CN110336299A - A Distribution Network Reconfiguration Method Considering Small Interference and Stability of Integrated Energy System - Google Patents

Abstract

The invention discloses a distribution network reconstruction method considering the small disturbance stability of an integrated energy system. Build their own small-disturbance stability models for various types of power sources in the integrated energy system, and form the final integrated energy system model through coordinate transformation. The output is set in the most unstable scenario of the system to ensure that the integrated energy system operates more economically on the basis of satisfying the stability of small disturbances.

Description

A Distribution Network Reconfiguration Method Considering Small Interference and Stability of Integrated Energy System

Technical field:

The invention relates to the field of power transmission and transformation, in particular to a distribution network reconstruction method considering the small disturbance and stability of an integrated energy system.

Background technique:

With the development of society and the improvement of people's living standards, people's demand for energy is gradually increasing. Continuing to develop and utilize limited fossil energy will not only cause environmental pollution, but also lead to energy depletion and energy crisis. The development and utilization of clean renewable energy and improving the utilization rate of energy have become effective means to solve the problems of environmental pollution and energy crisis. In recent years, researchers' research and application of renewable energy power generation technologies such as wind and light have effectively alleviated the above problems. In addition, the proposal of an integrated energy system is of great significance for improving the penetration rate of renewable energy and energy utilization efficiency. It aims to break down the barriers between various energy supply systems, promote the coupling of multi-energy systems, and coordinate and optimize the operation.

According to different utilization scenarios, the integrated energy system can be divided into cross-regional level, regional level and user level. For district-level integrated energy systems consisting of power distribution systems, natural gas systems and heating/cooling systems. Among them, the power distribution system includes renewable energy based on doubly-fed wind power generation technology and photovoltaic inverter power generation technology, and the natural gas system and heating system are coupled to the power distribution system through gas turbines and cogeneration units, respectively. Therefore, the entire integrated energy system includes synchronous generators, asynchronous generators and inverter power generation devices, and the time scale of dynamic processes in the system is large. Its operation stability can be divided into small disturbance stability and large disturbance stability according to the size of the disturbance. Among them, the characteristics of various power sources and the network structure of the distribution network are the main influencing factors.

Under the condition of high proportion of renewable energy connected to the grid, the small disturbance stability of the integrated energy system deserves attention. For different types of power sources (such as photovoltaics, wind power, and gas turbines), due to their different operating mechanisms and control methods, their small disturbance stability is also different. In addition, due to the small capacity of these power sources, power system stabilizers are generally not configured like synchronous machines in the transmission network. In addition, their output has a strong uncertainty, which makes the impact on the stability of the system with small disturbances. become more complex.

Distribution network reconstruction can reduce the loss of the system, but it also changes the operation mode of the system while changing the structure, which affects the stability of the system with small disturbances. When reconfiguring the distribution network, most researchers focus on economics, ignoring the dynamic process of various power sources and systems, that is, ignoring the stability of the system.

Distribution network reconstruction generally takes reducing network loss and improving network voltage level as the objective function. Constraints include power flow constraints, network radial constraints, branch power flow constraints, and active and reactive power output constraints. After the network structure is changed, the stability of small disturbances in the operation of various power sources will inevitably be affected to varying degrees. If the distribution network reconstruction only considers economics, it is very likely that some power sources cannot run stably, resulting in disconnection from the grid. In addition, the output of wind power and photovoltaics is random, and the uncertainty of their output will inevitably lead to changes in the power flow and node voltage in the system, which will affect the electromagnetic power of the units, and make the units in the distribution network continue to experience small disturbances. In the test, due to the different stability of small disturbances of various power sources, the network structure after distribution network reconstruction will have a positive or negative impact on the stability of small disturbances of the system. In the prior art, there is a distribution network reconfiguration method to ensure small disturbance and stability of distributed power sources, but all power sources are regarded as synchronous machines, and various types of power sources are not distinguished.

Invention content:

The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art, establish dynamic models for various types of power sources in the integrated energy system, and stably add small disturbances to the constraints of power distribution reconfiguration, so as to ensure that the integrated energy system meets the requirements of On the basis of small disturbance stability, a more economical operation considers a distribution network reconstruction method that considers the small disturbance stability of the integrated energy system.

The technical scheme of the present invention is: a distribution network reconfiguration method considering the small disturbance stability of the integrated energy system, establishing dynamic models for various types of power sources in the integrated energy system, and adding the small disturbance stability into the constraints of distribution reconfiguration , to ensure that the integrated energy system operates more economically on the basis of satisfying small disturbance and stability. The steps are: Step 1. Wind power based on doubly-fed wind power generation technology, photovoltaic power based on inverter power generation technology, and natural gas based on gas turbines. Taking the power supply as the object, establish their own small disturbance stability models respectively;

Step 2: Through coordinate transformation, the dq coordinate system of each model is converted into the common coordinate system DQ coordinate system for model integration;

Step 3: Calculate the operating state of each power supply under the initial network structure, and calculate the eigenvalue and eigenvector of the system under this condition, and linearize the small disturbance stability constraint;

Step 4: Taking the minimum network loss as the objective function, and introducing corresponding constraints, a reconstruction model considering small interference is established;

Step 5. Add the linearized small disturbance stability constraint into the reconstruction model to solve the distribution network reconstruction scheme;

Step 6: Calculate the operating state of each power supply under the reconstruction scheme, and recalculate the dominant eigenvalues of the system;

Step 7: Determine whether the dominant eigenvalue of the system satisfies the small disturbance stability constraint; if it is satisfied, output the reconstruction scheme; if not, take the reconstruction scheme as the initial condition, and return to step 3.

Further, in the first step, a small disturbance stability analysis model of the wind power source is established with the traditional system, the induction motor and the filter, and the linearization process is performed to obtain the state space expression of the wind power source:

In the formula, x _DFIG is the state quantity of the double-fed fan, u _DFIG is the control quantity of the double-fed fan, y _DFIG is the output of the double-fed fan, and A _DFIG is the state matrix of the double-fed fan, the elements of which are determined by the parameters of the fan. It is composed of the state quantity of the fan in this operating state.

Further, in the first step, a photovoltaic power supply small disturbance stability analysis model is established with the voltage controller, current controller, filter, capacitor, and circuit, and the linearization process is performed to obtain the state space expression of the photovoltaic power supply:

In the formula, x _pv is the photovoltaic state quantity, u _pv is the photovoltaic control quantity, y _pv is the photovoltaic output quantity, and A _pv is the photovoltaic state matrix, the elements of which are determined by the photovoltaic parameters and the photovoltaic state in this operating state. composed of quantity.

Further, in the first step, the synchronous generator is used as the link between the heating system and the natural gas system to connect the electrical system, the traditional third-order model is used as the natural gas power supply small disturbance stability analysis model, and the linearization process is performed to obtain the photovoltaic power station. The state space expression for :

In the formula, x _syn is the state quantity of the synchronous machine, u _syn is the control quantity of the synchronous machine, and A _syn is the state matrix of the synchronous machine, the elements of which are composed of the parameters of the synchronous machine and the state quantity of the synchronous machine in the running state. .

Further, in the second step, the current injected by the fan power source into the system is the sum of the stator current and the grid-side inverter outlet current; the current injected by the photovoltaic power source into the system is the filter outlet current; the natural gas power source is injected into the system. The current is the stator current;

According to the coordinate transformation formula, the respective dq coordinate systems are converted into the common coordinate system DQ coordinate system, and the coordinate transformation is as follows:

Among them, the DQ coordinate system represents the common coordinate system, the d _i q _i coordinate system represents the coordinate system of each power supply, and δ _i is the angle between the two coordinate systems;

According to the synchronous machine in natural gas power supply, the double-fed fan in wind power supply, the voltage and current increment of photovoltaic in photovoltaic power supply, the state space expression of combined wind power supply, the state space expression of photovoltaic power supply, and the state space expression of photovoltaic power station are combined The state space expression of the integrated energy system can be obtained:

In the formula, the state matrix A of the system consists of the network, doubly-fed wind turbines, photovoltaics, synchronous machines and their operating states.

Further, in the third step, the state space matrix A of the system can be obtained through the state space expression of the integrated energy system, and the oscillation mode of the system after small disturbance can be obtained by calculating the eigenvalues of the matrix A;

Taking the oscillation mode corresponding to the eigenvalue closest to the imaginary axis as the dominant oscillation mode, the eigenvalue is the dominant eigenvalue λ ₁ ; the constraint of the dominant eigenvalue is λ _ref , then the small disturbance stability constraint is:

λ ₁ ≤λ _ref (42)

According to the calculation formula of the eigenvalue:

|A-λE|=0 (43)

Linearize the small disturbance stability constraint.

Further, in the step 4, the objective function with the smallest network loss is:

The constraints include network radial constraints, power balance constraints, voltage constraints, branch power flow constraints and small disturbance stability constraints.

The beneficial effects of the present invention are:

1. The present invention mainly affects the influence of distribution network reconfiguration on various power sources in the system and the small disturbance stability of the entire system in a regional integrated energy system. By establishing dynamic models for various types of power sources in the integrated energy system, Small disturbance stability is added to the constraints of power distribution reconfiguration to ensure that the integrated energy system operates more economically on the basis of satisfying small disturbance stability.

2. In the present invention, the small disturbance stability constraint is added to the constraints of distribution network reconstruction, and the output of wind power and photovoltaics is set in the most unstable situation of the system operation, so that the result of the distribution network reconstruction can ensure the small disturbance of the system. On a stable basis, it operates more economically.

Description of drawings:

Figure 1 is a schematic diagram of the structure of a double-fed fan.

Figure 2 is a schematic diagram of the structure of a photovoltaic power station.

Figure 3 is a schematic diagram of a voltage and current controller.

Figure 4 shows the transformation of the coordinate system.

Figure 5 shows the power characteristics of the generator set.

Detailed ways:

Example: see Figure 1, Figure 2, Figure 3, Figure 4 and Figure 5; in Figure 1, 1-blade, 2-gearbox, 3-drive system, 4-induction motor, 5-converter, 6- Filter inductor, 7-transformer and line, 8-large power grid.

Considering the distribution network reconfiguration method with small disturbance and stability of the integrated energy system, a dynamic model is established for various types of power sources in the integrated energy system, and the small disturbance stability is added to the constraints of distribution reconfiguration to ensure that the integrated energy system meets the requirements of small disturbances. On a stable basis, it operates more economically.

Example: According to different utilization scenarios, the integrated energy system is divided into inter-regional level, regional level and user level. The embodiment of the present application adopts a regional comprehensive energy system composed of a power distribution system, a natural gas system, and a heating/cooling system. Among them, the power distribution system includes renewable energy based on doubly-fed wind power generation technology and photovoltaic inverter power generation technology, and the natural gas system and heating system are coupled to the power distribution system through gas turbines and cogeneration units, respectively. The steps are as follows: Step 1. Take the wind power source based on the doubly-fed wind power generation technology, the photovoltaic power source based on the inverter power generation technology, and the natural gas power source based on the gas turbine as objects, and establish their respective small disturbance stability models;

Step 2: Through coordinate transformation, the dq coordinate system of each model is converted into the common coordinate system DQ coordinate system for model integration;

Step 3: Calculate the operating state of each power supply under the initial network structure, and calculate the eigenvalue and eigenvector of the system under this condition, and linearize the small disturbance stability constraint;

Step 4: Taking the minimum network loss as the objective function, and introducing corresponding constraints, a reconstruction model considering small interference is established;

Step 5. Add the linearized small disturbance stability constraint into the reconstruction model to solve the distribution network reconstruction scheme;

Step 6: Calculate the operating state of each power supply under the reconstruction scheme, and recalculate the dominant eigenvalues of the system;

Step 7: Determine whether the dominant eigenvalue of the system satisfies the small disturbance stability constraint; if it is satisfied, output the reconstruction scheme; if not, take the reconstruction scheme as the initial condition, and return to step 3.

The process of establishing the small disturbance stability analysis model of wind power supply is as follows:

Due to its flexible control method and low operating cost, the double-fed fan is widely used in various wind farms, and its structure is shown in Figure 1. The double-fed fan is composed of a transmission system, an induction motor, a converter, and a filter inductance, and is connected to a large power grid through a transformer and a line. The dynamic process of the doubly-fed fan is complex, the time scale difference is obvious, the time scale of the converter is small, and the time scale of the transmission system is relatively large. Ignoring the dynamic process of the converter and its controller in the DFIG, a small disturbance stability analysis model including the traditional system, the induction motor and the filter is established.

The transmission system adopts a single-mass model, and the dynamic equation is as follows:

In the formula, ω _r is the rotor speed, T _m and T _e are the driving torque and electromagnetic torque, respectively, and H _g is the moment of inertia.

The induction motor adopts the induction generator model and introduces transient potential. The dynamic equation is as follows:

In the formula, i _ds , i _qs are the stator currents, i _dr , i _qr are the rotor currents, v' _d , v' _q are the transient voltages of the induction motor, v _dr , v _qr are the rotor voltages, L _ss , L _rr are respectively are the stator and rotor reactances, ω _s , ω _B are the per-unit value and reference value of the synchronous speed, respectively, X _s , X _s ' are the stator reactance and transient reactance, respectively, R _s is the stator resistance, L _m , L _rr , L _ss are the excitation inductance, rotor inductance and stator inductance, respectively.

Inverter outlet filter model:

In the formula, i _dg , i _qg are the filter current, R _g , L _g are the filter resistance and inductance respectively, v _ds , v _qs are the stator voltage.

The DFIG eventually injects the stator current and the inverter current into the grid. By linearizing equations (1)-(7) near the equilibrium point, the state space expression of the doubly-fed fan in a certain operating state can be obtained:

In the formula, x _DFIG is the state quantity of the double-fed fan, u _DFIG is the control quantity of the double-fed fan, y _DFIG is the output of the double-fed fan, and A _DFIG is the state matrix of the double-fed fan, the elements of which are determined by the parameters of the fan. It is composed of the state quantity of the fan in this operating state.

The establishment process of the small disturbance stability analysis model of photovoltaic power supply is as follows:

Compared with DFIGs, inverter-based PV power plants have smaller time constants and faster dynamic process changes, so the dynamic process of their controllers should also be taken into account. In this application, the photovoltaic power station is regarded as a constant voltage source, which is connected to a large power grid through a line. The schematic diagram of the structure is shown in FIG. 2 , and the schematic diagram of the controller is shown in FIG. 3 . In the figure, L _f and C _f are the filter inductance and capacitance, respectively, L _c is the line inductance, and v _b is the large power grid. Voltage controller: its input value is filter outlet voltage v _od , v _oq , current i _od , i _oq , its output value is As the target value of the current controller, the dynamic equation is as follows:

In the formula, x _vd , x _vq are the state variables of the voltage controller.

Current controller: receive the target value given by the voltage controller and the inverter outlet current i _ld , i _lq , and output the control voltage value of the inverter The dynamic equation is as follows:

Filters, capacitors, circuit models are as follows:

In the formula, ω is the grid frequency, v _id , v _iq are the output voltage of the inverter.

The photovoltaic power station finally injects the current output by the filter into the system, so its output is the filter outlet current. By linearizing equations (9)-(20), the state space expression of the photovoltaic power station in a certain operating state can be obtained:

In the formula, x _pv is the photovoltaic state quantity, u _pv is the photovoltaic control quantity, y _pv is the photovoltaic output quantity, and A _pv is the photovoltaic state matrix, the elements of which are determined by the photovoltaic parameters and the photovoltaic state in this operating state. composed of quantity.

The establishment process of the small disturbance stability analysis model of natural gas power supply is as follows:

In the integrated energy system, the synchronous generator acts as the link between the heating system and the natural gas system to connect the electrical system. The synchronous machine adopts the traditional third-order model as follows:

U _d =X _q I _q (22)

U _q =E' _q -X' _d I _d (23)

pδ=ω-1 (24)

In the formula, δ is the phase angle difference, ω is the rotor speed, T _J is the moment of inertia, T _m , T _e are the mechanical torque and electromagnetic torque, respectively, E _f , E' _q are the excitation voltage, the motor q-axis temporary State potential, X _d , X' _d are the d-axis reactance and transient reactance, respectively, id is the _d -axis stator current, and T' _d0 is the d-axis open-circuit transient time constant.

By linearizing equations (22)-(24), the state space expression of the photovoltaic power station in a certain operating state can be obtained:

In the formula, x _syn is the state quantity of the synchronous machine, u _syn is the control quantity of the synchronous machine, and A _syn is the state matrix of the synchronous machine, the elements of which are composed of the parameters of the synchronous machine and the state quantity of the synchronous machine in the running state. .

Through coordinate transformation, the dq coordinate system of each model is converted into the common coordinate system DQ coordinate system for model integration. The specific process is as follows:

The current injected by the DFIG into the system is the sum of the stator current and the output current of the grid-side inverter, namely ( _{ids + idg )} +j(i _qs +i _qg ); the current injected by the photovoltaic power station into the system is the filter The outlet current of the generator is i _od +ji _oq ; the current injected by the synchronous machine into the system is the stator current, i.e. i _d +ji _q . It is worth noting that the above models are all established in a single-machine infinite system, and these injected currents are all established in their respective dq coordinate systems. If you want to study the dynamic characteristics of the entire system, you need to perform coordinate transformation, and convert the respective dq coordinate systems into the common coordinate system DQ coordinate system. The coordinate transformation is as follows:

Among them, the DQ coordinate system represents the common coordinate system, the d _i qi coordinate system represents the coordinate system of each power supply _{, and δ i is} the angle between the two coordinate systems.

For photovoltaic power plants, there is no rotating rotor, so there is no torque balance equation; for synchronous machines and doubly-fed fans, if the internal resistance of the stator winding is ignored, the electromagnetic power increment of the unit can be obtained as:

ΔP _e =U _x0 ΔI _x +U _y0 ΔI _y +I _x0 ΔU _x +I _y0 ΔU _y (29)

In the formula, ΔI _x , ΔI _y are the current increments injected by the unit into the network, and ΔU _x , ΔU _y are the voltage increments at the grid connection point. Next, calculate the voltage and current increments of the synchronous machine, the doubly-fed fan, and the photovoltaic respectively. For a synchronous machine, from equations (22), (23) and (28), we can get

For doubly-fed fans, from equations (8) and (28), we can get

For photovoltaics, from equations (21) and (28), we can get

At the same time, eliminate the network equation The contact nodes in , and substitute into equations (30)-(32) to get,

Putting equations (30)-(33) into equation (29), the incremental expression of electromagnetic torque can be obtained, and combining equations (8), (21), (27), the state space expression of the integrated energy system can be obtained Mode:

In the formula, the state matrix A of the system consists of network, DFIG, photovoltaic, synchronous machine and their operating states, and the model is relatively complex.

Taking the minimum network loss as the objective function and introducing corresponding constraints, a reconstruction model considering small interference is established. The establishment process is as follows:

Distribution network reconstruction generally takes reducing network loss and improving network voltage level as the objective function. Constraints include power flow constraints, network radial constraints, branch power flow constraints, and active and reactive power output constraints. After the network structure is changed, the stability of small disturbances in the operation of various power sources will inevitably be affected to varying degrees. If the distribution network reconstruction only considers economics, it is very likely that some power sources cannot run stably, resulting in disconnection from the grid. In addition, the output of wind power and photovoltaics is random, and the uncertainty of their output will inevitably lead to changes in the power flow and node voltage in the system, which will affect the electromagnetic power of the units, and make the units in the distribution network continue to experience small disturbances. test.

The distribution network reconfiguration should ensure the stability of the small disturbance of the system operation before the next reconfiguration. In view of the uncertainty of wind power and photovoltaic output, it is necessary to ensure that it is still stable with small disturbances in the worst case. For wind turbines and synchronous machines, the power characteristics of a simple power system can be used to analyze the most unstable scenario, as shown in Figure 5.

Among them, P _m is the mechanical power, and _Pe is the electromagnetic power. There are two intersection points a and b between the two curves. When the unit is running at point a, it can be stabilized after a small disturbance; conversely, when the unit is running at point b , is unstable after a small disturbance. Therefore, when the mechanical power of the unit increases and the electromagnetic power decreases, the operating state of the unit is very easy to transition from point a to point b, that is, from stable with small disturbance to unstable with small disturbance. Therefore, the most unstable scenario in the system occurs when the output of the unit is large, but the electromagnetic torque of the network is small.

This application proposes to add the small-interference stability constraint to the constraints of distribution network reconstruction, and set the output of wind power and photovoltaics in the most unstable scenario of the system, so that the results of the distribution network reconstruction can ensure the stability of the system with small interference. On the basis of more economical operation. Modeled as follows:

1) Take the minimum network loss as the objective function:

2) The constraints are:

network radial constraints

Power Balance Constraints

Voltage constraints

V _kmin ≤V _k ≤V _kmax (39)

Branch flow constraints:

P _{ijmin ≤P ij} ×s _{ij ≤P ijmax} (40)

Q _{ijmin ≤Q ij} ×s _{ij ≤Q ijmax} (41)

Small disturbance stability constraint: The state space matrix A of the system can be obtained through the state space expression (34) of the integrated energy system, and the eigenvalues of the matrix A can be calculated to obtain the oscillation mode of the system after small disturbances. Among them, the oscillation mode corresponding to the eigenvalue closest to the imaginary axis has the smallest stability margin and the slowest decay, so this oscillation mode is called the dominant oscillation mode, and the eigenvalue is also called the dominant eigenvalue. is λ ₁ . In order to ensure the stability of the system with small disturbances, it is necessary to constrain the dominant eigenvalue of the system, which is set as λ _ref , then the small disturbance stability constraint is:

λ ₁ ≤λ _ref (42)

In the above model, how to linearize the small disturbance stability constraint becomes a very challenging task. According to the calculation formula of the eigenvalue

|A-λE|=0 (43)

It can be seen that the eigenvalues are obtained by solving the one-dimensional high-order equation, and it is difficult to directly obtain the analytical expressions of the eigenvalues, and only the numerical solutions can be obtained. In addition, the one-dimensional higher-order equation is a highly nonlinear equation and includes the operating state of the system, and the solution of the equation will change nonlinearly with the change of the operating state of the system.

Based on the above reasons, the present application proposes a solution method for small-interference stability verification, which aims to provide a fast solution method that considers the small-interference stable distribution network reconstruction, and cannot guarantee that the method will eventually converge to the global optimal solution.

(1) Calculate the operating state of each power supply under the initial network structure, and calculate the eigenvalue and eigenvector of the system under this condition, and linearize the small disturbance stability constraint accordingly;

(2) Add the linearized small disturbance stability constraint into the model to solve the distribution network reconstruction scheme;

(3) Calculate the operating state of each power supply under the reconstruction scheme, and recalculate the dominant eigenvalues of the system;

(4) Determine whether the dominant eigenvalues of the system satisfy the small disturbance stability constraint. If satisfied, output the reconstruction scheme, if not, take the reconstruction scheme as the initial condition, and return to step (1) to recalculate.

Although the scheme always uses the initial state to calculate in the iterative process, the small disturbance stability is verified after the reconstruction, which can ensure that the calculated result conforms to the small disturbance stability constraint.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to within the scope of the technical solution of the present invention.

Claims (7)

1. A distribution network reconfiguration method that considers the small disturbance and stability of the integrated energy system, establishes dynamic models for various types of power sources in the integrated energy system, and adds the stability of small disturbances to the constraints of distribution reconfiguration to ensure the integrated energy system. On the basis of satisfying the stability of small disturbance, the operation is more economical. The steps are: Step 1. Take wind power based on doubly-fed wind power technology, photovoltaic power based on inverter power generation technology, and natural gas power based on gas turbine as objects, respectively. Establish their respective small disturbance stabilization models; Step 2: Through coordinate transformation, the dq coordinate system of each model is converted into the common coordinate system DQ coordinate system for model integration; Step 3: Calculate the operating state of each power supply under the initial network structure, and calculate the eigenvalue and eigenvector of the system under this condition, and linearize the small disturbance stability constraint; Step 4: Taking the minimum network loss as the objective function, and introducing corresponding constraints, a reconstruction model considering small interference is established; Step 5. Add the linearized small disturbance stability constraint into the reconstruction model to solve the distribution network reconstruction scheme; Step 6: Calculate the operating state of each power supply under the reconstruction scheme, and recalculate the dominant eigenvalues of the system; Step 7: Determine whether the dominant eigenvalue of the system satisfies the small disturbance stability constraint; if it is satisfied, output the reconstruction scheme; if not, take the reconstruction scheme as the initial condition, and return to step 3. 2. The distribution network reconstruction method considering the small disturbance stability of the integrated energy system according to claim 1, characterized in that: in the step 1, a wind power source small disturbance stability analysis model is established with a traditional system, an induction motor and a filter , and perform linearization processing, the state space expression of wind power source can be obtained: In the formula, x _DFIG is the state quantity of the double-fed fan, u _DFIG is the control quantity of the double-fed fan, y _DFIG is the output of the double-fed fan, and A _DFIG is the state matrix of the double-fed fan, the elements of which are determined by the parameters of the fan. It is composed of the state quantity of the fan in this operating state. 3. The distribution network reconstruction method considering the small disturbance and stability of the integrated energy system according to claim 1, characterized in that: in the step 1, a photovoltaic controller is established with a voltage controller, a current controller, a filter, a capacitor, and a circuit. The stability analysis model of the power supply with small disturbance is linearized, and the state space expression of the photovoltaic power supply can be obtained: In the formula, x _pv is the photovoltaic state quantity, u _pv is the photovoltaic control quantity, y _pv is the photovoltaic output quantity, and A _pv is the photovoltaic state matrix, the elements of which are determined by the photovoltaic parameters and the photovoltaic state in this operating state. composed of quantity. 4. The distribution network reconfiguration method considering the small disturbance and stability of the integrated energy system according to claim 1, is characterized in that: in the step 1, the synchronous generator is used as the link between the heating system and the natural gas system to connect the electrical system, to The traditional third-order model is used as the small disturbance stability analysis model of natural gas power supply, and after linearization, the state space expression of the photovoltaic power station can be obtained: In the formula, x _syn is the state quantity of the synchronous machine, u _syn is the control quantity of the synchronous machine, and A _syn is the state matrix of the synchronous machine, the elements of which are composed of the parameters of the synchronous machine and the state quantity of the synchronous machine in the running state. . 5. The distribution network reconfiguration method considering the small disturbance and stability of the integrated energy system according to claim 1, wherein in the second step, the current injected by the fan power supply into the system is the stator current and the grid-side inverter. The sum of the outlet currents; the current injected by the photovoltaic power supply into the system is the filter outlet current; the current injected by the natural gas power supply into the system is the stator current; According to the coordinate transformation formula, the respective dq coordinate systems are converted into the common coordinate system DQ coordinate system, and the coordinate transformation is as follows: Among them, the DQ coordinate system represents the common coordinate system, the d _i q _i coordinate system represents the coordinate system of each power supply, and δ _i is the angle between the two coordinate systems; According to the synchronous machine in natural gas power supply, the double-fed fan in wind power supply, and the photovoltaic voltage and current increment in photovoltaic power supply, the state space expression of combined wind power supply, the state space expression of photovoltaic power supply, and the state space expression of photovoltaic power station are combined. The state space expression of the integrated energy system can be obtained: In the formula, the state matrix A of the system consists of the network, doubly-fed wind turbines, photovoltaics, synchronous machines and their operating states. 6. The distribution network reconstruction method considering the small disturbance and stability of the integrated energy system according to claim 1, wherein in the step 3, the state space matrix of the system can be obtained through the state space expression of the integrated energy system A, the eigenvalues of matrix A can be calculated to obtain the oscillation mode of the system after small disturbance; Taking the oscillation mode corresponding to the eigenvalue closest to the imaginary axis as the dominant oscillation mode, the eigenvalue is the dominant eigenvalue λ ₁ ; the constraint of the dominant eigenvalue is λ _ref , then the small disturbance stability constraint is: λ ₁ ≤λ _ref (42) According to the calculation formula of the eigenvalue: |A-λE|=0 (43) Linearize the small disturbance stability constraint. 7. The distribution network reconfiguration method considering the small disturbance and stability of the integrated energy system according to claim 1, is characterized in that: in the step 4, the objective function with the smallest network loss is: The constraints include network radial constraints, power balance constraints, voltage constraints, branch power flow constraints and small disturbance stability constraints.