Ramp type gravity energy storage system multi-unit rapid braking control strategy

Abstract

This invention proposes a rapid braking control strategy for multiple units in a ramp-type gravity energy storage system. By constructing an energy efficiency evaluation function, the optimal delay time for multi-stage braking that can balance small-power impacts and rapid shutdown braking is determined. This invention is based on the braking delay time Δt, the number of grid-connected units N, and the total braking time T of the entire unit in the ramp-type gravity energy storage system. brake Braking peak power P max By identifying the relationship between parameters and the speed curve of a single unit during braking, the delay time t of a single unit can be determined. brake By setting weight factors for the braking time and peak braking power of the entire unit and the number of units in the system, and fitting the braking time curve and peak braking power curve of the entire unit using the basic interpolation method, a multi-level braking energy efficiency evaluation function model for the sloped gravity energy storage system is constructed, and the optimal delay time setting scheme under different weight factors is studied.

Description

Technical Field

[0001] This invention belongs to the field of gravity energy storage technology and relates to a multi-stage braking energy efficiency evaluation function for a slope-type gravity energy storage system. Background Technology

[0002] In recent years, with the rapid development of new energy power systems, large-capacity, high-efficiency energy storage technologies have become increasingly diversified. Gravity energy storage, as a new type of long-duration, large-capacity energy storage method, boasts advantages such as high safety, high efficiency, long lifespan, and short construction cycle. However, it experiences significant power surges and slow braking times during the instantaneous braking of a heavy load. The basic process of gravity energy storage involves using surplus electricity to drive a motor to lift a heavy load, converting it into high-potential energy for storage; releasing the load then generates electricity. Due to its large storage capacity, long output time, and low unit energy cost, it can accurately track grid dispatch commands, improve the grid's secondary frequency regulation capacity, and has broad application prospects.

[0003] Similar to pumped storage, gravity energy storage technology based on discrete mass blocks has the functions of peak shaving, frequency regulation, phase regulation, energy storage, and system backup. It can use various types of motors such as asynchronous motors, synchronous motors, and doubly fed asynchronous motors. Combined with frequency converters, it can improve the operating characteristics of the power system, effectively enhance the comprehensive defense capabilities of the power grid, and ensure the safe and stable operation of the power grid.

[0004] In gravity energy storage systems, there are two main ways to achieve shutdown: regenerative braking and reverse braking. In multi-unit systems, regenerative braking can cause a large power surge. To achieve smooth control, a fixed delay is set for the braking time of each unit to avoid the power surge at the moment of braking. A short delay time cannot effectively reduce the peak braking power, while a long delay time is not conducive to the rapid shutdown of the system. Therefore, how to reasonably select the unit braking delay time is a problem that needs to be solved from the perspective of setting the delay time to achieve smooth power control. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by proposing a multi-unit rapid braking control strategy for a slope-type gravity energy storage system. By constructing an energy efficiency evaluation function, the optimal delay time for multi-stage braking that can take into account both low-power impact and rapid shutdown braking is determined.

[0006] Includes the following steps:

[0007] Measuring the braking time t of a single unit brake ;

[0008] Determine the delay time setting range 0 to t brake ;

[0009] Determine the number of units N in the gravity energy storage system;

[0010] Weighting factors P1 and P2 are set according to actual energy efficiency requirements; P1 is the weighting factor corresponding to the braking peak power, and P2 is the weighting factor corresponding to the delay time of the entire unit.

[0011] Set the coefficients k and α for the exponential term;

[0012] Construct a multi-level braking energy efficiency evaluation function S for a slope-type gravity energy storage system;

[0013] Calculate the extreme points of the multi-stage braking energy efficiency evaluation function S for a slope-type gravity energy storage system;

[0014] Determine whether the extreme point is located within the delay interval 0 to t. brake .

[0015] Based on the above scheme, the measurement of the braking time t of a single unit brake Determine the delay time setting range 0 to t brake Specifically:

[0016] The braking time t of a single unit in a gravity energy storage system is determined by analyzing its power and speed characteristics during the braking process. brake The system employs multi-unit delayed segmented braking, with the upper limit of the delay time Δt being the braking time t of a single unit. brake .

[0017] Based on the above scheme, different delay times t brake Set the corresponding multi-unit braking peak power P max Braking time T of the entire unit brake The delay time setting range for the number of generating units N is 0 to t. brake The delay time-to-the-whole-unit braking time and delay time-to-braking peak power curves are obtained.

[0018] Based on the above scheme, P1 and P2 satisfy P1+P2=1.

[0019] Based on the above scheme, the multi-stage braking energy efficiency evaluation function S of the slope-type gravity energy storage system is specifically as follows:

[0020]

[0021] Exponential term k·10 α To ensure that the nonlinear coefficients of the two weighting factors are of the same order of magnitude.

[0022] Based on the above scheme, the multi-stage braking energy efficiency function S of the slope-type gravity energy storage system is given by an equation for Δt.

[0023]

[0024] (0≤Δt≤t brake )

[0025]

[0026] The solution to the equation is the optimal delay time set according to the weights of P1 and P2.

[0027] Based on the above scheme, the step of determining whether the extreme point is located within the delay interval 0 to t is... brake Specifically: if the minimum point is located in the interval 0 to t brake In the interval t, the corresponding delay time is the optimal delay time; if the minimum point is not located in the interval 0 to t brake In the process, the optimal delay time is the braking energy efficiency evaluation function S in the interval 0 to t. brake Minimum point.

[0028] The beneficial effects of this invention are:

[0029] (1) Based on the braking time and braking peak power curve of the whole unit under different delay time settings, this invention selects different weight factors, constructs a multi-level braking energy efficiency evaluation function model, and studies the optimal delay time setting under different weight factors.

[0030] (2) In the process of proposing the multi-level braking energy efficiency evaluation function model, in order to accurately define the impact of braking peak power and the braking time of the whole unit on braking energy efficiency, this invention proposes a concept of braking energy efficiency weight factor, sets appropriate weight factors for different operating conditions, and realizes the maximization of braking energy efficiency. Attached Figure Description

[0031] The present invention includes the following figures:

[0032] Figure 1 This is a flowchart for setting the optimal delay time based on the multi-stage braking energy efficiency evaluation function of the slope-type gravity energy storage system.

[0033] Figure 2 This is a schematic diagram of a multi-unit delayed braking system for a slope-type gravity energy storage system.

[0034] Figure 3 These are the speed and power curves of a single unit in a single-machine system during reverse braking.

[0035] Figure 4 These are the energy efficiency evaluation function curves under different weight factor allocations when the number of generating units N=5;

[0036] Figure 5 These are power curves with improperly set delays, corresponding to situations where the delay is set too short or too long, respectively. Detailed Implementation

[0037] The following combination Figure 1-5 The present invention will be described in further detail below.

[0038] like Figure 1 This paper proposes a multi-unit rapid braking control strategy for a slope-type gravity energy storage system. By constructing an energy efficiency evaluation function, the optimal delay time for multi-stage braking that can take into account both low-power impact and rapid shutdown braking is determined.

[0039] The specific steps are as follows:

[0040] S1. Investigate the power and speed characteristics of a single unit in the gravity energy storage system during braking, and determine the braking time t of a single unit. brake The system employs multi-unit delayed segmented braking, with the upper limit of the delay time Δt being the braking time t of a single unit. brake Different delay time settings correspond to different multi-unit braking peak power P max Braking time T of the entire unit brake .

[0041] S2. To achieve rapid braking of the entire gravity energy storage system, the required braking time T for the entire unit is as follows: brake The delay time Δt should be set as small as possible, with the upper limit being the braking time t of a single unit. brake This ensures that the entire unit brakes quickly after triggering.

[0042] S3. To minimize power fluctuations during the braking process of the gravity energy storage system, the delay time range for the number of units N is set to 0 to t. brake The delay time-to-unit braking time-delay time-braking peak power curve is obtained. The delay time is set between 0 and t. brake Once the number of generating units N is determined, the delay time versus the braking time of all generating units exhibits an approximately proportional distribution, while the delay time versus the peak braking power exhibits an exponential decay and gradually stabilizes.

[0043] S4. The delay time setting needs to ensure rapid braking of the entire unit while minimizing the peak braking power. P1 is the weighting factor corresponding to the peak braking power, and P2 is the weighting factor corresponding to the delay time of the entire unit, satisfying P1 + P2 = 1. The optimal braking delay time under different weighting factors is calculated using the multi-stage braking energy efficiency evaluation function S of the ramp-type gravity energy storage system. (Exponential term k·10) α To ensure that the nonlinear coefficients of the two weighting factors are of the same order of magnitude.

[0044]

[0045] S5. The multi-stage braking efficiency evaluation function S effectively reflects the overall braking effect of the multi-stage braking process. The multi-stage braking efficiency evaluation function takes into account the weighted influence of the delay time on the braking peak power and the braking time of the entire unit. The smaller S is, the better the braking efficiency is under the weighting factors P1 and P2 corresponding to the delay time.

[0046]

[0047] (0≤Δt≤t brake )

[0048] Given the number of generating units N, and after setting weighting factors P1 and P2, the correspondence between the delay time and the energy efficiency function S is established. Substituting this into the multi-level braking energy efficiency evaluation function S yields an equation regarding Δt. The solution to this equation is the optimal delay time set with weights P1 and P2.

[0049]

[0050] like Figure 2 This is a basic structural diagram of a ramp-type gravity energy storage system. It illustrates the application background of a multi-unit rapid braking energy efficiency evaluation strategy, where five trolleys on the ramp brake at intervals of Δt.

[0051] like Figure 3 The above figure shows the speed curve of a single unit during braking. After the trolley traction motor reaches its rated speed, it is reverse-energized for 1 second, and the speed rapidly drops to 0. The braking time from rated speed to 0 speed is t. brake ;

[0052] like Figure 3 The figure below shows the power change during the braking process of a single unit. It can be seen that at 1 second, at the instant the trigger activates, a large negative power surge occurs, which then gradually stabilizes to zero. When multiple units are involved without delay, the power surge is even larger.

[0053] like Figure 4 The values ​​of the braking energy efficiency evaluation function vary under different weighting factors. It can be seen that when the weighting coefficient of P1 increases, the extreme point of the energy efficiency evaluation function shifts, meaning that the optimal delay time of the evaluation function that comprehensively considers braking energy efficiency changes.

[0054] If the delay time setting method for braking time and peak power is not comprehensively considered, such as Figure 5 The delay time shown in the diagram above allows for rapid braking, but it results in a significant peak power consumption. However, as... Figure 5 The delay time shown in the figure below can achieve a smaller power surge, but if the delay time is too long, it will affect the working efficiency of the gravity energy storage system.

[0055] The above embodiments are for illustrative purposes only and are not intended to limit the scope of this invention. Those skilled in the art can make various changes and modifications without departing from the essence and scope of this invention. Therefore, all equivalent technical solutions also fall within the scope of this invention, and the patent protection scope of this invention should be defined by the claims. Content not described in detail in this specification is prior art known to those skilled in the art.

Claims

1. A rapid braking control strategy for multiple units in a slope-type gravity energy storage system, characterized in that, Based on the multi-stage braking energy efficiency evaluation function of the slope-type gravity energy storage system, the optimal delay time of the multi-stage braking process is determined, including the following steps: Measuring the braking time t of a single unit brake ; Determine the delay time setting range: 0 ~ t brake ; Determine the number of units N in the gravity energy storage system; Weighting factors P1 and P2 are set according to actual energy efficiency requirements; P1 is the weighting factor corresponding to the braking peak power, and P2 is the weighting factor corresponding to the delay time of the entire unit. Set the coefficients k and α for the exponential term; Construct a multi-stage braking energy efficiency evaluation function S for a slope-type gravity energy storage system, specifically as follows: ; Among them, P max (N, Δt) represents the peak braking power of multiple generating units when the number of generating units is N and the delay time is Δt, T brake (N, Δt) represents the braking time of all units when the number of units is N and the delay time is Δt, where Δt is the delay time. To ensure that the two weight factor terms are nonlinear coefficient terms of the same order of magnitude; Calculate the multi-stage braking energy efficiency evaluation function S of the inclined gravity energy storage system in the time delay interval 0 ~ t brake The local minimum point within; The optimal delay time is determined based on the minimum point.

2. The multi-unit rapid braking control strategy for a slope-type gravity energy storage system as described in claim 1, characterized in that, The measurement of braking time t of a single unit brake Determine the delay time setting range: 0 ~ t brake Specifically: The braking time t of a single unit in a gravity energy storage system is determined by analyzing its power and speed characteristics during the braking process. brake The system employs multi-unit delayed segmented braking, with the upper limit of the delay time Δt being the braking time t of a single unit. brake .

3. The rapid braking control strategy for multiple units in a slope-type gravity energy storage system as described in claim 2, characterized in that, Different delay time Δt settings correspond to different multi-unit braking peak power P max Braking time T of the entire unit brake The delay time range for the number of generating units N is set to 0 ~ t. brake The delay time-to-the-whole-unit braking time and delay time-to-braking peak power curves are obtained.

4. The multi-unit rapid braking control strategy for a slope-type gravity energy storage system as described in claim 1, characterized in that, P1 and P2 satisfy P1+P2=1.

5. The rapid braking control strategy for multiple units in a slope-type gravity energy storage system as described in claim 1, characterized in that, The minimum point of the energy efficiency evaluation function S is calculated by solving the equation: ; ; The solution to the equation is the optimal delay time set according to the weights of P1 and P2.

6. The rapid braking control strategy for multiple units in a slope-type gravity energy storage system as described in claim 1, characterized in that, The specific method for determining the optimal delay time based on the minimum point is as follows: if the minimum point is located in the interval 0 ~ t brake In this context, the corresponding delay time is the optimal delay time; if the minimum point is not located in the interval 0 ~ t brake In this context, the optimal delay time is the time when the energy efficiency evaluation function S is in the interval 0 ~ t. brake Minimum point.

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