CN107332273A - A kind of extensive new energy access power grid cascading trouble-saving control device and method - Google Patents

Abstract

The invention discloses a control device for preventing large-scale new energy accessing grid cascading faults, which consists of a battery energy storage unit, a normally open relay, a normally closed relay, a step-down chopper circuit, a boost chopper circuit, a terminal capacitor, Converters and power smoothers are connected, and the devices exist in every transmission line connected to new energy. The invention also discloses a control method for preventing large-scale new energy access to the power grid cascading failure control device, which uses an intelligent PI controller to adjust the output of wind turbines transmitted to each transmission line in a closed loop, so that the load rate of high-risk lines is effectively reduced. At the same time, ensure that the load rate of other lines remains below the overload threshold, improve the power flow distribution, and prevent cascading failures.

Description

A large-scale new energy access grid cascading failure prevention control device and method

technical field

The invention belongs to the technical field of power system operation control, and in particular relates to a large-scale new energy access grid cascading failure prevention control device and method.

Background technique

With the deepening of grid interconnection and the access of large-scale new energy sources, while achieving greater economic benefits, the overall security of the grid has been seriously affected. The randomness and volatility of large-scale new energy may play a role in fueling some failures of local power grids, thereby inducing cascading failures, leading to large-scale power outages and even the collapse of the power grid. Therefore, how to prevent the occurrence of cascading failures has become a research topic that is widely concerned by scholars at home and abroad.

However, most of the current research on the prevention and control strategies of cascading failures is based on traditional power grids (excluding new energy sources). However, in recent years, with the increasing pressure of energy conservation, emission reduction and climate change, countries have begun to focus on the development of new energy sources, among which wind power is particularly popular. Due to the volatility and randomness of new energy, the mechanism of its impact on cascading failures is still unclear. It is of great practical significance to study the cascading failure prevention and control methods for complex power grids based on large-scale new energy access.

During the development of cascading failures, the change of power flow distribution is the key factor. It is the failure of a certain component that causes the power flow to shift in a large range, causing the power flow of other components to change, and the power flow distribution changes accordingly. If the power flow of the component increases to its operating area, it will cause these components to trip successively. Studies have shown that the risk of cascading failures in power grids with uniform power distribution is much lower than that of power grids with uneven power distribution. When the system is running in a steady state, the output of the conventional power supply can basically remain constant, and will not cause large-scale power fluctuations, which in turn will cause large-scale fluctuations in power flow entropy. However, large-scale wind power output may be at any value between zero output and maximum output, and a large-scale output change will inevitably bring about a large change in power flow entropy.

Before the centralized access of large-scale wind power, the load rate of the lines is concentrated in certain load rate ranges, and there are very few lines in the high load rate range and low load rate range. After the centralized access of large-scale wind power, due to the randomness and volatility of wind power, if the output of wind power increases instantaneously, the power flow near the access point will be heavy, and the load rate of the surrounding lines will increase rapidly. In order to keep the average load rate unchanged, hydropower The output of conventional power sources such as thermal power and thermal power will decrease accordingly, and the load rate of adjacent lines will decrease; similarly, if the output of wind power decreases instantaneously, the load rate of lines around the access point will decrease rapidly, and the output of other conventional power plants will decrease. Correspondingly, the load rate of adjacent lines increases. That is to say, wind power fluctuations greatly increase the number of lines in the high load rate range and low load rate range, and the power flow distribution becomes very uneven. The larger the wind power scale, the more obvious the trend of uneven power flow distribution. That is, the large-scale centralized connection of wind power to the power grid may increase the power flow entropy of the power grid, and then the risk of cascading failures will increase.

To sum up, it is particularly important to propose a device and method for improving power flow distribution, suppressing the cascading overload effect of power grids containing new energy, and ensuring uniform distribution of power flow under the background of large-scale new energy access.

Contents of the invention

The purpose of the present invention is to solve the problem of uneven power flow distribution in the power grid under the background of large-scale wind power centralized access, and to provide a power grid cascading failure prevention and control device and method under the background of large-scale new energy access. The output of each transmission line can effectively reduce the load rate of high-risk lines, and at the same time ensure that the load rate of other lines remains below the heavy load threshold, improve the power flow distribution, and prevent cascading failures.

In order to achieve the above purpose, the technical scheme adopted by the present invention to prevent large-scale new energy from connecting to the grid cascading failure control device is:

A large-scale new energy access grid cascading failure prevention control device, including multiple new energy transmission lines

Road control device and several independent new energy transmission lines,

Each new energy transmission line control device includes a battery energy storage unit, a normally open relay, a normally closed relay, a buck chopper circuit, a boost chopper circuit, a terminal capacitor, a converter, and a power smoother; wherein, the The output positive pole of the battery energy storage unit is divided into two branches, the first branch includes the first normally open relay, the first normally closed relay and the step-down chopper circuit connected in sequence; the second branch includes the second normally open relay connected in sequence , the second normally closed relay and the step-up chopper circuit, after the two circuits are connected in parallel, the output is connected to the terminal capacitor; the output of the terminal capacitor is connected to the converter, the first normally open relay, the first normally closed relay, the second normally open relay, the second A normally closed relay constitutes an interlocking device; the converter is formed by connecting three pairs of IGBT bridge arms in turn, and the input of the converter is connected to a power smoother;

Each new energy transmission line control device is connected to each independent new energy transmission line, and connected to the output end of the new energy transmission line.

Further, the step-down chopper circuit is used to reduce the voltage value of the terminal capacitor, so that the wind power line charges the battery energy storage unit and reduces the load rate of the wind power line.

Further, the step-up chopper circuit is used to increase the voltage value of the terminal capacitor, so that the battery energy storage unit discharges to the wind power line and increases the load rate of the wind power line.

Further, the power smoother is used to connect to the end of the wind turbine to smooth the power input from the wind turbine to the battery energy storage unit.

In addition, the present invention provides a control method for the above-mentioned large-scale new energy access grid cascading failure prevention control device, including the following steps:

(1) The plurality of independent new energy wind power transmission lines are respectively set as line 1, line 2 to line N, and the N is an integer greater than 2. When a certain new energy wind power transmission line plus a traditional generator set is output to When the power of the grid is greater than the average value of the entire N new energy wind power transmission lines output to the grid, the first normally open relay of the first branch of the new energy transmission line control device in the certain new energy wind power transmission line is closed , the first normally closed relay is in the closed state, the step-down chopper circuit is turned on, and the step-up chopper circuit is turned off; the switching tube of the step-down chopper circuit is controlled by PWM to reduce the energy storage of the output terminal capacitor value, so that the voltage value at both ends of the terminal capacitor is less than the output voltage value of the transmission line, and the new energy wind power transmission line charges the battery energy storage unit until the power output from the new energy wind power transmission line to the grid is dynamically equal to the output power of the entire N lines. balanced; in this case the converter in the line installation acts as a three-phase bridge rectifier;

Similarly, when the output power of any new energy wind power transmission line is greater than the average value of the entire N new energy wind power transmission lines output to the grid, the system will repeat the above process, so that the wind power transmission line charges the battery energy storage unit, reducing the transmission load rate of the line.

(2) When the output power of a new energy wind power transmission line plus traditional generator sets to the grid is less than the average value of the entire N lines output to the grid, the new energy transmission line control device in this certain new energy wind power line has The second normally open relay of the second branch is closed, the second normally closed relay is in the closed state, the step-up chopper circuit is turned on, and the step-down chopper circuit is turned off; the switch of the step-up chopper circuit is controlled by PWM The tube is turned on and off to increase the energy storage value of the output terminal capacitor, so that the voltage value at both ends of the terminal capacitor is greater than the output voltage value of the transmission line, and the battery energy storage unit discharges to the new energy wind power transmission line until the new energy wind power transmission line The power output to the grid is dynamically balanced with the output power of the entire N lines; at this time, the converter in the line device acts as a three-phase bridge inverter;

Similarly, when the output power of any wind power transmission line is lower than the average output power of the entire line, the system repeats the above process to make the battery energy storage unit discharge to the transmission line and increase the load rate of the transmission line.

In steps (1) and (2), in the new energy wind power transmission line, the PWM that controls the switching tubes of the step-down chopper circuit and the boost chopper circuit comes from a closed-loop output; specifically, the new energy wind power transmission line The difference between the output power of the line plus the traditional generator set and the average power of the entire N lines output to the grid is sent to an intelligent PI controller for correlation calculation and processing, and the output of the intelligent PI controller is converted into the corresponding PWM Control the on-off of the step-down chopper circuit and the step-up chopper circuit switch tube in the new energy wind power transmission line, and then control the charging of the new energy wind power transmission line to the battery energy storage unit and the discharge of the battery energy storage unit to the transmission line Finally, the power output from the new energy wind power transmission line plus the traditional generator set to the grid and the average power output from the entire N lines to the grid are dynamically balanced, maintaining the uniformity of the power flow distribution of the new energy wind power transmission line.

Further, the power output from the new energy wind power transmission line plus the traditional generating set to the grid is the sum of the output power of the wind generating set, the input/output power of the energy storage system and the output power of the traditional generating set.

Further, the PI limiting output value becomes a step-like decline with the power deviation; when the output power of the selected line deviates too much from the average output power of the N lines, the parameters of the P regulator remain unchanged; when the power deviation is small enough , the parameters of the P regulator gradually become smaller; when the deviation between the output power of the selected line and the average output power of the N lines is less than a certain degree, the parameters of the P regulator are set to 0.

Further, in step (1), the new energy wind power transmission line charges the battery energy storage unit, and when the fluctuation rate of the output power of the new energy wind power transmission line within 1 minute is greater than 10%, the power smoother is called to adjust the output power of the wind turbine Smoothing processing is performed to prevent large fluctuations from causing damage to the battery energy storage unit and affecting the power flow entropy of the grid system; the converter adopts a double closed-loop control based on the grid voltage vector orientation theory; the voltage control strategy adopts the voltage outer loop, current The inner loop structure, in which the direction of the current is chosen as the direction of the network voltage space vector; the current inner loop is designed under the voltage synchronous rotating coordinate system, and each AC component is converted into a DC flow, which is convenient for the design of the closed-loop regulator, and can be easily integrated with SPWM or SVPWM interface.

Compared with the prior art, the advantages and beneficial effects of the technical solution of the present invention are mainly:

1. The large-scale new energy access grid cascading failure prevention control device adopted in the present invention has simple structure, low cost, strong practicability, and convenient control. The step-down chopper circuit and the boost chopper circuit are used together to make the battery energy storage The unit is in a reasonable charge and discharge state, which can not only make the best use of fluctuating and intermittent wind power resources, but also maintain the dynamic balance of the power flow distribution of new energy wind power transmission lines, which is of great significance for preventing cascading failures of the power grid. At the same time, a power smoother is introduced at the wind power input port to effectively avoid the damage caused by the wind power output fluctuation to the battery energy storage unit and the impact on the power flow entropy of the power grid system.

2. The large-scale new energy access grid cascading fault prevention and control method of the present invention uses an intelligent PI controller to close-loop adjust the output of wind turbines transmitted to each transmission line, so that the load rate of high-risk lines can be effectively reduced, while ensuring other lines The load rate is maintained below the overload threshold, which improves the power flow distribution and prevents cascading failures.

Description of drawings

Figure 1 is a schematic structural diagram of a large-scale new energy access grid cascading failure prevention and control device according to a specific embodiment of the present invention;

Fig. 2 is a block diagram of prevention and control of large-scale new energy access grid cascading failures according to a specific embodiment of the present invention;

Fig. 3 is the schematic diagram of intelligent PI variable limiter;

Fig. 4 is the schematic diagram of intelligent PI variable P parameter;

Fig. 5 is a schematic diagram of converter control of the energy storage system of the device according to a specific embodiment of the present invention.

detailed description

A large-scale new energy access grid cascading failure prevention control device and method of the present invention will be further described in detail below in conjunction with accompanying drawings 1 to 5.

Figure 1 is a schematic structural diagram of a large-scale new energy access grid cascading failure prevention and control device in this embodiment. In this embodiment, the new energy is provided by wind turbines. As shown in Figure 1, the device system is divided into lines 1. There are N parts from line 2 to line N, where N is an integer greater than 2. The device of line 1 includes battery energy storage unit 1, first normally open relay KM11, first normally closed relay KM12, and second normally open relay KM13. And the second normally closed relay KM14, the step-down chopper composed of the switch tube IGBT11, the inductor Lf11 and the diode D11, the step-up chopper composed of the switch tube IGBT12, the inductor Lf12 and the diode D12, and the large-capacity energy storage terminal capacitor C1, a converter and a power smoother 1 composed of IGBT13-IGBT18. Wherein, the positive output of the battery energy storage unit 1 is divided into two branches for transmission, one branch is composed of the first normally open relay KM11, the first normally closed relay KM12 and the step-down chopper in turn; the other branch is routed by the second normally The open relay KM13, the second normally closed relay KM14 and the step-up chopper are composed of two circuits in parallel, the output connection terminal capacitor C1, the first normally open relay KM11, the first normally closed relay KM12, the second normally open relay KM13 and the second Two normally closed relays KM14 constitute a two-way interlocking device. The converter is formed by connecting three pairs of IGBT bridge arms in turn, and the input is connected to the power smoother 1 .

The line 2 device sequentially includes a battery energy storage unit 2, a third normally open relay KM21, a third normally closed relay KM22, a fourth normally open relay KM23 and a fourth normally closed relay KM24, a switching tube IGBT21, an inductor Lf21 and a diode D21. Step-down chopper, step-up chopper composed of switching tube IGBT22, inductor Lf22 and diode D22, large-capacity energy storage terminal capacitor C2, converter and power smoother 2 composed of IGBT23-IGBT28. Wherein, the positive output of the battery energy storage unit 2 is divided into two branches for transmission, and one branch is composed of the third normally open relay KM21, the third normally closed relay KM22 and the step-down chopper in turn; the other route is the fourth normally open The relay KM23, the fourth normally closed relay KM24 and the step-up chopper are composed of two circuits connected in parallel, the output connection terminal capacitor C2, the third normally open relay KM21, the third normally closed relay KM22, the fourth normally open relay KM23 and the fourth The normally closed relay KM24 constitutes a two-way interlocking device. The converter is formed by connecting three pairs of IGBT bridge arms in turn, and the input is connected to the power smoother 2 .

The line N device sequentially includes a battery energy storage unit N, a first normally open relay KMn1, a first normally closed relay KMn2, a second normally open relay KMn3 and a second normally closed relay KMn4, a switching tube IGBTn1, an inductor Lfn1 and a diode Dn1. step-down chopper, a step-up chopper composed of switching tube IGBTn2, inductor Lfn2 and diode Dn2, a large-capacity energy storage terminal capacitor Cn, a converter composed of IGBTn3-IGBTn8 and a power smoother N. Wherein, the positive output of the battery energy storage unit N is divided into two branches for transmission, one branch is composed of the first normally open relay KMn1, the first normally closed relay KMn2 and the step-down chopper in turn; the other branch is routed by the second normally The open relay KMn3, the second normally closed relay KMn4 and the step-up chopper are composed of two circuits in parallel, the output connection terminal capacitor Cn, the first normally open relay KMn1, the first normally closed relay KMn2, the second normally open relay KMn3 and the second Two normally closed relays KMn4 form two-way interlocking devices, and the converter is formed by connecting three pairs of IGBT bridge arms in turn, and the input is connected to the power smoother N.

The large-scale new energy access grid cascading fault prevention control method in this embodiment uses an intelligent PI controller to adjust the output of wind turbines transmitted to each transmission line in a closed-loop manner, so that the load rate of high-risk lines can be effectively reduced, and at the same time, the load of other lines can be guaranteed. The load rate is maintained below the heavy load threshold, the power flow distribution is improved, and the power flow distribution is maintained evenly, which plays a role in preventing cascading failures. The following is combined with Figure 1 to Figure 5 to compare the wind power transmission line of the line N plus the output power of the traditional generator set to the grid The large-scale new energy of the present invention is described in two situations that are greater than the average value of the entire N lines output to the grid and the line N wind power transmission line plus the traditional generating set output power to the grid is less than the average value of the entire N lines output to the grid A method for preventing and controlling cascading faults connected to the power grid. The specific control method is as follows:

1. The power output from the line N wind power transmission lines plus the traditional generator set to the grid is greater than the average value of the entire N lines output to the grid. The control method includes the following steps:

(1) When the sum PoutN of wind power transmission line (PwindN) of line N plus traditional generator set (PinN) output to the grid is greater than the average value Pavg of the entire N lines output to the grid, the first branch of the line N device The first normally open relay KMn1 is closed, the first normally closed relay KMn2 is still in the closed state, the step-down chopper circuit is turned on, and the step-up chopper circuit is turned off. The switch tube of the step-down chopper circuit is controlled by PWMn1 to reduce the energy storage value Vdcn of the output terminal capacitor Cn, so that the voltage value Vdcn at both ends of the terminal capacitor Cn is smaller than the output voltage value of the wind turbine, and the wind turbine on the transmission line N is sent to the battery storage. Energy unit N is charged. The converter in the Line N device now acts as a three-phase bridge rectifier.

(2) Further, in step (1), the PWMn1 in the line N device that controls the on-off of the switching tube of the step-down chopper circuit comes from a closed-loop output. Specifically, the power sum PoutN of the line N wind power transmission line (PwindN) plus the traditional generator set (PinN) output to the grid and the average value Pavg of the entire N lines output to the grid are sent to an intelligent PIN controller for correlation Calculation and processing, the output of the intelligent PIN controller is transformed into a corresponding PWM wave to control the on-off of the step-down chopper circuit switch tube in the line N device, and then control the line N wind power transmission line to charge the battery energy storage unit N (PbessN) Finally, the sum of the power output from the line N to the grid PoutN and the average value Pavg of the entire N lines output to the grid can reach a dynamic balance, maintaining the uniformity of the power flow distribution of the transmission line.

(3) Further, in step (2), the intelligent PIN controller combines two methods, which can not only maintain the uniformity of the power flow distribution of each transmission line, but also prevent the output power sum PoutN of the line from being output by the N lines If the deviation from the average value Pavg of the grid power is too large, the battery energy storage unit will be overcharged and discharged, and the service life of the battery energy storage unit N will be reduced. Specifically, the PI limiting output value becomes a step-like decline with the power deviation, the adjustment is relatively simple, and the speed response is fast, as shown in Figure 3; in addition, when the power deviation is too large (area 1 and area 5), P The regulator parameters remain unchanged; when the power deviation is small enough (2 regions and 4 regions), the parameters of the P regulator gradually become smaller; when the deviation is less than a certain degree (3 regions), the parameters of the P regulator are set to 0, such as Figure 4 shows. In this way, the convergence accuracy can be ensured while the maximum convergence speed is adopted. This method has a fast response speed and small overshoot, and effectively avoids the up and down vibration phenomenon when the total output power of the line is dynamically balanced.

(4) Further, in step (1), the wind power transmission line of the line N charges the battery energy storage unit N, and when the fluctuation rate of the output power PwindN of the wind turbine unit is greater than 10% within 1 minute, the system promptly calls the power smoother N to The output power PwindN of the wind turbine N is smoothed to prevent large fluctuations from causing damage to the battery energy storage unit N and increase the life of the energy storage battery.

(5) Further, in step (1), the converter in the line N device (acting as a rectifier at this time) adopts a double closed-loop control based on the grid voltage vector orientation theory, as shown in FIG. 5 . The voltage control strategy adopts the structure of the voltage outer loop and the current inner loop, and the current direction is selected as the space vector direction of the grid voltage. The current inner loop is designed under the voltage synchronous rotating coordinate system, and each AC component is converted into a DC flow, which is convenient for the design of the closed-loop regulator and can be easily interfaced with SPWM or SVPWM.

2. The power output from the line N wind power transmission line plus the traditional generating set to the grid is less than the average value of the entire N lines output to the grid. The control method includes the following steps:

(1) When the sum PoutN of wind power transmission line N (PwindN) plus traditional generator set (PinN) output to the grid is less than the average value Pavg of the entire N lines output to the grid, the second branch in the first area The second normally open relay KMn3 is closed, the second normally closed relay KMn4 is still in the closed state, the step-up chopper circuit is turned on, and the step-down chopper circuit is turned off. The energy storage value Vdcn of the output terminal capacitor Cn is increased by PWMn2 controlling the switch tube of the boost chopper circuit, so that the voltage value Vdcn at both ends of the terminal capacitor Cn is greater than the output voltage value of the wind turbine, and the battery energy storage unit N is connected to the transmission line N discharge. In this case the converter in the line N installation acts as a three-phase bridge inverter.

(2) Further, in step (1), the PWMn2 in the line N device that controls the on-off of the switching tube of the step-up chopper circuit comes from a closed-loop output. Specifically, the average value Pavg of the entire N lines output to the grid is sent to an intelligent PIN controller for correlation Calculation and processing, the output of the intelligent PIN controller is transformed into a corresponding PWM wave to control the switch tube of the boost chopper circuit in this area after relevant conversion, and then control the battery energy storage unit N in the line device to discharge to the transmission line N (PbessN ), finally makes the sum PoutN of the power output from the line N to the grid and the average value Pavg of the entire N lines output to the grid reach a dynamic balance, and maintain the uniformity of the power flow distribution of the transmission line.

(3) Further, in step (2), the intelligent PIN controller combines two methods, which can not only maintain the uniformity of the power flow distribution of each transmission line, but also prevent the output power sum PoutN of the line from being output by the N lines If the deviation from the average value Pavg of the grid power is too large, the battery energy storage unit will be overcharged and discharged, and the service life of the battery energy storage unit N will be reduced. Specifically, the PI limiting output value becomes a step-like decline with the power deviation, the adjustment is relatively simple, and the speed response is fast, as shown in Figure 3; in addition, when the power deviation is too large (area 1 and area 5), P The regulator parameters remain unchanged; when the power deviation is small enough (2 regions and 4 regions), the parameters of the P regulator gradually become smaller; when the deviation is less than a certain degree (3 regions), the parameters of the P regulator are set to 0, such as Figure 4 shows. In this way, the convergence accuracy can be ensured while the maximum convergence speed is adopted. This method has a fast response speed and small overshoot, and effectively avoids the up and down vibration phenomenon when the total output power of the line is dynamically balanced.

(4) Further, in step (1), the converter (acting as a rectifier at this time) adopts a double closed-loop control based on the grid voltage vector orientation theory, as shown in FIG. 5 . The voltage control strategy adopts the structure of the voltage outer loop and the current inner loop, and the current direction is selected as the space vector direction of the grid voltage. The current inner loop is designed under the voltage synchronous rotating coordinate system, and each AC component is converted into a DC flow, which is convenient for the design of the closed-loop regulator and can be easily interfaced with SPWM or SVPWM.

Claims (10)

1. A large-scale new energy access grid cascade failure prevention control device, characterized in that it includes a plurality of new energy transmission line control devices and several independent new energy transmission lines, Each new energy transmission line control device includes a battery energy storage unit, a normally open relay, a normally closed relay, a buck chopper circuit, a boost chopper circuit, a terminal capacitor, a converter, and a power smoother; wherein, the The output positive pole of the battery energy storage unit is divided into two branches, the first branch includes the first normally open relay, the first normally closed relay and the step-down chopper circuit connected in sequence; the second branch includes the second normally open relay connected in sequence , the second normally closed relay and the step-up chopper circuit, after the two circuits are connected in parallel, the output is connected to the terminal capacitor; the output of the terminal capacitor is connected to the converter, the first normally open relay, the first normally closed relay, the second normally open relay, the second A normally closed relay constitutes an interlocking device; the converter is formed by connecting three pairs of IGBT bridge arms in turn, and the input of the converter is connected to a power smoother; Each new energy transmission line control device is connected to each independent new energy transmission line, and connected to the output end of the new energy transmission line. 2. The large-scale new energy access grid cascading failure prevention control device according to claim 1, characterized in that, the step-down chopper circuit is used to reduce the voltage value of the terminal capacitor, so that the transmission line charges the battery energy storage unit , to reduce the load rate of the transmission line. 3. The large-scale new energy access grid cascading failure prevention and control device according to claim 1, characterized in that, the boost chopper circuit is used to boost the terminal capacitor voltage value, so that the battery energy storage unit discharges to the transmission line , to increase the load rate of the transmission line. 4. The large-scale new energy access grid cascading failure prevention control device according to claim 1, wherein the power smoother is used to connect to the end of the wind turbine to smooth the power input from the wind turbine to the battery energy storage unit. 5. The control method of the large-scale new energy access grid cascading failure prevention control device according to any one of claims 1 to 4, characterized in that it comprises the following steps: (1) The plurality of independent new energy wind power transmission lines are respectively set as line 1, line 2 to line N, and the N is an integer greater than 2. When a certain new energy wind power transmission line plus a traditional generator set is output to When the power of the grid is greater than the average value of the entire N new energy wind power transmission lines output to the grid, the first normally open relay of the first branch of the new energy transmission line control device in the certain new energy wind power transmission line is closed , the first normally closed relay is in the closed state, the step-down chopper circuit is turned on, and the step-up chopper circuit is turned off; the switching tube of the step-down chopper circuit is controlled by PWM to reduce the energy storage of the output terminal capacitor value, so that the voltage value at both ends of the terminal capacitor is less than the output voltage value of the transmission line, and the new energy wind power transmission line charges the battery energy storage unit until the power output from the new energy wind power transmission line to the grid is dynamically equal to the output power of the entire N lines. balanced; in this case the converter in the line installation acts as a three-phase bridge rectifier; Similarly, when the output power of any new energy wind power transmission line is greater than the average value of the entire N new energy wind power transmission lines output to the grid, the system will repeat the above process, so that the wind power transmission line charges the battery energy storage unit, reducing the transmission load rate of the line. (2) When the output power of a new energy wind power transmission line plus traditional generator sets to the grid is less than the average value of the entire N lines output to the grid, the new energy transmission line control device in this certain new energy wind power line has The second normally open relay of the second branch is closed, the second normally closed relay is in the closed state, the step-up chopper circuit is turned on, and the step-down chopper circuit is turned off; the switch of the step-up chopper circuit is controlled by PWM The tube is turned on and off to increase the energy storage value of the output terminal capacitor, so that the voltage value at both ends of the terminal capacitor is greater than the output voltage value of the transmission line, and the battery energy storage unit discharges to the new energy wind power transmission line until the new energy wind power transmission line The power output to the grid is dynamically balanced with the output power of the entire N lines; at this time, the converter in the line device acts as a three-phase bridge inverter; Similarly, when the output power of any wind power transmission line is lower than the average output power of the entire line, the system repeats the above process to make the battery energy storage unit discharge to the transmission line and increase the load rate of the transmission line. 6. The control method according to claim 5, characterized in that, in step (1) (2), in the new energy wind power transmission line, the switch tubes of the step-down chopper circuit and the step-up chopper circuit are controlled to be switched on and off. PWM comes from a closed-loop output; specifically, the difference between the new energy wind power transmission line plus the power output from the traditional generator set to the grid and the average power output from the entire N lines to the grid is sent to an intelligent PI controller for correlation calculation Processing, the output of the intelligent PI controller is transformed into a corresponding PWM wave to control the on-off of the step-down chopper circuit and the step-up chopper circuit switch tube in the new energy wind power transmission line, and then control the new energy wind power transmission line The rate at which the battery energy storage unit is charged and the battery energy storage unit is discharged to the transmission line ultimately makes the dynamic balance between the power output from the new energy wind power transmission line plus the traditional generator set to the grid and the average power output from the entire N lines to the grid, Maintain the uniformity of the power flow distribution of the new energy wind power transmission line. 7. The control method according to claim 5, characterized in that, in step (1)(2), the new energy wind power transmission line plus the power output from the traditional generator set to the grid is the wind turbine output power, energy storage The sum of system input/output power and traditional generating set output power. 8. The control method according to claim 6, characterized in that, the PI limiting output value becomes a stepwise decline with the power deviation; when the power deviation is too large, the P regulator parameter remains unchanged; when the power deviation is sufficient Hours, the parameters of the P regulator gradually become smaller; when the power deviation is less than a certain degree, the parameters of the P regulator are set to 0. 9. The control method according to claim 5, characterized in that in step (1), the new energy wind power transmission line charges the battery energy storage unit, and the fluctuation rate of the output power of Dangdang new energy wind power transmission line within 1 minute is greater than 10 %, the power smoother is called to smooth the output power of the wind turbine to prevent large fluctuations from causing damage to the battery energy storage unit and affecting the power flow entropy of the power grid system. 10. The control method according to claim 5, characterized in that, in step (1)(2), the converter adopts double-closed-loop control based on grid voltage vector orientation theory; the voltage control strategy adopts voltage outer loop, The current inner loop structure, in which the current direction is chosen as the network voltage space vector direction; the current inner loop is designed under the voltage synchronous rotating coordinate system, and each AC component is converted into a DC flow, which is convenient for the design of the closed-loop regulator, and can be easily integrated with SPWM or SVPWM interface.