Configuration method of distributed optical storage diesel comprehensive power supply system under off-grid condition

Abstract

The invention provides a configuration method of a distributed photovoltaic-storage-diesel comprehensive power supply system under an off-grid condition, and the configuration method comprises the steps: calculating a configuration value of a diesel generation capacity according to a preset boundary condition, and carrying out the simulation calculation according to local light resource data to obtain an initial combination value of a photovoltaic capacity and an energy storage capacity; according to the initial combination value of the diesel generator capacity, the photovoltaic capacity and the energy storage capacity, a plurality of different combinations of photovoltaic capacity and energy storage capacity are set for combined operation scheme comparison and selection, and calculated values of a plurality of evaluation indexes are obtained; determining an optimized combination value of the photovoltaic capacity and the energy storage capacity according to the calculated values of the plurality of evaluation indexes; and according to the configuration value of the diesel generator capacity and the optimal combination value of the photovoltaic capacity and the energy storage capacity, performing simulation fitting in combination with local light resource data to obtain a typical daily operation mechanism. The method solves the problems that photovoltaic power generation cannot be carried out at night, the generating capacity is low or power generation cannot be carried out in rainy days, independent self-sufficient clean energy power supply is achieved, and the problems of cost reduction and efficiency improvement of the system are solved.

Description

Technical Field

[0001] The present application belongs to the field of renewable energy power generation technology, and specifically, relates to a configuration method for a distributed photovoltaic, energy storage and diesel integrated power supply system under off-grid conditions. Background Art

[0002] Solar power generation is an effective and clean way of generating electricity by directly converting light energy into solar energy using the photoelectric effect. With the continuous changes and adjustments in the global energy strategy, the use of clean and efficient renewable energy for power generation, heating and other application developments is essential. Among them, photovoltaic power generation stands out for its unique advantages such as large reserves, wide coverage and sustainability.

[0003] Generally speaking, photovoltaic power generation technology is divided into large-scale centralized grid-connected photovoltaic systems and small and medium-sized distributed off-grid photovoltaic systems based on their scale and power supply mode. Distributed photovoltaic power generation systems are installed on household roofs, around factory areas, on the surface of small fish ponds, etc. Usually, the photovoltaic configuration is small in scale and connected to the power distribution system in the nearest site area. However, for remote mountainous areas, especially areas without electricity, pastoral areas, islands, communication base stations, wilderness Gobi and other areas.

[0004] The existing off-grid photovoltaic power generation system refers to a photovoltaic power generation system that relies solely on solar cells for power supply or a photovoltaic power generation system that relies mainly on solar cells for power supply. When necessary, it can be supplemented by diesel generators, wind power generation, grid power supply or other power sources. From the perspective of the power system, an independent photovoltaic power generation system above kW level is also called an off-grid photovoltaic power generation system. It usually includes photovoltaic modules, inverters or DC / DC, battery packs, monitoring systems, and loads. Its basic principle is to use photovoltaic power generation during the day and charge the excess power into the battery pack to power the system when photovoltaic power generation is unable to occur at night, thereby realizing a self-sufficient power supply operation mode.

[0005] Although the existing distributed off-grid photovoltaic system can solve the basic power supply problem in areas without or with little electricity, the following problems still exist: 1. Due to the characteristics of photovoltaic power generation technology itself, the photovoltaic output of this type of system increases sharply during the noon period during the day, resulting in redundant waste of power generation, while the photovoltaic system cannot provide continuous power supply at night. 2. Although the above problems can be solved in the form of energy transfer after energy storage is configured, the cost of the energy storage system is expensive, resulting in too high a system cost per kilowatt-hour, making this type of system have no practical application value. 3. In the event of extreme weather or continuous rainy days, the photovoltaic storage system will face the problem of no electricity to charge or discharge, and the entire system cannot achieve a stable operation mode of independent self-sufficiency. Summary of the invention

[0006] The technical problem solved by this application is: how to provide a configuration method for a distributed photovoltaic, energy-storage and diesel integrated power supply system under off-grid conditions that can solve the problems of photovoltaic power generation failure at night, low power generation on rainy days, or failure to generate electricity in extreme weather, as well as the problem of reducing system costs and increasing efficiency.

[0007] The present application provides a configuration method for a distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions, the configuration method comprising:

[0008] The configuration value of the diesel generation capacity is calculated based on the preset boundary conditions, and the initial combination value of the photovoltaic capacity and the energy storage capacity is calculated based on the simulation of the local light resource data;

[0009] According to the initial combination values ​​of the diesel generation capacity, the photovoltaic capacity and the energy storage capacity, several different combinations of photovoltaic capacity and energy storage capacity are set to compare and select joint operation schemes, and the calculated values ​​of several evaluation indicators are obtained;

[0010] Determine the optimal combination value of photovoltaic capacity and energy storage capacity based on the calculated values ​​of several evaluation indicators;

[0011] According to the configuration value of diesel generation capacity, the optimized combination value of photovoltaic capacity and energy storage capacity, and combined with the local light resource data simulation and fitting, the typical daily operation mechanism is obtained.

[0012] Optionally, the method for calculating the configuration value of the diesel generator capacity according to the preset boundary conditions includes:

[0013] According to the preset demand load and the power generation efficiency of the diesel generator, the configuration value of the diesel generator capacity is calculated.

[0014] Optionally, the method of obtaining the initial combination value of photovoltaic capacity and energy storage capacity by simulation calculation based on local light resource data includes:

[0015] The annual utilization hours of local photovoltaic power generation are obtained by simulation and calculation based on local light resource data;

[0016] The average value of the photovoltaic capacity is calculated based on the annual utilization hours, the preset demand load, and the system efficiency;

[0017] The average value of the energy storage capacity is calculated based on the average value of the photovoltaic capacity, the frequency regulation capacity reserved for the energy storage, and the preset duration of photovoltaic daily power generation. The average values ​​of the photovoltaic capacity and the average values ​​of the energy storage capacity are used as the initial combination value.

[0018] Optionally, the evaluation indicators include power generation, new energy utilization rate, power abandonment rate, investment, cost per kilowatt-hour, and diesel generator operation hours.

[0019] Optionally, the several different combinations of photovoltaic capacity and energy storage capacity include seven groups of combined values ​​of photovoltaic capacity and energy storage capacity.

[0020] Optionally, the method of obtaining a typical day operation mechanism by simulation fitting based on the configuration value of the diesel generation capacity, the optimized combination value of the photovoltaic capacity and the energy storage capacity in combination with the local light resource data includes:

[0021] According to the configuration value of diesel generation capacity, the optimal combination value of photovoltaic capacity and energy storage capacity, combined with local light resource data, simulation fitting is performed to obtain the operating output fitting curve of the pure photovoltaic system in each month and the operating output fitting curve of the solar-storage combined system in each month;

[0022] The typical daily operation mechanism of the photovoltaic-storage-diesel integrated power supply system is obtained by fitting the operating output fitting curve of the pure photovoltaic system in each month and the operating output fitting curve of the photovoltaic-storage combined system in each month.

[0023] The present application provides a configuration method for a distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions, which has the following technical effects:

[0024] This method can not only effectively solve the problems of photovoltaic power generation failure at night and low power generation on rainy days, and truly achieve 24-hour uninterrupted and stable operation, but also appropriately configure some diesel generators to replace some energy storage as backup power supply. It not only solves the problem of cost reduction and efficiency improvement of the system, but also can achieve independent and self-sufficient clean energy power supply in continuous rainy days or extreme weather. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A flowchart of a configuration method of a distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions according to one or more embodiments;

[0026] Figure 2 An operating output fitting curve of a pure photovoltaic system in each month according to one or more embodiments;

[0027] Figure 3 Fitting curves for the operation output of each moonlight storage combined system according to one or more embodiments;

[0028] Figure 4 is a schematic diagram of a typical day operation mechanism according to one or more embodiments. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0030] Before describing the various embodiments of the present application in detail, the technical concept of the present application is first briefly described: currently, it is difficult for off-grid photovoltaic power generation systems to solve problems such as photovoltaic power generation failure at night, low power generation on rainy days, or failure to generate power in extreme weather. For this reason, the configuration method of a distributed photovoltaic-storage-diesel integrated power supply system under off-grid conditions provided by the present application, combined with local light resource data, uses a simulation method to optimize the combined value of diesel generation capacity, photovoltaic capacity, and energy storage capacity, and a typical daily operation mechanism, so that the photovoltaic-storage-diesel integrated power supply system operates according to the typical daily operation mechanism, solving problems such as photovoltaic power generation failure at night, low power generation on rainy days, or failure to generate power in extreme weather, while reducing system costs and saving power generation. The following describes the specific principles of the configuration method and control method of a distributed photovoltaic-storage-diesel integrated power supply system under off-grid conditions of the present application in combination with more embodiments.

[0031] Specifically, Figure 1 As shown, the configuration method of the distributed photovoltaic storage diesel integrated power supply system under off-grid conditions in the first embodiment includes the following steps:

[0032] Step S10: Calculate the configuration value of the diesel generation capacity according to the preset boundary conditions, and calculate the initial combination value of the photovoltaic capacity and the energy storage capacity through PV system simulation according to the local light resource data;

[0033] Step S20: according to the initial combination values ​​of the diesel generation capacity, the photovoltaic capacity and the energy storage capacity, setting a number of different combinations of photovoltaic capacity and energy storage capacity to compare and select joint operation schemes, and obtaining calculated values ​​of a number of evaluation indicators;

[0034] Step S30, determining the optimal combination value of photovoltaic capacity and energy storage capacity according to the calculated values ​​of several evaluation indicators;

[0035] Step S40: According to the configuration value of the diesel generation capacity, the optimized combination value of the photovoltaic capacity and the energy storage capacity, a typical day operation mechanism is obtained by simulation fitting in combination with the local light resource data.

[0036] In one or more embodiments, the method for calculating the configuration value of the diesel generator capacity according to the preset boundary conditions in step S10 includes: calculating the configuration value of the diesel generator capacity according to the preset demand load and the power generation efficiency of the diesel generator. Exemplarily, the preset demand load is 500kW, and it operates stably for 24 hours. Since this microgrid is fully off-grid, the diesel generator configuration should consider the extreme situation of no sunlight. Combined with its own power generation efficiency (for example, 80%), the diesel generator capacity should be configured as:

[0037]

[0038] According to the actual situation, the 640kW diesel generator commonly found in the market can be used, whose capacity is closest to the designed diesel generator capacity.

[0039] Furthermore, when configuring photovoltaic capacity and energy storage capacity, the following points need to be considered: (1) When the sunlight is strong during the day, photovoltaic power supply should be used as much as possible to make full use of new energy and reduce environmental pollution, noise, etc. (2) Energy storage is used as a frequency regulation and peak-shaving power source. Due to the uncertainty and volatility of light resources, the system may have stability problems and a certain capacity of energy storage needs to be configured; at the same time, since photovoltaic power will have a higher abandonment rate when it is isolated, energy storage is used to charge during the peak photovoltaic power generation during the day and discharge when the photovoltaic power is low. (3) The configuration of energy storage capacity should fully consider economic factors to ensure that when operating on an isolated island, it can be fully charged with excess new energy and discharged when the new energy output is insufficient.

[0040] In one or more embodiments, the method for obtaining the initial combination value of photovoltaic capacity and energy storage capacity by simulating and calculating the local light resource data in step S20 includes: obtaining the annual utilization hours of local photovoltaic power generation by simulating and calculating the local light resource data; obtaining the average value of photovoltaic capacity by calculating the annual utilization hours and the preset demand load and system efficiency; obtaining the average value of energy storage capacity by calculating the average value of photovoltaic capacity, the frequency regulation capacity reserved for energy storage, and the preset duration of photovoltaic daily power generation, and taking the average values ​​of photovoltaic capacity and energy storage capacity as the initial combination value.

[0041] For example, based on the longitude and latitude data of the project, the location coordinates are imported through the software, the local light resource data is queried, and the data is corrected and evaluated using calculation methods such as spatial interpolation + climatological statistics, and representative annual irradiation data of typical projects are selected. Through PV system simulation, the local photovoltaic power generation annual utilization hours are about 1715 hours, and the average full-power generation is 4.7 hours per day. Therefore, if the photovoltaic storage system is used to cover the power generation of the whole day, considering the system average efficiency (including energy storage loss, line loss, etc.) of 80%, the average photovoltaic configuration can be preliminarily calculated by referring to the following formula:

[0042]

[0043] Where:

[0044] P 光伏 PV is the required configuration capacity for PV;

[0045] P 负荷 The load output power required by the power consumption side;

[0046] h 1 The system is running for 24 hours a day.

[0047] h 2 The equivalent full-generation hours of photovoltaic power generation at the project location;

[0048] η is the comprehensive photovoltaic system efficiency.

[0049] According to the above formula, we can get:

[0050]

[0051] For example, the photovoltaic power generation is considered to be 10 hours during the day, and the remaining power is used to charge the energy storage system. The energy storage reserves 30% frequency regulation capacity, and the energy storage energy configuration is calculated:

[0052]

[0053] Where:

[0054] S 储能 Configure the energy storage capacity required for the system;

[0055] ζ is the energy storage discharge depth, which is taken as 30% here for the initial calculation result to be relatively conservative;

[0056] p 光伏 Configure the capacity required for photovoltaic power generation;

[0057] P 负荷 The load output power required by the power consumption side;

[0058] h 2 The equivalent full-generation hours of photovoltaic power generation at the project location;

[0059] h 3 The duration of photovoltaic power generation during the day at the project location;

[0060] η is the comprehensive photovoltaic system efficiency.

[0061] According to the above formula, we can get:

[0062]

[0063] That is, from the perspective of the annual average, an ideal configuration of 3.2MW photovoltaic + 2.5MW / 9MWh energy storage is used as the initial combination value of photovoltaic capacity and energy storage capacity. Since this initial combination value does not take into account the changes in seasons and daily weather and the actual operation of abandoned photovoltaic and power, it is necessary to further provide key influencing factors such as the capacity, power, and investment cost of the photovoltaic and storage combined operation system, and at the same time combine the HOMER simulation platform to optimize the calculation results.

[0064] Since the system of this embodiment is equipped with diesel generators, it can provide power generation support when the photovoltaic storage system is insufficient. Therefore, a certain floating space is allowed for photovoltaic and energy storage. The following is a comparison of the joint operation scheme for 8760 hours a year based on the HOMER simulation platform to seek the best combination of photovoltaic + energy storage + diesel generator. The following modeling and simulation are carried out for seven combinations of photovoltaic configurations of 1.5MW, 2MW, 2.5MW, 3MW, 3.5MW, 4MW, and 4.5MW, and the evaluation indicators such as power generation, new energy utilization rate, power abandonment rate, investment, cost per kilowatt-hour, and diesel generator start-up hours are compared. The simulation results are shown in Table 1.

[0065] Table 1 Comparison of key indicators of various combination solutions

[0066]

[0067] From the above simulation results analysis, we can know that:

[0068] (1) As the photovoltaic configuration increases, the more photovoltaic power generation is surplus during the day, the greater the demand for energy storage capacity, the higher the proportion of new energy in the total load power consumption, and the greater the initial investment;

[0069] (2) As the PV configuration increases, more power abandonment will occur and the abandonment rate will increase;

[0070] (3) As the photovoltaic configuration increases, the startup time of the diesel generator becomes shorter and the cost per kilowatt-hour becomes lower.

[0071] In general, each plan has its own advantages and disadvantages. However, for plans with relatively small PV and storage capacity, the diesel generator operation hours are too high, the advantages of new energy are not obvious enough, and the cost per kilowatt-hour is high. For plans with relatively large PV and storage capacity, the initial investment cost is high, the power abandonment is serious, and the diesel generator operation hours are too few, the diesel generator operating status is poor, which is not conducive to the operating effect and service life of the diesel generator.

[0072] After comprehensive analysis, the ideal configuration plan is Plan 4: configuration of "3MW photovoltaic + 2.5MW / 9MWh energy storage + 640kW diesel generation", that is, obtaining the final configuration value of diesel generation capacity, the optimal combination value of photovoltaic capacity and energy storage capacity.

[0073] In one or more embodiments, the method of simulating and fitting a typical daily operation mechanism according to the configuration value of diesel generation capacity, the optimized combination value of photovoltaic capacity and energy storage capacity, combined with local light resource data includes: simulating and fitting the operating output fitting curve of the pure photovoltaic system of each month and the operating output fitting curve of the solar-storage combined system of each month according to the configuration value of diesel generation capacity, the optimized combination value of photovoltaic capacity and energy storage capacity, combined with local light resource data; obtaining the typical daily operation mechanism of the solar-storage-diesel integrated power supply system according to the operating output fitting curve of the pure photovoltaic system of each month and the operating output fitting curve of the solar-storage combined system of each month.

[0074] For example, by combining local sunshine hours, calculation project load energy consumption, new energy volatility, etc., and comprehensively considering factors such as system economy, clean energy utilization rate, energy storage configuration and power balance, the following fitting is obtained: Figure 2 The operating output fitting curves of the pure photovoltaic system in each month are shown as well as Figure 3 The operating output fitting curves of the combined solar-storage systems of each month are shown. For the traditional photovoltaic-storage microgrid system, the photovoltaic-storage output characteristic matching model can achieve a smooth output effect in the joint optimization scheduling mode, and can preliminarily meet the load power demand within about 17-18 hours. Now, with the addition of the diesel generator start-up hours and the operating mechanism matching, the actual operating mechanism and output curve of the off-grid photovoltaic-storage-diesel combined power supply system in the case of 24 hours without electricity are further fitted. This embodiment performs simulation calculations according to 3MW photovoltaic + 2.5MW / 9MWh energy storage + 640kW diesel generator, and the following is obtained: Figure 4 The typical daily operation mechanism shown is as follows:

[0075] (1) From 0:00 to 5:30, the energy storage system discharges alone to supply power to the load;

[0076] (2) Around 5:30-6:00, the energy storage cannot independently supply power to the load. At this time, the diesel generator starts, and the diesel generator and energy storage jointly supply power to the load.

[0077] (3) Around 6:00-7:00, the energy storage SOC (discharge depth) has reached the lower limit of discharge, and the diesel generator alone supplies power to the load;

[0078] (4) Around 7:00-8:30, the PV starts to generate power but the power generation is less than 500 kW. Then the power generation of the diesel generator decreases, and the diesel generator and the PV jointly supply power to the load.

[0079] (5) Around 8:30-18:30, the PV power generation capacity exceeds 500 kW, the diesel generator is shut down, and the PV alone supplies power to the load and charges the energy storage at the same time;

[0080] (6) Around 18:30-20:00, the photovoltaic power generation power is less than 500kW. At this time, the energy storage discharge and photovoltaic power supply the load together;

[0081] (7) From 20:00 to 0:00, the photovoltaic system has no output, and the energy storage system discharges to supply power to the load alone.

[0082] The configuration method of the distributed photovoltaic, energy storage and diesel integrated power supply system under off-grid conditions provided in this embodiment can not only effectively solve the problems of photovoltaic power generation failure at night and low power generation on rainy days, and truly achieve 24-hour uninterrupted and stable operation, but also appropriately configure some diesel generators to replace some energy storage as backup power supply. It not only solves the problem of cost reduction and efficiency improvement of the system, but also can realize independent and self-sufficient clean energy power supply in continuous rainy days or extreme weather.

[0083] The specific implementation methods of the present application are described in detail above. Although some embodiments have been shown and described, those skilled in the art should understand that these embodiments can be modified and improved without departing from the principles and spirit of the present application whose scope is defined by the claims and their equivalents. These modifications and improvements should also be within the scope of protection of the present application.

Claims

1. A configuration method for a distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions, characterized in that: The configuration method comprises: The configuration value of the diesel generation capacity is calculated based on the preset boundary conditions, and the initial combination value of the photovoltaic capacity and the energy storage capacity is calculated based on the simulation of the local light resource data; According to the initial combination values ​​of the diesel generation capacity, the photovoltaic capacity and the energy storage capacity, several different combinations of photovoltaic capacity and energy storage capacity are set to perform joint operation calculations to obtain calculated values ​​of several evaluation indicators; Determine the optimal combination value of photovoltaic capacity and energy storage capacity based on the calculated values ​​of several evaluation indicators; According to the configuration value of diesel generation capacity, the optimized combination value of photovoltaic capacity and energy storage capacity, and combined with the local light resource data simulation and fitting, the typical daily operation mechanism is obtained.

2. The configuration method of the distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions according to claim 1 is characterized in that: The method for calculating the configuration value of the diesel generator capacity according to the preset boundary conditions includes: According to the preset demand load and the power generation efficiency of the diesel generator, the configuration value of the diesel generator capacity is calculated.

3. The configuration method of the distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions according to claim 1 is characterized in that: The method for obtaining the initial combination value of photovoltaic capacity and energy storage capacity by simulation calculation based on local light resource data includes: The annual utilization hours of local photovoltaic power generation are obtained by simulation and calculation based on local light resource data; The average value of the photovoltaic capacity is calculated based on the annual utilization hours, the preset demand load, and the system efficiency; The average value of the energy storage capacity is calculated based on the average value of the photovoltaic capacity, the frequency regulation capacity reserved for the energy storage, and the preset duration of photovoltaic daily power generation. The average values ​​of the photovoltaic capacity and the average values ​​of the energy storage capacity are used as the initial combination value.

4. The configuration method of the distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions according to claim 1 is characterized in that: Several evaluation indicators include power generation, new energy utilization rate, power abandonment rate, investment, cost per kilowatt-hour, and diesel generator operating hours.

5. The configuration method of the distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions according to claim 4 is characterized in that: Several different combinations of photovoltaic capacity and energy storage capacity include seven groups of combined values ​​of photovoltaic capacity and energy storage capacity.

6. The configuration method of the distributed photovoltaic, storage and diesel integrated power supply system under off-grid conditions according to claim 1 is characterized in that: According to the configuration value of diesel generation capacity, the optimal combination value of photovoltaic capacity and energy storage capacity, and combined with the local light resource data simulation fitting, the methods for obtaining the typical daily operation mechanism include: According to the configuration value of diesel generation capacity, the optimal combination value of photovoltaic capacity and energy storage capacity, combined with local light resource data, simulation fitting is performed to obtain the operating output fitting curve of the pure photovoltaic system in each month and the operating output fitting curve of the solar-storage combined system in each month; The typical daily operation mechanism of the photovoltaic-storage-diesel integrated power supply system is obtained by fitting the operating output fitting curve of the pure photovoltaic system in each month and the operating output fitting curve of the photovoltaic-storage combined system in each month.

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