CN104967120B - A kind of hybrid dynamic simulation method based on invariable power interface - Google Patents

Abstract

The invention provides a hybrid dynamic simulation method based on a constant power interface, which includes the following steps: dividing the power system into a plurality of subsystems; obtaining time-series sequences with equal time intervals; obtaining the initial power flow of the subsystems; determining the injection current and Boundary bus voltage simulation curve. The constant power interface in the invention ensures that the exchange power of the research grid and the external grid is consistent with the measured value during the whole simulation period, which lays a foundation for the practical application of the hybrid dynamic simulation method.

Description

A Hybrid Dynamic Simulation Method Based on Constant Power Interface

technical field

The invention belongs to the technical field of power systems, and in particular relates to a hybrid dynamic simulation method based on a constant power interface.

Background technique

With the expansion of the grid scale and the strengthening of the grid structure, the influence of any disturbance is spread to a wide area, and each change is the result of a large number of intertwined factors, making it very difficult to verify the validity of the simulation and locate the cause of the simulation error. The traditional dynamic simulation is mainly based on the pre-set load generator operation mode and predefined fault form. During the simulation process, it completely depends on the accuracy of the model and algorithm, and has no connection with the actual system. Inaccuracies in models or parameters can cause deviations between simulation results and actual system dynamic behavior. At the same time, the wide area measurement system (WideArea Measurement System, WAMS) with phase measurement function is widely used in the power grid to accurately capture the dynamic behavior of the power grid, but it cannot be installed in every corner of the system, and it cannot predict the system like simulation the behavior of. Therefore, simulation and WAMS measurement have their own advantages and disadvantages. The power system hybrid dynamic simulation combines the advantages of the two, providing a measurement data interface for traditional dynamic simulation, and accurate comparison for system accident reproduction and simulation verification. The work of simulation results and measurement results provides a platform, which provides a method basis for deep mining of fault information contained in the measurement data itself.

The hybrid dynamic simulation uses the external signal collected by the Phasor Measurement Unit (PMU) to inject into the simulation subsystem, so that the external system of the power grid is equivalent, and the simulation result is compared with the WAMS measurement to locate the simulation subsystem. Deviation reasons, calibration component parameters, etc. Hybrid dynamic simulation needs to be able to reflect the role of the external power grid, but also cannot inject a large offset into the research grid to meet the interface requirements, so that the simulation process deviates from the normal operating characteristics of the research grid. Commonly used hybrid dynamic simulation methods mainly include phase-shifting transformer method, fast-response generator method, variable impedance method, V-θ node method and so on. These methods essentially make the voltage angle of the equivalent point consistent with the PMU data. When the current in the simulation process deviates greatly from the real value, it is equivalent to injecting a large deviation power, which forces the state of the internal power source of the research grid to change. It increases the difficulty of analyzing the behavioral characteristics of components and devices, which hinders the practical application of hybrid dynamic simulation methods.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a hybrid dynamic simulation method based on a constant power interface, which forms comprehensive flexible constraints on the boundary bus voltage and current, so that the research grid is less affected by the interface and can fully display the research grid itself characteristics. This method lays the foundation for the practical application of the hybrid dynamic simulation method.

In order to realize the above-mentioned purpose of the invention, the present invention takes the following technical solutions:

The invention provides a hybrid dynamic simulation method based on a constant power interface, the method comprising the following steps:

Step 1: Divide the power system into multiple subsystems;

Step 2: Obtain the sequence of time series with equal time intervals;

Step 3: Add a constant power interface at the boundary bus and obtain the initial power flow of the subsystem;

Step 4: Determine the injection current of the boundary bus and the simulation curve of the boundary bus voltage.

In the step 1, according to the layout of the phasor measurement units, the power system is divided into multiple subsystems, and each subsystem is connected by a boundary bus, and the boundary bus is the bus on which the phasor measurement units are installed.

Described step 2 specifically comprises the following steps:

Step 2-1: Collect boundary bus information and subsystem injection information at equal time intervals through the phasor measurement unit, the boundary bus information includes the voltage amplitude and voltage phase angle of the boundary bus, and the subsystem injection information includes subsystem injection active and reactive power;

Step 2-2: Preprocess the collected boundary bus information and subsystem injection information. Let the time series be {t ₁ ,t ₂ ,…,t _N }, and the corresponding sequence of equal time intervals is {y ₁ , y ₂ ,…,y _N }, N represents the number of data in the time series sequence, which can be divided into the following two situations:

1) If there are data missing points in the time series sequence, use the difference method to fill in the data missing points y _i , as follows:

In formula (1), y _i-1 represents the i-1th data integrity point in the time series sequence, y _i+1 represents the i+1th data integrity point in the time series sequence, and t _i-1 represents the data integrity point y _{i -1} corresponds to the time, t _i+1 represents the time corresponding to the data integrity point y _i+1 , t _i represents the time corresponding to the data missing point y _i ;

2) For any data in the time series, if it is greater than 3 times the average value of the two data before and after it, then the data is a data error point, denoted as y _j , and the average value method is used to remove the data error point y _j Glitches and sudden changes, a smooth curve is obtained, and y _j is expressed as:

In formula (2), y _j-1 represents the j-1th data non-error point in the time series sequence, y _j+1 represents the j+1th data non-error point in the time series sequence, and t _j-1 represents the data non-error point The time corresponding to point j-1, t _j+1 represents the time corresponding to data non-error point j+1, and t _j represents the time corresponding to data error point y _j .

In the step 3, first add a constant power interface at the boundary bus, the initial injected active power of the constant power interface is consistent with the injected active power of the subsystem collected by the phasor measurement unit, and the initial injected reactive power of the constant power interface is the same as the injected reactive power through the The injected reactive power of the subsystem collected by the phasor measurement unit is consistent; the initial power flow of the subsystem is obtained by using the interior point optimization power flow algorithm, so that the initial power flow is close to the voltage at the initial point of wave recording of the phasor measurement unit, and the initial point of wave recording of the phasor measurement unit is the first data point in the time series series.

The initial power flow of the subsystem is optimized through the objective function, which is:

In formula (3), u represents the control variable, including the active output of the generator and the reactive output of the generator; x represents the state variable to be obtained, including the voltage amplitude and voltage phase angle; v _l represents the lth boundary bus the measuring voltage, Indicates the initial voltage of the lth boundary bus, and M indicates the number of subsystem boundary buses;

The constraints corresponding to the objective function include equality constraints and inequality constraints, which are expressed as:

g(u,x)=0 (4)

h(u,x)≤0 (5)

In formulas (4) and (5), g(u,x) represents equality constraints, and h(u,x) represents inequality constraints.

Described step 4 specifically comprises the following steps:

Step 4-1: Set the initial simulation time T=0, and set the simulation step size according to the time interval of the sequence sequence;

Step 4-2: Use the trapezoidal integration algorithm for simulation to obtain the injection current at the boundary bus Expressed as:

In formula (6), I _x represents the injection current at the boundary bus The real part of , I _y represents the injection current at the boundary bus The imaginary part of ; and there are:

In formulas (7) and (8), P represents the active power injected by the subsystem collected by the vector measurement unit, Q represents the reactive power injected by the subsystem collected by the vector measurement unit, and S represents the power reference value; the boundary bus voltage Expressed as:

In formula (9), V _x represents the boundary bus voltage The real part of , V _y represents the boundary bus voltage the imaginary part of

Step 4-3: Obtain the boundary bus voltage simulation curve through hybrid dynamic simulation.

Compared with prior art, the beneficial effect of the present invention is:

The hybrid dynamic simulation method based on the constant power interface provided by the present invention divides the power system into multiple subsystems, and obtains the time series series at equal time intervals; after obtaining the initial power flow of the subsystems, the injection current of the boundary bus and the boundary bus Voltage simulation curve. The constant power interface ensures that the exchange power of the research grid and the external grid is consistent with the measured value during the whole simulation period, which lays the foundation for the practical application of the hybrid dynamic simulation method.

Description of drawings

Fig. 1 is a flowchart of a hybrid dynamic simulation method based on a constant power interface in an embodiment of the present invention;

Fig. 2 is a diagram of the relationship between the subsystem and the boundary bus in the embodiment of the present invention.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings.

As shown in Fig. 1, the present invention provides a kind of hybrid dynamic simulation method based on constant power interface, and described method comprises the following steps:

Step 1: Divide the power system into multiple subsystems;

Step 2: Obtain the sequence of time series with equal time intervals;

Step 3: Add a constant power interface at the boundary bus and obtain the initial power flow of the subsystem;

Step 4: Determine the injection current of the boundary bus and the simulation curve of the boundary bus voltage.

In the step 1, according to the layout of the phasor measurement units, the power system is divided into multiple subsystems, and each subsystem is connected by a boundary bus, and the boundary bus is the bus on which the phasor measurement units are installed.

Described step 2 specifically comprises the following steps:

Step 2-1: Collect boundary bus information and subsystem injection information at equal time intervals through the phasor measurement unit, the boundary bus information includes the voltage amplitude and voltage phase angle of the boundary bus, and the subsystem injection information includes subsystem injection active and reactive power;

Step 2-2: Preprocess the collected boundary bus information and subsystem injection information. Let the time series be {t ₁ ,t ₂ ,…,t _N }, and the corresponding sequence of equal time intervals is {y ₁ , y ₂ ,…,y _N }, N represents the number of data in the time series sequence, which can be divided into the following two situations:

1) If there are data missing points in the time series sequence, use the difference method to fill in the data missing points y _i , as follows:

In formula (1), y _i-1 represents the i-1th data integrity point in the time series sequence, y _i+1 represents the i+1th data integrity point in the time series sequence, and t _i-1 represents the data integrity point y _{i -1} corresponds to the time, t _i+1 represents the time corresponding to the data integrity point y _i+1 , t _i represents the time corresponding to the data missing point y _i ;

2) For any data in the time series, if it is greater than 3 times the average value of the two data before and after it, then the data is a data error point, denoted as y _j , and the average value method is used to remove the data error point y _j Glitches and sudden changes, a smooth curve is obtained, and y _j is expressed as:

In formula (2), y _j-1 represents the j-1th data non-error point in the time series sequence, y _j+1 represents the j+1th data non-error point in the time series sequence, and t _j-1 represents the data non-error point The time corresponding to point j-1, t _j+1 represents the time corresponding to data non-error point j+1, and t _j represents the time corresponding to data error point y _j .

In the step 3, first add a constant power interface at the boundary bus, the initial injected active power of the constant power interface is consistent with the injected active power of the subsystem collected by the phasor measurement unit, and the initial injected reactive power of the constant power interface is the same as the injected reactive power through the The injected reactive power of the subsystem collected by the phasor measurement unit is consistent; the initial power flow of the subsystem is obtained by using the interior point optimization power flow algorithm, so that the initial power flow is close to the voltage of the initial point of wave recording of the phasor measurement unit, and the initial point of wave recording of the phasor measurement unit is the first data point in the time series series.

The initial power flow of the subsystem is optimized through the objective function, which is:

In formula (3), u represents the control variable, including the active output of the generator and the reactive output of the generator; x represents the state variable to be obtained, including the voltage amplitude and voltage phase angle; v _l represents the lth boundary bus the measuring voltage, Indicates the initial voltage of the lth boundary bus, and M indicates the number of subsystem boundary buses;

The constraints corresponding to the objective function include equality constraints and inequality constraints, which are expressed as:

g(u,x)=0 (4)

h(u,x)≤0 (5)

In formulas (4) and (5), g(u,x) represents equality constraints, and h(u,x) represents inequality constraints.

Described step 4 specifically comprises the following steps:

Step 4-1: Set the initial simulation time T=0, and set the simulation step size according to the time interval of the sequence sequence;

Step 4-2: Use the trapezoidal integration algorithm for simulation to obtain the injection current at the boundary bus Expressed as:

In formula (6), I _x represents the injection current at the boundary bus The real part of , I _y represents the injection current at the boundary bus The imaginary part of ; and there are:

In formulas (7) and (8), P represents the active power injected by the subsystem collected by the vector measurement unit, Q represents the reactive power injected by the subsystem collected by the vector measurement unit, and S represents the power reference value; the boundary bus voltage Expressed as:

In formula (9), V _x represents the boundary bus voltage The real part of , V _y represents the boundary bus voltage the imaginary part of

Step 4-3: Obtain the boundary bus voltage simulation curve through hybrid dynamic simulation.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims (6)

1. a kind of hybrid dynamic simulation method based on invariable power interface, it is characterised in that：It the described method comprises the following steps：

Step 1：Power system is divided into multiple subsystems；

Step 2：Obtain the when ordinal series of constant duration；

Step 3：Increase invariable power interface at the bus of border, and obtain the initial trend of subsystem；

Step 4：Determine the Injection Current and border busbar voltage simulation curve of border bus.

2. the hybrid dynamic simulation method according to claim 1 based on invariable power interface, it is characterised in that：The step In 1, according to layouting for phasor measurement unit, power system is divided between multiple subsystems, each subsystem and passes through border Bus is connected, and the border bus is the bus for installing phasor measurement unit.

3. the hybrid dynamic simulation method according to claim 1 based on invariable power interface, it is characterised in that：The step 2 specifically include following steps：

Step 2-1：Information is injected by the collection border bus information and subsystem of phasor measurement unit constant duration, it is described Border bus information includes the voltage magnitude and voltage phase angle of border bus, the subsystem injection packet enclosed tool system injection Active power and reactive power；

Step 2-2：Border bus information and subsystem the injection information of collection are pre-processed, if time series is { t₁, t₂,…,t_N, then the when ordinal series of corresponding constant duration is { y₁,y₂,…,y_N, data amount check in ordinal series when N is represented, It is divided into following two situations：

If 1) there is shortage of data point when in ordinal series, using difference method to data missing point y_iPolishing is carried out, is had：

$y_i=y_{i-1}+\frac{y_{i+1}-y_{i-1}}{t_{i+1}-t_{i-1}}(t_i-t_{i-1})---\left(1\right)$

In formula (1), y_i-1The complete point of the i-th -1 data, y in ordinal series during expression_i+1I+1 data are complete in ordinal series during expression Integral point, t_i-1Represent data completely point y_i-1Corresponding time, t_i+1Represent data completely point y_i+1Corresponding time, t_iRepresent data Missing point y_iThe corresponding time；

2) for when ordinal series in any data, if it is more than 3 times of its front and rear 2 statistical average, the data are data Error dot, is designated as y_j, data error point y is removed using the method for average value_jIn burr and mutation, obtain smoothed curve, y_jTable It is shown as：

$y_j=y_{j-1}+\frac{y_{j+1}-y_{j-1}}{t_{j+1}-t_{j-1}}(t_j-t_{j-1})---\left(2\right)$

In formula (2), y_j-1The non-error dot of -1 data of jth, y in ordinal series during expression_j+1+ 1 data of jth in ordinal series during expression Non- error dot, t_j-1Represent the non-error dot j-1 of data corresponding times, t_j+1Represent the non-error dot j+1 of data corresponding times, t_j Represent data error point y_jThe corresponding time.

4. the hybrid dynamic simulation method according to claim 1 based on invariable power interface, it is characterised in that：The step In 3, first increase invariable power interface at the bus of border, the initial injection active power of invariable power interface is with passing through phasor measurement list The subsystem injection active power of member collection is consistent, and the initial injection reactive power of invariable power interface is with passing through phasor measurement unit The subsystem injection reactive power of collection is consistent；The initial trend of subsystem is obtained using interior Optimal Power Flow algorithm so that just Beginning trend is approached with phasor measurement unit record ripple initial point voltage, when phasor measurement unit record ripple initial point is first in ordinal series Individual data point.

5. the hybrid dynamic simulation method according to claim 4 based on invariable power interface, it is characterised in that：Subsystem Initial trend is optimized by object function, is had：

$\begin{array}{cc}\underset{u}{min}& f(u,x)=\underset{l\≤M}{\Σ}{(v_l-{\hat{v}}_l)}^2\end{array}---\left(3\right)$

In formula (3), u represents to control variable, including the active power output of generator and the idle of generator to exert oneself；X represents to wait to try to achieve State variable, including voltage magnitude and voltage phase angle；v_lThe measurement voltage of l-th of border bus is represented,Represent l-th of border The initial voltage of bus, M represents the number of subsystem border bus；

The corresponding constraints of object function include equality constraint and inequality constraints condition, equality constraint and Formula constraints is expressed as：

G (u, x)=0 (4)

h(u,x)≤0 (5)

In formula (4) and (5), g (u, x) represents equality constraint, and h (u, x) represents inequality constraints.

6. the hybrid dynamic simulation method according to claim 1 based on invariable power interface, it is characterised in that：The step 4 specifically include following steps：

Step 4-1：Set emulation initial time T=0, and according to when ordinal series time interval set simulation step length；

Step 4-2：Emulated using trapezoidal integration algorithm, obtain Injection Current at the bus of borderIt is expressed as：

$\stackrel{\·}{I}=I_x+{\mathrm{jI}}_y---\left(6\right)$

In formula (6), I_xRepresent Injection Current at the bus of borderReal part, I_yRepresent Injection Current at the bus of borderImaginary part；And Have：

$I_x=\frac{P\·V_x+Q\·V_y}{S\·({V_x}^2+{V_y}^2)}---\left(7\right)$

$I_y=\frac{P\·V_y-Q\·V_x}{S\·({V_x}^2+{V_y}^2)}---\left(8\right)$

In formula (7) and (8), P represents that the subsystem gathered by phasor measurement units injects active power, and Q is represented by vector The subsystem injection reactive power of measuring unit collection, S represents power reference value；Border busbar voltageIt is expressed as：

$\stackrel{\·}{V}=V_x+{\mathrm{jV}}_y---\left(9\right)$

In formula (9), V_xRepresent border busbar voltageReal part, V_yRepresent border busbar voltageImaginary part；

Step 4-3：Border busbar voltage simulation curve is obtained by hybrid dynamic simulation.