Benefit evaluation method for optical storage integrated system of bus station

Abstract

The invention relates to a benefit evaluation method for a bus station optical storage integrated system, and belongs to the field of renewable energy sources. The evaluation method comprises the following steps: selecting a target area, and obtaining retired battery evaluation data, photovoltaic power generation related data, bus operation energy consumption data, power grid data, environmental benefit data and cost data; evaluating the health state of the decommissioned battery, calculating the health state of the decommissioned battery and the availability coefficient of the decommissioned battery, and further judging whether the decommissioned battery can be used for constructing a bus station energy storage system or not; establishing a photovoltaic output prediction model under the condition of uncertain weather and equipment performance, and estimating the theoretical power generation power of the photovoltaic power station in the target region; establishing a'light-storage-network 'hybrid power supply strategy; constructing a system benefit evaluation index; and outputting a benefit evaluation result. According to the invention, a'photovoltaic-storage-grid 'cooperative power supply strategy is established, and the system economy and the power supply reliability are remarkably improved through dynamic charging and discharging control and safety threshold setting in combination with photovoltaic output fluctuation and power grid peak and valley electricity prices.

Description

Technical Field

[0001] This invention relates to the field of renewable energy and electric transportation, and in particular to a method for evaluating the benefits of a photovoltaic-storage integrated system for bus stops. Background Technology

[0002] With the rapid acceleration of urban public transport electrification, the energy systems of bus depots are facing a critical period of transformation and upgrading. Currently, bus depots mainly rely on traditional power grid supply, which presents two prominent contradictions: firstly, the power grid experiences heavy loads and high charging costs during peak hours; secondly, the power grid structure, dominated by thermal power, is unable to meet the requirements of green and low-carbon development for the public transport system. Meanwhile, although photovoltaic power generation technology is mature, its inherent intermittency and volatility mean that a single photovoltaic system cannot meet the continuous and stable power supply needs of bus depots.

[0003] Against this backdrop, the tiered utilization of retired power batteries provides a significant opportunity to construct a new "photovoltaic-energy storage integrated" system. Statistics show that retired electric bus batteries typically retain 60%-80% of their remaining capacity. Direct disposal not only wastes resources but also poses environmental pollution risks. However, existing research on the benefit evaluation methods of "photovoltaic-energy storage integrated" systems in bus depots has significant shortcomings: First, most studies focus on new battery energy storage systems, with few systematic evaluation studies on the tiered utilization of retired batteries; second, existing evaluation methods often only focus on single economic or environmental indicators, lacking a comprehensive evaluation system that considers multiple dimensions such as photovoltaic absorption rate, retired battery utilization rate, and grid interaction costs; finally, research on dynamic charging and discharging strategies and benefit quantification methods for mixed configurations of retired and new batteries is still lacking. These technological shortcomings severely restrict the large-scale application of retired batteries in bus depot energy storage systems. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for evaluating the benefits of a public transport station integrated photovoltaic and energy storage system, thus solving the deficiencies of the existing technology.

[0005] The objective of this invention is achieved through the following technical solution: a method for evaluating the benefits of an integrated photovoltaic and energy storage system for bus stops, the evaluation method comprising:

[0006] S1. Data Acquisition: Select the target area and acquire retired battery assessment data, photovoltaic power generation related data, public transportation operation energy consumption data, power grid data, environmental benefit data, and cost data;

[0007] S2. Decommissioned Battery Availability Assessment: Conduct a health status assessment on decommissioned batteries, calculate their health status and decommissioned battery availability coefficient, and then determine whether they can be used to construct a bus station energy storage system.

[0008] S3. Establish a photovoltaic power output prediction model under uncertain meteorological and equipment performance conditions to estimate the theoretical power generation of photovoltaic power plants in the target area;

[0009] S4. Establish a hybrid power supply strategy of "photovoltaic-storage-grid" that includes a hybrid charging strategy for bus fleets and a charging and discharging strategy for energy storage systems, in order to meet the charging and discharging needs of buses and energy storage systems.

[0010] S5. Construct a systematic benefit evaluation index that includes economic benefit indicators and environmental benefit indicators;

[0011] S6. Output includes economic benefit evaluation, environmental benefit evaluation, and benefit evaluation level classification results.

[0012] The retired battery assessment data in S1 includes the battery's current maximum charging capacity, battery rated capacity, retired battery procurement cost, retired battery market fair value, and retired battery reuse cost;

[0013] Photovoltaic power generation related data includes the effective solar radiation intensity received by photovoltaic modules, the total area of ​​photovoltaic modules, the conversion efficiency of photovoltaic modules, the aging loss coefficient of photovoltaic modules, the module mismatch loss coefficient, the dust shading loss coefficient, the line transmission and station power consumption loss coefficient, and the inverter efficiency.

[0014] Bus operation energy consumption data includes the total daily electricity consumption of buses and the total daily photovoltaic electricity consumption of buses.

[0015] Environmental benefit data include emission reductions from the cascade utilization of retired batteries, emission reductions from photovoltaic power grid replacement, carbon emission factors from new battery production, and carbon emission factors from the power grid.

[0016] Cost data includes the total area of ​​photovoltaic module panels, the unit purchase cost of photovoltaic modules, the total capacity of the energy storage system, the ratio of new and old batteries, and the unit cost of new batteries.

[0017] S2 specifically includes the following:

[0018] Get the current maximum charging capacity Q of the battery charge and rated capacity Q rated and through Calculate the SOH value, where SOH represents the battery's state of health;

[0019] Based on the SOH calculation results, the batteries are divided into three applicable levels. When the SOH range of the retired battery is in the first set range, this type of battery will be directly used in the energy storage system and occupy a large configuration ratio. When the SOH range of the retired battery is in the second set range, this type of battery will be used in combination with new batteries. When the SOH range of the retired battery is in the third set range, this type of battery will not be used.

[0020] And introduce the availability coefficient of retired batteries. The degree of decommissioning of retired batteries is quantitatively assessed by calculation, where k usable It is the availability coefficient of retired batteries, when k usable When the value is greater than 0.75, it can be used independently, k usable When the value is between 0.25 and 0.75, a mixed configuration is required, k usable If the concentration is less than 0.25, it should be discarded. min ΔSOH represents the minimum threshold for the secondary use of retired batteries. tran This indicates the span of the linear transition range for retired batteries.

[0021] S3 specifically includes the following:

[0022] Through P dc =G·S 总 ·η pv Calculate the DC output power of the photovoltaic module, where P dc G represents the DC output power of the photovoltaic module, and S represents the effective solar irradiance received by the photovoltaic module. 总 η represents the total area of ​​the photovoltaic module. pv Indicates the conversion efficiency of photovoltaic modules;

[0023] Through P acj =P dc ·(1-a)·(1-β)·(1-γ)·η inv Calculate the theoretical power generation, P acj P represents the theoretical power generation capacity of a photovoltaic power station. dc η represents the DC output power of the photovoltaic module, α represents the sum of the aging loss coefficient and mismatch loss coefficient of the photovoltaic module, β represents the dust shading loss coefficient, γ represents the line transmission and station power consumption loss coefficient, and η represents the DC output power of the photovoltaic module. inv This indicates the inverter efficiency.

[0024] The hybrid charging strategy for buses in S4 includes:

[0025] The day is divided into 24 time periods, and the total daily electricity consumption of the bus fleet is set as E. total The total photovoltaic power consumption of a single bus fleet is set at E. pv The hybrid charging strategy for electric buses is divided into the following three scenarios based on the actual situation of photovoltaic discharge:

[0026] 1. When the weather condition is the first type, the photovoltaic power is insufficient, i.e., E pv <E total In such cases, all available photovoltaic power will be used first, if the SOC of the energy storage system is greater than or equal to the SOC of the photovoltaic system.min The remaining electricity demand is supplemented by the energy storage system. If the energy storage system's SOC < SOC min If the power supply fails, the energy storage system enters protection mode and stops supplying power. In this case, the grid is activated to supplement power supply. (The remaining text appears to be incomplete and contains several typographical errors. A more accurate translation would require the full context.) min Indicates the minimum threshold for battery discharge;

[0027] 2. When the weather condition is the second type, the photovoltaic power supply just meets the demand, i.e., E. pv =E total At this time, the entire system is powered by photovoltaic electricity, and no energy storage system or grid power is required.

[0028] 3. When the weather condition is the third type, there is a surplus of photovoltaic power, i.e., E. pv >E total At the same time, photovoltaic power will be used first to meet the full needs of the electric bus fleet, and excess power will be stored in an energy storage system for later use, until the SOC of the energy storage system equals the SOC of the electric bus fleet. max Meanwhile, the power grid does not participate in power supply, where SOC max This indicates the highest threshold for battery charging.

[0029] The energy storage system charging and discharging strategy in S4 includes:

[0030] Energy storage system charging strategy: Specifically divided into three time periods, the charging behavior in each time period is as follows:

[0031] 1. Off-peak electricity price period at night: During this period, the grid electricity price is at its lowest level. Energy storage batteries prioritize charging from the grid to fully utilize the off-peak electricity price and reduce charging costs. Charging behavior is determined by the lower limit threshold of State of Charge (SOC). min The driver initiates charging when the State of Charge (SOC) falls below this threshold, continuing until the SOC reaches the upper limit threshold. max ;

[0032] 2. Daytime Photovoltaic Power Generation Phase: During this period, the photovoltaic power generation system begins operation. If the photovoltaic power generation exceeds the immediate load demand, the excess will be stored in the energy storage battery. The charging behavior is determined by the lower limit threshold SOC. min The driver initiates charging when the State of Charge (SOC) falls below this threshold, continuing until the SOC reaches the upper limit threshold. max ;

[0033] 3. Midday PV surplus period: During this period, PV power generation is high. If it exceeds the immediate load demand, the excess will be stored in energy storage batteries. The charging behavior is determined by the lower limit threshold of SOC. min The driver initiates charging when the State of Charge (SOC) falls below this threshold, continuing until the SOC reaches the upper limit threshold. max ;

[0034] Energy storage system discharge strategy: Specifically, it is executed based on the following two judgments:

[0035] Judgment 1: Peak electricity price period: During 07:00-09:00 and 17:00-19:00 daily, when the SOC of the energy storage system is higher than the SOC of the peak electricity price period. max At this time, the system prioritizes discharging electricity to the bus fleet. If there is still residual electricity after discharging, the excess energy is sold back to the grid to generate economic benefits, until the State of Charge (SOC) drops to the State of Charge (SOC). min until;

[0036] Judgment 2, Electricity Price Balance Phase: During 09:00-17:00 and 19:00-22:00 daily, when photovoltaic power generation is sufficient and the SOC of the energy storage system remains at a high level, the system discharges to reduce dependence on the grid. Conversely, if photovoltaic output is insufficient or the SOC is low, the discharge behavior is reduced to prioritize the charging needs of public transportation vehicles.

[0037] The calculation of the economic benefit indicators in S5 specifically includes the following:

[0038] According to C pv =S·C unit Calculate the construction cost of a photovoltaic system, where C pv C represents the construction cost of a photovoltaic system, S represents the total panel area of ​​the photovoltaic modules, and C represents the total cost of the photovoltaic system. unit This indicates the unit purchase cost of photovoltaic modules;

[0039] Introducing the Fair Market Value (FMV) of Retired Batteries t As a benchmark, and taking into account the cost of reuse, the unit purchase cost of the retired battery is calculated to be C. old =FMV t +Rt, and calculate the construction cost of the energy storage system as C. ess =x·E·C new +(1-x)·E·C old , where C old For the unit procurement cost of retired batteries, FMV t Let Rt be the fair market value of the retired battery, and C be the reuse cost of the retired battery. ess Let E be the construction cost of the energy storage system, E be the total capacity of the energy storage system, x be the proportion of new batteries in the total energy storage capacity, and C be the total capacity of the energy storage system. new The unit cost of the new battery.

[0040] The calculation of environmental benefit indicators in S5 specifically includes the following:

[0041] Based on the scale of photovoltaic (PV) infrastructure development, the charging needs of buses, and the actual power supply provided by the PV system to buses, the PV absorption rate index is calculated as follows: Where, η greenE is the ratio of photovoltaic power supply to the total electricity demand of the bus fleet. ptb E is the amount of electricity provided by the photovoltaic system for charging buses. total This is the total charging capacity of the bus;

[0042] Through ΔG battery =(E-xE)·g battery Calculate the carbon emissions from the secondary use of retired batteries using ΔG. pv =E ptb ·g grid The emission reduction of photovoltaic power generation replacing the power grid is calculated using ΔG = ΔG battery +ΔG pv Calculate greenhouse gas emission reductions, where ΔG battery E is the emission reduction from the reuse of retired batteries, E is the total capacity of the energy storage system, x is the proportion of new battery capacity in the total energy storage system capacity, and g is the emission reduction from the reuse of retired batteries. battery It is the carbon emission factor of new battery production, ΔG pv This refers to the emission reduction from solar power replacing the power grid, E ptb This refers to the charging power provided by the photovoltaic system for buses, g grid ΔG is the carbon emission factor of the power grid, and ΔG is the greenhouse gas emission reduction.

[0043] S6 specifically includes the following:

[0044] By comprehensively considering the construction cost C of photovoltaic systems pv Energy storage system construction cost C ess And the system's economic benefit indicators are obtained by calculating operating revenue. If I eco A value ≥0.15 indicates excellent economic efficiency; if 0.10≤I eco If I < 0.15, it indicates good economic benefits. eco If R < 0.10, it indicates that the economic benefits need to be optimized, where R op It is the annual operating revenue of the bus station;

[0045] Based on the comprehensive photovoltaic absorption rate η green The system's environmental benefit indicators are obtained by calculating the greenhouse gas emission reduction ΔG. If I env A value ≥0.9 indicates excellent environmental benefits; if 0.7≤I env If I < 0.9, it indicates excellent environmental benefits. env If the value is less than 0.7, it indicates that the environmental benefits need to be improved, where ΔG max That is the theoretical maximum emission reduction.

[0046] The present invention has the following advantages:

[0047] 1. An evaluation system for the cascade utilization of retired batteries based on SOH was established. The applicability of retired batteries in energy storage systems was quantitatively evaluated through availability coefficients, which solved the problem of insufficient systematic evaluation of retired batteries in existing technologies.

[0048] 2. A "photovoltaic-storage-grid" coordinated power supply strategy was established. By combining photovoltaic power output fluctuations with grid peak and valley electricity prices, dynamic charge and discharge control and safety threshold settings significantly improved the system's economy and power supply reliability.

[0049] 3. A multi-dimensional benefit evaluation model that includes economic and environmental factors was constructed, providing a scientific basis for the optimized configuration and operation management of new and old batteries in the "photovoltaic-storage integrated" system of bus depots.

[0050] 4. By combining the tiered utilization of retired batteries with the emission reduction quantification method of photovoltaic energy storage, and by accurately calculating the photovoltaic absorption rate and carbon emission reduction, the green and low-carbon transformation of bus stations has been promoted. Attached Figure Description

[0051] Figure 1 This is a flowchart illustrating the modeling process of the method of the present invention.

[0052] Figure 2 This is a schematic diagram illustrating the configuration for SOH assessment and cascade utilization of retired batteries according to the present invention;

[0053] Figure 3 This is a schematic diagram of the electric bus charging strategy of the present invention;

[0054] Figure 4 This is a schematic diagram of the charging and discharging strategy of the energy storage system of the present invention. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of this application provided below with reference to the accompanying drawings is not intended to limit the scope of protection of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. The present invention will be further described below with reference to the accompanying drawings.

[0056] This invention specifically relates to a method for evaluating the benefits of a "photovoltaic-storage integrated" system for bus depots that considers the tiered utilization of retired batteries. This method constructs a comprehensive evaluation system with multi-dimensional indicators by comprehensively considering factors such as the health status of retired batteries, the ratio of new to old batteries in the energy storage system, the output characteristics of the photovoltaic system, and peak-valley electricity prices. Simultaneously, this invention also proposes a "photovoltaic-storage-grid" hybrid power supply strategy to adjust the charging and discharging operation of the energy storage system and electric buses, ensuring efficient system operation and stable power supply.

[0057] like Figure 1 As shown, it specifically includes the following:

[0058] S1. Select the target area and obtain retired battery assessment data, photovoltaic power generation related data, public transportation operation energy consumption data, power grid data, environmental benefit data, and cost data.

[0059] Among them, the assessment data of retired batteries includes the current maximum charging capacity of the battery, the rated capacity of the battery, the purchase cost of retired batteries, the fair market value of retired batteries, and the cost of reusing retired batteries. These data can be obtained through standard charge and discharge tests, battery nameplate parameter queries, market price surveys, data analysis of second-hand trading platforms, and cost calculation of dismantling and reassembly tests.

[0060] Photovoltaic power generation related data includes the effective solar radiation intensity received by photovoltaic modules, the total area of ​​photovoltaic modules, the conversion efficiency of photovoltaic modules, the aging loss coefficient of photovoltaic modules, the module mismatch loss coefficient, the dust shading loss coefficient, the line transmission and station power consumption loss coefficient, and the inverter efficiency. These data can be obtained through meteorological data and installation tilt angle, site planning drawings, product technical manuals, industry accelerated aging test results, local environmental characteristics, electrical design specifications, and product specifications.

[0061] The energy consumption data for bus operation includes the total daily electricity consumption of buses and the total daily photovoltaic electricity consumption of buses, which can be obtained by matching historical data from the on-board BMS, photovoltaic output curves and charging periods.

[0062] The power grid data mainly involves the time-of-use electricity price of the power grid, including peak hours, off-peak hours, and low-peak hours. This data can be obtained by visiting the official website of the target region's government and finding relevant electricity price policy documents and announcements.

[0063] Cost data includes the total area of ​​photovoltaic module panels, the unit purchase cost of photovoltaic modules, the total capacity of energy storage systems, the ratio of new to old batteries, and the unit cost of new batteries. It can be obtained through site measurement data, supplier quotations, peak load of public transportation and photovoltaic complementary demand, cascade utilization optimization models, and current market prices.

[0064] Environmental benefit data includes carbon emission reductions from the cascade utilization of retired batteries, carbon emission reductions from photovoltaic power grid replacement, carbon emission factors from new battery production, and grid carbon emission factors. These data can be obtained through the "Calculation Method for Carbon Emissions from the Cascade Utilization of Power Batteries," grid carbon emission factors and photovoltaic power generation, industry life cycle assessment databases, and the latest data published by local power grid companies.

[0065] Furthermore, the assessment data for retired batteries are as follows: current maximum charging capacity of 140Ah, rated capacity of 200Ah, procurement cost of retired batteries of RMB 0.05 million / kWh, fair market value of retired batteries of RMB 0.03 million / kWh, and reuse cost of retired batteries of RMB 0.02 million / kWh.

[0066] The relevant data for photovoltaic power generation is as follows: the effective solar radiation intensity received by the photovoltaic module is 600 W / m². 2 The total area of ​​photovoltaic modules is 1000m². 2 The photovoltaic module conversion efficiency is 20%, the photovoltaic module aging loss coefficient and mismatch loss coefficient combined is 4.5%, the dust shading loss coefficient is 2%, the line transmission and station power consumption loss coefficient is 2.5%, and the inverter efficiency is 96%.

[0067] The energy consumption data for bus operation is as follows: the total daily electricity consumption of buses is 800 kWh, and the total daily photovoltaic electricity consumption of buses is 320 kWh.

[0068] Cost data: Total area of ​​photovoltaic module panels 1000m² 2 The unit procurement cost of photovoltaic modules is 0.15 million yuan / m². 2 The total capacity of the energy storage system is 2100kWh, the proportion of new batteries in the total energy storage capacity is 0.5, and the unit cost of new batteries is 0.12 million yuan / kWh.

[0069] The environmental benefit data are as follows: carbon emission factor of new battery production is 0.12 tCO2 / kWh, and carbon emission factor of power grid is 0.583 × 10⁻⁶. -3 tCO2 / kWh.

[0070] S2, such as Figure 2 As shown, the State of Harm (SOH) of retired batteries is evaluated, and based on this, the availability coefficient of retired batteries is calculated to determine whether they can be used to construct energy storage systems for bus depots. The current maximum charging capacity Q of the retired batteries is known. charge Rated capacity Q rated Then the corresponding value of SOH is:

[0071]

[0072] According to the SOH (Sustainability of Harmony) classification standard [60%, 80%], this retired battery needs to be used in conjunction with a new battery, and the availability coefficient k of the retired battery should be calculated based on this. usable Among them, SOH min Take 60%; ΔSOH tran Take 20%:

[0073]

[0074] The usability factor of the retired battery is 0.5, indicating that its capacity has degraded to a moderate level and needs to be mixed with new batteries in proportion to ensure the charging and discharging efficiency and safety performance of the energy storage system.

[0075] S3. Based on the photovoltaic power output prediction model under uncertain meteorological and equipment performance conditions, estimate the theoretical power generation P of the photovoltaic power station in the target area. acj Specifically, it includes the following steps:

[0076] S31. Calculate the DC output power of the photovoltaic module. Given the effective solar irradiance G received by the photovoltaic module and the total area S of the photovoltaic module... 总 Photovoltaic module conversion efficiency η pv Then we have:

[0077] P dc =600×1000×0.2=120kW;

[0078] S32. Calculate the theoretical power generation of the photovoltaic power station. The DC output power P of the photovoltaic module is known. dc The sum of photovoltaic module aging loss coefficient and mismatch loss coefficient 'a', dust shading loss coefficient 'β', line transmission and station power consumption loss coefficient 'γ', and inverter efficiency 'η'. inv Then, considering all losses, the theoretical power generation of the photovoltaic power station is:

[0079] P acj =120×(1-4.5%)×(1-2%)×(1-2.5%)×96%≈105.12kW.

[0080] S4. This invention establishes a hybrid power supply strategy of "photovoltaic-storage-grid" to meet the charging needs of buses and the charging and discharging needs of energy storage systems; at the same time, it considers the SOC of retired energy storage batteries to prevent excessive charging or discharging from accelerating battery degradation. SOC min Indicates the minimum threshold for battery discharge, SOC max This indicates the maximum charging threshold for the battery. When the battery reaches this threshold, charging or discharging stops to ensure battery performance. The specific charging and discharging strategy is as follows:

[0081] S41, such as Figure 3 As shown, the hybrid charging strategy for electric buses;

[0082] This invention divides the day into 24 time periods by hour, and defines the total electrical energy consumed by the bus fleet in a single day as E. total The total photovoltaic power consumed by a bus fleet in a single day is defined as E. pv The hybrid charging strategy for electric buses is divided into the following three scenarios based on the actual situation of photovoltaic power generation:

[0083] Scenario 1 – Rainy / foggy weather, insufficient solar power, i.e.: E pv <E total ;

[0084] When photovoltaic power generation is insufficient to support the full-day operation of electric buses, all available photovoltaic power will be used first. Surplus power demand will be supplemented by an energy storage system. It is important to note that, to extend the lifespan of the energy storage system, this invention stipulates that if the energy storage system's SOC ≥ SOC... min Then it is supplemented by the energy storage system; if the SOC of the energy storage system < SOC min If the energy storage system fails to meet the demand, it will enter protection mode and will not participate in power supply. If the energy storage system is also insufficient to meet the demand, the power grid will be activated to supplement the power supply.

[0085] Scenario 2 – On a typical sunny day, the photovoltaic power output is just enough to meet the demand, i.e., E pv =E total ;

[0086] When the photovoltaic power generation is exactly equal to the daily operating needs of the electric bus, the entire bus is powered by photovoltaic electricity, without the need for an energy storage system or additional power from the grid.

[0087] Scenario 3 – Sunny weather, surplus photovoltaic power, i.e.: E pv >E total ;

[0088] When photovoltaic power generation exceeds the daily operating needs of the electric bus fleet, photovoltaic power will be used first to meet the entire demand of the electric bus fleet, and the excess power will be stored in an energy storage system for later use, until the SOC of the energy storage system equals the SOC of the electric bus fleet. max Meanwhile, the power grid does not participate in power supply.

[0089] S42, such as Figure 4 As shown, the energy storage system's charging and discharging strategy;

[0090] S421, Energy storage system charging strategy;

[0091] The charging behavior of the energy storage system is jointly determined by the time-of-use electricity price and the output of photovoltaic power. During periods of low electricity prices, it prioritizes charging from the grid to reduce costs, while during periods of sufficient photovoltaic power, it prioritizes storing excess photovoltaic power. At the same time, it strictly adheres to the safety limits of battery SOC to ensure that the system balances economy and clean energy utilization under the optimal charging path.

[0092] The charging strategy of the energy storage system is divided into three main periods, and the charging behavior in each period is as follows:

[0093] Scenario 1 – Off-peak electricity pricing period at night (19:00-06:00 the next day);

[0094] During this period, grid electricity prices are at their lowest, and energy storage batteries prioritize charging from the grid to fully utilize off-peak electricity prices and reduce charging costs. Charging behavior is determined by the State of Charge (SOC) lower limit threshold. min The driver initiates charging when the State of Charge (SOC) falls below this threshold, continuing until the SOC reaches the upper limit threshold. max .

[0095] Scenario 2 – Daytime photovoltaic power generation periods (07:00-11:00) and (15:00-18:00);

[0096] During this period, the photovoltaic power generation system begins operation. If the photovoltaic power generation exceeds the immediate load demand, the excess will be stored in energy storage batteries to avoid energy waste. Charging behavior is determined by the State of Charge (SOC) lower limit threshold. min The driver initiates charging when the State of Charge (SOC) falls below this threshold, continuing until the SOC reaches the upper limit threshold. max .

[0097] Scenario 3 – Midday solar power surplus period (12:00-14:00);

[0098] Photovoltaic power generation is typically high during this period. If it exceeds immediate load demand, the excess will be stored in energy storage batteries to avoid energy waste. Charging behavior is determined by the lower limit threshold of State of Charge (SOC). min The driver initiates charging when the State of Charge (SOC) falls below this threshold, continuing until the SOC reaches the upper limit threshold. max .

[0099] S422, Discharge strategy for energy storage system;

[0100] The energy storage system's discharge strategy is also based on a collaborative decision-making mechanism between time-of-use pricing and photovoltaic (PV) output. During peak grid pricing periods, when the SOC (State of Charge) of the energy storage system exceeds a preset safety threshold, the system will prioritize discharge to meet electricity demand and can sell excess energy back to the grid, generating economic benefits through peak-valley price differences. During off-peak grid pricing periods, the system adopts an intelligent adjustment mode, dynamically adjusting the discharge strategy based on real-time PV output and the energy storage system's status. This optimizes battery usage to extend battery life while ensuring power supply reliability.

[0101] The discharge behavior of the energy storage system is based on the following judgments:

[0102] Judgment 1 – Peak electricity price period;

[0103] Between 07:00-09:00 and 17:00-19:00 daily, when the SOC of the energy storage system is higher than the SOC max At this time, the system prioritizes discharging electricity to the bus fleet. If there is still residual electricity after discharging, the excess energy is sold back to the grid to generate economic benefits, until the State of Charge (SOC) drops to the State of Charge (SOC). min until.

[0104] Judgment 2 – Period of flat electricity price;

[0105] Between 09:00 and 17:00 and between 19:00 and 22:00 daily, the energy storage system's discharge behavior is more flexible. When photovoltaic power generation is sufficient and the energy storage system's SOC remains at a high level, the system will discharge moderately to further reduce its dependence on the grid; conversely, if photovoltaic output is insufficient or the SOC is low, the discharge behavior will be reduced to prioritize the charging needs of public transportation vehicles.

[0106] S5. System Benefit Evaluation Indicators. Economic benefits, environmental benefits, and system benefits are calculated using existing data. This includes the following steps:

[0107] S51. Calculation of Economic Benefit Indicators. Economic benefits mainly include the construction cost of the photovoltaic system and the construction cost of the energy storage system. Given the total panel area S of the photovoltaic modules and the unit purchase cost C of the photovoltaic modules. unit Fair market value (FMV) of retired batteries t The reuse cost Rt of retired batteries, the total capacity E of the energy storage system, the proportion x of new batteries in the total energy storage capacity, and the unit cost C of new batteries. new The operational benefits of the bus station are:

[0108] C pv =1000×0.15=1.5 million yuan,

[0109] C old =0.03+0.02=0.05 million yuan,

[0110] C ess =0.5×2100×0.12+(1-0.5)×2100×0.05=1.785 million yuan.

[0111] S52. Calculation of Environmental Benefit Indicators. Based on the scale of photovoltaic (PV) construction, the charging demand of buses, and the actual power supply from the PV system to electric buses, calculate the PV absorption rate. The known charging power E provided by the PV system to the buses is... ptb The total charging capacity of the bus E total Then we have:

[0112]

[0113] The reuse of retired batteries and the replacement of grid power with photovoltaic power generation both reduce greenhouse gas emissions from public transportation depots. Given the total capacity E of the energy storage system, the percentage x of the new battery capacity in the energy storage system, and the carbon emission factor g of the new battery production... battery The photovoltaic system provides E power for charging buses. ptb Grid carbon emission factor g grid The specific calculation method is as follows:

[0114] ΔG battery =(2100-0.5×2100)×0.12=126tCO 2 ,

[0115] ΔG pv =320 × 0.583 × 10 -3 =0.18656tCO 2 ,

[0116] ΔG=126+0.18656=126.18656tCO 2 .

[0117] S6. Output the system benefit evaluation results, which include system economic benefit indicators, system environmental benefit indicators, and system benefit evaluation level classification.

[0118] S61. The system economic benefit evaluation is calculated based on the system economic benefit indicators, where R... op = 500,000 yuan, the specific calculation formula is as follows:

[0119]

[0120] Because I eco =0.152≥0.15, therefore the system has excellent economic benefits.

[0121] S62. The system environmental benefit evaluation is calculated based on the system environmental benefit indicators, where ΔG max=200tCO 2 The specific calculation formula is as follows:

[0122]

[0123] Because I env =0.492<0.7, therefore the environmental benefits of this system need to be improved.

[0124] S63. System Benefit Evaluation Level Classification. Based on the data evaluation results of economic and environmental indicators, the system benefit evaluation level is divided into nine levels: Recommended (A), Economically Advantageous with Need for Environmental Improvement (B), Requires Comprehensive Optimization (C), and Not Meets Standards (D). Each level corresponds to different optimization suggestions, as shown in Table 1.

[0125] Table 1. Risk Registration and Classification Table

[0126]

[0127] In summary, the system's economic benefit evaluation I eco =0.152, System Environmental Benefits Evaluation I env =0.492. According to the rating table, the system has excellent overall economic benefits, but its environmental benefits need improvement. The system is ultimately rated as Grade B, meaning it has excellent economic performance but requires environmental improvement.

[0128] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and improvements, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1.A method for evaluating benefits of a bus station light storage integrated system, characterized in that: The evaluation method comprises: S1, data acquisition: select the target area, obtain the retired battery evaluation data, photovoltaic power generation related data, bus operation energy consumption data, power grid data, environmental benefit data and cost data; S2, retired battery availability judgment: the health state of the retired battery is evaluated, the health state and the retired battery availability coefficient are calculated, and then it is judged whether it can be used to build a bus station energy storage system; S3, establish a photovoltaic output prediction model under the condition of uncertain weather and equipment performance, and estimate the theoretical power generation of the photovoltaic power station in the target area; S4, establish a "light-storage-grid" hybrid power supply strategy including a mixed charging strategy of the bus fleet and a charging and discharging strategy of the energy storage system to meet the charging and discharging demands of the bus and the energy storage system; S5, build a system benefit evaluation index including economic benefit index and environmental benefit index; S6, output the benefit evaluation result including economic benefit evaluation, environmental benefit evaluation and benefit evaluation grade division. 2.The bus station light storage integrated system benefit evaluation method according to claim 1, characterized in that: The retired battery evaluation data in S1 includes the current maximum charging capacity of the battery, the rated capacity of the battery, the procurement cost of the retired battery, the market fair value of the retired battery and the reuse cost of the retired battery; The photovoltaic power generation related data includes the effective solar radiation intensity received by the photovoltaic module, the total area of the photovoltaic module, the conversion efficiency of the photovoltaic module, the aging loss coefficient of the photovoltaic module, the component mismatch loss coefficient, the dust shielding loss coefficient, the line transmission and station power loss coefficient and the inverter efficiency; The bus operation energy consumption data includes the total amount of daily bus operation consumption power and the total amount of daily bus operation consumption photovoltaic power; The environmental benefit data includes the carbon emission reduction of the retired battery cascade utilization, the carbon emission reduction of the photovoltaic power grid replacement, the carbon emission factor of the new battery production and the carbon emission factor of the power grid; The cost data includes the total area of the photovoltaic module panel, the unit photovoltaic module procurement cost, the total capacity of the energy storage system, the new and old battery ratio and the unit cost of the new battery. 3.The bus station light storage integrated system benefit evaluation method according to claim 1, characterized in that: S2 specifically includes the following contents: Get the current maximum charging capacity Q of the battery charge and rated capacity Q rated and through Calculate the SOH value, where SOH represents the battery's state of health; Based on the calculation results of SOH, the battery is divided into three application levels, when the SOH interval of the retired battery is in the first set interval, the battery is directly used for the energy storage system and occupies a large configuration proportion, when the SOH interval of the retired battery is in the second set interval, the battery is used with the new battery, and when the SOH interval of the retired battery is in the third set interval, the battery is not used; And the availability coefficient of the retired battery is introduced The retirement degree of the retired battery is evaluated by calculating the quantification, wherein k usable is the availability coefficient of the retired battery, when k usable > 0.75, it can be used independently, k usable when between 0.25 and 0.75, it needs to be mixedly configured, k usable < 0.25, it is eliminated, SOH min represents the minimum threshold of the retired battery gradient utilization, ΔSOH tran represents the linear transition interval span of the retired battery. 4.The bus station light storage integrated system benefit evaluation method according to claim 1, characterized in that: S3 specifically includes the following contents: By P dc = G · S 总 · η pv The direct current output power of a photovoltaic module is calculated, wherein P dc represents the direct current output power of the photovoltaic module, G represents the effective solar radiation intensity received by the photovoltaic module, S 总 represents the total area of the photovoltaic module, and η pv represents the conversion efficiency of the photovoltaic module. By P acj = P dc · (1 - a) · (1 - β) · (1 - γ) · η inv Theoretical power generation, P acj represents the theoretical power generation of the photovoltaic power plant, P dc represents the direct current output power of the photovoltaic module, a represents the sum of the aging loss coefficient of the photovoltaic module and the mismatch loss coefficient, β represents the dust shading loss coefficient, γ represents the line transmission and station power loss coefficient, and η inv represents the inverter efficiency. 5.The bus station light storage integrated system benefit evaluation method according to claim 1, characterized in that: The bus mixed charging strategy in S4 includes: The whole day is divided into 24 time periods by hours, and the total amount of electric energy consumed by the single-day bus fleet operation is set as E total The total amount of photovoltaic electric energy consumed by the single-day bus fleet operation is set as E pv The hybrid charging strategy of the electric bus is divided into the following three scenarios according to the actual situation of photovoltaic discharge: 1) When the first weather condition, photovoltaic power is insufficient, that is, E pv <E total , then the priority use of all available photovoltaic power, if the energy storage system SOC ≥ SOC min , then the remaining power demand is supplemented by the energy storage system, if the energy storage system SOC < SOC min , then the energy storage system enters the protection mode and does not participate in power supply, at this time, the grid is started to supplement power supply, wherein, SOC min represents the minimum threshold of battery discharge; 2) When it is the second weather condition, the photovoltaic power just meets the demand, i.e. E pv = E total At this time, all photovoltaic power is used for power supply, and the energy storage system or the power grid is not needed for power supply. 3) When it is the third weather condition, photovoltaic power is surplus, i.e. E pv > E total , the photovoltaic power is used preferentially to meet the entire demand of the electric bus fleet, and the excess power is stored in the energy storage system for subsequent use until the energy storage system SOC = SOC max , at the same time, the power grid does not participate in power supply, wherein SOC max represents the highest threshold value of battery charging. 6.The bus station light storage integrated system benefit evaluation method according to claim 1, characterized in that: The charging and discharging strategy of the energy storage system in S4 includes: The energy storage system charging strategy is specifically divided into three periods, and the charging behavior of each period is as follows: 1) Night valley electricity price stage: At this time, the grid electricity price is at the lowest level, and the energy storage battery is preferentially charged from the grid to fully utilize the valley electricity price to reduce the charging cost. The charging behavior is determined by the SOC lower threshold SOC min drive, when the SOC is lower than the threshold, the charging starts until the SOC reaches the upper threshold SOC max ; 2) Daytime photovoltaic power generation stage: During this period, the photovoltaic power generation system starts to work, and if the photovoltaic power generation capacity exceeds the timely load demand, the excess part will be stored in the energy storage battery, and the charging behavior starts when SOC is lower than the lower threshold SOC min drive, and charging starts when SOC is lower than the threshold value, until SOC reaches the upper threshold SOC max ; 3) Midday photovoltaic surplus period: In this period, the photovoltaic power generation is high, and if it exceeds the instantaneous load demand, the excess part will be stored in the energy storage battery, and the charging behavior is determined by the lower threshold SOC min of the SOC. When the SOC is lower than the threshold, charging is started until the SOC reaches the upper threshold SOC max of the SOC. The energy storage system discharging strategy is specifically executed according to the following two judgments: Judgment 1, peak tariff phase: at 07:00-09:00 and 17:00-19:00 of each day, when the SOC of the energy storage system is higher than SOC max , the system preferentially discharges to the bus fleet, if there is still surplus power after discharging, then the excess power is resold to the grid to obtain economic benefits, until the SOC is reduced to SOC min . Judgment 2, flat electricity price stage: during 09:00-17:00 and 19:00-22:00 every day, when the photovoltaic power generation is sufficient and the energy storage system SOC remains high, the system discharges to reduce the dependence on the power grid, otherwise, if the photovoltaic output is insufficient or the SOC is low, the discharging behavior is reduced, and the charging demand of the bus is preferentially guaranteed. 7.The method of claim 1, wherein the method further comprises: determining the benefit of the bus station optical storage integrated system based on the obtained data. The calculation of the economic benefit index in S5 specifically includes the following contents: According to C pv = S · C unit The construction cost of the photovoltaic system is calculated, wherein C pv represents the construction cost of the photovoltaic system, S represents the total area of panels of the photovoltaic assembly, and C unit represents the unit photovoltaic assembly procurement cost; Introducing the fair market value (FMV) of the retired battery t As a benchmark, the unit procurement cost of the retired battery is calculated as C old = FMV t + Rt, and the construction cost of the energy storage system is calculated as C ess = x·E·C new + (1-x)·E·C old , where C old is the unit procurement cost of the retired battery, FMV t is the fair market value of the retired battery, Rt is the repurposing cost of the retired battery, C ess is the construction cost of the energy storage system, E is the total capacity of the energy storage system, x is the proportion of new batteries in the total energy storage capacity, and C new is the unit cost of the new battery. 8.The bus station light storage integrated system benefit evaluation method of claim 1, wherein: The calculation of the environmental benefit index in the S5 embodiment includes the following contents: Based on the photovoltaic construction scale, the charging demand of the bus, and the actual power supply of the photovoltaic system to the bus, the photovoltaic consumption rate index is calculated as η green is the ratio of photovoltaic power supply of the bus to the total demand of the bus fleet, that is, the photovoltaic consumption rate, E ptb is the charging power provided by the photovoltaic system for the bus, and E total is the total charging power of the bus. By ΔG battery = (E - xE)·g battery Calculate the carbon emissions of retired battery gradient utilization, by ΔG pv = E ptb ·g grid Calculate the emission reduction of photovoltaic alternative power grid, by ΔG = ΔG battery + ΔG pv Calculate the greenhouse gas emission reduction, where ΔG battery is the emission reduction of retired battery gradient utilization, E is the total capacity of the energy storage system, x is the proportion of new battery capacity in the capacity of the energy storage system, g battery is the carbon emission factor of new battery production, ΔG pv is the emission reduction of photovoltaic alternative power grid, E ptb is the charging power provided by the photovoltaic system for the bus, g grid is the carbon emission factor of the power grid, and ΔG is the greenhouse gas emission reduction. 9.The bus station light storage integrated system benefit evaluation method of claim 1, wherein: The S6 specifically includes the following contents: The system economic benefit index I is calculated by comprehensively considering the construction cost C of the photovoltaic system pv , the construction cost C of the energy storage system ess , and the operation income. If I eco ≥ 0.15, it indicates excellent economic benefit; if 0.10 ≤ I eco < 0.15, it indicates good economic benefit; and if I eco < 0.10, it indicates that the economic benefit needs to be optimized, wherein R op is the annual operation income of the bus station. The system environmental benefit index is calculated by comprehensively considering the photovoltaic consumption rate η green and the greenhouse gas emission reduction amount ΔG If I env ≥ 0.9, it means that the environmental benefit is excellent, if 0.7 ≤ I env < 0.9, it means that the environmental benefit is good, if I env < 0.7, it means that the environmental benefit needs to be improved, wherein ΔG max is the theoretical maximum emission reduction amount.

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