A method for dispatching a power grid using supercapacitor energy storage

Abstract

The present invention discloses a method for dispatching an energy storage type supercapacitor energy storage grid. In order to overcome the problem that the fluctuation of power generation power and load of new energy sources easily causes fluctuation of system voltage and frequency during the operation of the existing microgrid, and easily causes abnormal operation of the grid, the present invention adopts a microgrid combined with a supercapacitor energy storage structure, which can reasonably dispatch the storage and release of electric energy in the grid under different states of the grid energy storage structure, and effectively ensure the stable operation of the grid.

Description

Technical Field

[0001] The present invention relates to the technical field of microgrids, and in particular to a method for dispatching an energy storage supercapacitor energy storage grid. Background Art

[0002] A microgrid is a small power generation and distribution system comprised of distributed power sources, energy storage devices, energy conversion devices, related loads, and monitoring and protection devices. It is an autonomous system capable of self-control, protection, and management. Existing microgrid energy storage scheduling strategies typically assess grid voltage and frequency in real time, dynamically dispatching energy storage based on frequency deviations. This can reduce frequency fluctuations and mitigate system frequency oscillations. The energy storage charging and discharging mode is determined based on generated power, load demand, and the state of charge of the energy storage batteries. During microgrid operation, fluctuations in renewable energy generation power and load can easily cause fluctuations in system voltage and frequency, potentially destabilizing grid operation.

[0003] The "Microgrid and Energy Storage Scheduling Method Thereof," disclosed in Chinese patent literature and with publication number CN103050986B, comprises photovoltaic modules, an inverter, a battery, a main grid, a rotating load, a supercapacitor, and a variable frequency starting device. The photovoltaic modules are connected to the AC busbar via an inverter; the supercapacitors convert AC power via the inverter and connect it to the AC busbar; and the energy storage battery is connected to the AC busbar via an inverter. This method adjusts energy storage operation based on the state of the microgrid. When the rotating load is started, the supercapacitor discharge balance is used. During the operation of the rotating load, the supercapacitor output is prioritized, and after the supercapacitor discharge is completed, the energy storage battery output is used. This scheme primarily determines the energy storage operation mode based on the main grid voltage and frequency. If the main grid voltage and frequency are normal, grid-connected operation is used; if the main grid voltage and frequency are abnormal, off-grid operation is used. However, in the existing technology, when the main grid and the main grid frequency are abnormal and the microgrid is operated off-grid, due to the large power fluctuations of the microgrid, the power of its power supply and the power of the energy storage device may not be able to meet its load, but it is impossible to obtain sufficient power through grid-connected operation. The only way to achieve matching of output power and load is to limit the internal load of the microgrid, such as cutting off equipment, which will affect the use of user equipment. Summary of the Invention

[0004] The present invention mainly solves the problem that during the operation of existing microgrids, fluctuations in renewable energy power generation power and load fluctuations easily cause fluctuations in system voltage and frequency, and even cause abnormal operation of the power grid; and provides a method for dispatching a power grid using a supercapacitor energy storage system. This scheme adopts a microgrid combined with a supercapacitor energy storage structure, which can reasonably dispatch the storage and release of electric energy in the power grid under different states of the power grid storage structure, effectively ensuring the stable operation of the power grid.

[0005] The above technical problems of the present invention are mainly solved by the following technical solutions:

[0006] The present invention comprises the following steps: firstly, establishing a microgrid combined with a supercapacitor energy storage structure, setting a scheduling factor and a state of the energy storage structure, and performing energy storage scheduling according to the energy storage structure state combined with the scheduling factor; adding supercapacitors to the microgrid,

[0007] Preferably, the energy storage structure is divided into three layers according to the order of access to the microgrid, namely, the first layer of supercapacitors, energy storage batteries and the second layer of supercapacitors; the first layer of supercapacitors is connected to the adjacent microgrid 1 and microgrid 2 through the grid-connected node, serving as shared energy storage for the two adjacent microgrids; the second layer of supercapacitors and energy storage batteries are both connected to the same microgrid, used to supply power to microgrid 1 or microgrid 2 separately; this access method can effectively avoid the occurrence of unstable power supply in a single microgrid.

[0008] Preferably, the scheduling factors include: the discharge power P1 of the first-layer supercapacitor connected to the grid-connected node of microgrid 1, the discharge power P2 of the first-layer supercapacitor connected to the grid-connected node of microgrid 2, the discharge power PC of the energy storage battery and the discharge power P3 of the second-layer supercapacitor. The above scheduling factors will serve as the basis for subsequent judgment of the energy storage structure status.

[0009] Preferably, the energy storage structure state includes energy storage operation state, energy storage transient state, compensation energy storage state and abnormal energy storage state; dividing the energy storage structure state into the above four categories is conducive to the subsequent reasonable scheduling measures for different energy storage structure states, and can more effectively maintain the safe operation of the microgrid in each energy storage structure state.

[0010] Preferably, a detection cycle is set for each microgrid 1 and microgrid 2, and the values ​​of P1, P2, PC and P3 are detected and recorded in each detection cycle. The purpose of setting the detection cycle is to regularly understand the operating status of the energy storage structure in the microgrid to facilitate timely control and maintenance.

[0011] Preferably, the safe power range of the grid-connected nodes of the first-layer supercapacitor connected to microgrids 1 and 2 is set to PX~PY. It is determined whether P1 and P2 are the same, and then whether P1 and P2 are within the range of PX~PY. If P1 is the same as P2 and both are within this range, the energy storage structure state at this time is the energy storage operation state; if P1 is lower than PX and P2 is within this range, the energy storage structure state at this time is the energy storage transient state; if P2 is higher than PY and P1 is within this range, the energy storage structure state at this time is the abnormal energy storage state. By determining whether the scheduling factor is within the safe power range, the current energy storage structure state of the microgrid can be obtained, which is conducive to the subsequent scheduling operation.

[0012] Preferably, the relationship between the discharge power PC of the energy storage battery and the discharge power P3 of the second layer supercapacitor is determined. If PC is greater than P3, the energy storage structure state at this time is a compensation energy storage state. By determining the discharge power relationship between the energy storage battery and the second layer supercapacitor, it is possible to determine whether the current energy storage structure of the microgrid is in a compensation energy storage state.

[0013] Preferably, in the energy storage operation state: microgrid 1 and microgrid 2 both enable the first-layer supercapacitor to discharge. At this time, the working mode of the first-layer supercapacitor is that the discharge is greater than the storage, that is, energy is stored while discharging, but the energy storage power is less than the discharge power, so the discharge is not terminated until the discharge power is lower than the minimum safe power PX; in the transient energy storage state: the power supplied by the first-layer supercapacitor to microgrid 1 is lower than the minimum safe power PX and drops outside the safe power range. At this time, the power supply of the first-layer supercapacitor is insufficient, so the grid-connected node between the first-layer supercapacitor and microgrid 1 is turned off, and the energy storage battery is turned on in microgrid 1 for power supply, and microgrid 2 maintains safe power supply until P2 is lower than PX, the grid-connected node between the first-layer supercapacitor and microgrid 2 is turned off, and the energy storage battery is turned on in microgrid 2 for power supply.

[0014] Preferably, in the compensation energy storage state: the first layer of supercapacitors finishes discharging and enters the energy storage state. In the energy storage state, the first layer of supercapacitors only stores electricity but does not discharge, and the energy storage battery outputs power to a single microgrid 1 or microgrid 2, while the second layer of supercapacitors continuously supplies power to the energy storage battery; in the abnormal energy storage state, the power supply of the first layer of supercapacitors to microgrid 2 is too large, which can easily cause damage to microgrid 2. At this time, the grid-connected node of the first layer of supercapacitors connected to microgrid 2 should be shut down, and an inspection instruction should be sent to the base station to perform a detailed inspection of the grid-connected node of microgrid 2; before the first layer of supercapacitors resumes power supply, the energy storage structure state of microgrid 2 is transformed into the compensation energy storage state, and is powered by the energy storage battery.

[0015] The beneficial effects of the present invention are:

[0016] 1. The energy storage supercapacitor energy storage grid dispatching method of the present invention adopts a three-layer energy storage structure, which can effectively avoid the fluctuation of system voltage and frequency caused by the fluctuation of renewable energy power generation power and load;

[0017] 2. The energy storage supercapacitor energy storage grid scheduling method of the present invention adopts a reasonable scheduling method to judge the status of the energy storage structure according to the scheduling factor, thereby performing more comprehensive scheduling of the microgrid power supply and maintaining the safe operation of the microgrid. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a method for dispatching an energy storage type supercapacitor energy storage grid according to the present invention. DETAILED DESCRIPTION

[0019] The technical solution of the present invention will be further specifically described below through embodiments and in conjunction with the accompanying drawings.

[0020] Example:

[0021] A method for scheduling an energy storage grid using a supercapacitor energy storage system according to this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0022] Step 1: Establish a three-layer energy storage structure of microgrid combined with supercapacitors, including: the first layer of supercapacitors, energy storage batteries and the second layer of supercapacitors.

[0023] Step 2: Connect the first-layer supercapacitors to adjacent microgrids 1 and 2 through the grid-connected nodes, and connect the second-layer supercapacitors and energy storage batteries to the same microgrid.

[0024] Step 3: Set the dispatch factor of the energy storage structure, including the discharge power P1 of the first-layer supercapacitor connected to the grid-connected node of microgrid 1, the discharge power P2 of the first-layer supercapacitor connected to the grid-connected node of microgrid 2, the discharge power PC of the energy storage battery, and the discharge power P3 of the second-layer supercapacitor.

[0025] Step 4: Set the energy storage structure state of the energy storage structure, including energy storage operation state, energy storage transient state, compensation energy storage state and abnormal energy storage state.

[0026] Step 5: Assume that the safe power range of the first-layer supercapacitor connected to the grid-connected nodes of microgrid 1 and microgrid 2 is PX~PY.

[0027] Step 6: Determine whether P1 and P2 are the same, and then determine whether P1 and P2 are within the range of PX~PY. If they are the same and both are within the range of PX~PY, the energy storage structure state at this time is the energy storage operation state. At this time, both microgrid 1 and microgrid 2 start the first layer supercapacitor to discharge. The first layer supercapacitor discharges and stores energy, and the energy storage power is less than the discharge power.

[0028] Step 7: Determine whether P1 and P2 are the same, and then determine whether P1 and P2 are within the range of PX~PY. If P1 is lower than PX and P2 is within the range of PX~PY, the energy storage structure is in a transient state. At this time, the first-layer supercapacitor and the grid-connected node of microgrid 1 are turned off, and the energy storage battery is turned on in microgrid 1 for power supply. Microgrid 2 maintains a safe power supply until P2 is lower than PX, and then the first-layer supercapacitor and the grid-connected node of microgrid 2 are turned off.

[0029] Step 8: Determine whether P1 and P2 are the same, and then determine whether P1 and P2 are within the range of PX~PY. If P2 is higher than PY and P1 is within the range of PX~PY, the energy storage structure state at this time is an abnormal energy storage state. At this time, the first layer supercapacitor is connected to the grid-connected node of microgrid 2 and an inspection instruction is sent to the base station. Before the first layer supercapacitor resumes power supply, the energy storage structure state of microgrid 2 is transformed into a compensation energy storage state.

[0030] Step 9: Determine the relationship between the energy storage battery discharge power PC and the second-layer supercapacitor discharge power P3. If PC is greater than P3, the energy storage structure is in a compensation energy storage state. The first-layer supercapacitor stops discharging, and the energy storage battery outputs power to a single microgrid 1 or microgrid 2. At the same time, the second-layer supercapacitor continues to supply power to the energy storage battery.

[0031] It should be understood that the embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the appended claims of the application.

Claims

1. A method for dispatching an energy storage type supercapacitor energy storage grid, characterized in that: The following steps are involved: S1: Establish a microgrid combined with supercapacitor energy storage structure; It includes the first layer of supercapacitors, which are connected to adjacent microgrids 1 and 2 through grid-connected nodes; S2: Set the dispatch factor and state of the energy storage structure; The dispatching factors include the discharge power P1 of the first-layer supercapacitor connected to the microgrid 1 grid-connected node and the discharge power P2 of the first-layer supercapacitor connected to the microgrid 2 grid-connected node; S3: Energy storage dispatching is performed based on the energy storage structure status combined with dispatching factors; Assume that the safe power range of the first-layer supercapacitor connected to the grid-connected nodes of microgrid 1 and microgrid 2 is PX~PY; If P1 and P2 are the same and both are within the range of PX~PY, it is the energy storage operation state; both microgrid 1 and microgrid 2 start the first layer supercapacitor discharge, and the working mode of the first layer supercapacitor is that the discharge is greater than the storage; If P1 is lower than PX and P2 is in the range of PX~PY, it is a transient energy storage state; turn off the first-layer supercapacitor and the grid-connected node of microgrid 1, and turn on the energy storage battery in microgrid 1 to supply power. Microgrid 2 maintains safe power supply until P2 is lower than PX, then turn off the first-layer supercapacitor and the grid-connected node of microgrid 2; If P2 is higher than PY and P1 is within the range of PX~PY, it is an abnormal energy storage state; the first layer of supercapacitors connected to the grid-connected node of microgrid 2 is turned off, and an inspection instruction is sent to the base station.

2. A method for dispatching an energy storage type supercapacitor energy storage grid according to claim 1, characterized in that: The S1 further comprises: S1.1: The energy storage structure further includes an energy storage battery and a second layer of supercapacitors; S1.2: The second layer supercapacitors and energy storage batteries are connected to the same microgrid.

3. A method for dispatching an energy storage type supercapacitor energy storage grid according to claim 1 or 2, characterized in that: The S2 includes: S2.1: The scheduling factor also includes the discharge power PC of the energy storage battery and the discharge power P3 of the second layer supercapacitor.

4. The energy storage type supercapacitor energy storage grid scheduling method according to claim 1 is characterized in that: The S2 further includes: S2.2: The energy storage structure state includes energy storage operation state, energy storage transient state, compensation energy storage state and abnormal energy storage state.

5. The energy storage type supercapacitor energy storage grid dispatching method according to claim 3 is characterized in that: The S2 further includes: S2.1.1: Set a detection cycle for a single microgrid 1 and microgrid 2; S2.1.2: During each test cycle, measure and record the values ​​of P1, P2, PC, and P3.

6. The energy storage type supercapacitor energy storage grid scheduling method according to claim 1 is characterized in that: The S3 further includes: S3.3: Determine the relationship between the discharge power PC of the energy storage battery and the discharge power P3 of the second layer supercapacitor. If PC is greater than P3, the energy storage structure state at this time is a compensation energy storage state.

7. A method for dispatching an energy storage type supercapacitor energy storage grid according to claim 6, characterized in that: The S3 further includes: S3.5: In the transient state of energy storage, the power supplied by the first layer supercapacitor to microgrid 1 drops to outside the safe power range. At this time, the power supply of the first layer supercapacitor is insufficient.

8. The energy storage type supercapacitor energy storage grid dispatching method according to claim 6 is characterized in that: The S3 further includes: S3.6: In the compensation energy storage state, the first layer of supercapacitors finishes discharging and enters the energy storage state. The energy storage battery outputs power to a single microgrid 1 or microgrid 2, and the second layer of supercapacitors continuously supplies power to the energy storage battery. S3.7: Under abnormal energy storage state, the power supplied by the first layer supercapacitor to microgrid 2 is too large, which may cause damage to microgrid 2. Before the first layer supercapacitor resumes power supply, the energy storage structure state of microgrid 2 is changed to compensation energy storage state.

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