprises a rectifier, an inverter, a control system and a filter; the method comprises the following steps: The rectifier controls the direct current voltage stability through the control system, the inverter controls the power grid simulation device alternating current output 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 topology structure of the power grid simulation device; The mathematical model of the inverter side of the power grid simulation device is standardized to obtain an uncertain dynamic standardized model of the double-loop control of the power grid simulation device; Based on the uncertain dynamic standardized model, a reference model based on uncertain disturbance estimation, an error equation and a lumped disturbance estimation value of the control system are obtained; According to the reference model based on uncertain disturbance estimation, the error equation and the lumped disturbance estimation strategy, a control law of the voltage and current double-loop control of the inverter side of the power grid simulation device based on the uncertain disturbance estimator is obtained.

2. The power system simulator based on an uncertain disturbance estimator control method according to claim 1, characterized by, The step of "constructing the mathematical model of the inverter side of the power grid simulation device" is: where u d , u q are the d, q-axis components of the inverter output voltage, e d , e q are the d, q-axis components of the load voltage, i d , i q are the d, 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; where i od , i oq are the d, q-axis components of the inverter load current, C is the filter capacitance.

3. The power system simulator based on an uncertain disturbance estimator control method according to claim 2, characterized by, According to the mathematical model of the inverter side of the power grid simulation device, an uncertain dynamic model of the inverter side of the power grid simulation device is obtained: The uncertain dynamic model of the current loop is: where f id , f iq are the uncertainties of the current loop control equation in d, q axes, D id , D iq are unknown disturbances in d, q axes; The uncertain dynamic model of the voltage loop is: where f vd , f vq are the uncertainties of the voltage loop control equation in d, q axes, D vd , D vq are the unknown disturbances in d, q axes.

4. The power grid simulation device control method based on the uncertain disturbance estimator according to claim 3, characterized in that, The uncertain dynamic standardized model of the double-loop control of the power grid simulation device is: The standardized model of the uncertain dynamic of the current loop is: where 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 are constant coefficient matrices, the standardized model of the voltage loop uncertain dynamics is: where x v (t) = [e d , e q ] T are state variables of the voltage loop system, u v (t) = [i d , i q ] T are control inputs of the voltage loop system, f v (t) = [f vd , f vq ] T , D v (t) = [D vd , D vq ] T , A v , B v are constant coefficient matrices, 5. The power grid simulation device control method based on the uncertain disturbance estimator according to claim 4, characterized in that, The reference model based on the uncertain disturbance estimation of the control system is: where x m (t) is the input reference signal of the current loop reference model, A m (t) is the input reference signal of the current loop reference model, A m , B m are the coefficient matrices corresponding to x m (t), u m (t), A m = B m ; where 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 are the coefficient matrices corresponding to x n (t), u n (t), A n = B n .

6. The power system simulator based on an uncertain disturbance estimator control method according to claim 5, characterized by, The error equation based on the uncertain disturbance 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) Wherein, e(t) is the state error of the control loop at t moment.

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

8. The power system simulator based on an uncertain disturbance estimator control method according to claim 7, characterized by, The lumped disturbance estimation strategy is that 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 disturbance is estimated by the estimation value of the lumped disturbance, and the current loop input of the control system 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 disturbance is estimated by the estimation value of the lumped disturbance, and the voltage loop input of the control system is obtained as: where G i (s) is a first order filter, B v (s) is a first order filter, B i , B v is a constant coefficient matrix.

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

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