A wind-solar-hydrogen hybrid energy storage planning method based on electrical pinch point theory

Abstract

This invention proposes a planning method for wind-solar-hydrogen hybrid energy storage based on the electric pinch theory. First, a marginal utility evaluation model for the absorption and supply guarantee of wind-solar-hydrogen hybrid energy storage is constructed, quantifying its diminishing marginal returns and saturation characteristics. Second, a comprehensive marginal cost model based on the entire life-cycle cost is established, constructing a cost function for hybrid energy storage technology decoupled in both power and energy dimensions. Based on the electric pinch theory, isolines of marginal utility for system absorption and supply guarantee and isolines of energy storage cost are plotted on a two-dimensional power-energy plane. By translating the cost isolines, the tangent points with the feasible region boundary are found, identifying the pinch point where marginal benefit exactly equals marginal cost. The comprehensive regulation demand for system absorption and supply guarantee is vertically segmented, the optimal segmentation height is calculated, and a coordinated configuration strategy for wind-solar-hydrogen hybrid energy storage is formulated based on the pinch point location. This invention provides a mathematically supported decision-making basis for the planning of wind-solar-hydrogen hybrid energy storage in the context of new power systems.

Description

Technical Field

[0001] This invention belongs to the technical field of power system planning, and in particular relates to a planning method for wind-solar-hydrogen hybrid energy storage based on the electric pinch theory. Background Technology

[0002] With the increasing penetration rates of wind and solar power, the power balance model of power systems has shifted from the traditional load-driven model to a source-load dual-side stochastic coupling driven model, exacerbating the difficulty of energy and power balance across multiple time scales. Enhancing the absorption of new energy sources while ensuring power security has become a core issue in current research on new power system planning. Energy storage systems, as a key flexible regulation resource, possess the dual function of participating in energy balance and power support through dynamic energy transfer across time periods. However, the system value of energy storage does not increase linearly with the scale of deployment, but rather exhibits a clear characteristic of diminishing marginal utility.

[0003] Traditional production simulation methods, while capable of verifying schemes through massive time-series simulations, suffer from high computational costs and often focus on result verification, failing to intuitively reveal the underlying physical mechanisms of utility saturation. Pinch analysis, taking a holistic system perspective, identifies system bottlenecks by matching the "quality" and "quantity" of resources. It can determine the system's ultimate targets without getting bogged down in complex time-series calculations, offering advantages such as strong mathematical foundations, computational convenience, and intuitive physical meaning. However, how to organically combine the pinch diagram concept with the dynamic iterative process of energy storage marginal utility, especially how to quantitatively characterize the synergistic contribution of energy storage to consumption and supply guarantee under power-energy dual constraints, remains a crucial scientific challenge that urgently needs to be overcome. Summary of the Invention

[0004] To address the aforementioned issues, this invention proposes a wind-solar-hydrogen hybrid energy storage planning method based on the electric pinch theory. Based on the electric pinch analysis method and the comprehensive marginal cost model, it provides a mathematically supported decision-making basis for the coordinated planning of electric-hydrogen under the new power system environment.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A planning method for wind-solar-hydrogen hybrid energy storage based on the electrical pinch theory includes the following steps: Step 1: Obtain time-series power data of wind power, photovoltaic power generation and load in the planning area for historical years, and construct a marginal utility evaluation model for wind-solar-hydrogen hybrid energy storage in terms of consumption and supply guarantee; Step 2: On the power-energy two-dimensional plane (i.e., the PE two-dimensional plane), draw the marginal utility contour lines of the system's absorption and supply, and construct the operating domain boundaries of the hybrid energy storage characteristic variables P and E; Step 3: Based on the comprehensive marginal cost model of the whole life cycle cost, establish the cost function of hybrid energy storage technology decoupled in the two dimensions of power and energy; Step 4: Construct a single energy storage cost contour line on the PE two-dimensional plane, find the tangent point with the feasible region boundary by translating the cost contour line, and identify the pinch point where the marginal benefit is exactly equal to the marginal cost. Step 5: Vertically divide the system's comprehensive adjustment needs for consumption and supply guarantee into layers, and calculate the optimal dividing height. x A strategy for the coordinated configuration of wind, solar, and hydrogen energy storage was developed based on the location of the pinch points.

[0006] Furthermore, step 1 specifically includes: At any given moment t The theoretical maximum potential for renewable energy consumption can be expressed as: (1); In the formula: for t The maximum renewable energy power that can be absorbed at any given time. for t Electrical load at any given moment; for t Regular units i Minimum technical output, for t The operating capacity of the conventional unit i at any given time. Indicates the unit i The proportionality coefficient between the minimum and maximum output; A binary variable, representing t Time crew i The operating status is indicated by 1 for unit operation and 0 for unit shutdown. I This represents the total number of all conventional units in the system.

[0007] When the theoretical power of new energy sources exceeds this limit, power curtailment occurs. Energy storage systems alter the net load curve through charging and discharging behavior. The new energy absorption rate is defined as: (2); In the formula: R AC It is the ratio of the actual electricity consumed by new energy sources to the theoretical electricity generated. express t The theoretical power of new energy sources at any given time for t Real-time output of new energy.

[0008] Calculate the probability of load shedding as an indicator for power supply assurance assessment: (3); In the formula: for t Insufficient power at any time For the probability of load failure and the expected power shortage, I For an exponential function, when The value is 1 if it is greater than 0, otherwise it is 0.

[0009] Furthermore, step 1 specifically includes: The marginal utility of energy storage is defined as the improvement in renewable energy consumption and power supply by increasing the unit energy storage capacity or power. To uniformly measure the system value of energy storage, the system marginal utility function is defined as follows: U ( P , E This function characterizes the overall improvement in renewable energy absorption rate and power supply reliability after configuring an energy storage system with power of P and energy of E. (4); (5); In the formula, This indicates that energy storage promotes the consumption of electricity from new energy sources. This indicates the demand for electricity supply for energy storage. and For energy storage S Rated capacity and rated power.

[0010] The utility function exhibits significant nonlinearity and saturation characteristics on the PE two-dimensional plane: increasing either P or E alone will lead to diminishing marginal utility, and only when both are increased in a specific proportion can the utility be maximized.

[0011] Furthermore, step 1 specifically includes: Within the theoretical framework of electrical pinch analysis, the marginal utility of energy storage is defined as a generalized quality index. Power marginal utility is the increase in system utility per unit power increment, while energy marginal utility is the increase in system utility per unit energy capacity increment. , (6); In the formula, and These are the marginal utility of energy and power, respectively.

[0012] Therefore, an equivalent curve is constructed: (7); On the equivalence curve, the overall benefit of the system remains constant, i.e., d U=0, which means there is a marginal technological substitution relationship between power and energy. This ratio reflects the increase in energy demand required to reduce unit power demand while keeping system objectives unchanged, revealing the system's inherent preference for short-term high power and long-term large capacity resources.

[0013] Furthermore, step 2 specifically includes: System utility contour lines represent the set of power and energy (PE) combinations that can achieve a predetermined absorption rate or supply guarantee rate target given source-load data. On the PE two-dimensional plane, marginal utility contour lines for system absorption and supply guarantee are constructed. Due to the diminishing marginal utility of power and energy in maintaining system equilibrium, these contour lines typically exhibit an "L-shaped" characteristic convex to the origin. The steep upper left segment indicates that the marginal utility of a unit of energy is much greater than that of a unit of power, meaning that increasing energy capacity can more effectively replace power demand. The gentler lower right segment reflects the strong substitution effect of a unit of power for energy capacity.

[0014] Under multi-objective constraints, the effective feasible region boundary of the system is formed by the outer envelope of the supply guarantee constraint curve and the absorption constraint curve. This means that for any given energy capacity, the power configured by the system must simultaneously meet the dual physical requirements of reducing wind and solar curtailment and lowering the load shedding rate.

[0015] Furthermore, step 3 specifically includes: Considering the physical and economic differences of energy storage technologies in terms of both power and energy, a comprehensive marginal cost is introduced to construct a generalized cost constraint model for planning decisions, establishing the following decoupled cost function: (8); In the formula, The annualized total lifecycle cost of the system is calculated as follows: For fixed construction costs (such as land, access engineering, etc.), they are constants in marginal analysis and do not affect the slope; and These are the annualized investment cost per unit of power and the annualized investment cost per unit of energy, respectively. Their physical meaning is the equivalent annual cost required for each additional unit of power or unit of capacity configuration over the entire life cycle.

[0016] On the PE two-dimensional plane, the cost contour lines under a given budget are represented by a set of slopes. k Parallel lines: (9); This slope intuitively reflects the marginal technology substitution rate of power resources and energy resources in different energy storage technology paths, assuming the total investment remains unchanged.

[0017] Furthermore, step 4 specifically includes: Starting from the origin, maintain the slope of the cost contour lines. k Moving the line unchanged and upwards to the right, the point where the line first becomes tangent to the boundary of the effective feasible region is the investment pinch point. At the pinch point, the marginal benefit of the flexibility of the energy storage alternative system is exactly equal to its marginal cost; this point is the globally economically optimal solution that satisfies all technical constraints.

[0018] Furthermore, step 5 specifically includes: For wind-solar-hydrogen hybrid energy storage systems, the total annualized cost is no longer determined by a single slope, but rather represents the superimposed envelope of costs from multiple resource types. According to Leibniz's integral law, the energy area affects the cutting height. x The derivative is physically equivalent to the comprehensive adjustment demand being greater than the height. x The cumulative duration is used to calculate the critical duration. T ( x ) and optimal cutting height x The overall adjustment requirements of the system are vertically segmented into different layers: (10); In the formula, , These are the annualized investment costs for energy storage A and B, respectively. , The annualized energy investment costs for energy storage systems A and B are respectively.

[0019] For each candidate point within the feasible region, the comprehensive adjustment requirements are displayed using a continuous power curve, and the optimal cutting height is dynamically searched. x This strategy leverages the complementarity of different technologies across short, medium, and long timescales to eliminate ineffective investment gaps between single-slope tangents and high-curvature boundaries, thereby optimizing life-cycle costs. Beneficial effects

[0020] This invention constructs a marginal utility evaluation model under the constraints of energy storage capacity and power, quantitatively revealing the marginal diminishing and saturation characteristics of energy storage system value as scale expands; it introduces electrical pinch analysis theory and a comprehensive marginal cost model to construct system utility isolines and cost isolines in the PE two-dimensional plane, achieving a deep mapping between physical adjustment boundaries and techno-economic characteristics; addressing the long-cycle energy balance problem, it proposes a collaborative configuration strategy for electric-hydrogen hybrid energy storage based on critical duration; through a case study analysis of a typical high-proportion renewable energy power grid in Northwest my country, it verifies the effectiveness of this invention in identifying energy storage configuration bottlenecks and guiding the collaborative optimization of hybrid energy storage. Attached Figure Description

[0021] Figure 1 A framework for analyzing and planning hybrid energy storage pinch points; Figure 2 This is a schematic diagram of the grip point location identification process; Figure 3 Flowchart for Hybrid Energy Storage Pinch Analysis Figure 4 The distribution characteristics of the pinch points under different landscape resource conditions; Figure 5 Comparison of the cost of optimal configuration points and different combinations of hybrid energy storage; Figure 6 The optimal dividing line for different combinations of hybrid energy storage. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other. The embodiments of this invention will be further described in detail below with reference to the accompanying drawings.

[0023] Step 1: Obtain time-series power data of wind power, photovoltaic power generation and load in the planning area for historical years, and construct a marginal utility evaluation model for wind-solar-hydrogen hybrid energy storage in terms of consumption and supply guarantee.

[0024] In practice, time-series power data of wind, solar and load measured in 2024 from a provincial power grid in Northwest China were obtained through energy statistical yearbooks and official platforms. The power data at any given time were calculated according to equation (1). t Theoretically, the maximum potential for new energy consumption.

[0025] (1); In the formula: for t The maximum renewable energy power that can be absorbed at any given time. for t Electrical load at any given moment; for t Regular units i Minimum technical output, for t The operating capacity of the conventional unit i at any given time. Indicates the unit i The proportionality coefficient between the minimum and maximum output; A binary variable, representing t Time crew i The operating status is indicated by 1 for unit operation and 0 for unit shutdown. I This represents the total number of all conventional units in the system.

[0026] When the theoretical power of new energy exceeds this space, power curtailment occurs, and the energy storage system changes the net load curve through charging and discharging behavior. The new energy absorption rate and the probability of load shedding are calculated according to equations (2) and (3), and the probability of load shedding is used as an indicator for power supply guarantee assessment.

[0027] (2); (3); In the formula: R AC It is the ratio of the actual electricity consumed by new energy sources to the theoretical electricity generated. express t The theoretical power of new energy sources at any given time for t Real-time output of new energy sources for t Insufficient power at any time For the probability of load failure and the expected power shortage, I For an exponential function, when The value is 1 if it is greater than 0, otherwise it is 0.

[0028] In the implementation, to explore the differences in the impact of different power structure, renewable energy penetration rate, and peak-shaving rate of thermal power units on the system flexibility and supply guarantee requirements, two typical comparison scenarios were set: photovoltaic-dominated and wind power-dominated. The key parameters are shown in Table 1, and the comparison scenarios are shown in Table 2.

[0029] Table 1 Key Parameter Settings

[0030] Table 2 Scene Settings

[0031] marginal utility function U ( P , E The marginal utility of energy storage is represented by the improvement effect of increasing unit energy storage capacity or power on renewable energy consumption and power supply security. This function characterizes the overall improvement of the system in terms of renewable energy consumption rate and power supply reliability after configuring an energy storage system with power of P and energy of E. (4); (5); In the formula, This indicates that energy storage promotes the consumption of electricity from new energy sources. This indicates the power supply demand for energy storage; and For energy storage S Rated capacity and rated power.

[0032] The utility function exhibits significant nonlinearity and saturation characteristics in the PE two-dimensional plane: a single increase P or E Both will face diminishing marginal utility; only when both increase in a specific proportion can the utility be maximized. Therefore, within the theoretical framework of electrical pinch analysis, the marginal utility of energy storage is defined as a generalized quality index; power marginal utility is the increase in system utility per unit power increment, and energy marginal utility is the increase in system utility per unit energy capacity increment, thereby constructing an isoutility curve: , (6); (7); In the formula, and These are the marginal utility of energy and power, respectively.

[0033] On the equivalence curve, the overall benefit of the system remains constant, i.e., d U =0, which means there is a marginal technological substitution relationship between power and energy. This ratio reflects the increase in energy demand required to reduce unit power demand while keeping system objectives unchanged, revealing the system's inherent preference for short-term high power and long-term large capacity resources.

[0034] Step 2: On the P-E two-dimensional plane, draw the marginal utility contour lines of system absorption and supply guarantee, and construct the operating domain boundary of the hybrid energy storage characteristic variables P and E.

[0035] In implementation, based on the model calculations in step 1, a set of power generation (PE) combinations that enable the system to achieve the predetermined absorption rate or supply guarantee rate target is obtained. On the PE two-dimensional plane, isopleths of the marginal utility of system absorption and supply guarantee are constructed. The supply guarantee constraint curve and the absorption constraint curve are used to construct the effective feasible region boundary of the system. This means that for any given energy capacity, the power configured by the system must simultaneously meet the dual physical requirements of reducing wind and solar curtailment and lowering the load shedding rate. Under different proportions of renewable energy penetration and different wind-solar ratios, the effective feasible region boundary of the system will exhibit different shapes, ultimately affecting the distribution of the pinch points.

[0036] Step 3: Based on the comprehensive marginal cost model of the whole life cycle cost, establish the cost function of hybrid energy storage technology decoupled in the two dimensions of power and energy.

[0037] Due to the physical and economic differences in both power and energy dimensions of energy storage technologies, the following decoupled cost function is established to calculate the total lifecycle cost of energy storage: (8); In the formula, The annualized total lifecycle cost of the system is calculated as follows: For fixed construction costs (such as land, access engineering, etc.), they are constants in marginal analysis and do not affect the slope; and These are the annualized investment cost per unit of power and the annualized investment cost per unit of energy, respectively. Their physical meaning is the equivalent annual cost required for each additional unit of power or unit of capacity configuration over the entire life cycle.

[0038] On a two-dimensional plane (PE), given a fixed total cost, plotting cost contour lines will result in a set of lines with slopes of... k The slope of the parallel straight line intuitively reflects the marginal technology substitution rate of power resources and energy resources in different energy storage technology paths, under the premise of keeping the total investment unchanged.

[0039] (9); Step 4: Construct cost contour lines for a single type of energy storage on the PE two-dimensional plane, find the tangent points with the feasible region boundary by translating the cost contour lines, and identify the pinch points where the marginal benefit is exactly equal to the marginal cost.

[0040] In implementation, we will first consider a single type of energy storage mode. On the PE two-dimensional plane, starting from the origin, we will maintain the slope of the cost contour lines. k The line remains unchanged and is shifted upwards and to the right. When the line first becomes tangent to the boundary of the feasible region, this point of tangency is the investment pinch point. Figure 2 As shown in the diagram, at the pinch point, the slope of the tangent line to the system utility curve equals the cost slope of the energy storage technology. Physically, this means that the marginal benefit of energy storage in replacing system flexibility is exactly equal to its marginal cost, and this point represents the globally economically optimal solution that satisfies all technical constraints.

[0041] Different types of energy storage technologies exhibit significantly different distributions of their optimal configuration points on the curve due to varying cost slopes. Because of the diminishing marginal utility of power and energy in maintaining system balance, the feasible region boundary for system absorption and supply typically exhibits an "L-shaped" characteristic convex towards the origin. The steep upper left segment indicates that the marginal utility of a unit of energy is far greater than that of a unit of power, meaning that increasing energy capacity can more effectively substitute for power demand. The gentler lower right segment reflects the stronger substitution effect of a unit of power for energy capacity.

[0042] Power-type energy storage has a relatively high marginal cost, resulting in an extremely steep cost contour line. During the optimization process, this line tends to form a tangent point in the upper left segment of the feasible region boundary, potentially leading to power configurations far exceeding the minimum physical requirements for system supply. Energy-type energy storage, on the other hand, has a relatively low marginal cost, resulting in a flatter cost contour line. This line tends to form a tangent point in the lower right segment of the feasible region boundary, easily leading to capacity configurations far exceeding the minimum physical requirements for system absorption.

[0043] The specific process of the entire pinch analysis is as follows: Figure 3 As shown. After translating the cost contour line to its tangency with the feasible region boundary to obtain the pinch point, it is determined whether the result exceeds the physical range of the energy storage configuration. If it exceeds the normal range, an additional energy storage type needs to be added. Based on the tangency point location, it is determined whether to add energy-type or power-type energy storage. If the tangent line is steep, power-type energy storage needs to be added; if the tangent line is gentle, energy-type energy storage needs to be added. After adding energy storage, the cost contour line is recalculated, and the tangent slope is redefined. k and pinch points.

[0044] In implementation, the feasible region calculation results for Class A scenarios with different landscape ratios are as follows: Figure 4 As shown, according to Figure 2 The pinch points calculated by the Chinese method reveal the optimal configuration boundary under the dominance of a single technology route. By comparing the total investment costs of different technology cut-off points, the dominant technology in the current scenario can be identified. If the total cost of the battery cut-off point is less than that of the pumped storage cut-off point, it indicates that the current scenario has a power-type energy gap, and battery energy storage is more economical than pumped storage. If the pumped storage cut-off point is better, it indicates that the current scenario has an energy-type energy gap, and long-duration energy storage is more advantageous. Differences in power structure determine the shape of the feasible region for energy storage, thus affecting the selection of the optimal technology route. In the photovoltaic scenario, the feasible region boundary is steep, and the economic configuration range of both batteries and pumped storage is concentrated in the high-power, short-duration region (about 5-6 hours), favoring short-duration energy storage. Due to its higher power cost, pumped storage is difficult to enter the feasible region within an economically reasonable range and is at a disadvantage. Therefore, to solve the photovoltaic grid integration problem, electrochemical energy storage with low power cost and fast response should be given priority. In wind power scenarios, the economic configuration ranges of the two are significantly separated along the feasible region boundary: battery energy storage is still concentrated at the high-power, short-duration cutoff point, while pumped hydro storage slides towards the low-power, long-duration region (about 30 hours). Pumped hydro storage is economically competitive in long-duration energy storage due to its low capacity cost, proving that it can support daily or even weekly regulation in wind power bases.

[0045] Step 5: Vertically divide the system's comprehensive adjustment needs for consumption and supply guarantee into layers, and calculate the optimal dividing height. x A strategy for the coordinated configuration of wind, solar, and hydrogen energy storage was developed based on the location of the pinch points.

[0046] In implementation, for wind-solar-hydrogen hybrid energy storage systems, the cost contour lines are no longer determined by a single slope, but rather represent the superposition of costs from multiple resources. According to Leibniz's integral law, the energy area affects the cutting height. x The derivative is physically equivalent to the comprehensive adjustment demand being greater than the height. x The cumulative duration. The critical duration is then calculated from this: (10); In the formula, , These are the annualized investment costs for energy storage A and B, respectively. , The annualized energy investment costs for energy storage systems A and B are respectively.

[0047] Optimal cutting height x It is precisely located at a position where the duration of demand equals the ratio of the rate of change of the marginal cost of the two types of energy storage technologies, based on this cutting height. x The overall regulation requirements of the system are vertically segmented. At each candidate point within the feasible region, the overall regulation requirements are visualized using a continuous power curve, and the optimal segmentation height is dynamically searched. x The configuration cost is calculated. This hybrid energy storage configuration strategy can leverage the complementarity of different technologies on short, medium, and long time scales to eliminate the ineffective investment gaps formed between a single slope tangent and a high curvature boundary, thereby achieving the optimization of the entire life cycle cost.

[0048] This study investigates the optimal configuration of hybrid energy storage for a scenario with a 60% renewable energy penetration rate and a target absorption rate of 80%. It compares and analyzes the techno-economic feasibility of four technical solutions: battery + pumped storage (BP), battery + hydrogen (BH), pumped storage + hydrogen (PH), and battery + pumped storage + hydrogen (BPH). Within the PE two-dimensional plane, the effective feasible region of the system represents the task boundary that satisfies the dual physical constraints of an 80.0% absorption rate and 99.9% power supply reliability. Figure 5 As shown in (a), the cost of the BPH scheme exhibits a partially linear distribution, where the points marked with pentagrams represent the globally optimal investment pinch points identified after a double-layer nested optimization process. The annualized total cost comparison results for the four schemes are as follows: Figure 5 As shown in (b), due to the lack of long-term energy regulation capabilities, the BP scheme forces pumped-storage units to undertake energy balancing tasks for extended periods when dealing with the long-term surplus task brought about by the 80% energy consumption target, making it impractical from a techno-economic perspective. In stark contrast, the costs of the BH, PH, and BPH schemes, after introducing hydrogen energy, have all decreased significantly, proving that hydrogen energy, with its technological advantage of complete decoupling of power and capacity, effectively eliminates the investment redundancy in the power dimension caused by short / medium-term energy storage being forced to meet energy shortages by undertaking long-term energy regulation tasks.

[0049] The optimal allocation results of the four schemes under the comprehensive adjustment requirements are as follows: Figure 6 As shown, the combined demand curve and cutting line for absorbing surpluses and supply shortages intuitively reflect the physical cooperation boundaries between different regulatory resources. In contrast, Figure 6 The BPH scheme shown in (d) exhibits a more refined division of responsibilities. The bottom layer uses hydrogen storage as a long-term energy transfer carrier, responsible for transporting massive amounts of electricity across weeks or even months; the middle layer is a pumped hydro storage regulation layer, handling intraday cyclical fluctuations; and the top layer is a battery storage peak layer, handling high-frequency power surplus fluctuations. Further analysis confirms that only when the system faces extreme regulation depth and long-term power balance challenges can the system value of long-term hydrogen storage be fully realized, becoming a key force in breaking through the bottleneck of new energy consumption and achieving overall system optimization.

Claims

1. A planning method for wind-solar-hydrogen hybrid energy storage based on the electrical pinch theory, characterized in that, Includes the following steps: Step 1: Obtain time-series power data of wind power, photovoltaic power generation and load in the planning area for historical years, and construct a marginal utility evaluation model for wind-solar-hydrogen hybrid energy storage in terms of consumption and supply guarantee; Step 2: On the P-E two-dimensional plane, draw the marginal utility contour lines of system absorption and supply guarantee, and construct the operating domain boundary of the hybrid energy storage characteristic variables P and E; Step 3: Based on the comprehensive marginal cost model of the whole life cycle cost, establish the cost function of hybrid energy storage technology decoupled in the two dimensions of power and energy; Step 4: Construct a single energy storage cost contour line on the PE two-dimensional plane, find the tangent point with the feasible region boundary by translating the cost contour line, and identify the pinch point where the marginal benefit is exactly equal to the marginal cost. Step 5: Vertically divide the system's comprehensive adjustment needs for consumption and supply guarantee into layers, and calculate the optimal dividing height. x A strategy for the coordinated configuration of wind, solar, and hydrogen energy storage was developed based on the location of the pinch points.

2. The wind-solar-hydrogen hybrid energy storage planning method based on the electrical pinch theory according to claim 1, characterized in that, Step 1 includes: At any given moment t The theoretical maximum renewable energy absorption capacity can be represented by equation (1). When the theoretical power of renewable energy exceeds this capacity, power curtailment occurs. The energy storage system changes the net load curve through charging and discharging behavior. The renewable energy absorption rate is defined as equation (2). Therefore, the power supply guarantee assessment index can be represented by equation (3): （1）； （2）； （3）； In the formula: for t The maximum renewable energy power that can be absorbed at any given time. for t Electrical load at any given moment; for t Regular units i Minimum technical output, for t The operating capacity of the conventional unit i at any given time. Indicates the unit i The proportionality coefficient between the minimum and maximum output; A binary variable, representing t Time crew i The operating status is indicated by 1 for unit operation and 0 for unit shutdown. I This represents the total number of all conventional units in the system. R AC It is the ratio of the actual electricity consumed by new energy sources to the theoretical electricity generated. express t The theoretical power of new energy sources at any given time for t Real-time output of new energy sources; for t Insufficient power at any time For the probability of load failure and the expected power shortage, I For an exponential function, when The value is 1 if it is greater than 0, otherwise it is 0.

3. The wind-solar-hydrogen hybrid energy storage planning method based on the electrical pinch theory according to claim 1, characterized in that, Step 1 includes: The marginal utility of energy storage is defined as the improvement in renewable energy consumption and power supply by increasing the unit energy storage capacity or power. To uniformly measure the system value of energy storage, the system marginal utility function is defined as follows: U ( P , E This function characterizes the overall improvement in the renewable energy absorption rate and power supply reliability of the system after configuring an energy storage system with power of P and energy of E, as shown in equations (4) and (5). This utility function exhibits significant nonlinearity and saturation characteristics on the PE two-dimensional plane. That is, increasing P or E alone will lead to diminishing marginal utility. Only when both are increased in a specific proportion can the utility be maximized. （4）； （5）； In the formula: This indicates that energy storage promotes the consumption of electricity from new energy sources. This indicates the demand for energy storage to ensure power supply. and For energy storage S Rated capacity and rated power.

4. The wind-solar-hydrogen hybrid energy storage planning method based on the electrical pinch theory according to claim 1, characterized in that, Step 1 includes: Within the theoretical framework of electric pinch analysis, the marginal utility of energy storage is defined as a generalized quality index, and the marginal utility of power is... The improvement in system utility per unit power increment, energy marginal utility The system utility increase per unit energy capacity increment is considered, and an isoutility curve is constructed accordingly. On the isoutility curve, the overall system benefit remains constant, i.e., d. U =0, which means that there is a marginal technology substitution relationship between power and energy. This ratio reflects the increase in energy demand required to reduce the unit power demand while keeping the system objectives unchanged, revealing the system's inherent preference for short-term high power and long-term large capacity resources. ， （6）； （7）。 5. The wind-solar-hydrogen hybrid energy storage planning method based on the electrical pinch theory according to claim 1, characterized in that, Step 2 includes: The system utility contour lines represent the set of PE combinations that can achieve a predetermined absorption rate or supply guarantee rate under a given source-load data background. Due to the diminishing marginal utility of power and energy in maintaining system balance, the marginal utility contour lines of system absorption and supply guarantee constructed on the PE two-dimensional plane usually exhibit an "L-shaped" feature convex to the origin. The steep segment in the upper left indicates that the marginal utility of unit energy is much greater than that of unit power, that is, increasing energy capacity can more effectively replace power demand, while the gentle segment in the lower right reflects the strong substitution effect of unit power for energy capacity. Under multi-objective constraints, the effective feasible region boundary of the system is formed by the outer envelope of the supply guarantee constraint curve and the absorption constraint curve. This means that for any given energy capacity, the power configured by the system must simultaneously meet the dual physical requirements of reducing wind and solar curtailment and reducing load shedding rate.

6. The wind-solar-hydrogen hybrid energy storage planning method based on the electrical pinch theory according to claim 1, characterized in that, Step 3 includes: Considering the physical and economic differences of energy storage technologies in the P and E dimensions, a comprehensive marginal cost is introduced to construct a generalized cost constraint model for planning decisions. A decoupled cost function is established as shown in equation (8). On the PE two-dimensional plane, the cost contour lines under a given budget are represented by a set of slopes. k The parallel straight line, the slope of which intuitively reflects the marginal technology substitution rate of power resources and energy resources in different energy storage technology paths under the premise of keeping the total investment unchanged, as shown in equation (9): （8）； （9）； In the formula: The annualized total lifecycle cost of the system is calculated as follows: For fixed construction costs (such as land, access engineering, etc.), they are constants in marginal analysis and do not affect the slope; and These are the annualized investment cost per unit of power and the annualized investment cost per unit of energy, respectively. Their physical meaning is the equivalent annual cost required for each additional unit of power or unit of capacity configuration over the entire life cycle.

7. The wind-solar-hydrogen hybrid energy storage planning method based on the electrical pinch theory according to claim 1, characterized in that, Step 4 includes: Starting from the origin, maintain the slope of the cost contour lines. k If the line remains unchanged and is shifted to the upper right, the point of tangency when it first intersects the boundary of the effective feasible region is the investment pinch point. At the pinch point, the marginal benefit of the flexibility of the energy storage alternative system is exactly equal to its marginal cost. This point is the global economic optimal solution that satisfies all technical constraints.

8. The wind-solar-hydrogen hybrid energy storage planning method based on the electrical pinch theory according to claim 1, characterized in that, Step 5 includes: The system's overall adjustment requirements are vertically segmented into layers, with the optimal segmentation height determined. x It is precisely located at a point where the duration of demand for both energy consumption and supply guarantee equals the ratio of the marginal cost change rates of the two types of energy storage technologies; according to Leibniz's integral law, the energy area is proportional to the cutting height. x The derivative is physically equivalent to the comprehensive adjustment demand being greater than the height. x The cumulative duration is used to calculate the critical duration. T ( x At each candidate point within the feasible region, the comprehensive adjustment requirements are demonstrated using a continuous power curve, and the optimal cutting height is dynamically searched. x By calculating configuration costs, the complementarity of different technologies can be achieved on short, medium, and long timescales; （10）； In the formula: , These are the annualized investment costs for energy storage A and B, respectively. , The annualized energy investment costs for energy storage systems A and B are respectively.

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