An alternative energy storage planning method for improving power supply capacity of a distribution network and related device

Abstract

The application discloses a kind of alternative energy storage planning method for improving distribution network power supply capacity and related device, belong to electrical engineering technical field, including: build function alternative energy storage optimization planning double-layer model, the upper layer of the double-layer model is planning layer, lower layer is running layer;Optimization solution is carried out to double-layer model, and the electrochemical energy storage system planning scheme is obtained, and the electrochemical energy storage system planning scheme includes electrochemical energy storage system access node and configuration scale.The planning method of the application takes the difficult area of power grid extension in remote mountainous area, island and the like as application scene, promotes distribution network side new energy access and consumption at the same time, guarantees the power supply capacity of distribution network end, and will provide technical support for the efficient planning of energy storage under the scene of improving the power supply capacity of distribution network end.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrical engineering, and particularly relates to a replacement energy storage planning method for improving power supply capacity of a distribution network and a related device. BACKGROUND

[0002] At present, in many remote areas and islands, due to geographical conditions, it is difficult to build a conventional power distribution system interconnected with a large power grid, or the built power distribution system is relatively weak and has insufficient power supply reliability. The power supply mode mainly using diesel generators has the disadvantages of low reliability, high operation and maintenance cost, and environmental pollution. With the construction of new power systems, distributed photovoltaic systems are developing rapidly. In remote mountainous areas, islands and other areas where the power grid is difficult to extend, a large number of distributed photovoltaic systems connected to the power grid can provide power supply for the distribution network, but at the same time, may cause problems such as voltage fluctuation and over-limit of the distribution network, and reduction of power quality.

[0003] Specific problems are as follows:

[0004] I. In remote mountainous areas, islands and other areas where the power grid is difficult to extend, the power supply system is often far away from the main grid and needs to be supplied by long-distance power transmission. The power supply system often faces challenges such as unstable power supply and large energy fluctuation.

[0005] II. The time sequence characteristics of distributed photovoltaic output and load demand are misaligned. During the day, photovoltaic output may be greater than load, which is easy to cause overvoltage risk. During the evening peak load period, photovoltaic output is low or even zero, which is easy to cause under-voltage risk. Moreover, the closer the distributed photovoltaic connection point is to the end of the distribution network, the greater the voltage deviation range caused by photovoltaic output fluctuation. When the voltage regulation capacity of the distribution network is insufficient, the voltage deviation problem will directly affect the power supply safety of the distribution network.

[0006] III. Photovoltaic power generation systems are easily affected by environmental factors such as light intensity and temperature. After a large number of distributed photovoltaic systems are connected to the power grid, the fluctuation of output will cause power impact on the power grid, causing power fluctuation. When the distributed photovoltaic output is higher than the load, the tide will flow in the reverse direction in the medium-voltage or high-voltage transformer and line. The configuration of the capacity of the traditional distribution network transformer is mainly based on the level of the load, without considering the distributed photovoltaic output. If the capacity of the distributed photovoltaic system is too large, it may cause the reverse power to exceed the capacity of the transformer, causing overload of the equipment and line, and thermal stability problem. At present, the development speed of distributed photovoltaic systems is much higher than the speed of distribution network transformation, and the problem of transformer overload is often difficult to solve quickly. SUMMARY

[0007] The purpose of the present application is to provide a replacement energy storage planning method for improving power supply capacity of a distribution network and a related device, to solve the problems of insufficient power supply capacity at the end of the distribution network, voltage fluctuation and over-limit of the distribution network, and reduction of power quality caused by a large number of local distributed photovoltaic systems.

[0008] To achieve the above object, the present application adopts the following technical solutions:

[0009] A replacement energy storage planning method for improving distribution network power supply capacity, comprising the following steps:

[0010] A functional replacement energy storage optimization planning double-layer model is built, the upper layer of the double-layer model is a planning layer, and the lower layer is a running layer; the planning layer takes the maximum annual net income after configuring the functional replacement energy storage as a target, and takes the reasonable new energy curtailment rate constraint and the power supply reliability rate constraint as the first constraint condition; the running layer takes the minimum node voltage fluctuation and load fluctuation of the distribution network after applying the electrochemical energy storage system as a target, and takes the power balance constraint, the safe and stable operation constraint of the electrochemical energy storage system, the node voltage fluctuation range constraint and the line capacity constraint as the second constraint condition;

[0011] The double-layer model is optimized and solved based on the distribution network framework data and time sequence data and example boundary parameters, and an electrochemical energy storage system planning scheme is obtained, the electrochemical energy storage system planning scheme comprising an electrochemical energy storage system access node and a configuration scale.

[0012] Further, the annual net income after configuring the functional replacement energy storage is represented as follows:

[0013] f1=E rel +E lvy -C LCC -C cur

[0014] In the formula: f1 is the annual net income after configuring the functional replacement energy storage; E rel is the annual power supply reliability improvement income after configuring the functional replacement energy storage; E lvy is the income brought by the improvement of power quality after configuring the functional replacement energy storage; C LCC is the annual value of the cost of the electrochemical energy storage system in the planning year; C cur is the annual distributed photovoltaic power generation curtailment cost.

[0015] Further, the annual power supply reliability improvement income after configuring the functional replacement energy storage is represented as follows:

[0016] E rel =F loss -F l ' oss

[0017] In the formula: F loss , F' loss are respectively the system power loss before and after configuring the functional replacement energy storage, and:

[0018]

[0019] M is the number of load points; K j is the number of outages of load point j; P jk is the load value of load point j at the kth outage; is the outage time of load point j at the kth outage; is the average outage loss cost per unit of electricity of load point j at the kth outage;

[0020] The benefits of the configuration function after the alternative energy storage are represented as follows:

[0021] E lvy = F lvy - F' lvy

[0022] wherein,

[0023]

[0024]

[0025] wherein, F lvy , are the voltage out-of-limit penalty costs before and after the configuration function replaces the alternative energy storage, respectively; f v is the voltage out-of-limit penalty cost coefficient; U i (t) is the voltage of node i at time period t; U N is the rated voltage of node i; A i (t) is a binary variable representing the voltage out-of-limit condition of node i at time period t, A i (t) = 0 when the voltage is not out-of-limit, and vice versa A i (t) = 1, and n is the number of nodes in the distribution system, and T is the total number of time periods in a year.

[0026] Further, the annual cost of the electrochemical energy storage system in the planning year is represented as follows:

[0027] C LCC = C inv + C om + C rec

[0028] wherein, C inv is the initial annual construction cost of the electrochemical energy storage system; C om is the annual operation and maintenance cost of the electrochemical energy storage system; C rec is the annual equipment residual value and recovery cost of the electrochemical energy storage system.

[0029] The initial annual construction cost of the electrochemical energy storage system is represented as follows:

[0030]

[0031] wherein: C is the unit power investment cost of the electrochemical energy storage system; C is the unit capacity investment cost of the electrochemical energy storage system; P is the rated power of the electrochemical energy storage system; Q is the rated capacity of the electrochemical energy storage system; r is the discount rate, and m is the service life of the electrochemical energy storage system;

[0032] The annual operation and maintenance cost of the electrochemical energy storage system is represented as follows:

[0033]

[0034] wherein: C is the unit charge / discharge capacity operation and maintenance cost of the electrochemical energy storage system; E disch (t) is the discharge capacity of the electrochemical energy storage system at time t;

[0035] The annual equipment residual value and recycling cost of the electrochemical energy storage system is represented as follows:

[0036]

[0037] wherein: C rc , C rv are the recycling cost and equipment residual value of the electrochemical energy storage system when the equipment needs to be scrapped, respectively;

[0038] The annual distributed photovoltaic power generation curtailment cost is represented as follows:

[0039]

[0040] wherein: γ pv,i (t) is the curtailment ratio of the i-th photovoltaic power station at time t; P pv,i (t) is the theoretical power generation of the i-th photovoltaic power station at time t; C Ecur is the value per unit of curtailed power; I is the number of distributed photovoltaic power stations; and T is the total number of time periods in the year.

[0041] Further, the new energy reasonable curtailment rate constraint is represented as follows:

[0042]

[0043] wherein: θ pv，max is the upper limit of the distributed photovoltaic reasonable curtailment rate;

[0044] The power supply reliability rate constraint is represented as follows:

[0045]

[0046] wherein: ξ r is the power supply reliability limit; t k,l is the power outage duration of the kth user in the lth power outage; k l is the number of users affected by the lth power outage; K is the total number of users in statistics.

[0047] Further, the application of the electrochemical energy storage system minimizes the voltage fluctuation and load fluctuation of the post-distribution network node, which is expressed as follows:

[0048] f2 = min{G1, G2}

[0049] wherein, the calculation formula of the distribution network node load fluctuation G1 is:

[0050]

[0051] The calculation formula of the distribution network node voltage fluctuation G2 is:

[0052]

[0053] wherein: P(t) represents the total active load of the system at time t; P load (t) represents the active power of the load when the electrochemical energy storage system is not connected to the system at time t; P bess,m (t) represents the active power of the mth electrochemical energy storage system connected at time t; U i (t) represents the voltage value of the ith node at time t; U N represents the rated voltage value of the distribution network.

[0054] Further, the power balance constraint is expressed as follows:

[0055]

[0056] wherein: P G (t) is the active power of the power grid for the distribution network at time t; P pv,i (t) is the active output of the ith photovoltaic at time t; n pv , n bess respectively represent the installation number of photovoltaic and electrochemical energy storage system; P bess,i (t) is the active output of the ith electrochemical energy storage system at time t;

[0057] The safe and stable operation constraints of the electrochemical energy storage system include electrochemical energy storage system charging and discharging power constraints and electrochemical energy storage system state of charge constraints;

[0058] The electrochemical energy storage system charging and discharging power constraint is expressed as follows:

[0059]

[0060] Where: and They represent the charging power and discharging power of the electrochemical energy storage system at time t respectively; is the rated power of the electrochemical energy storage system;

[0061] The state of charge constraint of the electrochemical energy storage system is expressed as follows:

[0062]

[0063]

[0064] Where: SOC bess (t) is the SOC value of the electrochemical energy storage system at time t; is the upper and lower limits of the SOC operating range of the electrochemical energy storage system; Δt represents the time interval; η ch and η dis They are respectively represented as the charging and discharging efficiency of the electrochemical energy storage system;

[0065] The node voltage fluctuation range constraint is expressed as follows:

[0066] U i min ≤U i (t)≤U i max

[0067] Where: U i max is the maximum voltage allowed at node i; U i min is the minimum voltage allowed at node i;

[0068] The line capacity constraint is expressed as follows:

[0069]

[0070] Where: is the upper limit of active power of line i, P i,load (t) is the actual power of line i during period t.

[0071] A distribution network functional substitution energy storage optimization planning system, comprising:

[0072] The building module is used for building a function alternative energy storage optimization planning bi-level model, wherein an upper layer of the bi-level model is a planning layer, and a lower layer is a running layer; the planning layer takes maximizing annual net income after configuring the function alternative energy storage as a target, and takes a reasonable new energy curtailment rate constraint and a power supply reliability rate constraint as first constraint conditions; the running layer takes minimizing power grid node voltage fluctuation and load fluctuation after applying the electrochemical energy storage system as a target, and takes a power balance constraint, an electrochemical energy storage system safe and stable operation constraint, a node voltage fluctuation range constraint and a line capacity constraint as second constraint conditions;

[0073] The solving module is used for optimizing and solving the bi-level model based on distribution network framework data and time sequence data and example boundary parameters, so as to obtain an electrochemical energy storage system planning scheme, wherein the electrochemical energy storage system planning scheme includes an electrochemical energy storage system access node and a configuration scale.

[0074] Further, the annual net income after configuring the function alternative energy storage is represented as follows:

[0075] f1=E rel +E lvy -C LCC -C cur

[0076] In the formula, f1 is the annual net income after configuring the function alternative energy storage; E rel is an annual power supply reliability improvement income after configuring the function alternative energy storage; E lvy is an annual power quality improvement income after configuring the function alternative energy storage; C LCC is an annual value of the electrochemical energy storage system cost in the planning year; C cur is an annual distributed photovoltaic power generation curtailment cost.

[0077] Further, the reasonable new energy curtailment rate constraint is represented as follows:

[0078]

[0079] In the formula, θ pv，max is an upper limit value of the reasonable distributed photovoltaic curtailment rate;

[0080] The power supply reliability rate constraint is represented as follows:

[0081]

[0082] In the formula, ξ r is a power supply reliability rate limit value; t k,l is a power outage duration of the kth user in the lth power outage; k l is a number of users affected by the lth power outage; and K is a total number of users.

[0083] Further, the voltage fluctuation of the power distribution network node after the application of the electrochemical energy storage system is minimum, which is represented as follows:

[0084] f2 = min{G1, G2}

[0085] The calculation formula of the voltage fluctuation G2 of the power distribution network node is as follows:

[0086]

[0087] The calculation formula of the voltage fluctuation G2 of the power distribution network node is as follows:

[0088]

[0089] In the formula, P(t) represents the total active load of the system at time t; P load (t) represents the active power of the load when the electrochemical energy storage system is not connected to the system at time t; P bess,m (t) represents the active power of the mth electrochemical energy storage system connected at time t; U i (t) represents the voltage value of the ith node at time t; U N represents the rated voltage value of the power distribution network.

[0090] Further, the power balance constraint is represented as follows:

[0091]

[0092] In the formula, P G (t) is the active power supplied by the power grid to the power distribution network at time t; P pv,i (t) is the active power output of the ith photovoltaic at time t; n pv , n bess respectively represent the installation number of photovoltaics and electrochemical energy storage systems; P bess,i (t) is the active power output of the ith electrochemical energy storage system at time t;

[0093] The safe and stable operation constraints of the electrochemical energy storage system include electrochemical energy storage system charging and discharging power constraints and electrochemical energy storage system state of charge constraints.

[0094] The electrochemical energy storage system charging and discharging power constraints are represented as follows:

[0095]

[0096] In the formula: and respectively represent the charging power and discharging power of the electrochemical energy storage system at time t; is the rated power of the electrochemical energy storage system;

[0097] The SOC constraint of the electrochemical energy storage system is represented as follows:

[0098]

[0099]

[0100] In the formula, SOC bess (t) is the SOC value of the electrochemical energy storage system at time t; are the upper and lower limit values of the SOC operating range of the electrochemical energy storage system; Δt represents a time interval; η ch and η dis respectively represent the charging and discharging efficiencies of the electrochemical energy storage system;

[0101] The node voltage fluctuation range constraint is represented as follows:

[0102] U i min ≤U i (t)≤U i max

[0103] In the formula, U i max is the maximum voltage allowed for node i; U i min is the minimum voltage allowed for node i;

[0104] The line capacity constraint is represented as follows:

[0105]

[0106] In the formula, is the active power upper limit value of line i, P i,load (t) is the actual power of line i at time t.

[0107] A computer device comprises a memory, a processor, and a computer program stored in the memory and executable on the processor, and the processor implements the steps of the alternative energy storage planning method for improving the power supply capacity of a distribution network when executing the computer program.

[0108] A computer readable storage medium stores a computer program, and the computer program implements the steps of the alternative energy storage planning method for improving the power supply capacity of a distribution network when executed by a processor.

[0109] Compared with the prior art, the present application has the following beneficial technical effects:

[0110] The present invention is applicable to areas with difficulty in extending power grids, such as remote mountainous areas and islands. In view of the insufficient power supply capacity at the end of the distribution network, the large number of distributed photovoltaic accesses may lead to voltage fluctuations and over-limits in the distribution network, and the reduction of power quality. A functional alternative energy storage optimization planning method for improving the power supply capacity at the end of the distribution network is proposed. A two-layer model for functional alternative energy storage optimization planning to improve the power supply capacity at the end of the distribution network is established. The upper layer is the planning layer. With the maximum annual net profit of the electrochemical energy storage system as the goal, the configuration capacity and access nodes of the electrochemical energy storage system are determined, and the reasonable power abandonment rate constraint of new energy is considered. The lower layer is the operation layer. With the goal of minimizing the voltage fluctuation level and the load fluctuation level of the regional distribution network after the electrochemical energy storage system is configured, the charging and discharging operation strategy of the electrochemical energy storage system is optimized, and the power balance constraint, the safe and stable operation constraint of the electrochemical energy storage system, the node voltage fluctuation range constraint, and the line capacity constraint are considered. The planning method of the present invention is applied in remote mountainous areas, islands and other areas where power grid extension is difficult. The two-layer planning model established comprehensively considers the capacity requirements and operation process of energy storage during the planning process, and takes improving power supply reliability and power quality as optimization configuration goals. The proposed planning method promotes the access and absorption of new energy on the distribution network side while ensuring the power supply capacity and power quality at the end of the distribution network. It will provide technical support for the efficient planning of energy storage in the scenario of improving the power supply capacity at the end of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0111] The drawings in the specification are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0112] Figure 1 This is a flow chart of an alternative energy storage planning method for improving the power supply capacity of a distribution network according to the present invention;

[0113] Figure 2 This is a structural diagram of an alternative energy storage planning system for improving the power supply capacity of a distribution network according to the present invention. DETAILED DESCRIPTION

[0114] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0115] It should be noted that the terms "first", "second", and the like in the description and claims of the application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0116] Embodiment one

[0117] The application takes a power distribution network with a high proportion of distributed photovoltaic or an island power distribution network as an application scenario, and proposes an alternative energy storage planning method for improving the power supply capacity of the power distribution network. The main functions of the energy storage device include reducing voltage fluctuation and flicker, solving the risk of voltage overrun, improving power quality, promoting local consumption of distributed photovoltaic under the boundary of reasonable power abandonment and reverse sending, and improving the power supply capacity at the end of the power distribution network. The specific steps include the following steps:

[0118] Referring to Figure 1 The application provides an alternative energy storage planning method for improving the power supply capacity of the power distribution network, which includes the following steps:

[0119] A double-layer model for functional alternative energy storage optimization planning is built, the upper layer of the double-layer model is a planning layer, and the lower layer is a running layer; the planning layer takes the maximum annual net income after configuring the functional alternative energy storage as the target, and takes the reasonable power abandonment rate of new energy and the power supply reliability rate as the first constraint condition; the running layer takes the minimum voltage fluctuation and load fluctuation of the power distribution network after the application of the electrochemical energy storage system as the target, and takes the power balance constraint, the safe and stable operation constraint of the electrochemical energy storage system, the node voltage fluctuation range constraint, and the line capacity constraint as the second constraint condition.

[0120] Then, the double-layer model is optimized and solved based on the power distribution network frame data and time sequence data and the boundary parameters of the example by calling a solver, and an electrochemical energy storage system planning scheme is obtained, the electrochemical energy storage system planning scheme includes an electrochemical energy storage system access node and a configuration scale.

[0121] Distribution network data and time series data mainly include the distribution network structure data, line capacity data, load time series data connected to each node, photovoltaic time series data connected to each node, and other data; case boundary parameters mainly include the range of energy storage access nodes and the maximum number of energy storage configurations, photovoltaic unit power curtailment cost, voltage over-limit penalty cost coefficient, load shedding unit electricity cost, energy storage unit capacity cost, unit maintenance cost, energy storage SOC range and other parameters.

[0122] The present invention selects electrochemical energy storage as a functional alternative energy storage. Electrochemical energy storage has the characteristics of flexible site selection, short construction period, fast response speed, high adjustment accuracy, and flexible four-quadrant adjustment capability. It can provide the power system with multi-time scale, full-process balancing, support and regulation capabilities, and can be applied to the end of the distribution network to improve the power supply capacity of the end of the distribution network.

[0123] The present invention is aimed at areas with high proportions of distributed photovoltaic power generation, such as remote mountainous areas and islands where power grid extension is difficult. It aims to solve problems such as insufficient power supply capacity at the end of the distribution network, voltage fluctuations and over-limits in the distribution network, and reduced power quality caused by the large-scale access of local distributed photovoltaic power generation. A method for optimizing planning of functional alternative energy storage in the distribution network is proposed, and a two-layer model for optimizing planning of functional alternative energy storage in the distribution network is constructed. The upper layer is the planning layer, and functional alternative energy storage is planned with the goal of maximizing the annual net profit of the electrochemical energy storage system. The lower layer is the operation layer, and the operation strategy of the electrochemical energy storage system is optimized with the goal of minimizing voltage fluctuations and load fluctuations in the distribution network nodes after the application of the electrochemical energy storage system.

[0124] Example 2

[0125] The present invention provides a method for planning alternative energy storage for improving the power supply capacity of a distribution network, comprising: constructing a two-layer model for optimizing planning of functional alternative energy storage for distribution networks, wherein the upper layer is a planning layer, and functional alternative energy storage is planned with the goal of maximizing the annual net profit of the electrochemical energy storage system, and the configuration capacity and access nodes of the electrochemical energy storage system are determined, taking into account the constraints of a reasonable power abandonment rate of new energy and the power supply reliability rate; and the lower layer is an operation layer, and the operation strategy of the electrochemical energy storage system is optimized with the goal of minimizing voltage fluctuations and load fluctuations at distribution network nodes after the application of the electrochemical energy storage system, taking into account power balance constraints, constraints on the safe and stable operation of the electrochemical energy storage system, constraints on the node voltage fluctuation range, and constraints on line capacity.

[0126] (1) Planning level

[0127] (1) Objective function

[0128] With the goal of maximizing the annual net benefit after configuring functional alternative energy storage, decisions are made on the configuration capacity and access nodes of functional alternative energy storage (electrochemical energy storage system), taking into account the constraints of reasonable power curtailment rate of new energy and power supply reliability.

[0129] f1 = E rel + E lvy - C LCC - C cur (1)

[0130] Where: f1 is the annual net income brought by the configuration of functional alternative energy storage; E rel is the annual improvement of power supply reliability income after the configuration of functional alternative energy storage; E lvy is the income brought by the annual improvement of power quality after the configuration of functional alternative energy storage; C LCC is the annual value of the cost of the electrochemical energy storage system in the planning year; C cur is the annual cost of abandoned electricity of distributed photovoltaic power generation.

[0131] 1) Improvement of power supply reliability income

[0132] The improvement of power supply reliability income brought by the configuration of functional alternative energy storage is calculated by reducing the loss of system power supply caused by system failure or non-failure reasons.

[0133] E rel = F loss - F' loss (2)

[0134] Where: F loss , F' loss are the loss of system power supply before and after the configuration of functional alternative energy storage, respectively.

[0135] The calculation formula of the loss of system power supply is:

[0136]

[0137] Where: M is the number of load points; K j is the number of power outages of load point j; P jk is the load value of load point j at the kth power outage; is the power outage time of load point j at the kth power outage; is the average power outage loss cost per unit of load point j at the kth power outage, which is determined by the load type and power outage time.

[0138] 2) Income brought by voltage fluctuation suppression and improvement of power quality

[0139] The connection of distributed photovoltaic may exacerbate the voltage fluctuation of the nodes at the end of the distribution network, and voltage out-of-limit may occur. After the configuration of electrochemical energy storage system, voltage fluctuation can be suppressed, power quality can be improved, and voltage out-of-limit penalty cost can be reduced. Therefore, the voltage out-of-limit penalty cost is taken as an income of the electrochemical energy storage system:

[0140] E lvy= F lvy -F’ lvy (4)

[0141]

[0142] F lvy , F’ lvy are the voltage out-of-limit penalty cost before and after the configuration function alternative energy storage, respectively; f v is the voltage out-of-limit penalty cost coefficient; U i (t) is the voltage of node i at time t; U N is the rated voltage of node i; A i (t) is a binary variable representing the voltage out-of-limit condition of node i at time t, A i (t) = 0 when the voltage is not out-of-limit, otherwise A i (t) = 1, and n is the number of nodes in the distribution system; T is the total number of time periods in a year.

[0143] 3) Annual cost of electrochemical energy storage system

[0144] Considering the initial investment cost, operation and maintenance cost, equipment scrap value and recovery cost of the electrochemical energy storage system, the annual cost C LCC of the electrochemical energy storage system is calculated:

[0145] C LCC = C inv + C om + C rec (6)

[0146] wherein C inv is the initial annual construction cost of the electrochemical energy storage system; C om is the annual operation and maintenance cost of the electrochemical energy storage system; C rec is the annual equipment scrap value and recovery cost of the electrochemical energy storage system.

[0147] a) Initial annual construction cost

[0148] The initial annual construction cost is mainly the purchase cost of the electrochemical energy storage system equipment, which is determined by the rated power and rated capacity of the electrochemical energy storage system.

[0149]

[0150] wherein: is the unit power investment cost of the electrochemical energy storage system; is the unit capacity investment cost of the electrochemical energy storage system; is the rated power of the electrochemical energy storage system; is the rated capacity of the electrochemical energy storage system; r is the discount rate, and m is the service life of the electrochemical energy storage system.

[0151] b) Annual operation and maintenance costs

[0152] The cost of equipment operation and maintenance generated within the planning year of the electrochemical energy storage system is included.

[0153]

[0154] In the formula: is the operation and maintenance cost per unit charge / discharge of the electrochemical energy storage system; E disch (t) is the discharge capacity of the electrochemical energy storage system at time t.

[0155] c) Annual equipment scrap value and recycling costs

[0156]

[0157] In the formula: C rc , C rv are the recycling costs and equipment scrap value generated when the equipment in the electrochemical energy storage system needs to be scrapped, respectively.

[0158] 4) Annual abandoned electricity cost

[0159] When distributed photovoltaic grid-connected power is consumed, it may cause voltage fluctuations at the nodes of the distribution network and fluctuations in the system net load. In order to ensure the safe and stable operation of the distribution network system and optimize the system operation cost, reasonable distributed photovoltaic power is considered, and the distributed photovoltaic power abandonment cost is introduced, as shown in the following formula:

[0160]

[0161] In the formula: γ pv,i (t) is the abandoned electricity ratio of the i th photovoltaic power station at time t; P pv,i (t) is the theoretical power generation of the i th photovoltaic power station at time t; C Ecur is the value per unit of power cut; I is the number of distributed photovoltaic power stations.

[0162] (2) Constraints

[0163] 1) The reasonable abandoned electricity rate of new energy is constrained as:

[0164]

[0165] In the formula: θ pv，max is the upper limit of the reasonable abandoned electricity rate of distributed photovoltaic power.

[0166] 2) The power supply reliability rate constraint is:

[0167]

[0168] In the formula: ξ ris the power supply reliability limit value; t k,l is the power outage duration of the kth user in the lth power outage; k l is the number of users affected by the lth power outage; k is the total number of users.

[0169] (ii) Operation layer

[0170] The lower layer is the operation layer, which aims to minimize the voltage fluctuation level and load fluctuation level of the regional power distribution network after configuring the electrochemical energy storage system, optimizes the charge and discharge optimization operation strategy of the electrochemical energy storage system, and considers the power balance constraint, the safe and stable operation constraint of the electrochemical energy storage system, the node voltage fluctuation range constraint, and the line capacity constraint.

[0171] (1) Objective function

[0172] The two objective functions of minimizing the node load fluctuation level and minimizing the node voltage fluctuation level of the distribution network are used as the optimization objective, and the charge and discharge strategy of the electrochemical energy storage system is optimized. The objective function is:

[0173] f2 = min{G1, G2} (13)

[0174] 1) The calculation formula of the distribution network node load fluctuation level G1 is:

[0175]

[0176] In the formula: P(t) represents the total active load of the system at time t; P load (t) represents the active power of the load at time t when the system is not connected to the energy storage; P bess,m (t) represents the active power of the mth electrochemical energy storage system connected at time t.

[0177] 2) The calculation formula of the voltage fluctuation level G2 is:

[0178]

[0179] In the formula: U i (t) represents the voltage value of the ith node at time t; U N is the rated voltage value of the distribution network.

[0180] (2) Constraint condition

[0181] 1) Power balance constraint

[0182]

[0183] In the formula: P G (t) is the active power of the power grid supplying power to the distribution network at time t; P pv,i (t) is the active output of the ith photovoltaic at time t; npv , n bess respectively represent the number of photovoltaic and electrochemical energy storage systems installed; P bess,i (t) is the active power output of the i-th electrochemical energy storage system at time t.

[0184] 2) Electrochemical energy storage system charge and discharge power constraints

[0185]

[0186] In the formula: and respectively represent the charging power and discharging power of the electrochemical energy storage system at time t; is the rated power of the electrochemical energy storage system.

[0187] 3) Electrochemical energy storage system state of charge constraints

[0188]

[0189] In the formula: SOC bess (t) is the SOC value of the electrochemical energy storage system at time t; is the upper and lower limit value of the SOC operating range of the electrochemical energy storage system; Δt represents the time interval; η ch and η dis respectively represent the charging and discharging efficiency of the electrochemical energy storage system.

[0190] 4) Node voltage constraints

[0191] U i min ≤ U i (t) ≤ U i max (20)

[0192] In the formula: U i max is the maximum allowed voltage of node i; U i min is the minimum allowed voltage of node i. U i max and U i min are determined according to the requirements of the International "Power Quality Power Supply Voltage Allowance" (GB12325-90).

[0193] 5) Line capacity constraints

[0194] It is usually required that the forward direction does not exceed the rated capacity, and the negative direction does not exceed 80% of the rated capacity. The line capacity should satisfy:

[0195]

[0196] In the formula: P is the active upper limit value of the line i, P i,load (t) is the actual power of line i at time t.

[0197] The double-layer model is optimized and solved to obtain an electrochemical energy storage system planning scheme, the electrochemical energy storage system planning scheme including an electrochemical energy storage system access node and a configuration scale.

[0198] Embodiment three

[0199] Referring to Figure 2 , the application provides a power distribution network function alternative energy storage optimization planning system, comprising:

[0200] A building module is configured to build a function alternative energy storage optimization planning double-layer model, the upper layer of the double-layer model being a planning layer and the lower layer being a running layer; the planning layer taking the maximum annual net income after configuring the function alternative energy storage as a target, and taking the reasonable new energy curtailment rate constraint and the power supply reliability rate constraint as the first constraint condition; the running layer taking the minimum power distribution network node voltage fluctuation and load fluctuation after the application of the electrochemical energy storage system as a target, and taking the power balance constraint, the electrochemical energy storage system safe and stable operation constraint, the node voltage fluctuation range constraint and the line capacity constraint as the second constraint condition.

[0201] The annual net income after configuring the function alternative energy storage is represented as follows:

[0202] f1=E rel +E lvy -C LCC -C cur

[0203] In the formula: f1 is the annual net income after configuring the function alternative energy storage; E rel is the annual power supply reliability improvement income after configuring the function alternative energy storage; E lvy is the annual income brought by the improvement of power quality after configuring the function alternative energy storage; C LCC is the annual value of the cost of the electrochemical energy storage system in the planning year; C cur is the annual distributed photovoltaic curtailment cost.

[0204] The reasonable new energy curtailment rate constraint is represented as follows:

[0205]

[0206] In the formula: θ pv，max is the upper limit value of the distributed photovoltaic reasonable curtailment rate;

[0207] The power supply reliability rate constraint is represented as follows:

[0208]

[0209] wherein: ξ r is the power supply reliability limit; t k,l is the power outage duration of the kth user in the lth power outage; k l is the number of users affected by the lth power outage; K is the total number of users for statistics.

[0210] A solving module: based on the grid network frame data and time sequence data and the example boundary parameters, the double-layer model is optimized and solved to obtain an electrochemical energy storage system planning scheme, the electrochemical energy storage system planning scheme including an electrochemical energy storage system access node and configuration scale.

[0211] Wherein, the minimum node voltage fluctuation and load fluctuation of the distribution network after the application of the electrochemical energy storage system are represented as follows:

[0212] f2 = min{G1, G2}

[0213] Wherein, the calculation formula of the distribution network node load fluctuation G1 is:

[0214]

[0215] The calculation formula of the distribution network node voltage fluctuation G2 is:

[0216]

[0217] Wherein: P(t) represents the total active load of the system at t time; P load (t) represents the active power of the load when the electrochemical energy storage system is not connected to the system at t time; P bess,m (t) represents the active power of the mth electrochemical energy storage system connected at t time; U i (t) represents the voltage value of the ith node at t time; U N represents the rated voltage value of the distribution network.

[0218] The power balance constraint is represented as follows:

[0219]

[0220] Wherein: P G (t) is the active power of the power grid for the distribution network at t time; P pv,i (t) is the active output of the ith photovoltaic at t time; n pv , n bess respectively represent the installation number of photovoltaics and electrochemical energy storage systems; P bess,i (t) is the active output of the ith electrochemical energy storage system at t time;

[0221] The safe and stable operation constraints of the electrochemical energy storage system include electrochemical energy storage system charging and discharging power constraints and electrochemical energy storage system state of charge constraints.

[0222] The electrochemical energy storage system charging and discharging power constraints are expressed as follows:

[0223]

[0224] In the formula: and respectively represent the charging power and discharging power of the electrochemical energy storage system at time t; is the rated power of the electrochemical energy storage system;

[0225] The electrochemical energy storage system state of charge constraints are expressed as follows:

[0226]

[0227]

[0228] In the formula: SOC bess (t) is the SOC value of the electrochemical energy storage system at time t; is the upper and lower limit value of the SOC operating range of the electrochemical energy storage system; Δt represents the time interval; η ch and η dis respectively represent the charging and discharging efficiency of the electrochemical energy storage system;

[0229] The node voltage fluctuation range constraints are expressed as follows:

[0230] U i min ≤U i (t)≤U i max

[0231] In the formula: U i max is the maximum voltage allowed for node i; U i min is the minimum voltage allowed for node i;

[0232] The line capacity constraints are expressed as follows:

[0233]

[0234] In the formula: is the active power upper limit value of line i, P i,load (t) is the actual power of line i at time t.

[0235] Embodiment Four

[0236] The application provides a computer device, comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements steps of the alternative energy storage planning method for improving power supply capacity of distribution network when executing the computer program.

[0237] Embodiment five

[0238] The application provides a computer readable storage medium, which stores a computer program, wherein the computer program implements steps of the alternative energy storage planning method for improving power supply capacity of distribution network when executed by a processor.

[0239] Those skilled in the art should understand that embodiments of the application can be provided as a method, a system or a computer program product. Therefore, the application can adopt a completely hardware embodiment, a completely software embodiment or an embodiment combining software and hardware aspects. Moreover, the application can adopt a computer program product implemented on one or more computer usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer usable program codes.

[0240] The application is described with reference to flowcharts and / or block diagrams of the method, device (system) and computer program product according to embodiments of the application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams and the combination of the flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate a means for implementing the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 means for performing the functions specified in one or more flows and / or blocks.

[0241] These computer program instructions can also be stored in a computer readable memory capable of guiding a computer or other programmable data processing device to work in a specific way, so that the instructions stored in the computer readable memory produce a product comprising instruction means, which implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one or more flows and / or blocks Figure 1 means for performing the functions specified in one or more flows and / or blocks.

[0242] These computer program instructions can also be loaded into a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer implemented process, so that the instructions executed on the computer or other programmable device provide a means for implementing the functions specified in the flowcharts and / or block diagrams.Figure 1 one or more processes and / or functions specified in one or more blocks Figure 1 one or more processes and / or functions specified in one or more blocks

[0243] Finally, it should be noted that the above examples are merely used to illustrate the technical solutions of the present application but not to limit the protection scope thereof, and although the present application has been described in detail with reference to the above examples, those of ordinary skill in the art should understand that after reading the present application, various modifications, changes or equivalent replacements of the specific embodiments of the present application can be made by those of ordinary skill in the art, but these modifications, changes or equivalent replacements all fall within the protection scope of the claims of the present application.

Claims

1. An alternative energy storage planning method for improving the power supply capacity of a distribution network, characterized in that: The steps include: A two-layer model for optimizing and planning functional alternative energy storage is constructed, with the upper layer being the planning layer and the lower layer being the operation layer. The planning layer aims to maximize the annual net profit after configuring functional alternative energy storage, and has the reasonable curtailment rate of new energy and the power supply reliability rate as the first constraint. The operation layer aims to minimize the voltage fluctuation and load fluctuation at the distribution network nodes after the application of the electrochemical energy storage system, and has the power balance constraint, the safe and stable operation constraint of the electrochemical energy storage system, the node voltage fluctuation range constraint, and the line capacity constraint as the second constraint. Optimizing and solving the double-layer model based on distribution network data and time series data as well as example boundary parameters to obtain an electrochemical energy storage system planning scheme, which includes electrochemical energy storage system access nodes and configuration scale; The annual net income after configuring the functional alternative energy storage is expressed as follows: Where: The annual net income after configuring functional alternative energy storage; To improve the annual power supply reliability benefits after configuring functional alternative energy storage; The benefits of improving power quality in the year after configuring functional alternative energy storage; The annual cost value of the electrochemical energy storage system in the planning year; is the annual cost of abandoned electricity from distributed photovoltaic power generation; The annual benefits of improved power supply reliability after configuring the functional alternative energy storage are expressed as follows: Where: 、 are the power loss of the system before and after the functional alternative energy storage configuration, and: Where: M is the number of load points; is the number of power outages at load point j; is the load value of load point j at the kth power outage; is the kth power outage time of load point j; is the average power outage loss cost per unit of electricity at the kth power outage at load point j; The annual benefits of improved power quality after configuring the functional alternative energy storage are expressed as follows: in, Where: 、 They are the voltage over-limit penalty fees before and after configuring functional alternative energy storage; is the voltage over-limit penalty fee coefficient; is the voltage of node i during period t; is the rated voltage of node i; is a binary variable that represents the voltage exceeding the limit at node i during period t. When the voltage does not exceed the limit, ,on the contrary , n is the number of nodes in the distribution network system; T is the total number of time periods in a year; The annual cost value of the electrochemical energy storage system in the planning year is expressed as follows: Where: is the initial annual construction cost of the electrochemical energy storage system; is the annual operation and maintenance cost of the electrochemical energy storage system; The annual equipment residual value and recovery cost of the electrochemical energy storage system; The initial annual construction cost of the electrochemical energy storage system is expressed as follows: Where: is the unit power investment cost of the electrochemical energy storage system; is the unit capacity investment cost of the electrochemical energy storage system; is the rated power of the electrochemical energy storage system; is the rated capacity of the electrochemical energy storage system; is the discount rate, m is the service life of the electrochemical energy storage system; The annual operation and maintenance cost of the electrochemical energy storage system is expressed as follows: Where: The operation and maintenance cost per unit charge / discharge capacity of the electrochemical energy storage system; is the discharge capacity of the electrochemical energy storage system during period t; The annual equipment residual value and recovery cost of the electrochemical energy storage system are expressed as follows: Where: 、 They are the recovery cost and residual value of the equipment in the electrochemical energy storage system when the equipment needs to be scrapped; The annual cost of abandoned distributed photovoltaic power generation is expressed as follows: Where: is the power abandonment ratio of the i-th PV power station in period t; is the theoretical power generation of the ith photovoltaic power station in period t; is the value of unit power limit; I is the number of distributed photovoltaic power stations; T is the total number of time periods in a year; The constraints on the reasonable curtailment rate of new energy are expressed as follows: Where: The upper limit of the reasonable power abandonment rate of distributed photovoltaics; The power supply reliability constraint is expressed as follows: Where: is the power supply reliability rate limit; For the kth user in The duration of the power outage; For the The number of users affected by the power outage; K is the total number of users counted; After the electrochemical energy storage system is applied, the voltage fluctuation and load fluctuation of the distribution network nodes are minimized, as shown below: Among them, the load fluctuation of distribution network nodes The calculation formula is: Voltage fluctuations at distribution network nodes The calculation formula is: Where: Expressed as the total active load of the system at time t; Represents the active power of the load when the system is not connected to the electrochemical energy storage system at time t; represents the active power of the mth electrochemical energy storage system connected at time t; represents the voltage value of the i-th node at time t; Indicates the rated voltage value of the distribution network; The power balance constraint is expressed as follows: Where: is the active power supplied by the power grid to the distribution network at time t; is the active power output of the i-th photovoltaic at time t; 、 are respectively the number of installed photovoltaic and electrochemical energy storage systems; is the active power output of the i-th electrochemical energy storage system at time t; The safe and stable operation constraints of the electrochemical energy storage system include the charge and discharge power constraints of the electrochemical energy storage system and the charge state constraints of the electrochemical energy storage system; The charge and discharge power constraints of the electrochemical energy storage system are expressed as follows: Where: and They represent the charging power and discharging power of the electrochemical energy storage system at time t respectively; is the rated power of the electrochemical energy storage system; The state of charge constraint of the electrochemical energy storage system is expressed as follows: Where: is the SOC value of the electrochemical energy storage system at time t; 、 The upper and lower limits of the SOC operating range of the electrochemical energy storage system; Indicates a time interval; and They are respectively represented as the charging and discharging efficiency of the electrochemical energy storage system; The node voltage fluctuation range constraint is expressed as follows: Where: is the maximum voltage allowed at node i; is the minimum voltage allowed at node i; The line capacity constraint is expressed as follows: Where: is the upper limit of active power of line i, is the actual power of line i during period t.

2. A distribution network functional substitution energy storage optimization planning system, used to implement the method of claim 1, characterized in that: include: Construction module: used to build a two-layer model for functional alternative energy storage optimization planning, with the upper layer of the two-layer model being the planning layer and the lower layer being the operation layer; the planning layer aims to maximize the annual net profit after configuring functional alternative energy storage, and has the reasonable power curtailment rate constraint of new energy and the power supply reliability constraint as the first constraint condition; the operation layer aims to minimize the voltage fluctuation and load fluctuation of the distribution network nodes after the application of the electrochemical energy storage system, and has the power balance constraint, the safe and stable operation constraint of the electrochemical energy storage system, the node voltage fluctuation range constraint, and the line capacity constraint as the second constraint condition; Solution module: Optimizes and solves the double-layer model based on distribution network data, time series data, and case boundary parameters to obtain an electrochemical energy storage system planning scheme, which includes the electrochemical energy storage system access nodes and configuration scale.

3. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of an alternative energy storage planning method for improving the power supply capacity of a distribution network as described in claim 1 are implemented.

4. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of an alternative energy storage planning method for improving the power supply capacity of a distribution network as claimed in claim 1 are implemented.

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