Power distribution network planning method for collaborative optimization of micro-grid and flexibility resources

Abstract

The invention relates to the technical field of new energy grid connection, and particularly discloses a micro-grid and flexible resource collaborative optimization power distribution network planning method, which comprises the steps of setting two groups of energy storage devices to store electric energy of new energy power generation equipment, arranging the two groups of energy storage devices in parallel, and connecting the two groups of energy storage devices with a micro-grid through power electronic interfaces, and a bidirectional energy storage converter is selected as interface equipment for grid-connected operation of the micro-grid and the power distribution network. According to the technical scheme, the two sets of energy storage devices are designed to be used for alternately storing energy and continuously and stably supplying power, waste of electric energy of new energy power generation equipment is avoided, the two sets of energy storage devices adopt delay disconnection design during switching, the electric energy of the energy storage devices is continuously supplied to the micro-grid, the power supply quality of the micro-grid is improved, and the power supply efficiency is improved. Meanwhile, a monitoring device is arranged to monitor power data of the micro-grid in real time, the micro-grid is disconnected in time, the power distribution network is started to transmit power, and the power utilization stability of a user is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy grid connection, and specifically to a distribution network planning method for coordinated optimization of microgrids and flexibility resources. Background Art

[0002] At present, new energy sources such as solar energy and wind energy have the advantages of being renewable, environmentally friendly, and pollution-free. Connecting these energy sources to microgrids and distribution networks can achieve energy complementarity and optimal configuration, thereby improving energy utilization efficiency. As an important part of the distributed energy system, microgrids can achieve flexible scheduling and efficient utilization of energy through connection with distribution networks, reduce energy waste, and the access to new energy sources can also enhance the security and stability of the power grid. Microgrids have flexible operation control and energy management capabilities, and can respond quickly to load fluctuations and emergencies to ensure the reliability and stability of power supply. In addition, microgrids can also serve as a beneficial supplement to large power grids, providing emergency power supply in the event of power grid failure or power outage to ensure the power needs of important users.

[0003] However, since renewable energy power generation is not continuous and there are peak and trough periods, if the continuous stability of renewable energy power transmission is not solved, renewable energy power generation cannot be connected to microgrids and distribution networks for stable operation and use. Improvements are needed. Therefore, we propose a distribution network planning method that coordinates the optimization of microgrids and flexible resources. Summary of the invention

[0004] The purpose of the present invention is to provide a distribution network planning method for coordinated optimization of microgrids and flexibility resources, which solves the problems raised in the background technology.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a distribution network planning method for coordinated optimization of microgrids and flexibility resources, comprising step S1: setting two groups of energy storage devices to store the electric energy of the new energy power generation equipment, and the two groups of energy storage devices are arranged in parallel with each other; S2: Both energy storage devices are connected to the microgrid through separate power electronic interfaces, and a bidirectional energy storage converter is selected as the power electronic interface device for the microgrid to be connected to the distribution network; S3: An electric energy detection device is set to monitor the electric energy storage amount of the energy storage device, and a power switching structure 1 is set between the two groups of energy storage devices and the new energy power generation equipment, and a power switching structure 2 is set between the two groups of energy storage devices and the microgrid; S4: The electric energy storage of the energy storage device is uploaded to the control center through the electric energy detection device. The two groups of energy storage devices include energy storage device 1 and energy storage device 2. In the initial state, the energy storage device 1 is connected to the new energy power generation equipment for electric energy storage, and the energy storage device 2 is disconnected from the new energy power generation equipment. When the storage capacity of the energy storage device 1 reaches the set value, the power switching structure 1 is actuated, so that the energy storage device 1 is disconnected from the new energy power generation equipment, and the energy storage device 2 is connected to the new energy power generation equipment for electric energy storage; S5: After the energy storage device 1 is disconnected from the new energy power generation equipment, the power generation mode is started. The energy storage device 1 stably transmits electric energy to the microgrid. At this time, the energy storage device 2 is in the energy storage state, and the energy storage device 2 does not transmit electric energy to the microgrid. When the remaining power of the energy storage device 1 is lower than the set value, the power switching structure 2 first connects the energy storage device 2 with the microgrid, and then the power switching structure 1 is actuated, the energy storage device 1 is delayedly connected with the new energy power generation equipment, the energy storage device 2 is disconnected from the new energy power generation equipment, and the energy storage device 2 starts the power generation mode. When the energy storage device 2 stably transmits electric energy to the microgrid, the power switching structure 2 disconnects the energy storage device 1 from the microgrid, and the energy storage device 1 is connected with the new energy power generation equipment for energy storage, and the energy storage device 2 provides stable power supply.

[0006] As a preferred implementation of the technical solution of the present application, both sets of energy storage devices are flywheel storage system devices, and the flywheel energy storage has good stability and a high mechanical energy-electrical energy conversion rate.

[0007] As a preferred implementation of the technical solution of the present application, the electric energy detection device includes a rotation speed sensor and a signal amplifier, and the rotation speed sensor is any one of a photoelectric encoder and a Hall sensor.

[0008] As a preferred implementation of the technical solution of the present application, the power switching structure 1 includes an industrial-grade remote control relay A connected in series with the circuit between the energy storage device 1 and the new energy power generation equipment, and an industrial-grade remote control relay B connected in series with the circuit between the energy storage device 2 and the new energy power generation equipment; the power switching structure 2 includes an industrial-grade remote control relay A1 connected in series with the circuit between the energy storage device 1 and the microgrid, and an industrial-grade remote control relay B2 connected in series with the circuit between the energy storage device 2 and the microgrid.

[0009] As a preferred implementation of the technical solution of the present application, the new energy power generation equipment includes any one of wind power generation system equipment and photovoltaic power generation system equipment.

[0010] As a preferred implementation of the technical solution of the present application, the flywheel speed standard when the energy storage device reaches the set value of the storage capacity is 30,000 rpm to 60,000 rpm, and the flywheel speed standard when the energy storage device has insufficient remaining capacity is 600 rpm to 1,200 rpm.

[0011] As a preferred implementation scheme of the technical solution of the present application, step S2 also includes a high-voltage circuit breaker connected in series between the microgrid and the distribution network, and a monitoring device is provided to monitor the voltage, frequency, and harmonics of the electric energy output by the microgrid. When the voltage, frequency, and harmonics of the electric energy output by the microgrid do not meet the standards of the distribution network, the high-voltage circuit breaker promptly disconnects the connection with the microgrid.

[0012] As a preferred implementation of the technical solution of the present application, the high-voltage circuit breaker is a remote-controlled high-voltage relay.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The technical solution of the present application avoids the waste of electric energy of new energy power generation equipment by designing two groups of energy storage devices for alternate energy storage and continuous and stable power supply. The delayed disconnection design is adopted when the two groups of energy storage devices are switched, so that the electric energy of the energy storage device is continuously supplied to the microgrid, thereby improving the quality of power supply of the microgrid, and providing stable power transmission after the microgrid is connected to the distribution network. At the same time, a monitoring device is set to monitor the power data of the microgrid in real time, disconnect the microgrid in time, and enable the distribution network to transmit electricity, so as to ensure the stability of user power consumption. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0015] Embodiment 1, the present invention provides a technical solution: a distribution network planning method for coordinated optimization of microgrids and flexibility resources, comprising step S1: setting two groups of energy storage devices to store electric energy of new energy power generation equipment, and the two groups of energy storage devices are arranged in parallel with each other; S2: Both sets of energy storage devices are connected to the microgrid through separate power electronic interfaces, and a bidirectional energy storage converter is selected as a power electronic interface device for the microgrid and the distribution network to be connected to the grid; in step S2, a high-voltage circuit breaker is connected in series with the microgrid and the distribution network, and a monitoring device is set to monitor the voltage, frequency, and harmonics of the microgrid output power. When the voltage, frequency, and harmonics of the microgrid output power do not meet the standards of the distribution network, the high-voltage circuit breaker is disconnected from the microgrid in time. S3: An electric energy detection device is set to monitor the electric energy storage amount of the energy storage device, and a power switching structure 1 is set between the two groups of energy storage devices and the new energy power generation equipment, and a power switching structure 2 is set between the two groups of energy storage devices and the microgrid; S4: The electric energy storage of the energy storage device is uploaded to the control center through the electric energy detection device. The two groups of energy storage devices include energy storage device 1 and energy storage device 2. In the initial state, the energy storage device 1 is connected to the new energy power generation equipment for electric energy storage, and the energy storage device 2 is disconnected from the new energy power generation equipment. When the storage capacity of the energy storage device 1 reaches the set value, the power switching structure 1 is actuated, so that the energy storage device 1 is disconnected from the new energy power generation equipment, and the energy storage device 2 is connected to the new energy power generation equipment for electric energy storage; S5: After the energy storage device 1 is disconnected from the new energy power generation equipment, the power generation mode is started. The energy storage device 1 stably transmits electric energy to the microgrid. At this time, the energy storage device 2 is in the energy storage state, and the energy storage device 2 does not transmit electric energy to the microgrid. When the remaining power of the energy storage device 1 is lower than the set value, the power switching structure 2 first connects the energy storage device 2 with the microgrid, and then the power switching structure 1 is actuated, the energy storage device 1 is delayedly connected with the new energy power generation equipment, the energy storage device 2 is disconnected from the new energy power generation equipment, and the energy storage device 2 starts the power generation mode. When the energy storage device 2 stably transmits electric energy to the microgrid, the power switching structure 2 disconnects the energy storage device 1 from the microgrid, and the energy storage device 1 is connected with the new energy power generation equipment for energy storage, and the energy storage device 2 provides stable power supply.

[0016] In a specific embodiment of the present invention, the new energy power generation equipment is a wind power generation system component, and the key components are: a wind wheel, a generator, and a transmission cable. The mechanical energy generated by the wind wheel drives the generator, and the magnetic field induction principle inside the generator generates electrical energy, which is transmitted to the energy storage device through the cable; The energy storage device is a flywheel energy storage device, which consists of key parts such as a flywheel, a bearing system, a vacuum chamber, a motor, and a monitoring system. The flywheel is the core component of the energy storage device and is responsible for storing energy. The bearing system is used to support the flywheel and reduce its friction loss during rotation. The bearing types include mechanical bearings and magnetic bearings. The magnetic bearing uses magnetic force to suspend the flywheel, further reducing friction loss and improving energy storage efficiency. The vacuum chamber provides a low vacuum environment to reduce the impact of air resistance on the rotation of the flywheel, thereby reducing friction loss and improving energy storage efficiency. The motor plays a dual role in the flywheel energy storage device. In the charging stage, it acts as a motor to drive the flywheel to rotate; in the discharge stage, it acts as a generator to convert the mechanical energy of the flywheel into electrical energy. A DC permanent magnet brushless synchronous motor is used to achieve efficient and stable energy conversion. The monitoring system is used to monitor various parameters of the flywheel energy storage device in real time, such as flywheel speed, motor temperature, vacuum degree, etc., and provide fault warning and alarm functions; Wind power generation of new energy power generation equipment generates direct current, while the drive motor requires alternating current. Therefore, an inverter is needed to convert direct current into alternating current. The alternating current drives the flywheel of the energy storage device to rotate, converting electrical energy into mechanical energy for the flywheel to rotate. When the flywheel of the energy storage device reaches the set speed, continuing to increase the speed is prone to safety accidents. Therefore, the stored mechanical energy needs to be released into electrical energy and transmitted to the microgrid. In the flywheel energy storage device, the flywheel stores a large amount of kinetic energy when it rotates at high speed. When it is necessary to release electrical energy, the flywheel begins to slow down and its kinetic energy is converted into electrical energy. The flywheel energy storage device converts the generated electrical energy into AC or DC power that meets the requirements of the microgrid through power electronic equipment (such as inverters). The flywheel energy storage device is connected to the microgrid through connecting lines (such as cables). In the microgrid, the energy management system (EMS) is responsible for monitoring and controlling the operating status of each distributed power source and energy storage system. When the flywheel energy storage device releases electrical energy, the EMS will monitor and adjust it to ensure that it works in coordination with other components in the microgrid and is connected to the grid during operation. In the off-grid operation mode, the electric energy released by the flywheel energy storage device is directly transmitted to the microgrid through the connecting line and exchanges electric energy with the main grid. At this time, the EMS will ensure that the output power of the flywheel energy storage device matches the demand of the microgrid. In the off-grid operation mode (also known as island operation), the microgrid is disconnected from the distribution network, and the distributed power supply and energy storage device jointly supply power to the load. At this time, the electric energy released by the flywheel energy storage device becomes one of the important power supply sources in the microgrid. The EMS will monitor the load demand and adjust the output power of the flywheel energy storage device to ensure the stable operation of the microgrid. The specific steps for alternating charging of the two energy storage devices and stably supplying the microgrid are as follows: In the initial state, industrial remote control relay A is closed, industrial remote control relay B is disconnected, industrial remote control relay A1 is closed, industrial remote control relay B2 is disconnected, the motor of energy storage device 1 is in charging function, energy storage device 1 stores the electric energy of new energy power generation equipment and converts it into mechanical energy, the flywheel speed of energy storage device 1 is continuously increased, and the flywheel speed of energy storage device 1 is set to 50,000 rpm as the limit speed. When the speed sensor of energy storage device 1 detects that the flywheel speed reaches 50,000 rpm, the controller of the control center connected to the power switching structure 1 remotely controls Industrial remote control relay A is in the disconnected state and industrial remote control relay B is in the closed state. At this time, the motor of energy storage device 2 is in the charging function, and the electric energy continues to be stored in the flywheel of energy storage device 2. The electric energy of energy storage device 1 is converted into AC or DC power that meets the requirements of the microgrid through power electronic equipment. The microgrid first transmits the electric energy to the nearby area. If the power consumption in the nearby area is much lower than the power generation, the excess electric energy is transmitted to the distribution network. The speed sensor is used to monitor the speed of the flywheel of energy storage device 1 in real time. When the speed of the flywheel of energy storage device 1 is lower than 1000 rpm, continuing to supply power will cause the risk of power outage in the microgrid. When the power switching structure 2 is needed to first connect the energy storage device 2 with the microgrid (that is, to control the industrial-grade remote control relay B2 to be in the closed state), the power switching structure 1 is then activated, and the energy storage device 1 is connected with the new energy power generation equipment with a delayed connection (the energy storage device 2 is set to be connected after stable power supply), the energy storage device 2 is disconnected from the new energy power generation equipment, and the energy storage device 2 starts the power generation mode. When the energy storage device 2 stably transmits electric energy to the microgrid, the power switching structure 2 disconnects the energy storage device 1 from the microgrid, and the energy storage device 1 is connected with the new energy power generation equipment for energy storage, and the energy storage device 2 provides stable power supply; when the flywheel of the energy storage device 2 is lower than the above speed , switch according to the above steps to ensure the continuity of power transmission by the energy storage device; if the power generation of the new energy power generation equipment is lower than the power consumption of the microgrid area, disconnect the remote control high-voltage relay between the microgrid and the distribution network to prevent the instability of the microgrid from affecting the distribution network. Among them, the remote control high-voltage relay is a reliable remote control device suitable for power control in various harsh environments. They have multiple input and output control terminals, which can be easily connected to the photoelectric circuit and control its opening and closing state through remote signals. The industrial-grade remote control relay supports a variety of communication protocols and interface methods, and can be easily connected to various control systems and communication networks.

[0017] In summary, the embodiment of the present invention introduces in detail the design of two groups of energy storage devices for alternate energy storage and continuous and stable power supply to avoid waste of electric energy from new energy power generation equipment. The two groups of energy storage devices are switched by a delayed disconnection design so that the electric energy of the energy storage device is continuously supplied to the microgrid, thereby improving the quality of power supply of the microgrid and providing stable power transmission after the microgrid is connected to the distribution network. At the same time, a monitoring device is set to monitor the power data of the microgrid in real time, disconnect the microgrid in time, and enable the distribution network to transmit power to ensure the stability of user power consumption.

Claims

1. A distribution network planning method for coordinated optimization of microgrids and flexibility resources, characterized by: The steps include: S1: two sets of energy storage devices are set to store the electric energy of the new energy power generation equipment, and the two sets of energy storage devices are arranged in parallel with each other; S2: Both energy storage devices are connected to the microgrid through separate power electronic interfaces, and a bidirectional energy storage converter is selected as the power electronic interface device for the microgrid to be connected to the distribution network; S3: An electric energy detection device is set to monitor the electric energy storage amount of the energy storage device, and a power switching structure 1 is set between the two groups of energy storage devices and the new energy power generation equipment, and a power switching structure 2 is set between the two groups of energy storage devices and the microgrid; S4: The electric energy storage of the energy storage device is uploaded to the control center through the electric energy detection device. The two groups of energy storage devices include energy storage device 1 and energy storage device 2. In the initial state, the energy storage device 1 is connected to the new energy power generation equipment for electric energy storage, and the energy storage device 2 is disconnected from the new energy power generation equipment. When the storage capacity of the energy storage device 1 reaches the set value, the power switching structure 1 is actuated, so that the energy storage device 1 is disconnected from the new energy power generation equipment, and the energy storage device 2 is connected to the new energy power generation equipment for electric energy storage; S5: After the energy storage device 1 is disconnected from the new energy power generation equipment, the power generation mode is started. The energy storage device 1 stably transmits electric energy to the microgrid. At this time, the energy storage device 2 is in the energy storage state, and the energy storage device 2 does not transmit electric energy to the microgrid. When the remaining power of the energy storage device 1 is lower than the set value, the power switching structure 2 first connects the energy storage device 2 with the microgrid, and then the power switching structure 1 is actuated, the energy storage device 1 is delayedly connected with the new energy power generation equipment, the energy storage device 2 is disconnected from the new energy power generation equipment, and the energy storage device 2 starts the power generation mode. When the energy storage device 2 stably transmits electric energy to the microgrid, the power switching structure 2 disconnects the energy storage device 1 from the microgrid, and the energy storage device 1 is connected with the new energy power generation equipment for energy storage, and the energy storage device 2 provides stable power supply.

2. The distribution network planning method for coordinated optimization of microgrid and flexibility resources according to claim 1 is characterized by: The two groups of energy storage devices are both flywheel storage system devices.

3. The distribution network planning method for coordinated optimization of microgrid and flexibility resources according to claim 2 is characterized by: The electric energy detection device comprises a rotation speed sensor and a signal amplifier, and the rotation speed sensor is any one of a photoelectric encoder and a Hall sensor.

4. The distribution network planning method for coordinated optimization of microgrid and flexibility resources according to claim 1 is characterized by: The power switching structure 1 includes an industrial-grade remote control relay A connected in series with the circuit between the energy storage device 1 and the new energy power generation equipment, and an industrial-grade remote control relay B connected in series with the circuit between the energy storage device 2 and the new energy power generation equipment. The power switching structure 2 includes an industrial-grade remote control relay A1 connected in series with the circuit between the energy storage device 1 and the microgrid, and an industrial-grade remote control relay B2 connected in series with the circuit between the energy storage device 2 and the microgrid.

5. The distribution network planning method for coordinated optimization of microgrid and flexibility resources according to claim 1 is characterized by: The new energy power generation equipment includes any one of wind power generation system equipment and photovoltaic power generation system equipment.

6. The distribution network planning method for coordinated optimization of microgrid and flexibility resources according to claim 3 is characterized by: The flywheel speed standard when the energy storage device reaches a set storage capacity is 30,000 rpm to 60,000 rpm, and the flywheel speed standard when the energy storage device has insufficient remaining capacity is 600 rpm to 1,200 rpm.

7. The distribution network planning method for coordinated optimization of microgrid and flexibility resources according to claim 1 is characterized by: In step S2, a high-voltage circuit breaker is connected in series between the microgrid and the distribution network, and a monitoring device is set to monitor the voltage, frequency, and harmonics of the power output by the microgrid. When the voltage, frequency, and harmonics of the power output by the microgrid do not meet the standards of the distribution network, the high-voltage circuit breaker promptly disconnects the microgrid.

8. The distribution network planning method for coordinated optimization of microgrid and flexibility resources according to claim 7 is characterized by: The high-voltage circuit breaker is a remote-controlled high-voltage relay.