Alternative energy storage planning method for improving power supply capability of distribution network and related device

Abstract

The invention discloses an alternative energy storage planning method for improving the power supply capability of a distribution network and a related device, and belongs to the technical field of electrical engineering, and the method comprises the steps: building a function alternative energy storage optimization planning double-layer model, the upper layer of the double-layer model is a planning layer, and the lower layer is an operation layer; the double-layer model is optimized and solved, an electrochemical energy storage system planning scheme is obtained, and the electrochemical energy storage system planning scheme comprises an electrochemical energy storage system access node and a configuration scale. According to the planning method, remote mountainous areas, islands and other areas where power grids are difficult to extend serve as application scenes, the power supply capacity of the distribution network tail end is guaranteed while new energy access and consumption of the distribution network side are promoted, and technical support is provided for efficient energy storage planning under the scene that the power supply capacity of the distribution network tail end is improved.

Description

Technical Field

[0001] The present invention belongs to the field of electrical engineering technology, and specifically relates to an alternative energy storage planning method and related devices for improving the power supply capacity of a distribution network. Background Art

[0002] At present, due to geographical restrictions, it is difficult to build a conventional distribution system that is interconnected with the large power grid in many remote areas and islands, or the existing distribution system is relatively weak and the power supply reliability is insufficient. The power supply mode with diesel generators as the main power source has the disadvantages of low reliability, high operating and maintenance costs, and environmental pollution. With the advancement of the construction of new power systems, distributed photovoltaics are developing rapidly on a large scale. In remote mountainous areas, islands and other areas where power grid extension is difficult, a large number of distributed photovoltaics can provide power for the distribution network, but at the same time, it may cause problems such as voltage fluctuations and over-limits in the distribution network and reduced power quality.

[0003] The specific questions are as follows:

[0004] 1. Remote mountainous areas, islands and other areas where it is difficult to extend the power grid are usually far away from the main grid and require long-distance power transmission. Their power supply systems often face challenges such as unstable power supply and large energy fluctuations.

[0005] Second, the output characteristics of distributed photovoltaic power generation are misaligned with the timing characteristics of load demand. During the day, the photovoltaic output may be greater than the load, which may easily cause overvoltage risks. During the evening peak load period, the photovoltaic output is low or even no, which may easily cause undervoltage risks. In addition, the closer the distributed photovoltaic access point is to the end of the distribution network, the greater the voltage deviation range caused by the fluctuation of photovoltaic output. 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] 3. Photovoltaic power generation systems are easily affected by environmental factors such as light intensity and temperature. After being connected to the power grid in large quantities, the volatility of the output will cause power shocks to the power grid and cause power fluctuations. When the output of distributed photovoltaics is higher than the power load, medium-voltage or even high-voltage transformers and lines will experience power flow reverse transmission. The configuration of the capacity of traditional distribution network transformers is mainly based on the level of load, without considering the output of distributed photovoltaics. If the capacity of distributed photovoltaics is too large, the reverse power may exceed the capacity of the transformer, causing equipment and line overloads and thermal stability problems. At present, the development speed of distributed photovoltaics is much higher than the speed of distribution network transformation, and the problem of transformer overload is often difficult to solve quickly. Summary of the invention

[0007] The purpose of the present invention is to provide an alternative energy storage planning method and related devices for improving the power supply capacity of the distribution network, so as 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 reduced power quality caused by the large-scale access of local distributed photovoltaics.

[0008] In order to achieve the above object, the present invention adopts the following technical scheme:

[0009] An alternative energy storage planning method for improving the power supply capacity of a distribution network comprises the following steps:

[0010] A two-layer model for optimizing planning of functional alternative energy storage is constructed, wherein the upper layer of the two-layer model is the planning layer and the lower layer is the operation layer; the planning layer aims to maximize the annual net profit after configuring functional alternative energy storage, and takes the reasonable power abandonment 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 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 data, time series data and example boundary parameters to obtain an electrochemical energy storage system planning scheme, which includes access nodes and configuration scale of the electrochemical energy storage system.

[0012] Furthermore, the annual net income after configuring the functional alternative energy storage is expressed as follows:

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

[0014] Where: f1 is the annual net income after configuring functional alternative energy storage; E rel To improve the annual power supply reliability benefits after configuring functional alternative energy storage; E lvy The benefits of improving power quality in one year after configuring functional alternative energy storage; C LCC is the annual cost value of the electrochemical energy storage system in the planning year; C cur is the annual cost of abandoned electricity from distributed photovoltaic power generation.

[0015] Furthermore, the annual benefit of improving power supply reliability after configuring the functional alternative energy storage is expressed as follows:

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

[0017] Where: F loss 、F' loss They are respectively the power loss of the system before and after the functional alternative energy storage configuration, and:

[0018]

[0019] Where: M is the number of load points; K j is the number of power outages at load point j; P jk is the load value at load point j during 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;

[0020] The benefits of annual improvement in power quality after configuring the functional alternative energy storage are expressed as follows:

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

[0022] in,

[0023]

[0024]

[0025] Where: F lvy , are the voltage over-limit penalty costs before and after configuring functional alternative energy storage; f v U is the voltage over-limit penalty cost coefficient; i (t) is the voltage of node i during period t; U N is the rated voltage of node i; A i (t) is a binary variable, representing the voltage limit of node i in time period t. When the voltage does not exceed the limit, A i (t) = 0, otherwise A i (t) = 1, n is the number of nodes in the distribution network system; T is the total number of time periods in a year.

[0026] Furthermore, the annual cost value of the electrochemical energy storage system in the planning year is expressed as follows:

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

[0028] Where: 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 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 expressed as follows:

[0030]

[0031] 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; 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 expressed as follows:

[0033]

[0034] Where: E is the operation and maintenance cost per unit charge / discharge of the electrochemical energy storage system; disch (t) is the discharge capacity of the electrochemical energy storage system during period t;

[0035] The annual equipment residual value and recovery cost of the electrochemical energy storage system are expressed as follows:

[0036]

[0037] Where: C rc , C rv They are the recovery cost and residual value of the equipment in the electrochemical energy storage system when the equipment needs to be scrapped;

[0038] The annual cost of abandoned electricity of distributed photovoltaic power generation is expressed as follows:

[0039]

[0040] Where: γ pv,i (t) is the power abandonment ratio of the ith PV power station in period t; P pv,i (t) is the theoretical power generation of the ith photovoltaic power station in period t; C Ecur 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.

[0041] Furthermore, the constraint on the reasonable power abandonment rate of new energy is expressed as follows:

[0042]

[0043] Where: θ pv，max It is the upper limit of reasonable power abandonment rate of distributed photovoltaic;

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

[0045]

[0046] Where: r is the power supply reliability rate 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 counted.

[0047] Furthermore, after the electrochemical energy storage system is applied, the voltage fluctuation and load fluctuation of the distribution network node are minimized, as shown below:

[0048] f2=min{G1,G2}

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

[0050]

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

[0052]

[0053] Where: 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 system is not connected to the electrochemical energy storage 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 Indicates the rated voltage value of the distribution network.

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

[0055]

[0056] Where: P G (t) is the active power supplied by the power grid to the distribution network at time t; P pv,i (t) is the active power output of the ith photovoltaic power plant at time t; n pv 、n bess Respectively represent the number of photovoltaic and electrochemical energy storage systems installed; P bess,i (t) is the active output of the i-th electrochemical energy storage system at time t;

[0057] 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;

[0058] The charge and discharge power constraints of the electrochemical energy storage system are 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] Construction module: used to build a two-layer model for functional alternative energy storage optimization planning, the upper layer of the two-layer model is the planning layer, and the lower layer is the operation layer; the planning layer aims to maximize the annual net profit after configuring functional alternative energy storage, and takes the reasonable power abandonment 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 node after the application of the electrochemical energy storage system, 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;

[0073] Solution module: Based on the distribution network data, time series data and example boundary parameters, the double-layer model is optimized and solved to obtain an electrochemical energy storage system planning scheme, which includes the access nodes and configuration scale of the electrochemical energy storage system.

[0074] Furthermore, the annual net income after configuring the functional alternative energy storage is expressed as follows:

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

[0076] Where: f1 is the annual net income after configuring functional alternative energy storage; E rel To improve the annual power supply reliability benefits after configuring functional alternative energy storage; E lvy The benefits of improving power quality in one year after configuring functional alternative energy storage; C LCC is the annual cost value of the electrochemical energy storage system in the planning year; C cur is the annual cost of abandoned electricity from distributed photovoltaic power generation.

[0077] Furthermore, the constraint on the reasonable power abandonment rate of new energy is expressed as follows:

[0078]

[0079] Where: θ pv，max It is the upper limit of reasonable power abandonment rate of distributed photovoltaic;

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

[0081]

[0082] Where: r is the power supply reliability rate 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 counted.

[0083] Furthermore, after the electrochemical energy storage system is applied, the voltage fluctuation and load fluctuation of the distribution network node are minimized, as shown below:

[0084] f2=min{G1,G2}

[0085] Among them, the calculation formula of the distribution network node load fluctuation G1 is:

[0086]

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

[0088]

[0089] Where: 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 system is not connected to the electrochemical energy storage 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 Indicates the rated voltage value of the distribution network.

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

[0091]

[0092] Where: P G (t) is the active power supplied by the power grid to the distribution network at time t; P pv,i (t) is the active power output of the ith photovoltaic power plant at time t; n pv 、n bess Respectively represent the number of photovoltaic and electrochemical energy storage systems installed; P bess,i (t) is the active output of the i-th electrochemical energy storage system at time t;

[0093] 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;

[0094] The charge and discharge power constraints of the electrochemical energy storage system are expressed as follows:

[0095]

[0096] 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;

[0097] The state of charge constraint of the electrochemical energy storage system is expressed as follows:

[0098]

[0099]

[0100] 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;

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

[0102] U i min ≤U i (t)≤U i max

[0103] Where: U i max is the maximum voltage allowed at node i; U i min is the minimum voltage allowed at node i;

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

[0105]

[0106] 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.

[0107] A computer device comprises 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 are implemented.

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

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

[0110] The present invention is applicable to areas with difficult power grid extension, such as remote mountainous areas and islands. In view of the insufficient power supply capacity at the end of the distribution network, a large number of distributed photovoltaic access may lead to voltage fluctuations and over-limits in the distribution network, and reduced 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 built. The upper layer is the planning layer, which takes the maximum annual net profit of the electrochemical energy storage system as the goal, decides the configuration capacity and access nodes of the electrochemical energy storage system, and considers the constraints of the reasonable power abandonment rate of new energy; the lower layer is the operation layer, which takes the minimum voltage fluctuation level and the minimum load fluctuation level of the regional distribution network after the configuration of the electrochemical energy storage system as the goal, optimizes the charging and discharging operation strategy of the electrochemical energy storage system, and considers the power balance constraints, the safe and stable operation constraints of the electrochemical energy storage system, the node voltage fluctuation range constraints, and the line capacity constraints. The planning method of the present invention takes remote mountainous areas, islands and other areas where power grid extension is difficult as application scenarios, and constructs a two-layer planning model. During the planning process, the capacity demand and operation process of energy storage are comprehensively considered, and improving power supply reliability and power quality are simultaneously taken as optimization configuration goals. The proposed planning method not only promotes the access and absorption of new energy on the distribution network side, but also ensures the power supply capacity and power quality at the end of the distribution network, which will provide technical support for the efficient planning of energy storage in the scenario of improving the power supply capacity of 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 schematic 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 A schematic 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 schematic diagram of the structure 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 scheme of the present invention, the technical scheme 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 described embodiments 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 creative work should fall within the scope of protection of the present invention.

[0115] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0116] Embodiment 1

[0117] The present invention takes the distribution network or island distribution network with a high proportion of distributed photovoltaic as the application scenario, and proposes an alternative energy storage planning method for improving the power supply capacity of the distribution network. The main functions of the energy storage equipment include reducing voltage fluctuations and flickers, solving the risk of voltage over-limit, improving the quality of power, promoting the local consumption of distributed photovoltaics under the reasonable boundary of power abandonment and reverse transmission, and improving the power supply capacity of the end of the distribution network. Specifically, the following steps are included:

[0118] See also Figure 1 The present invention provides an alternative energy storage planning method for improving the power supply capacity of a distribution network, comprising the following steps:

[0119] A two-layer model for optimizing planning of functional alternative energy storage is constructed, wherein the upper layer of the two-layer model is the planning layer and the lower layer is the operation layer; the planning layer aims to maximize the annual net profit after configuring functional alternative energy storage, and takes the reasonable power abandonment 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 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, by calling the solver, the double-layer model is optimized and solved based on the distribution network grid data, time series data and the example boundary parameters to obtain an electrochemical energy storage system planning scheme, which includes the electrochemical energy storage system access nodes and configuration scale.

[0121] Distribution network data and time series data, mainly including the distribution network grid 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 including the range of energy storage access nodes and the maximum number of energy storage configurations, photovoltaic unit power abandonment 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 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 capability, support capability and regulation capability, 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 difficult power grid extension, such as remote mountainous areas and islands with a high proportion of distributed photovoltaics. It aims 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 reduced power quality caused by the large-scale access of local distributed photovoltaics. A distribution network functional alternative energy storage optimization planning method is proposed, and a two-layer model for distribution network functional alternative energy storage optimization planning is constructed. The upper layer is the planning layer, and the 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 the voltage fluctuation and load fluctuation of the distribution network nodes after the application of the electrochemical energy storage system.

[0124] Embodiment 2

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

[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 abandonment rate of new energy and power supply reliability rate.

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

[0130] Where: f1 is the annual net benefit brought by configuring functional alternative energy storage; E rel To improve the annual power supply reliability benefits after configuring functional alternative energy storage; E lvy The benefits of improving power quality in one year after configuring functional alternative energy storage; C LCC is the annual cost value of the electrochemical energy storage system in the planning year; C cur is the annual cost of abandoned electricity from distributed photovoltaic power generation.

[0131] 1) Improve the reliability of power supply

[0132] The benefits of improving the reliability of distribution network power supply brought by configuring functional alternative energy storage are calculated in order to reduce the system power supply loss caused by system failure or non-fault reasons.

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

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

[0135] The calculation formula for power failure loss is:

[0136]

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

[0138] 2) Benefits from smoothing voltage fluctuations and improving power quality

[0139] The access of distributed photovoltaics may aggravate the voltage fluctuations at the nodes at the end of the distribution network, resulting in voltage exceeding the limit. After configuring the electrochemical energy storage system, the voltage fluctuations can be smoothed, the power quality can be improved, and the voltage exceeding the limit penalty fee can be reduced. Therefore, the reduction of voltage exceeding the limit penalty fee is regarded as a benefit of the electrochemical energy storage system:

[0140] E lvy=F lvy -F' lvy (4)

[0141]

[0142] Where: F lvy , F' lvy are the voltage over-limit penalty costs before and after configuring functional alternative energy storage; f v U is the voltage over-limit penalty cost coefficient; i (t) is the voltage of node i during period t; U N is the rated voltage of node i; A i (t) is a binary variable, representing the voltage limit of node i in time period t. When the voltage does not exceed the limit, A i (t) = 0, otherwise A i (t) = 1, n is the number of nodes in the distribution network system; T is the total number of time periods in a year.

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

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

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

[0146] Where: 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.

[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] 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; 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] Included in the costs of equipment operation and maintenance during the planning year of the electrochemical energy storage system.

[0153]

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

[0155] c) Annual equipment scrap value and recovery cost

[0156]

[0157] Where: C rc , C rv They are the recovery cost and residual value of the equipment in the electrochemical energy storage system when the equipment needs to be scrapped.

[0158] 4) Annual curtailment cost

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

[0160]

[0161] Where: γ pv,i (t) is the power abandonment ratio of the ith PV power station in period t; P pv,i (t) is the theoretical power generation of the ith photovoltaic power station in period t; C Ecur is the value of unit power limit; I is the number of distributed photovoltaic power stations.

[0162] (2) Constraints

[0163] 1) The reasonable power abandonment rate of new energy is constrained as follows:

[0164]

[0165] Where: θ pv，max It is the upper limit of reasonable power abandonment rate of distributed photovoltaic.

[0166] 2) Power supply reliability constraints:

[0167]

[0168] Where: ris the power supply reliability rate 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 counted.

[0169] (II) Operational Layer

[0170] The lower layer is the operation layer, which aims to minimize the voltage fluctuation level and load fluctuation level of the regional distribution network after the electrochemical energy storage system is configured, and optimizes the charging and discharging optimization operation strategy of the electrochemical energy storage system, taking into account power balance constraints, safe and stable operation constraints of the electrochemical energy storage system, node voltage fluctuation range constraints, and line capacity constraints.

[0171] (1) Objective function

[0172] Taking the minimum node load fluctuation level and the minimum node voltage fluctuation level of the distribution network as the optimization objectives, the charging and discharging 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 load fluctuation level G1 of the distribution network node is:

[0175]

[0176] Where: 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 system is not connected to energy storage at time t; 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 voltage fluctuation level G2 is:

[0178]

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

[0180] (2) Constraints

[0181] 1) Power balance constraints

[0182]

[0183] Where: P G (t) is the active power supplied by the power grid to the distribution network at time t; P pv,i (t) is the active power output of the ith photovoltaic power plant 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 output of the i-th electrochemical energy storage system at time t.

[0184] 2) Charge and discharge power constraints of electrochemical energy storage systems

[0185]

[0186] Where: and They are respectively represented as 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) State of charge constraints of electrochemical energy storage systems

[0188]

[0189] 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.

[0190] 4) Node voltage constraints

[0191] U i min ≤U i (t)≤U i max (20)

[0192] Where: U i max is the maximum voltage allowed at node i; U i min is the minimum voltage allowed at node i. i max and U i min It is determined in accordance with the requirements of the international "Permissible Deviation of Power Quality Supply Voltage" (GB12325-90).

[0193] 5) Line capacity constraints

[0194] It is usually required that the positive direction does not exceed the rated capacity, and the negative direction does not exceed 80% of the rated capacity. Should meet:

[0195]

[0196] 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.

[0197] The double-layer model is optimized and solved to obtain an electrochemical energy storage system planning scheme, which includes access nodes and configuration scale of the electrochemical energy storage system.

[0198] Embodiment 3

[0199] See also Figure 2 The present invention provides a distribution network function alternative energy storage optimization planning system, comprising:

[0200] Construction module: used to build a two-layer model for functional alternative energy storage optimization planning, the upper layer of the two-layer model is the planning layer, and the lower layer is the operation layer; the planning layer aims to maximize the annual net profit after configuring functional alternative energy storage, and takes the reasonable power abandonment 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 node after the application of the electrochemical energy storage system, 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;

[0201] Among them, the annual net income after configuring functional alternative energy storage is expressed as follows:

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

[0203] Where: f1 is the annual net income after configuring functional alternative energy storage; E rel To improve the annual power supply reliability benefits after configuring functional alternative energy storage; E lvy The benefits of improving power quality in one year after configuring functional alternative energy storage; C LCC is the annual cost value of the electrochemical energy storage system in the planning year; C cur is the annual cost of abandoned electricity from distributed photovoltaic power generation.

[0204] The constraints on the reasonable power abandonment rate of new energy are as follows:

[0205]

[0206] Where: θ pv，max It is the upper limit of reasonable power abandonment rate of distributed photovoltaic;

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

[0208]

[0209] Where: r is the power supply reliability rate 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 counted.

[0210] Solution module: Based on the distribution network data, time series data and example boundary parameters, the double-layer model is optimized and solved to obtain an electrochemical energy storage system planning scheme, which includes the access nodes and configuration scale of the electrochemical energy storage system.

[0211] Among them, after the application of the electrochemical energy storage system, the voltage fluctuation and load fluctuation of the distribution network node are the smallest, as shown below:

[0212] f2=min{G1,G2}

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

[0214]

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

[0216]

[0217] Where: 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 system is not connected to the electrochemical energy storage 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 Indicates the rated voltage value of the distribution network.

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

[0219]

[0220] Where: P G (t) is the active power supplied by the power grid to the distribution network at time t; P pv,i (t) is the active power output of the ith photovoltaic power plant at time t; n pv 、n bess Respectively represent the number of photovoltaic and electrochemical energy storage systems installed; P bess,i (t) is the active output of the i-th electrochemical energy storage system at time t;

[0221] 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;

[0222] The charge and discharge power constraints of the electrochemical energy storage system are expressed as follows:

[0223]

[0224] 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;

[0225] The state of charge constraint of the electrochemical energy storage system is expressed as follows:

[0226]

[0227]

[0228] 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;

[0229] The node voltage fluctuation range constraint is expressed as follows:

[0230] U i min ≤U i (t)≤U i max

[0231] Where: U i max is the maximum voltage allowed at node i; U i min is the minimum voltage allowed at node i;

[0232] The line capacity constraint is expressed as follows:

[0233]

[0234] 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.

[0235] Embodiment 4

[0236] The present invention provides a computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. 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 are implemented.

[0237] Embodiment 5

[0238] The present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and 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 are implemented.

[0239] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of 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 code.

[0240] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, 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 instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0241] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0242] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0243] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

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 planning of functional alternative energy storage is constructed, wherein the upper layer of the two-layer model is the planning layer and the lower layer is the operation layer; the planning layer aims to maximize the annual net profit after configuring functional alternative energy storage, and takes the reasonable power abandonment 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 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; The double-layer model is optimized and solved based on the distribution network data, time series data and example boundary parameters to obtain an electrochemical energy storage system planning scheme, which includes access nodes and configuration scale of the electrochemical energy storage system.

2. According to claim 1, a method for planning alternative energy storage for improving the power supply capacity of a distribution network is characterized in that: The annual net income after configuring the functional alternative energy storage is expressed as follows: f1=E rel +E lvy -W LCC -W cur Where: f1 is the annual net income after configuring functional alternative energy storage; E rel To improve the annual power supply reliability benefits after configuring functional alternative energy storage; E lvy The benefits of improving power quality in one year after configuring functional alternative energy storage; C LCC is the annual cost value of the electrochemical energy storage system in the planning year; C cur is the annual cost of abandoned electricity from distributed photovoltaic power generation.

3. According to claim 2, a method for planning alternative energy storage for improving the power supply capacity of a distribution network is characterized in that: The annual benefit of improving power supply reliability after configuring the functional alternative energy storage is expressed as follows: E rel =F loss -F′ loss Where: F loss , F′ loss They are respectively the power loss of the system before and after the functional alternative energy storage configuration, and: Where: M is the number of load points; K j is the number of power outages at load point j; P jk is the load value at load point j during 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 benefits of annual improvement in power quality after configuring the functional alternative energy storage are expressed as follows: E lvy =F lvy -F′ lvy in, Where: F lvy , F′ lvy are the voltage over-limit penalty costs before and after configuring functional alternative energy storage; f v U is the voltage over-limit penalty cost coefficient; i (t) is the voltage of node i during period t; U N is the rated voltage of node i; A i (t) is a binary variable, representing the voltage limit of node i in time period t. When the voltage does not exceed the limit, A i (t) = 0, otherwise A i (t) = 1, n is the number of nodes in the distribution network system; T is the total number of time periods in a year.

4. The alternative energy storage planning method for improving the power supply capacity of a distribution network according to claim 2, characterized in that: The annual cost value of the electrochemical energy storage system in the planning year is expressed as follows: C LCC =C inv +C om +C rec Where: 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 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; r is the discount rate, and 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: E is the operation and maintenance cost per unit charge / discharge of the electrochemical energy storage system; disch (t) 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: C rc , C rv 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 electricity of distributed photovoltaic power generation is expressed as follows: Where: γ pv,i (t) is the power abandonment ratio of the ith PV power station in period t; P pv,i (t) is the theoretical power generation of the ith photovoltaic power station in period t; C Ecur 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.

5. The alternative energy storage planning method for improving the power supply capacity of the distribution network according to claim 4 is characterized in that: The constraints on the reasonable power abandonment rate of new energy are expressed as follows: Where: θ pv，max It is the upper limit of reasonable power abandonment rate of distributed photovoltaic; The power supply reliability constraint is expressed as follows: Where: r is the power supply reliability rate 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 first power outage; K is the total number of users counted.

6. The alternative energy storage planning method for improving the power supply capacity of a distribution network according to claim 1, characterized in that: After the electrochemical energy storage system is applied, the voltage fluctuation and load fluctuation of the distribution network nodes are minimized, as shown below: f2=min{G1,G2} Among them, the calculation formula of the distribution network node load fluctuation G1 is: The calculation formula of the voltage fluctuation G2 of the distribution network node is: Where: 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 system is not connected to the electrochemical energy storage 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 Indicates the rated voltage value of the distribution network.

7. The alternative energy storage planning method for improving the power supply capacity of a distribution network according to claim 1, characterized in that: The power balance constraint is expressed as follows: Where: P G (t) is the active power supplied by the power grid to the distribution network at time t; P pv,i (t) is the active power output of the ith photovoltaic power plant at time t; n pv 、n bess Respectively represent the number of photovoltaic and electrochemical energy storage systems installed; P bess,i (t) is the active 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: 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; The node voltage fluctuation range constraint is expressed as follows: U i min ≤U i (t)≤U i max Where: U i max is the maximum voltage allowed at node i; U i min 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, P i,load (t) is the actual power of line i during period t.

8. A distribution network functional substitution energy storage optimization planning system, characterized in that: include: Construction module: used to build a two-layer model for functional alternative energy storage optimization planning, the upper layer of the two-layer model is the planning layer, and the lower layer is the operation layer; the planning layer aims to maximize the annual net profit after configuring functional alternative energy storage, and takes the reasonable power abandonment 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 node after the application of the electrochemical energy storage system, 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; Solution module: Based on the distribution network data, time series data and example boundary parameters, the double-layer model is optimized and solved to obtain an electrochemical energy storage system planning scheme, which includes the access nodes and configuration scale of the electrochemical energy storage system.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: 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 any one of claims 1 to 7 are implemented.

10. 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 described in any one of claims 1 to 7 are implemented.

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