Energy element-based optimization and control method for energy utilization systems

Abstract

The present invention discloses an optimization and regulation method for an energy-using system based on energy elements. According to the physical and economic attributes of energy elements, an energy-right circulation price model based on energy elements is constructed to determine the price range in the circulation of energy elements. With the price range in the circulation of energy elements and the balance of energy supply and demand as constraint conditions, and the minimum user energy cost as the objective function, a user energy-using optimization and regulation model based on the energy element price is constructed. The user energy-using optimization and regulation model is solved to obtain the optimal user energy-using strategy under the minimum user energy cost. A power system network power flow model is established. According to the optimal user energy-using strategy and the energy element circulation state, combined with the power system network constraints, the energy element supply and demand are matched to determine the actual user energy demand. With the minimum voltage deviation as the objective function, the power system network power flow model is solved to obtain the optimal power flow distribution of the power system network, realizing the unification of heterogeneous energy and the optimization and regulation method of the energy-using system.

Description

Technical Field

[0001] The present invention relates to the technical field of energy optimization, and particularly relates to an optimization and regulation method for an energy - using system based on energy elements. Background Technique

[0002] The user side is the main source of energy consumption and carbon emissions. The energy - using behavior of users directly affects the energy efficiency, carbon emissions, and renewable energy carrying capacity of the energy - using system. Driving the green and low - carbon transformation of energy based on the user side deserves attention. However, the energy - using system involves the coupling and transformation of multiple heterogeneous energies such as electricity / heat / cold / gas. Due to the lack of a unified benchmark quantification and evaluation method, it is very difficult to compare the actual values of heterogeneous energies; the energy - using values of distributed renewable energies and user - side flexible resources are different, and the energy - using values corresponding to different time periods are also different, making calculation and analysis difficult. If the value differences cannot be reflected, it is difficult to guide users to optimize resource allocation; the content of user interaction and circulation includes delivery items such as energy usage rights and data. Relying solely on the existing electricity quantity / power / timing information is difficult to support market players to participate in the multi - category market circulation. The above problems lead to the inability to achieve efficient circulation and reasonable allocation of energy - using resources, and then hinder the green and low - carbon transformation of the energy system. Summary of the Invention

[0003] Objective of the Invention: The present invention aims to provide an optimization and regulation method for an energy - using system with energy elements as the basic unit of the circulation of energy usage rights.

[0004] Technical Solution: The optimization and regulation method for an energy - using system based on energy elements according to the present invention includes the following steps:

[0005] (1) According to the physical and economic attributes of energy elements, construct a price model for the circulation of energy - using rights based on energy elements, and determine the price range in the circulation of energy elements;

[0006] (2) Taking the price range in the circulation of energy elements and the balance of energy supply and demand as constraint conditions, and taking the minimum user energy - using cost as the objective function, construct a user energy - using optimization and regulation model based on the energy - element price;

[0007] (3) Solve the user energy - using optimization and regulation model to obtain the optimal user energy - using strategy under the minimum user energy - using cost;

[0008] (4) Establish a power system network power flow model. According to the optimal user energy - using strategy and the energy - element circulation state, combined with the power system network constraints, match the energy - element supply and demand, determine the actual user energy - using demand, and solve the power system network power flow model with the minimum voltage deviation as the objective function to obtain the optimal power flow distribution of the power system network.

[0009] Further, step (1) is specifically as follows:

[0010] (11) Obtain the energy consumption system parameters, natural environment parameters, and social environment parameters;

[0011] (12) Construct an energy element model based on the energy consumption system parameters, natural environment parameters, and social environment parameters, and determine the energy equivalent of the energy element E , and determine the energy equivalent of the energy element ;

[0012] (13) Based on the determined energy equivalent of the energy element , construct an energy use right circulation price model based on the energy element, and determine the price range in the energy element circulation .

[0013] Further, the energy element model E is

[0014] ;

[0015] ;

[0016] In the formula, A is the attribute set of the energy element, including the physical attribute set of the energy element P and the economic attribute set W ; X is the influence factor set; are the influence factors, respectively representing the influence factors of the energy consumption system, energy form, natural environment, and social environment, n is the number of influence factors; R is the attribute set of the energy element A and the influence factor set X between the mapping relationship set; is from X to P mapping function; is from X to W mapping function.

[0017] Further, the energy equivalent of the energy element is

[0018] ;

[0019] ;

[0020] In the formula, is the energy equivalent of the energy element, with the unit of kWh; is the evaluation function of the energy equivalent of the energy element ; is the heterogeneous energy i energy equivalent conversion function; is the heterogeneous energyi The throughput, in units of J; I is the set of heterogeneous energy sources contained in the energy element; P is the set of physical properties.

[0021] Furthermore, the set of physical properties of the energy element P is

[0022] ;

[0023] ;

[0024] ;

[0025] In the formula, is the physical property of the energy element; m is the number of physical properties; is a mapping from the set X to the physical property of.

[0026] Furthermore, the set of economic properties W is

[0027] ;

[0028] ;

[0029] ;

[0030] In the formula, W is the set of economic properties; is the economic property of the energy element; k is the number of economic properties; is from X to the economic property of the mapping.

[0031] Furthermore, the price range in the circulation of the energy element , is solved by the following formula:

[0032] ;

[0033] In the formula, / is the energy element price given by the energy element provider / receiver, in units of yuan / kWh; / is the change in energy utilization efficiency after providing / receiving the energy element, in units of yuan; / is the energy element expenditure cost from the perspective of the energy element provider / receiver, in units of yuan; The lower price bound for the energy element provider, in yuan; The upper price bound for the energy element receiver, in yuan; U The set of energy utilization utilities for the energy element; / The set of energy element expenditure costs from the perspective of the energy element provider / receiver.

[0034] Furthermore, in step (2), the user energy utilization optimization control model with the energy element price range and energy supply-demand balance as constraints and the minimum user energy utilization cost as the objective function is

[0035] ;

[0036] ;

[0037] ;

[0038] ;

[0039] ;

[0040] ;

[0041] In the formula, C is the user energy utilization cost, t is the serial number of the control period, T is the number of control periods, e is the serial number of the energy element type, E is the number of energy element types, is the length of the control period, is t the power of electricity purchased by the user from the power grid within the , respectively represent the power of receiving the energy element e and the power of providing the energy element e in the energy utilization right circulation, is t the unit energy price of electricity purchased by the user from the power grid within the is t the unit energy price of receiving the energy element in the energy utilization right circulation of the user within the is t the unit energy price of providing the energy element in the energy utilization right circulation of the user within the is the user's t energy utilization demand within the and respectively represent the fixed energy utilization demand and the adjustable energy utilization demand of the user within the t period, is tThe maximum adjustable ability of users up / down within a time period.

[0042] Furthermore, in step (3), methods such as mixed-integer linear programming and intelligent algorithms are used to solve the user energy consumption optimization control model, obtaining the energy element circulation situation and the corresponding optimal user energy consumption strategy.

[0043] Furthermore, in step (4), the power flow model of the power system network is solved with the minimum voltage deviation as the objective function, obtaining the optimal power flow distribution of the power system network:

[0044] ;

[0045] ;

[0046] ;

[0047] ;

[0048] In the formula, 、 are t the active and reactive power injected into node j during the time period, 、 are t the active and reactive power generation of node j during the time period, 、 are t the active and reactive power of the branch from node j to node l at the head node j during the time period, 、 are the actual energy consumption demands of the users at node j , 、 are respectively the resistance and reactance of the branch from node i to node j , is the set of head nodes with node j as the end node; is the set of end nodes with node j as the head node, 、 are respectively t the square values of the voltages of node i and node j during the time period, is the square value of the reference voltage, is the total voltage deviation of the system.

[0049] Beneficial effects: Compared with the prior art, the significant advantages of the present invention are as follows: By optimizing and regulating the energy consumption of users based on the circulation of energy use rights, the present invention determines the optimal power flow distribution of the power system, can effectively achieve the unified measurement of the value of heterogeneous energy, realize the optimal allocation of users' energy consumption, and achieve green and low-carbon energy use. Brief description of the drawings

[0050] Figure 1 It is a schematic framework diagram of the energy element model;

[0051] Figure 2 It is a schematic diagram of the evaluation result of the energy equivalent of the energy element. Specific implementation manners

[0052] The present invention will be further described below with reference to the drawings.

[0053] The method for optimizing and regulating the energy consumption system based on energy elements according to the present invention includes the following steps:

[0054] (1) Obtain the parameter set of influencing factors of the energy element.

[0055] Obtain the energy consumption system parameters such as green energy assets and system source-load power, the energy form parameters of energy resources such as solar energy, wind energy, biomass energy, and water energy, the natural environment parameters such as temperature, humidity, light intensity, and wind speed, and the social environment parameters such as national policies, consumer psychology, market demand, and market supply.

[0056] (2) Establish an energy element model.

[0057] The energy element is an energy unit that can be used or traded in the energy consumption system, is a commodity with physical and economic attributes, is a unity that describes the physical and economic attributes of the energy use right in the market. The physical attribute reflects the physical properties in the optimization and regulation process of a certain or multiple heterogeneous energies, and the economic attribute reflects its value in a specific environment based on the influencing factors and the physical properties of the energy element;

[0058] Establish a standardized energy element model as follows:

[0059] ;

[0060] In the formula, E is the general model of the energy element; among them,

[0061] ;

[0062] In the formula, A is the attribute set of the energy element, including the physical attribute set P and the economic attribute set W ; X is the influencing factor set; are influencing factors, representing the influencing factors of the energy utilization system, energy form, natural environment, and social environment respectively; n is the number of influencing factors; R is the attribute set of energy elements A and the influencing factor set X the mapping relationship set between them; is from X to P mapping function; is from X to W mapping function.

[0063] (3)Physical property evaluation of energy elements.

[0064] The physical properties of energy elements are affected by multiple dimensional factors such as the energy utilization system, energy form, natural environment, and social environment, and are functions of the influencing factors X ;

[0065] Establish a physical property evaluation model for energy elements. The physical properties of energy elements P describe the specific situation of the delivery energy in the process of energy rights flow as follows:

[0066] ;

[0067] ;

[0068] ;

[0069] In the formula, P is the physical property set, is the physical property of the energy element; m is the number of physical properties; is the mapping from the set X to the physical property .

[0070] Design an energy equivalent conversion function to convert heterogeneous energy into energy equivalent properties that can be fairly compared. In order to provide a unified benchmark reference measurement standard, the energy consumed by 1 kW of electric power continuously for 1 hour is taken as 1 energy equivalent, which is called the energy equivalent reference value. As follows:

[0071] ;

[0072] ;

[0073] In the formula, is the energy equivalent of the energy element, with the unit of kWh; is the evaluation function of the energy equivalent of the energy element ; is heterogeneous energy i 's energy equivalent conversion function; is the flux of heterogeneous energy i in J; I is the set of heterogeneous energy contained in the energy element.

[0074] (4)Evaluation of the economic attributes of energy elements.

[0075] Establish an evaluation model for the economic attributes of energy elements. The economic attributes of energy elements are affected by multiple factors such as the energy consumption system, energy form, natural environment, and social environment, and are also affected by physical attributes. Therefore, the economic attributes of energy elements are described as a function of influencing factors and physical attributes, and are transformed into a function of influencing factors X as follows:

[0076] ;

[0077] ;

[0078] ;

[0079] In the formula, W is the set of economic attributes; is the economic attribute of the energy element, including equivalent value, energy consumption utility, economic benefit, expenditure cost, etc.; k is the quantity of economic attributes; is from X to the economic attribute 's mapping. Considering that the set P is also X 's function, so is introduced and constructed and to directly describe W and X 's functional relationship.

[0080] (5)Establish an energy use right circulation pricing model based on energy elements.

[0081] Construct an initial price generation model as follows:

[0082] ;

[0083] ;

[0084] ;

[0085] In the formula, / is the economic benefit of the energy element provider / receiver in yuan; / It is the price of the energy element provided by the energy element provider / receiver, with the unit of yuan / kWh; It is the energy equivalent of the energy element, with the unit of kWh.

[0086] Considering that the equivalent value of the energy element is jointly affected by multiple economic attributes, the cost analysis method is used to equivalently convert the total value of the energy element into the energy element cost of the energy element receiver / provider, and a cost-benefit equilibrium model for calculating the equivalent value of the energy element is established as follows:

[0087] ;

[0088] ;

[0089] ;

[0090] ;

[0091] ;

[0092] ;

[0093] ;

[0094] In the formula, / It is the benchmark price of the energy equivalent of the energy element from the perspective of the energy element provider / receiver, with the unit of yuan / kWh; and are respectively the consumer surplus (profit) of the energy element provider / receiver, in yuan; / It is the change in energy consumption utility after providing / receiving the energy element, with the unit of yuan; / It is the energy element expenditure cost from the perspective of the energy element provider / receiver, with the unit of yuan; U It is the set of energy consumption utilities of the energy element; / It is the set of energy element expenditure costs from the perspective of the energy element provider / receiver.

[0095] Determine the price range in the energy element circulation as follows:

[0096] ;

[0097] In the formula, It is the lower bound of the price of the energy element provider, with the unit of yuan; It is the upper bound of the price of the energy element receiver, with the unit of yuan; Obviously, when and only when the energy element may circulate, and at this time the price range given by both parties is Otherwise, the circulation fails, and both parties need to reselect the energy elements for circulation.

[0098] (6) Establish a user energy consumption optimization regulation model based on the energy element price;

[0099] The user's energy demand is jointly met by purchasing electricity from the power grid and various energy consumption right transactions based on energy elements. Therefore, the user's energy consumption optimization scheduling model is as follows:

[0100] ;

[0101] ;

[0102] ;

[0103] ;

[0104] ;

[0105] ;

[0106] In the formula, C is the user's energy consumption cost, t is the serial number of the regulation period, T is the number of regulation periods, e is the serial number of the energy element type, E is the number of energy element types, is the length of the regulation period, is t the power of electricity purchased by the user from the power grid during the , respectively represent the power of receiving the energy element e and the power of providing the energy element e during the energy consumption right circulation, is t the unit energy price of electricity purchased by the user from the power grid during the is t the unit energy price of receiving the energy element during the user's energy consumption right circulation in the is t the unit energy price of providing the energy element during the user's energy consumption right circulation in the is the user's t energy consumption demand during the and respectively represent the fixed energy consumption demand and the adjustable energy consumption demand of the user during the t period, is t the maximum upward / downward adjustable capacity of the user during the

[0107] Based on the above scheduling model, users adjust the operating status of energy-consuming equipment by changing their own energy consumption behaviors according to market information such as grid electricity prices and tradable energy rights circulation prices, so as to regulate the callable energy demand, obtain the optimal energy consumption strategy of users at the minimum energy consumption cost, and achieve the optimization of energy consumption strategies.

[0108] (7) Optimal power flow calculation method for power systems based on the circulation of tradable energy rights;

[0109] Various energy users solve their own energy consumption optimization scheduling models to obtain their own optimal energy consumption strategies and the circulation status of energy elements. The tradable energy rights circulation platform maximally matches the supply and demand of energy elements in the system based on the network constraints of the power system, and solves the power flow model with the goal of minimizing voltage deviation according to the actual energy consumption demands of each user after matching. The simplified model of power system power flow optimization is as follows:

[0110] ;

[0111] ;

[0112] ;

[0113] ;

[0114] In the formula, , are t the active and reactive powers injected into node j at time period , are t the active and reactive power generations of node j at time period , are t the active and reactive powers of the branch from node j to node l at the head node j , , are the actual energy consumption demands of the users at node j , , are respectively the resistance and reactance of the branch from node i to node j , is the set of head nodes with node j as the end node; is the set of end nodes with node j as the head node, , are respectively t the active and reactive powers of node at time periodi and the node j the square value of the voltage, is the reference voltage square value, is the total voltage deviation of the system.

[0115] Based on the above model, the optimal power flow distribution of the power system can be obtained by adjusting behaviors such as power generation; thus, on the basis of promoting the circulation of energy use rights, the voltage deviation of the power system can be reduced, the power quality can be improved, and the operation cost can be reduced.

[0116] To verify the effectiveness and rationality of the energy element-based optimization and control method for the energy use system proposed in the present invention, a certain 10 kV distribution network is selected for verification, two comparison methods are set, and a comparative analysis of the operation of the distribution network and the energy use cost of users under the three methods is carried out.

[0117] Based on the actual load data of a certain 10 kV distribution network, 1.2 MW, 1.6 MW, and 1.3 MW of photovoltaic power are installed at nodes 3, 7, and 12 respectively, and nodes 6 and 10 are energy use entities aggregated by a large number of small users.

[0118] Design 2 comparative operation scenarios:

[0119] (1) Surplus power grid connection scenario:

[0120] The power supply sources of the energy use entities are divided into grid power purchase and self-generated photovoltaic power. Power transactions cannot be carried out between energy use entities, and the surplus power grid connection price is 0.391 yuan / kWh.

[0121] (2) Surplus power grid connection + demand response scenario:

[0122] The power supply sources of the energy use entities are divided into grid power purchase and self-generated photovoltaic power. Power transactions cannot be carried out between energy use entities, and the surplus power grid connection price is 0.391 yuan / kWh. The power grid company conducts two types of demand response interactions, namely new energy consumption and peak shaving, with some energy use entities during two time periods: 11:00 - 12:00 and 17:30 - 18:30. Among them, the new energy consumption subsidy is 0.6 yuan / kWh, and the peak shaving subsidy is 3 yuan / kWh.

[0123] Based on the energy element model, the physical properties of the energy elements in the system of this case are evaluated. In this case, the physical property is the energy equivalent of the energy element, and the evaluation results are as Figure 2 shown.

[0124] The economic properties of the energy elements are evaluated. Taking the evaluation results of the economic properties of the photovoltaic energy element during the period from 11:30 to 11:45 as an example, the lower limit of each price range in the following table is the unit cost price of the energy element seller, and the upper limit of the range is the unit energy use utility equivalent price (i.e., the highest bid) of the energy element buyer.

[0125]

[0126] Based on the above evaluation results of the physical and economic attributes of energy elements, each energy user optimizes its own energy consumption behavior. After the energy use rights are matched in the system, iterative optimization is carried out based on the energy use right matching situation within the entire system. After the iteration is completed, the energy use right circulation results shown in the following table are obtained, which illustrate the energy use right circulation volume and circulation price among users at each node.

[0127]

[0128] Based on the above energy use right circulation results, by solving the optimal power flow based on the distribution network parameters, the optimal operation condition of the distribution network system can be obtained; the operation conditions of the distribution network in three scenarios are shown in the following table:

[0129]

[0130] From the perspective of power purchase from the superior power grid, the power purchase volume from the superior power grid is inversely proportional to the PV accommodation rate. Therefore, in the scenario of the present invention, the power purchase volume from the power grid is the least. In the scenario of PV self-consumption + demand response, since the power grid uses demand response interaction to adjust the energy consumption behavior to a certain extent, the power purchase volume from the power grid is also reduced to a certain extent compared with the PV self-consumption scenario.

[0131] From the perspective of the power grid's profitability, since the power grid cannot earn the price difference from buying and selling PV in the scenario of the present invention and can only charge the PV transmission fee, its profitability has decreased significantly compared with the other two scenarios. In the scenario of PV self-consumption + demand response, due to the relatively high demand response subsidy price, the power grid's profitability has also decreased.

[0132] From the perspective of the average voltage of the distribution network, in the scenario of the present invention, the PV price is low at noon, and the energy users have the motivation to shift part of the load during the peak period from 17:00 to 21:00 to noon, which reduces the energy consumption cost, also reduces the peak load of the distribution network, and improves the voltage level of the distribution network to a certain extent. In the scenario of PV self-consumption + demand response, the demand response behavior of the power grid also realizes peak shaving and valley filling to a certain extent. However, since both noon and evening are high electricity price periods, the energy users lack the motivation to actively adjust the load, and the average voltage level of the distribution network has a slight increase compared with the PV self-consumption scenario.

[0133] In summary, the present invention can achieve the accurate evaluation of the energy element attributes and the reasonable pricing of the energy use right circulation, reduce the energy consumption cost of users, fully explore and release the potential of flexibility resources on the user side, provide an effective way for the resources of a large number of small-scale energy users widely distributed to participate in the market circulation, greatly improve the resource liquidity, promote the efficient allocation and value circulation of user-side resources, and ultimately achieve green and low-carbon energy use.

Claims

1. An energy system optimization and control method based on energy element, characterized in that: The following steps are involved: (1) According to the physical and economic properties of energy units, a price model for energy rights circulation based on energy units is constructed to determine the price range of energy unit circulation; (2) Taking the price range of energy element circulation and the balance of energy supply and demand as constraints, and minimizing the user's energy cost as the objective function, a user energy optimization control model based on energy element prices is constructed; (3) Solve the user energy consumption optimization control model and obtain the optimal user energy consumption strategy with the minimum user energy consumption cost; (4) Establish a power system network flow model, match the supply and demand of energy elements according to the optimal user energy consumption strategy and energy element flow status, combined with the power system network constraints, determine the actual energy consumption demand of users, solve the power system network flow model with the minimum voltage deviation as the objective function, and obtain the optimal power flow distribution of the power system network; Step (1) is as follows: Obtain energy system parameters, natural environment parameters and social environment parameters; According to the energy system parameters, natural environment parameters and social environment parameters, the energy element model E is constructed to determine the energy equivalent of the energy element. ; According to the energy equivalent of energy element , build an energy right circulation price model based on energy units, and determine the price range in energy unit circulation ; Price range in energy circulation for ； In the formula, / The energy price given by the energy provider / receiver, in yuan / kWh; / It is the change of energy utility after providing / receiving energy yuan, in yuan; / The energy cost from the perspective of the energy provider / receiver, in yuan; The price lower bound for the energy yuan provider, in yuan; is the upper limit of the price for the energy yuan receiver, in yuan; U is the energy utility set of energy elements; / It is the set of energy element expenditure costs from the perspective of energy element provider / receiver.

2. The energy system optimization and control method based on energy element according to claim 1 is characterized in that: Energy Metamodel E for ； ； In the formula, A is the property set of the energy element, including the physical property set of the energy element P and economic attribute set W ; X is the set of influencing factors; are influencing factors, which represent the influencing factors of energy use system, energy form, natural environment and social environment respectively. n is the number of influencing factors; R is the attribute set of energy element A and the set of influencing factors X A set of mapping relationships between them; For X arrive P The mapping function of For X arrive W The mapping function of .

3. The energy system optimization and control method based on energy element according to claim 2 is characterized in that: Energy Equivalent of Energy Element for ； ； In the formula, is the energy equivalent of the energy element, in kWh; The energy equivalent of the energy element The evaluation function of Heterogeneous Energy i Energy equivalent conversion function of Heterogeneous Energy i The circulation volume, in J; I It is a collection of heterogeneous energy contained in the energy element; P A collection of physical properties.

4. The energy system optimization and control method based on energy element according to claim 3 is characterized in that: The physical properties of energy elements P for ； ； ； In the formula, is the physical property of the energy element; m is the number of physical attributes; It is from the collection X To physical properties 's mapping.

5. The energy system optimization and control method based on energy element according to claim 4 is characterized in that: Economic attribute collection W for ； ； ； In the formula, W is a set of economic attributes; It is the economic attribute of energy element; k is the number of economic attributes; For X To economic attributes 's mapping.

6. The energy system optimization and control method based on energy element according to claim 1 is characterized in that: In step (2), the user energy optimization control model with energy unit price range and energy supply and demand balance as constraints and minimum user energy cost as the objective function is: ； ； ； ； ； ； In the formula, C Energy cost for users, t To control the time period sequence number, T To control the number of time slots, e is the serial number of the energy element type, E is the number of energy element types, To control the length of the time period, for t The power purchased by the user from the power grid during the period, , Respectively represent the energy element received in the energy right circulation e Power and energy supply e The power, for t The unit energy price of electricity purchased by users from the power grid during the period, for t The energy price per unit of energy received by the user in the energy rights circulation during the time period, for t The energy price per unit of energy is provided in the circulation of energy rights of users during the period. For users t Energy demand during the period, and Separate users t Fixed energy demand and adjustable energy demand in different time periods, for t The maximum upward / downward adjustment capability of the user within the time period.

7. The energy system optimization and control method based on energy element according to claim 1 is characterized in that: In step (3), mixed integer linear programming and intelligent algorithm methods are used to solve the user energy consumption optimization control model to obtain the energy element circulation situation and the corresponding optimal user energy consumption strategy.

8. The energy system optimization and control method based on energy element according to claim 1 is characterized in that: In step (4), the power system network flow model is solved with the minimum voltage deviation as the objective function to obtain the optimal power flow distribution of the power system network: ； ； ； ； In the formula, , for t Time injection node j The active and reactive power, , for t Time period node j The active and reactive power generation power, , for t Time period node j To Node l The branch is at the head end node j The active and reactive power at , For Node j The actual energy demand of users, , Node i To Node j The branch resistance and reactance, Node j The head node set of the terminal node; Node j is the set of end nodes of the first end node, , They are t Time period node i and nodes j The square value of the voltage, is the square value of the reference voltage, is the total system voltage deviation.

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