A distributed photovoltaic hierarchical production and sales method based on a virtual multi-stack hydrogen system

Abstract

The present invention relates to the technical field of new power system dispatching and operation, and specifically to a distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack electric hydrogen system. The method first establishes a virtual multi-stack electric hydrogen system with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack electric hydrogen devices; using small battery energy storage, according to the relationship between the electric hydrogen conversion efficiency and the electrolyzer load rate, a hydrogen production formula is constructed; a power control model of the energy router modulated by new energy is constructed; based on the transformer power backfeed risk, a first-tier and second-tier distributed photovoltaic hierarchical assessment mechanism is established. The present invention realizes the efficient absorption of distributed photovoltaic grading.

Description

Technical Field

[0001] The present invention relates to the technical field of new power system dispatching and operation, and in particular to a distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack electric-hydrogen system. Background Art

[0002] Electric hydrogen production systems can be divided into two types: "multi-stack" and "single-stack". The load coordination and balancing capabilities of multi-stack electric hydrogen systems show significant technical advantages. Especially when using price-advantaged second-tier renewable energy, the power supply will fluctuate significantly. Among them, the part that will not cause the transformer power to increase and has a high prediction accuracy will continue to be connected to the main grid. This part of new energy is called first-tier renewable energy, while the remaining price-advantaged renewable energy with high random volatility and the possibility of power increase is called second-tier renewable energy. The multi-stack architecture can optimize the distribution of the load rate of each electrolyzer so that the entire electric hydrogen production system always operates in the optimal efficiency range. However, due to the high investment cost of the multi-stack electric hydrogen system and the limited second-tier renewable energy supply capacity of a single distributed photovoltaic cluster, it is difficult to widely deploy multi-stack electric hydrogen systems in every village and town.

[0003] By deploying multiple single-stack hydrogen-electricity systems within a certain range (several natural villages), combined with energy routing devices and connected to multiple distributed photovoltaic clusters, a "virtual multi-stack hydrogen-electricity system" can be established. This can simulate the load balancing optimization function of multiple hydrogen-electricity stacks to a certain extent, effectively improving the hydrogen preparation efficiency and the second-tier new energy grid-connected electricity price.

[0004] How to use energy routing devices to connect multiple single-stack hydrogen-electricity systems and distributed photovoltaic clusters to form a "virtual multi-stack hydrogen-electricity system", and implement a distributed photovoltaic grading assessment and management mechanism to divide photovoltaic power generation into system-friendly first-tier new energy and price-competitive second-tier new energy, and design a reasonable optimization control method to absorb the second-tier photovoltaic power generation to improve operational efficiency. The problem needs to be solved urgently. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a distributed photovoltaic hierarchical production and sales method based on a virtual multi-stack hydrogen system. The technical solutions adopted are as follows:

[0006] Establish a virtual multi-stack hydrogen-electric system with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen-electric devices;

[0007] Using small battery energy storage, a hydrogen production formula is constructed based on the relationship between electricity-to-hydrogen conversion efficiency and electrolyzer load rate; a power control model for an energy router modulated by new energy is constructed;

[0008] Establish a distributed photovoltaic grading assessment mechanism based on transformer power backflow risks and construct first-tier and second-tier distributed photovoltaic grading assessment mechanisms.

[0009] Furthermore, the establishment of a virtual multi-stack hydrogen power system with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen power devices, includes:

[0010] The core structure of the energy routing device is a number of parallel multiplexers, each of which is connected to a household's distributed photovoltaic system;

[0011] The multiplexer is composed of multiple low-voltage switches connected in parallel, and the number of switches is the number of electrolytic cells plus 1;

[0012] The control logic of the multiplexer is that only one of the switches can be closed at the same time, and the expression is as follows:

[0013] ;

[0014] ;

[0015] in, is the off-state characteristic function of the switch j in branch i of the multiplexer in period t, where a value of 0 indicates open and a value of 1 indicates closed; is the indicative function of the off-state of the switch of the transmission line from multiplexer i to the main grid in period t, where a value of 0 indicates disconnection and a value of 1 indicates closing; is the number of electrolytic cells in the system;

[0016] When each branch j of the multiplexer is connected to electrolytic cell j, the formula for calculating the transmission power of each electrolytic cell in time period t is:

[0017] ;

[0018] in, is the transmission power of electrolyzer-j in period t; is the power generation of distributed photovoltaic-i in period t; is the number of distributed photovoltaics.

[0019] Furthermore, a virtual multi-stack hydrogen power system is established with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen power devices, and also includes:

[0020] Determine the total power transmitted from the distributed photovoltaic cluster to the main grid during period t The calculation formula is:

[0021] ;

[0022] in, is the number of distributed photovoltaics; is the power generation of distributed photovoltaic i in period t; is the indicative function of the off-state of the switch of the transmission line from the multiplexer to the main grid corresponding to the distributed photovoltaic i. When the value is 0, it means disconnection, and when the value is 1, it means closing; is the charging power of the battery energy storage during period t; is the discharge power of the battery energy storage during period t.

[0023] Furthermore, a virtual multi-stack hydrogen power system is established with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen power devices, and also includes:

[0024] Build an operational model for battery energy storage during operation;

[0025] When operating battery energy storage, we must also consider charging power limits, discharging power limits, state of charge range limits, and charging and discharging losses. The specific operating model is as follows:

[0026] ;

[0027] ;

[0028] ;

[0029] ;

[0030] in, is the SOC of the battery energy storage during period t; The SOC of the battery energy storage during period t+1; Charging efficiency for battery energy storage; The discharge efficiency of battery energy storage; The rated capacity of the battery energy storage; The length of the preset scheduling period; Maximum charging power for battery energy storage; The maximum discharge power of the battery energy storage; The upper limit of the SOC value range; The lower limit of the SOC value range; is the charging power of the battery energy storage during period t; is the discharge power of the battery energy storage during period t.

[0031] Furthermore, by utilizing small battery energy storage, a hydrogen production capacity formula is constructed based on the relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate, including:

[0032] The dynamic load rate of the electrolytic cell in each period is the ratio of the operating power to the rated power in the period;

[0033] The relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate is expressed as follows:

[0034]

[0035]

[0036]

[0037]

[0038] in, is the load rate of the electrolytic cell during period t; is the power of the electrolytic cell during period t; is the rated power of the electrolyzer; is the hydrogen production capacity of the electrolyzer during period t; is the Faraday efficiency; F is the Faraday constant, F=96485 C / mol; is the electrolytic cell voltage during period t; is the theoretical decomposition voltage of hydrogen; a and b are polarization constants; is the characteristic load rate; is the hydrogen decomposition efficiency of the electrolyzer during period t;

[0039] The relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate is linearized, and the simplified calculation formula is as follows:

[0040]

[0041]

[0042]

[0043] in, is the load rate segment number of the electrolytic cell during period t; The electrolytic cell is in Hydrogen production capacity at the load rate; The width of each load factor segment; The number of load factor segments.

[0044] Furthermore, using small battery energy storage, a hydrogen production formula is constructed based on the relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate; a power control model for the energy router modulated by new energy is constructed, which also includes:

[0045] Taking into account the hydrogen price and the profit requirements of investors in the electric hydrogen system, the relationship between the operating power of each electrolyzer and the second-tier new energy price in the current period is determined. The formula is as follows:

[0046] ;

[0047] in, is the selling price of hydrogen; is the second-tier new energy price in period t; is the hydrogen production capacity of electrolyzer j during period t; is the total output of the second-tier new energy in period t; The profitability demand index for the electric hydrogen system; is the number of electrolytic cells; is the power of electrolytic cell j during period t;

[0048] Determine the first-tier and second-tier on-grid electricity assessment fees based on the specific supply conditions of the first-tier and second-tier energy systems;

[0049] Calculate the total system revenue for each period. The optimization goal of electrolyzer load balancing is to maximize the total revenue:

[0050]

[0051] When U takes the maximum value as well as , enter the following formula:

[0052]

[0053] in, 、 The first and second tiers of new energy output during period t; This is the first-tier new energy on-grid electricity price; The second-tier grid-connected electricity assessment fee for the i-th photovoltaic household; The first-tier on-grid electricity assessment fee for the ith household’s photovoltaic system during period t; is the expected power of the photovoltaic power generation of household i during period t; is the total number of distributed photovoltaics.

[0054] Furthermore, using small battery energy storage, a hydrogen production formula is constructed based on the relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate; a power control model for the energy router modulated by new energy is constructed, which also includes:

[0055] As of time t-1, all distributed photovoltaics are supplying power to the main grid. At time t, there is a distributed photovoltaic set to be operated. The distributed photovoltaic set contains n t distributed photovoltaics, the longest action time is t max , then the action delay is t max / n tThe actions include switching in and switching out. The calculation method for the battery charging power, discharging power, and transmission power of the main network and incremental distribution network at each moment during this period is as follows:

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] in, The value of the photovoltaic power changed by the energy router during period t, a positive value indicates switching out, and a negative value indicates switching out; Ω t is the distributed photovoltaic collection in period t; n t Ω t The number of distributed photovoltaics included in t max The maximum operating time of the energy router; is the first-step new energy power in period t, is the second-tier new energy power in period t; t max The number of moments contained in ; is the battery energy storage charging power at the kth moment in the energy router operation cycle during period t; is the battery energy storage discharge power at the kth moment in the energy router operation cycle during period t; Ω t The nth distributed photovoltaic; is the photovoltaic collection to be cut Ω t The power of the nth photovoltaic cell to be switched off in period t.

[0063] Furthermore, using small battery energy storage, a hydrogen production formula is constructed based on the relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate; a power control model for the energy router modulated by new energy is constructed, which also includes:

[0064] The energy router is subjected to additional charging and discharging tasks. The constraints that need to be satisfied by the additional charging and discharging tasks are to make the SOC return to the base point periodically. The specific constraints are:

[0065]

[0066]

[0067]

[0068] in, is the length of the SOC regression cycle; is the starting SOC of the mth regression cycle; The total external exchange power of the battery energy storage. A positive value indicates charging, and a negative value indicates discharging. 、 The additional charging and discharging power required for battery energy storage to periodically return the SOC to the base point; is the charging power of the battery energy storage during period t; is the discharge power of the battery energy storage during period t.

[0069] Furthermore, using small battery energy storage, a hydrogen production formula is constructed based on the relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate; a power control model for the energy router modulated by new energy is constructed, which also includes:

[0070] Establish an assessment fairness index, and the calculation method of the assessment fairness index is:

[0071]

[0072]

[0073]

[0074] in, To assess fairness indicators; is the grid-connected electricity price per unit of distributed photovoltaic i; The unit electricity price for all distributed photovoltaics; The first-tier renewable energy grid price. The second-tier renewable energy grid price; is the total number of scheduling periods within the statistical period; is the indicative function of the off-state of the switch of the transmission line from the multiplexer to the main grid corresponding to the distributed photovoltaic i. When the value is 0, it means disconnection, and when the value is 1, it means closing.

[0075] Furthermore, a distributed photovoltaic grading assessment mechanism based on transformer power reverse transmission risk and first-tier and second-tier assessment mechanisms will be established, including:

[0076] If distributed photovoltaics report the first-tier power generation plan to the power grid, they need to undergo power reverse transmission assessment and power generation curve execution assessment. The specific calculation method is as follows:

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084] in, The planned power generation capacity of distributed photovoltaic i reported to the power grid the day before; 、 are the upper and lower limits of the assessment standard for the power generation curve of distributed photovoltaic i in period t; They are the positive and negative deviation assessment coefficients of distributed photovoltaic power generation power; It is the first-tier new energy generated by distributed photovoltaic-i in period t; Assess the unit price for power generation curve deviation; The power generation curve deviation assessment fee paid for distributed photovoltaic-i in period t; Contribute power to the power reverse transmission of distributed photovoltaic-i in period t; is the load power consumption during period t; Assess the unit price for power reverse transmission; The power reverse transmission assessment fee for distributed photovoltaic i in period t; is the total assessment fee for the first-tier new energy sold by distributed photovoltaic i in period t;

[0085] For the second-tier new energy, only the total power generation within one day needs to be assessed. The specific assessment method is as follows:

[0086]

[0087]

[0088]

[0089]

[0090] in, It is the second-tier new energy generated by distributed photovoltaic-i during period t; 、 The upper and lower limits of the total power assessment standard for distributed photovoltaic-i; 、 This is the positive and negative assessment standard for the second-tier new energy assessment; The unit price for the second-tier new energy assessment; This is the second-tier new energy assessment fee for distributed photovoltaic-i.

[0091] The embodiments of the present invention have at least the following beneficial effects:

[0092] In order to take into account both grid security and distributed photovoltaic absorption, distributed photovoltaics are divided into first-tier and second-tier new energy sources according to whether they will cause transformer power to increase and prediction accuracy. Assessment and management are carried out according to assessment indicators and methods with different degrees of strictness. Energy routers are used to supply second-tier photovoltaic power generation to multiple single-stack hydrogen-electric devices in dispersed locations to form a "virtual multi-stack hydrogen-electric system". Combined with dynamic optimization technology of multi-electrolyzer load rates, distributed photovoltaic hierarchical and efficient absorption is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0094] Figure 1 A method flow chart of a distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system provided by one embodiment of the present invention;

[0095] Figure 2 A schematic structural diagram of a virtual multi-stack electric hydrogen system provided by one embodiment of the present invention;

[0096] Figure 3 A schematic diagram showing the relationship between the electrolytic cell load rate and conversion efficiency provided in one embodiment of the present invention;

[0097] Figure 4 A schematic diagram showing the relationship between the load rate and energy consumption of an electrolytic cell provided in one embodiment of the present invention;

[0098] Figure 5 A schematic diagram of one-time control during the delayed switching process of a multiplexer provided by one embodiment of the present invention;

[0099] Figure 6 A schematic diagram of delay segmentation control during the delayed switching process of a multiplexer provided by one embodiment of the present invention;

[0100] Figure 7 A schematic diagram illustrating the auxiliary control effect of battery energy storage on an energy router provided by one embodiment of the present invention;

[0101] Figure 8 A schematic diagram of battery-free assisted control provided by one embodiment of the present invention;

[0102] Figure 9 A schematic diagram of battery-assisted regulation provided by one embodiment of the present invention;

[0103] Figure 10 A schematic diagram of the total output curve and load curve of distributed photovoltaic power generation in a certain area within 30 days provided by one embodiment of the present invention;

[0104] Figure 11 A schematic diagram of the hierarchical production and sales ratios of first-tier and second-tier new energy sources provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0105] To further illustrate the technical means and effectiveness of the present invention to achieve its intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, describes in detail the specific implementation, structure, features, and effectiveness of a distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system proposed by the present invention. In the following description, different references to "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0106] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0107] The following describes in detail a specific scheme of a distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system provided by the present invention with reference to the accompanying drawings.

[0108] Example 1:

[0109] See also Figure 1 , which shows a flowchart of a distributed photovoltaic hierarchical production and sales method based on a virtual multi-stack hydrogen system provided by one embodiment of the present invention, the method comprising the following steps:

[0110] Step S100: establishing a virtual multi-stack hydrogen-electric system with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen-electric devices.

[0111] In order to balance the safety of the power grid and the absorption of distributed photovoltaic power, distributed photovoltaic power is divided into high-quality and low-quality new energy sources according to whether it will cause the transformer power to increase and the prediction accuracy. In the embodiment of the present invention, high-quality new energy is recorded as the first-tier new energy source, and low-quality new energy is recorded as the second-tier new energy source. It is assessed and managed according to assessment indicators and methods with different degrees of strictness, and energy routers are used to supply "low-quality" photovoltaic power generation to multiple single-stack hydrogen-electric devices in dispersed locations to form a "virtual multi-stack hydrogen-electric system". Combined with the dynamic optimization technology of multi-electrolyzer load rate, distributed photovoltaic hierarchical and efficient absorption is achieved.

[0112] The present invention uses energy routers to dynamically and freely distribute the output of several adjacent distributed photovoltaic clusters to the main grid or any single hydrogen stack, so as to build a "virtual multi-stack hydrogen stack system" that can dynamically balance the load rate of each discretely distributed electrolyzer.

[0113] The core structure of the above energy routing device is a plurality of parallel multiplexers, each of which is connected to a distributed photovoltaic household, that is, the number of multiplexers and distributed photovoltaic connected households is the same.

[0114] The multiplexer consists of multiple low-voltage switches connected in parallel. The number of switches is equal to the number of electrolyzers plus one, allowing flexible selection of power supply to any electrolyzer or the main grid. A small battery energy storage system is also required to mitigate the impact of the power distribution process on the main grid.

[0115] See also Figure 2 , Figure 2 This is a structural diagram of a virtual multi-stack electric hydrogen system.

[0116] Let's introduce the energy distribution logic of the energy router. First, the control logic of the multiplexer, that is, all switches can only be in the closed state at the same time. The expression is as follows:

[0117] ;

[0118] ;

[0119] in, is the off-state characteristic function of the switch j in branch i of the multiplexer in period t, where a value of 0 indicates open and a value of 1 indicates closed; is the indicative function of the off-state of the switch of the transmission line from multiplexer i to the main grid in period t, where a value of 0 indicates disconnection and a value of 1 indicates closing; is the number of electrolytic cells in the system.

[0120] Assuming that each branch j of the multiplexer is connected to electrolytic cell j, the transmission power of each electrolytic cell in time period t is ;

[0121] in, is the power delivered by electrolyzer-j during period t, in megawatts (MW); is the power generation of distributed PV-i in period t, in megawatts (MW); is the number of distributed photovoltaics.

[0122] That is, the transmission power of each electrolyzer in period t is the sum of the power generation power of all distributed photovoltaics in period t.

[0123] The calculation method for power transmitted to the main grid is different from that for power transmitted to the electrolyzer. The auxiliary regulation role of battery energy storage must also be considered. The calculation method is as follows:

[0124] ;

[0125] in, is the number of distributed photovoltaics; is the power generation of distributed photovoltaic i in period t; is the indicative function of the off-state of the switch of the transmission line from the multiplexer to the main grid corresponding to the distributed photovoltaic i. When the value is 0, it means disconnection, and when the value is 1, it means closing; is the charging power of the battery energy storage during period t, in megawatts (MW); is the discharge power of the battery energy storage during period t, in megawatts (MW); is the total power transmitted from the distributed photovoltaic cluster to the main grid during period t.

[0126] When battery energy storage is operating, it is also necessary to consider charging power limits, discharging power limits, state of charge (SOC) range limits, and charging and discharging losses. The specific operating model is as follows:

[0127] ;

[0128] ;

[0129] ;

[0130] ;

[0131] in, is the SOC of the battery energy storage during period t; The SOC of the battery energy storage during period t+1; Charging efficiency for battery energy storage; The discharge efficiency of battery energy storage; is the rated capacity of the battery energy storage, in milliwatt-hours (MWh); The preset scheduling period length is 0.25h in the embodiment of the present invention, and the unit is hour; Maximum charging power for battery energy storage; The maximum discharge power of the battery energy storage; The upper limit of the SOC value range; The lower limit of the SOC value range; is the charging power of the battery energy storage during period t, in MW; is the discharge power of the battery energy storage during period t, in MW.

[0132] Step S200: Using small battery energy storage, a hydrogen production formula is constructed based on the relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate; and a power control model of the energy router modulated by new energy is constructed.

[0133] The hydrogen production efficiency is closely related to the electrolyzer load rate, and the correlation is nonlinear. When the electrolyzer load rate is too low, the active surface area of ​​the electrode is not fully utilized, resulting in a rapid increase in the proportion of activation loss in total energy consumption. When the electrolyzer load rate is too high, the ohmic loss caused by the ion transfer impedance increases sharply, which leads to a rapid decrease in the production efficiency.

[0134] See also Figure 3 and Figure 4 , Figure 3 Schematic diagram of the relationship between electrolytic cell load rate and conversion efficiency; Figure 4 Schematic diagram of the relationship between electrolytic cell load rate and energy consumption.

[0135] The dynamic load rate of the electrolyzer at each time period is the ratio of the operating power to the rated power during that period. Hydrogen production is related to the cell voltage and power, while the cell voltage has a nonlinear relationship with the load rate. The relationship between the electric-hydrogen conversion efficiency and the electrolyzer load rate is expressed as follows:

[0136]

[0137]

[0138]

[0139]

[0140] in, is the load rate of the electrolytic cell during period t; is the power of the electrolytic cell during period t, in MW; is the rated power of the electrolyzer, in MW; is the hydrogen production capacity of the electrolyzer during period t, in m³ / h; is the Faraday efficiency; F is the Faraday constant, F=96485 C / mol; is the electrolytic cell voltage during period t, in V; is the theoretical decomposition voltage of hydrogen, =1.23; a and b are polarization constants; is the characteristic load rate; is the hydrogen decomposition efficiency of the electrolyzer during period t.

[0141] Since the above formula is highly nonlinear and the “conversion rate-load rate” relationship of the same electric hydrogen system can be approximately considered fixed, it can be linearized based on experimental results. The simplified calculation formula is as follows:

[0142]

[0143]

[0144]

[0145] in, is the load rate segment number of the electrolytic cell during period t; The electrolytic cell is in Hydrogen production capacity at the load rate, m³ / h; The width of each load factor segment; The number of load factor segments.

[0146] After that, the relationship between the operating power of each electrolyzer and the second-tier new energy price in the current period can be calculated by combining the hydrogen price and the profit requirements of the electric hydrogen system investors. The formula is as follows:

[0147] ;

[0148] in, is the price of hydrogen, in yuan / Nm 3 ; is the second-tier new energy price in period t; is the hydrogen production capacity of electrolyzer j during period t, in m³ / h; is the total power of the second-tier renewable energy in period t, in MW; It is the profit demand index of the electric hydrogen system.

[0149] The first-tier grid-connected electricity assessment fee is determined based on the specific supply conditions of the first-tier and second-tier new energy sources. and the second-tier on-grid electricity assessment fee After that, the total system revenue for each period can be calculated. The optimization goal of electrolytic cell load balancing is to maximize the total revenue. The optimization goal is as follows:

[0150]

[0151] When U takes the maximum value as well as , enter the following formula:

[0152]

[0153] in, 、 The first and second tiers of new energy output during period t; The first-tier renewable energy on-grid electricity price, in MW; The second-tier grid-connected electricity assessment fee for the i-th photovoltaic household; The first-tier grid-connected electricity assessment fee for the ith PV household during period t, in yuan; is the expected power of the photovoltaic power generation of household i during period t; is the total number of distributed photovoltaics.

[0154] The preset scheduling period length in step S100 is This timescale considers energy balance, but in actual operation, multiplexer switching speeds are very fast, typically measured in seconds. When distributed photovoltaic systems are instantly connected to or disconnected from the grid, rapid power fluctuations can impact the main grid, posing a safety hazard. Therefore, the power change rate must be controlled within an acceptable range while meeting the energy redistribution speed requirements.

[0155] First, the redistribution process of power flow cannot be too slow. If the energy router takes too long to operate, it may reduce the "quality" of the new energy input to the main grid. All operations must be completed within a certain time, which can be called the maximum operation time. Within this maximum operation time, if it is necessary to disconnect or connect multiple distributed photovoltaics, a certain time interval can be added during the disconnection or connection process to reduce the power change rate. Figure 5 and Figure 6 As shown, Figure 5 This is a schematic diagram of one-time control during the delayed switching process of the multiplexer; Figure 6 This is a schematic diagram of delay segmentation control during the delayed switching process of the multiplexer.

[0156] Figure 6 The power change rate after adopting the delay strategy has been significantly reduced compared with the one-time interruption, but its smoothness is insufficient, and the input to the main grid is a pulse-type fluctuation. Therefore, battery energy storage is also needed for fine correction. Please refer to Figure 7 , Figure 7 Schematic diagram of the auxiliary control effect of battery energy storage on the energy router.

[0157] According to the above control strategy, assuming that all distributed photovoltaics are supplying power to the main grid by the end of period t-1, there are distributed photovoltaic groups to be cut out / in during period t. t , the distributed photovoltaic set to be cut out / cut in here is also the distributed photovoltaic set to be operated, and the actions include: cutting in and cutting out; Ω t Contains n t distributed photovoltaics, the longest action time is t max , then the cut-out / cut-in action delay is t max / n t The calculation method for battery charging and discharging power at each moment during this period, as well as the transmission power of the main network and incremental distribution network, is as follows:

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164] in, The value of the photovoltaic power changed by the energy router during period t, a positive value indicates switching out, and a negative value indicates switching out; Ω t is the distributed photovoltaic aggregate in operation during period t, in MW; is the power of the i-th distributed photovoltaic in period t; n t Ω t The number of distributed photovoltaics included in t max The maximum operating time of the energy router, in hours; is the first-tier renewable energy power in period t, in MW; is the second-tier renewable energy power in period t, in MW; t max The number of moments included in , where each moment lasts 1 second in the present invention; is the battery energy storage charging power at the kth moment in the energy router operation cycle during period t; is the battery energy storage discharge power at the kth moment in the energy router operation cycle during period t; Ω t The nth distributed photovoltaic; is the photovoltaic collection to be cut Ω t The power of the nth photovoltaic cell to be switched off in period t.

[0165] The energy router's own battery storage capacity is relatively small, so during the control process, it is important to control the SOC to return to the base point (SOC=0.5) periodically to dynamically maintain sufficient auxiliary control capabilities. To this end, additional charging and discharging tasks must be arranged in addition to the necessary control tasks to help the SOC return to the base point periodically. Please refer to Figure 8 and Figure 9 As shown, Figure 8 Schematic diagram of non-battery assisted regulation; Figure 9 Schematic diagram of battery-assisted regulation.

[0166] The energy router is subjected to additional charging and discharging tasks. The constraints that need to be met by the additional charging and discharging tasks are to make the SOC return to the base point periodically. The specific constraints are as follows:

[0167]

[0168]

[0169]

[0170] in, is the length of the SOC regression period, h; is the starting SOC of the mth regression cycle; The total external exchange power of the battery energy storage. A positive value indicates charging, and a negative value indicates discharging. 、 The additional charging and discharging power required for battery energy storage to periodically return the SOC to the base point; is the charging power of the battery energy storage during period t; is the discharge power of the battery energy storage during period t.

[0171] Typically, each distributed photovoltaic power plant uses a separate meter for electricity billing, and each household has relatively independent interests. Furthermore, the on-grid price for second-tier renewable energy sources is typically lower than that for first-tier renewable energy sources. Therefore, each distributed photovoltaic owner seeks to maximize their profits, meaning they want to transmit as much electricity as possible to the main grid rather than consume it locally at low prices. Therefore, when deciding which plants to include or exclude, fairness must be considered, meaning that each household's revenue from electricity sales per unit of generated electricity must remain within a certain range.

[0172] Based on this, an assessment fairness index is established, and the calculation method of the assessment fairness index is:

[0173]

[0174]

[0175]

[0176] in, It is an indicator for evaluating fairness, and the smaller its value is, the fairer the profit distribution is in the process of graded production and marketing; is the unit electricity price of distributed photovoltaic i, RMB / MWh; The unit electricity price for all distributed photovoltaics; The first-tier renewable energy grid price is RMB / MWh; The second-tier renewable energy grid price is RMB / MWh; The total number of scheduling periods in the statistical period.

[0177] Step S300: Establish a distributed photovoltaic grading assessment mechanism based on transformer power backflow risk and construct first-tier and second-tier distributed photovoltaic grading assessment mechanisms.

[0178] Before establishing a “high and low quality” distributed photovoltaic grading assessment mechanism, we must first clarify the definitions of first-tier new energy and second-tier new energy.

[0179] The so-called first-tier renewable energy refers to the part that does not cause power backflow and has a high degree of power generation curve execution. If distributed photovoltaics report a first-tier power generation plan to the power grid, they will be subject to power backflow assessment and power generation curve execution assessment. The specific calculation method is as follows:

[0180]

[0181]

[0182]

[0183]

[0184]

[0185]

[0186]

[0187] in, The planned power generation capacity of distributed photovoltaic i reported to the grid the day before, in MW; 、 The upper and lower limits of the assessment standard for the power generation curve of distributed photovoltaic i in period t, in MW; is the first-tier renewable energy generated by distributed photovoltaic-i in period t, in MW; The unit price for power generation curve deviation assessment is RMB / MWh; The power generation curve deviation assessment fee paid by distributed photovoltaic-i in period t, RMB; The power reverse contribution of distributed PV-i in period t, in MW; is the load power consumption in period t, in MW; The unit price for power reverse transmission assessment is RMB / MWh; The power reverse transmission assessment fee for distributed photovoltaic i in period t; is the total assessment cost of the first-tier new energy sold by distributed photovoltaic i in period t, in yuan.

[0188] Second-tier renewable energy sources are those that may cause power backflow and have a lower generation curve compliance. This electricity will power the "virtual multi-stack hydrogen system." Electrolyzers can withstand relatively high load regulation rates, so it's not necessary to assess the generation curve compliance of second-tier renewable energy sources at each time period; only the total power generation within a day is sufficient.

[0189] For the second-tier new energy, only the total power generation within one day needs to be assessed. The specific assessment method is as follows:

[0190]

[0191]

[0192]

[0193]

[0194] in, The second-tier renewable energy generated by distributed photovoltaic-i during period t, in MW; 、 The upper and lower limits of the total power assessment standard for distributed photovoltaic-i, in MW; 、 This is the positive and negative assessment standard for the second-tier new energy assessment; The unit price for the second-tier new energy assessment is RMB / MWh; It is the second-tier new energy assessment fee for distributed photovoltaic-i, in yuan.

[0195] Example 2:

[0196] A set of examples are used to verify the effectiveness of the hierarchical production and marketing system established by the present invention.

[0197] Scenario setting: Assuming that a township area contains 100 distributed photovoltaic households, the total output curve within 30 days is as follows: Figure 10 As shown, Figure 10This diagram shows the total output and load curves for distributed photovoltaic power generation in a specific region over a 30-day period. In this region, a main grid line and three incremental lines are connected to three single-stack hydrogen generators, each with a rated capacity of 0.5 MW. The load factor-energy consumption ratio for each unit is shown in Table 1.

[0198] Table 1 Relationship between “load rate-energy consumption rate” of electrolytic cell

[0199]

[0200] Setting: The main grid electricity price = 400 yuan / MWh, the local price of green hydrogen is 25 yuan / kg (1 kg of hydrogen ≈ 11.2 Nm³ of hydrogen), and the profit coefficient is =0.2, first-tier new energy assessment standard =0.1 / 0.1, power generation curve deviation assessment unit price =100 yuan / MWh, power reverse transmission assessment unit price =200 yuan / MWh, the second-tier new energy assessment standard =0.2 / 0.2, the second-tier new energy assessment unit price =50 yuan / MWh. In addition, the energy router is equipped with a small battery with a storage capacity of =0.5MWh, SOC upper / lower limit / =0.9 / 0.1, the charge / discharge efficiency is / =0.95 / 0.95, maximum charge / discharge power / =1.0 / 1.0MW.

[0201] According to the "high and low quality" new energy hierarchical production and sales scheduling method of the present invention, a portion of the second-tier new energy that does not meet the safe operation requirements of the power grid will be diverted to the "virtual multi-stack hydrogen system" for consumption. The daily consumption of new energy of different qualities can be found in the table below. Figure 11 , Figure 11 This is a schematic diagram of the production and sales ratios of first-tier and second-tier new energy sources.

[0202] In this scenario, compared to a distributed photovoltaic production and marketing system where each individual hydrogen reactor operates independently and imposes a one-size-fits-all power curtailment, the hierarchical production and marketing system based on a virtual multi-hydrogen reactor system proposed in this paper can increase the net benefits of distributed photovoltaic users while significantly reducing the operating pressure on the power grid. A comparison of various indicators is shown in Table 2.

[0203] Table 2 Comparison of the effects of different production and marketing systems

[0204]

[0205] The above calculation example illustrates that the distributed photovoltaic hierarchical production and sales method based on the virtual multi-stack hydrogen system proposed in the present invention can effectively reduce the "power restriction" rate, improve the hydrogen production efficiency, and improve the accuracy of the power generation curve transmitted to the main grid while ensuring the distributed photovoltaic grid-connected benefits of township residents. It can also alleviate the reverse heavy overload phenomenon of transformers caused by distributed photovoltaic overgeneration, and achieve a win-win situation for users and the power grid.

[0206] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0207] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

Claims

1. A distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system, characterized in that: The method comprises the following steps: Establish a virtual multi-stack hydrogen-electric system with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen-electric devices; Using small battery energy storage, a hydrogen production formula is constructed based on the relationship between electricity-to-hydrogen conversion efficiency and electrolyzer load rate. A power control model for an energy router modulated by new energy sources is also constructed, including: The dynamic load rate of the electrolytic cell in each period is the ratio of the operating power to the rated power in the period; The relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate is expressed as follows: in, is the load rate of the electrolytic cell during period t; is the power of the electrolytic cell during period t; is the rated power of the electrolyzer; is the hydrogen production capacity of the electrolyzer during period t; is the Faraday efficiency; F is the Faraday constant, F=96485 C / mol; is the electrolytic cell voltage during period t; is the theoretical decomposition voltage of hydrogen; a and b are polarization constants; is the characteristic load rate; is the hydrogen decomposition efficiency of the electrolyzer during period t; The relationship between the electricity-to-hydrogen conversion efficiency and the electrolyzer load rate is linearized, and the simplified calculation formula is as follows: in, is the load rate segment number of the electrolytic cell during period t; The electrolytic cell is in Hydrogen production capacity at the load rate; The width of each load factor segment; is the number of load factor segments; Establish a distributed photovoltaic grading assessment mechanism based on the risk of transformer power backflow, and construct the first and second tiers; among them, the first tier new energy is the part that does not cause power backflow and has a higher power generation curve execution degree. When distributed photovoltaics report the first tier power generation plan to the power grid, they need to accept power backflow assessment and power generation curve execution assessment; the second tier new energy is the part that may cause power backflow and has a lower power generation curve execution degree, and only the total power generation within one day needs to be assessed.

2. The distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system according to claim 1 is characterized in that: The virtual multi-stack hydrogen-electric system is established with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen-electric devices, including: The core structure of the energy routing device is a number of parallel multiplexers, each of which is connected to a household's distributed photovoltaic system; The multiplexer is composed of multiple low-voltage switches connected in parallel, and the number of switches is the number of electrolytic cells plus 1; The control logic of the multiplexer is that only one of the switches can be closed at the same time, and the expression is as follows: ； ； in, is the off-state characteristic function of the switch j in branch i of the multiplexer in period t, where a value of 0 indicates open and a value of 1 indicates closed; is the indicative function of the off-state of the switch of the transmission line from multiplexer i to the main grid in period t, where a value of 0 indicates disconnection and a value of 1 indicates closing; is the number of electrolytic cells in the system; When each branch j of the multiplexer is connected to electrolytic cell j, the formula for calculating the transmission power of each electrolytic cell in time period t is: ； in, is the transmission power of electrolyzer-j in period t; is the power generation of distributed photovoltaic-i in period t; is the number of distributed photovoltaics.

3. The distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system according to claim 2 is characterized in that: Establish a virtual multi-stack hydrogen system with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen devices, and also include: Determine the total power transmitted from the distributed photovoltaic cluster to the main grid during period t The calculation formula is: ； in, is the number of distributed photovoltaics; is the power generation of distributed photovoltaic i in period t; is the indicative function of the off-state of the switch of the transmission line from the multiplexer to the main grid corresponding to the distributed photovoltaic i. When the value is 0, it means disconnection, and when the value is 1, it means closing; is the charging power of the battery energy storage during period t; is the discharge power of the battery energy storage during period t.

4. The distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system according to claim 3 is characterized in that: Establish a virtual multi-stack hydrogen system with an energy routing device as the core mechanism, connecting multiple distributed photovoltaic clusters and single-stack hydrogen devices, and also include: Build an operational model for battery energy storage during operation; When operating battery energy storage, we must also consider charging power limits, discharging power limits, state of charge range limits, and charging and discharging losses. The specific operating model is as follows: ； ； ； ； in, is the SOC of the battery energy storage during period t; The SOC of the battery energy storage during period t+1; Charging efficiency for battery energy storage; The discharge efficiency of battery energy storage; The rated capacity of the battery energy storage; The length of the preset scheduling period; Maximum charging power for battery energy storage; The maximum discharge power of the battery energy storage; The upper limit of the SOC value range; The lower limit of the SOC value range; is the charging power of the battery energy storage during period t; is the discharge power of the battery energy storage during period t.

5. The distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system according to claim 1 is characterized in that: Using small battery energy storage, a hydrogen production formula is constructed based on the relationship between electricity-to-hydrogen conversion efficiency and electrolyzer load rate. A power control model for an energy router modulated by renewable energy is also constructed, including: Taking into account the hydrogen price and the profit requirements of investors in the electric hydrogen system, the relationship between the operating power of each electrolyzer and the second-tier new energy price in the current period is determined. The formula is as follows: ； in, is the selling price of hydrogen; is the second-tier new energy price in period t; is the hydrogen production capacity of electrolyzer j during period t; is the total output of the second-tier new energy in period t; The profitability demand index for the electric hydrogen system; is the number of electrolytic cells; is the power of electrolytic cell j during period t; Determine the first-tier and second-tier on-grid electricity assessment fees based on the specific supply conditions of the first-tier and second-tier new energy sources; Calculate the total system revenue for each period. The optimization goal of electrolyzer load balancing is to maximize the total revenue: When U takes the maximum value as well as , enter the following formula: in, 、 The first and second tiers of new energy output during period t; This is the first-tier new energy on-grid electricity price; The second-tier grid-connected electricity assessment fee for the i-th photovoltaic household; The first-tier on-grid electricity assessment fee for the ith household’s photovoltaic system during period t; is the expected power of the photovoltaic power generation of household i during period t; is the total number of distributed photovoltaics.

6. The distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system according to claim 5 is characterized in that: Using small battery energy storage, a hydrogen production formula is constructed based on the relationship between electricity-to-hydrogen conversion efficiency and electrolyzer load rate. A power control model for an energy router modulated by new energy sources is also constructed, including: As of time t-1, all distributed photovoltaics are supplying power to the main grid. At time t, there is a distributed photovoltaic set to be operated. The distributed photovoltaic set contains n t distributed photovoltaics, the longest action time is t max , then the action delay is t max / n t The actions include switching in and switching out. The calculation method for the battery charging power, discharging power, and transmission power of the main network and incremental distribution network at each moment during this period is as follows: in, The value of the photovoltaic power changed by the energy router during period t, a positive value indicates switching out, and a negative value indicates switching out; Ω t is the distributed photovoltaic collection in period t; n t Ω t The number of distributed photovoltaics included in t max The maximum operating time of the energy router; is the first-step new energy power in period t, is the second-tier new energy power in period t; t max The number of moments contained in ; is the battery energy storage charging power at the kth moment in the energy router operation cycle during period t; is the battery energy storage discharge power at the kth moment in the energy router operation cycle during period t; Ω t The nth distributed photovoltaic; is the photovoltaic collection to be cut Ω t The power of the nth photovoltaic cell to be switched off in period t.

7. The distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system according to claim 6 is characterized in that: Using small battery energy storage, a hydrogen production formula is constructed based on the relationship between electricity-to-hydrogen conversion efficiency and electrolyzer load rate. A power control model for an energy router modulated by new energy sources is also constructed, including: The energy router is subjected to additional charging and discharging tasks. The constraints that need to be satisfied by the additional charging and discharging tasks are to make the SOC return to the base point periodically. The specific constraints are: in, is the length of the SOC regression cycle; is the starting SOC of the mth regression cycle; The total external exchange power of the battery energy storage. A positive value indicates charging, and a negative value indicates discharging. 、 The additional charging and discharging power required for battery energy storage to periodically return the SOC to the base point; is the charging power of the battery energy storage during period t; is the discharge power of the battery energy storage during period t.

8. The distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system according to claim 7 is characterized in that: Establish a distributed photovoltaic grading assessment mechanism based on transformer power reverse transmission risk and build first-tier and second-tier distributed photovoltaic grading assessment mechanisms, including: Establish an assessment fairness index, and the calculation method of the assessment fairness index is: in, To assess fairness indicators; is the grid-connected electricity price per unit of distributed photovoltaic i; The unit electricity price for all distributed photovoltaics; The first-tier renewable energy grid price. The second-tier renewable energy grid price; is the total number of scheduling periods within the statistical period; is the indicative function of the off-state of the switch of the transmission line from the multiplexer to the main grid corresponding to the distributed photovoltaic i. When the value is 0, it means disconnection, and when the value is 1, it means closing.

9. The distributed photovoltaic hierarchical production and marketing method based on a virtual multi-stack hydrogen system according to claim 8 is characterized in that: Establish a distributed photovoltaic grading assessment mechanism based on transformer power reverse transmission risk and build first-tier and second-tier distributed photovoltaic grading assessment mechanisms, including: If distributed photovoltaics report the first-tier power generation plan to the power grid, they need to undergo power reverse transmission assessment and power generation curve execution assessment. The specific calculation method is as follows: in, The planned power generation capacity of distributed photovoltaic i reported to the power grid the day before; 、 are the upper and lower limits of the assessment standard for the power generation curve of distributed photovoltaic i in period t; They are the positive and negative deviation assessment coefficients of distributed photovoltaic power generation power; It is the first-tier new energy generated by distributed photovoltaic-i in period t; Assess the unit price for power generation curve deviation; The power generation curve deviation assessment fee paid for distributed photovoltaic-i in period t; Contribute power to the power reverse transmission of distributed photovoltaic-i in period t; is the load power consumption during period t; Assess the unit price for power reverse transmission; The power reverse transmission assessment fee for distributed photovoltaic i in period t; is the total assessment fee for the first-tier new energy sold by distributed photovoltaic i in period t; For the second-tier new energy, only the total power generation within one day needs to be assessed. The specific assessment method is as follows: in, It is the second-tier new energy generated by distributed photovoltaic-i during period t; 、 The upper and lower limits of the total power assessment standard for distributed photovoltaic-i; 、 This is the positive and negative assessment standard for the second-tier new energy assessment; The unit price for the second-tier new energy assessment; This is the second-tier new energy assessment fee for distributed photovoltaic-i.

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