CN106549419A - Independent microgrid system method for designing based on universal gravitation algorithm - Google Patents

Abstract

The present invention provides a kind of independent microgrid system method for designing based on universal gravitation algorithm, and which comprises the steps：Step S1, sets up the independent microgrid system model with Multi-target evaluation index；Step S2, by the independent microgrid system model that the independent microgrid system model conversion of Multi-target evaluation index is single goal evaluation index；Step S3, chooses blower fan number of units Num that may be incorporated into_wt, photovoltaic battery array string number Num in parallel_pv, accumulator string number Num in parallel_batAs optimized variable；Step S4, determine the operation control strategy of independent microgrid system, pay the utmost attention to workload demand be met with renewable energy power generation amount, according to renewable energy power generation amount and the difference of load institute subfam. Spiraeoideae, determine the start-stop of the charging and discharging state and diesel-driven generator of accumulator；Step S5, is solved to independent microgrid system model using universal gravitation algorithm.The economical good, feature of environmental protection of independent microgrid system designed using the method for designing is high, renewable energy utilization rate is high, power supply safety high reliability.

Description

Independent microgrid system method for designing based on universal gravitation algorithm

Technical field

The invention belongs to the technical field of distributed power generation independent microgrid system, more particularly to it is a kind of based on gravitation calculation The independent microgrid system method for designing of method.

Background technology

Independent microgrid system refer to isolate with bulk power grid completely, the small electrical system of self independent operating, with remote Area or island are main supply object, while make full use of local renewable new energy to generate electricity, such as wind-power electricity generation (wind Power), photovoltaic generation (photovoltaic, PV), wave-energy power generation (wave power) etc..

Power supply in typical island independent microgrid system is controlled typically by photovoltaic, blower fan, energy storage device, diesel-driven generator System and electric load composition, there is provided reliable and stable electric energy.As solar energy and wind energy have stronger complementarity, island is only Vertical micro-grid system adopts wind-driven generator and solar combined power generating mode, can reduce single forms of electricity generation to a certain extent Intermittent and undulatory property；Energy storage device is commonly used to maintain microgrid self-energy balance, it is ensured that the transient stability of system；Diesel-driven generator As back-up source, support is in case of emergency provided.All there is shortage of fresh water on general island, therefore, remove Outside daily load, sea water desalinating unit is also one kind than more typical load.Solaode and energy-storage battery in microgrid It is DC source；And wind-power electricity generation and diesel-driven generator are alternating current power supply.

As shown in figure 1, alternating current-direct current mixed structure, accumulator battery and photovoltaic are adopted power supply in existing independent microgrid system more Jing DC/DC are connected in parallel to dc bus, then are connected to ac bus by DC/AC；Wind-driven generator Jing AC/DC/AC connect best friend Stream bus；Diesel-driven generator and other AC loads are connected directly to ac bus.

Existing independent microgrid system method for designing only only accounts for the index of load point, one kind does not also occur and rationally examines Consider Safety Evaluation Index, make corresponding strategy, seek the optimal balance method for designing of economy and safety.If energy Enough develop a kind of not only about generation load demand, risk, safety that generator unit random failure causes can also be quantified and filled The independent microgrid system method for designing of abundant property totality measurement index.The independent micro-grid that will then make to design using the method for designing The great economic benefit of system, environmental benefit, social benefit etc..

The content of the invention

It is an object of the invention to provide a kind of independent microgrid system method for designing based on universal gravitation algorithm, the present invention will Multi-objective problem is converted into single-object problem, and weighs surely method using paried comparison and determine each sub-goal weight, then using ten thousand There is gravitation algorithm to be solved.The economical good, feature of environmental protection of independent microgrid system designed using the method for designing is high, can Utilization of regenerative energy rate is high, power supply safety high reliability.

The purpose of the present invention is achieved through the following technical solutions, a kind of independent micro-grid system based on universal gravitation algorithm System method for designing comprises the steps：

Step S1, sets up the independent microgrid system model with Multi-target evaluation index；

Step S2, the independent microgrid system model conversion of Multi-target evaluation index is micro- for the independence of single goal evaluation index Net system model；

Step S3, chooses blower fan number of units Num that may be incorporated into_wt, photovoltaic battery array string number Num in parallel_pv, accumulator simultaneously Connection string number Num_batAs optimized variable；

Step S4, determines the operation control strategy of independent microgrid system, pays the utmost attention to be met with renewable energy power generation amount Workload demand, according to the difference of renewable energy power generation amount and load institute subfam. Spiraeoideae, determine accumulator charging and discharging state and The start-stop of diesel-driven generator；

Step S5, is solved to independent microgrid system model using universal gravitation algorithm.

The independent microgrid system model process set up with Multi-target evaluation index in step S1 is as follows：

Using Model for Multi-Objective Optimization, the optimum capacity allocation plan of each distributed power source in microgrid, energy-storage system is determined； Its concrete scheme include four can quantitatively evaluating index：Economic index, with the total net ready-made NPC table in life cycle management Show；Feature of environmental protection index, uses carbon emission amount E_CO2Represent；Renewable energy utilization rate index, uses R_renRepresent；Microgrid security reliability Index, is represented with load short of electricity rate LPSP；

Total net ready-made NPC refer to microgrid in the life cycle management produced by net charge, it include initial outlay cost, Each several part operation expense, fuel cost and displacement cost in the engineering life-span, income part includes that sale of electricity income and equipment are residual Value；Mathematic(al) representation is：

In formula：X is optimized variable, and engineering life-spans [year] of the N for microgrid, r are discount rate, and C (i), B (i) are respectively 1 year Cost and income [$/year]；C (i) computing formula are as follows：

C (i)=C_I(i)+C_M(i)+C_F(i)+C_R(i)

In formula：C_I(i)、C_M(i)、C_F(i)、C_R(i) respectively 1 year initial outlay cost, operation expense, combustion Material cost and displacement cost；Concrete variable computing formula point row are as follows：

C_I(k)=C_Iwt+C_Ipv+C_Ibat+C_Ide+C_Iconverter+C_Icontrol

Wherein, C_Iwt、C_Ipv、C_Ibat、C_Ide、C_Iconverter、C_IcontrolRespectively wind-driven generator, photovoltaic cell, electric power storage The cost of investment of pond, diesel-driven generator, current transformer and microgrid management control system；

C_M(i)=C_Mwt(i)+C_Mpv(i)+C_Mbat(i)+C_Mde(i)+C_Mconverter(i)

Wherein, C_Mwt(i)、C_Mpv(i)、C_Mbat(i)、C_Mde(i)、C_Mconverter(i) respectively 1 year wind-driven generator, The operation maintenance of photovoltaic cell, accumulator, diesel-driven generator and current transformer into；

C_F(i)=C_Fde(i)

Represent the fuel cost of the diesel-driven generator of 1 year；

C_R(i)=C_Rwt(i)+C_Rpv(i)+C_Rbat(i)+C_Rde(i)+C_Rconverter(i)

C_Rwt(i)、C_Rpv(i)、C_Rbat(i)、C_Rde(i)、C_RconverterI () is respectively wind-driven generator, the photovoltaic electric of 1 year The displacement cost of pond, accumulator, diesel-driven generator and current transformer；

B (i)=B_sell(i)+B_sal

In formula, B_sell(i)、B_salThe power selling income of respectively 1 year, remanent value of equipment；Remanent value of equipment is referred to During micro-grid system usage cycles, the surplus value that equipment component does not also arrive service life and remains；

Carbon emission amountRefer to CO of the microgrid to environmental emission in life cycle management₂Amount, introduces discharge punishment to calculate ring Border cost：

In formula：Unit CO is produced for diesel oil₂Caused punishment expenses standard [$/kg]；For Diesel Emissions coefficient [kg/L], i.e. CO produced by mean unit diesel oil₂Amount；v_dieselI () is year diesel-fuel consumption [L] of 1 year microgrid；

The ratio of whole micro- source annual electricity generating capacities in regenerative resource annual electricity generating capacity and independent microgrid system is defined as can be again Raw energy utilization rate R_ren；Regenerative resource energy to not utilizing in life cycle management carries out economic punishment：

In formula：p_unExpenses standard [] is punished caused by the regenerative resource not utilized for unit；T_unI () is i-th The regenerative resource energy [kWh] that year does not utilize.

By the independent microgrid system model conversion of Multi-target evaluation index for single goal evaluation index in step S2 The detailed process of independent microgrid system model is as follows：

Multi-objective optimization question is converted to by single-object problem using linear weighted function summation, introduce a punishment because Sub- σ, specific expression formula is：

In formula, the weight coefficient of each sub-goal weighs method determination surely using paried comparison；G (X) is for expression by load short of electricity rate The constraint function that LPSP is introduced；LPSP is defined as the ratio for not meeting workload demand energy and total capacity requirement energy, and its value is got over Little, power supply safety reliability is higher, is converted into constraints and is expressed as：

I.e.：

G (X)=LPSP- λ≤0

Wherein, ∑ P_load-unFor total load and energy that do not meet, ∑ P_loadFor total workload demand energy, if λ is 0.1%；

Simultaneously, it is considered to constraints below：

(1) restriction of the charged state of accumulator no more than accumulator maximum carrying capacity and minimum carrying capacity, i.e.,

SOC_min≤SOC(t)≤SOC_max

(2) within the 20% of the provided electricity of system, i.e., diesel-driven generator year generated energy accounts for

P_DG/(P_RE+P_DG)≤0.2

In formula：P_DGFor the power that diesel-driven generator is provided, P_RE=Num_pvP_pv+Num_wtP_wtFor the work(that regenerative resource is provided Rate.

The detailed process of step S4 is：

According to renewable energy power generation amount and the difference of load institute subfam. Spiraeoideae, the charging and discharging state and bavin of accumulator are determined The start-stop of oily hair motor；

△ P (t)=P_RE(t)-P_L(t)

In formula：P_RET () represents the power in moment t by produced by regenerative resource；

P_RE(t)=Num_pvP_pv(t)+Num_wtP_wt(t)

P_LT () represents current transformer DC side power demand, calculated with equation below：

P_L(t)=P_load(t)/η_i

P_loadT () represents t load power demand, η_iRepresent the conversion efficiency of DC/AC current transformers；

When △ P (t) >=0, unnecessary capacity is to battery charging, if the electricity of accumulator reaches SOC charging upper limits, Pay the utmost attention to put into cold-storage ice making load, such as have unnecessary again, then cut-out regenerative resource；

As △ P (t)<0, unsatisfied power can be provided by diesel-driven generator or accumulator, specially：

If 1. the electric energy stored by accumulator battery can meet workload demand, by battery discharging, diesel-driven generator is closed.

P_bat(t)=△ P (t)

If 2. the electric energy stored by accumulator battery can not meet remaining workload demand, start diesel-driven generator, now Accumulator is neither discharged nor is charged；

P_de(t)=P_L(t)-P_RE(t)

In formula：P_deT () represents the power that diesel-driven generator need to be provided.

The detailed process of step S5 is：

1) independent microgrid system topological structure to be optimized is input into, including blower fan, photovoltaic, accumulator, diesel engine, current transformer Parameter and constraints；

2) population scale N, gravitational constant initial value G are set₀, gravitation variation coefficient α, maximum iteration time T；

3) with X=[Num_wt,Num_pv,Num_bat] for variable to be optimized, initial population is generated at random, by independent microgrid system Single-goal function after design conversionAs fitness index, population at individual fitness value is evaluated, is obtained To the initial value of globally optimal solution；

4) gravitational constant G (t) in Population Regeneration, optimum best (t), worst-case value worst (t)；

5) each mass of object M, and number Kbest (t) of regeneration function object are calculated；

6) calculating each object is attracted generation to be made a concerted effort by effect object, calculates resultant acceleration；

7) speed and the position of object are updated；

If 8) reach maximum iteration time T, terminate computing, return independent microgrid system design optimal solution；Otherwise iteration Number of times adds one, goes to step 3) enter next iteration.

The independent microgrid system method for designing of the present invention stores independent microgrid system around wind-light-diesel, with wind-power electricity generation in system Board number, photovoltaic cell string number in parallel and accumulator string number in parallel are optimized variable, establish and consider its economy, environmental protection The objective design model of the technical-economic index such as property, renewable energy utilization rate, power supply safety reliability.Then by multiple target Problem converts single-object problem, and weighs surely method using paried comparison and determine each sub-goal weight.By the single goal after conversion Fitness index of the function as GSA algorithms, devises the capacity of the rated power and energy-storage system of distributed power source in system, And fully ensured that economy and the safety of independent microgrid system.

Description of the drawings

The description of the drawings of the present invention is as follows.

Fig. 1 is the structural representation of independent microgrid system in prior art；

Fig. 2 is schematic flow sheet of the present invention based on the independent microgrid system method for designing of universal gravitation algorithm.

Specific embodiment

As shown in Fig. 2 a kind of independent microgrid system method for designing based on universal gravitation algorithm provided for the present invention Schematic flow sheet.

The present invention stores independent microgrid system around wind-light-diesel, with the string in parallel of wind-driven generator number of units, photovoltaic cell in system Count and accumulator string number in parallel is optimized variable, set up and consider its economy, the feature of environmental protection, renewable energy utilization rate, confession Multi-objective problem is converted into single-object problem by the objective design model of the technical-economic indexes such as electric security reliability, And weigh surely method using paried comparison and determine each sub-goal weight, then solved using universal gravitation algorithm.

First, consider the Model for Multi-Objective Optimization of independent microgrid system safety

The main target of independent microgrid system design is interior during the design according to need for electricity, local regenerative resource confession Basic condition to situation and existing network etc., it is determined that the system Construction scheme of optimum so that the construction of system and operating cost It is minimum.Therefore, independent microgrid system design needs to consider the economy of microgrid, the feature of environmental protection, renewable energy utilization rate, peace The technical-economic indexes such as full reliability.Using Model for Multi-Objective Optimization, determine that each distributed power source, energy-storage system are most in microgrid Good capacity configuration scheme.Concrete scheme evaluation index includes：1. economic index, with total net ready-made in life cycle management NPC is represented；2. feature of environmental protection index, is converted into carbon emission amount E_CO2Represent；3. renewable energy utilization rate index, uses R_renRepresent； 4. microgrid security reliability index, is represented with load short of electricity rate LPSP.In 4 quantizating index, the 1st index is economic cost, 2nd, 3 indexs can be converted into economic punishment expense, and the 4th index is examined as constraints because of its particularity, the present invention Consider.

Total net ready-made NPC refers to the produced net charge in life cycle management of microgrid, can be with institute in life cycle management There are cost and the fund present worth of income to represent.Wherein, include initial outlay cost into this part, each several part runs in the engineering life-span Maintenance cost, fuel cost and displacement cost, income part includes sale of electricity income and remanent value of equipment.Mathematic(al) representation is：

In formula：X is optimized variable, and in engineering life-spans [year] of the N for microgrid, r is discount rate.C (i), B (i) are respectively 1 year Cost and income [$/year].C (i) computing formula are as follows：

C (i)=C_I(i)+C_M(i)+C_F(i)+C_R(i) (2)

In formula：C_I(i)、C_M(i)、C_F(i)、C_R(i) respectively 1 year initial outlay cost, operation expense, combustion Material cost and displacement cost.Concrete variable computing formula point row are as follows：

C_I(k)=C_Iwt+C_Ipv+C_Ibat+C_Ide+C_Iconverter+C_Icontrol (3)

Wherein, C_Iwt、C_Ipv、C_Ibat、C_Ide、C_Iconverter、C_IcontrolRespectively wind-driven generator, photovoltaic cell, electric power storage The cost of investment of pond, diesel-driven generator, current transformer and microgrid management control system.

C_M(i)=C_Mwt(i)+C_Mpv(i)+C_Mbat(i)+C_Mde(i)+C_Mconverter(i) (4)

Wherein, C_Mwt(i)、C_Mpv(i)、C_Mbat(i)、C_Mde(i)、C_Mconverter(i) respectively 1 year wind-driven generator, The operation expense of photovoltaic cell, accumulator, diesel-driven generator and current transformer.

C_F(i)=C_Fde(i) (5)

Represent the fuel cost of the diesel-driven generator of 1 year.

C_R(i)=C_Rwt(i)+C_Rpv(i)+C_Rbat(i)+C_Rde(i)+C_Rconverter(i) (6)

C_Rwt(i)、C_Rpv(i)、C_Rbat(i)、C_Rde(i)、C_RconverterI () is respectively wind-driven generator, the photovoltaic electric of 1 year The displacement cost of pond, accumulator, diesel-driven generator and current transformer.

B (i)=B_sell(i)+B_sal (7)

In formula, B_sell(i)、B_salThe power selling income of respectively 1 year, remanent value of equipment.Remanent value of equipment is referred to During construction period, the surplus value that equipment component does not also arrive service life and remains.

Carbon emission amountRefer to CO of the microgrid to environmental emission in life cycle management₂Amount.Diesel power generation is microgrid discharge CO₂Source, therefore CO₂Discharge capacity be directly related with diesel-fuel consumption.Open diesel-driven generator as far as possible less, can reduce complete Diesel-fuel consumption in life cycle, reduces CO to reach₂The purpose of discharge capacity.Microgrid year CO₂Discharge capacity is equal to year diesel-fuel consumption With its CO₂The product of emission factor.It is that discharge capacity is converted into into economic cost, introduces discharge punishment and carry out computing environment cost：

In formula：Unit CO is produced for diesel oil₂Caused punishment expenses standard [$/kg]；For Diesel Emissions coefficient [kg/L], i.e. CO produced by mean unit diesel oil₂Amount；v_dieselI () is year diesel-fuel consumption [L] of 1 year microgrid.

Ratio of the regenerative resource annual electricity generating capacity with whole micro- source annual electricity generating capacities in microgrid is defined as into regenerative resource profit Use rate R_ren.The regenerative resource energy that reduction is not utilized just can improve renewable energy utilization rate.Equally, to life cycle management The regenerative resource energy inside not utilized carries out economic punishment：

In formula：p_unExpenses standard [] is punished caused by the regenerative resource not utilized for unit；T_unI () is i-th The regenerative resource energy [kWh] that year does not utilize.

2nd, multiple-objection optimization is converted to single object optimization

There is certain conflict between 3 indexs of the above, for example, carbon emission amount E will be made_CO2It is less, diesel oil is required accordingly The opening time of electromotor is shorter, then the regenerative resource for needing is then more, and works as regenerative resource and reach certain permeability Afterwards, the regenerative resource energy not utilized will be increased, causes R_renReduce.Accordingly, it would be desirable to weigh each index of consideration.

Multi-objective optimization question is converted to by single-object problem using linear weighted function summation, it is designed in order to consider The safety of microgrid, introduces a penalty factor σ, and specific expression formula is：

In formula, the weight coefficient of each sub-goal weighs method determination surely using paried comparison.G (X) is for expression by load short of electricity rate The constraint function that LPSP is introduced.LPSP is defined as the ratio for not meeting workload demand energy and total capacity requirement energy, and its value is got over Little, power supply safety reliability is higher, is converted into constraints and is represented by：

I.e.：

G (X)=LPSP- λ≤0 (13)

Wherein, ∑ P_load-unFor total load and energy that do not meet, ∑ P_loadFor total workload demand energy, the present invention set λ as 0.1%.

In order to protect accumulator and the feature of environmental protection, the design of microgrid should also need to consider following constraints：

(1) restriction of the charged state of accumulator no more than accumulator maximum carrying capacity and minimum carrying capacity.

SOC_min≤SOC(t)≤SOC_max (14)

(2) within the 20% of the provided electricity of system, i.e., diesel-driven generator year generated energy accounts for

P_DG/(P_RE+P_DG)≤0.2 (15)

In formula：P_DGFor the power that diesel-driven generator is provided, P_RE=Num_pvP_pv+Num_wtP_wtFor the work(that regenerative resource is provided Rate.

3rd, optimized variable is chosen

Microgrid design first need to constitute system various lectotype selections, technical staff according to the actual type selecting of engineering, it is determined that Fan parameter, photovoltaic cell parameter, energy-storage battery parameter, choose blower fan number of units Num that may be incorporated into_wt, photovoltaic battery array simultaneously Connection string number Num_pv, accumulator string number Num in parallel_batAs optimized variable.

4th, independent microgrid system operation control strategy

Each microgrid design, needs using specific operation control strategy.The present invention adopts following control plan Slightly：In microgrid operation, pay the utmost attention to meet workload demand with renewable energy power generation amount, according to renewable energy power generation amount with it is negative The difference of lotus institute subfam. Spiraeoideae, determines the start-stop of the charging and discharging state and diesel-driven generator of accumulator.

△ P (t)=P_RE(t)-P_L(t) (16)

In formula：P_RET () represents the power in moment t by produced by regenerative resource.

P_RE(t)=Num_pvP_pv(t)+Num_wtP_wt(t) (17)

P_LT () represents current transformer DC side power demand, calculated with equation below：

P_L(t)=P_load(t)/η_i (18)

P_loadT () represents t load power demand, η_iRepresent the conversion efficiency of DC/AC current transformers.

(1) when △ P (t) >=0, unnecessary capacity is to battery charging, if the electricity of accumulator is reached in SOC chargings Limit, then pay the utmost attention to put into cold-storage ice making load, such as have unnecessary again, then cut-out regenerative resource.

(2) as △ P (t)<0, unsatisfied power can be provided by diesel-driven generator or accumulator, be divided into two kinds of situations：

If 1. the electric energy stored by accumulator battery can meet workload demand, by battery discharging, diesel-driven generator is closed.

P_bat(t)=△ P (t) (19)

If 2. the electric energy stored by accumulator battery can not meet remaining workload demand, start diesel-driven generator, now Accumulator is neither discharged nor is charged.

P_de(t)=P_L(t)-P_RE(t) (20)

In formula：P_deT () represents the power that diesel-driven generator need to be provided.

5th, the design based on universal gravitation algorithm to independent microgrid system

The design mathematic model of independent microgrid system is solved using universal gravitation algorithm, which realizes flow process such as Fig. 2 Shown, concrete implementation procedure is following (present invention is minimum problems)：

1) independent microgrid system topological structure to be optimized, blower fan, photovoltaic, accumulator, diesel engine, the correlation of current transformer are input into Parameter, load parameter, and constraints.

2) population scale N, gravitational constant initial value G are set₀, gravitation variation coefficient α, maximum iteration time T.

3) with X=[Num_wt,Num_pv,Num_bat] for variable to be optimized, initial population is generated at random, by independent microgrid system Single-goal function (formula (10)) after design conversion evaluates population at individual fitness value as fitness index, obtains the overall situation most The initial value of excellent solution.

4) gravitational constant G (t) in Population Regeneration, optimum best (t), worst-case value worst (t).

5) each mass of object M, and number Kbest (t) of regeneration function object are calculated.

6) calculating each object is attracted generation to be made a concerted effort by effect object, calculates resultant acceleration.

7) speed and the position of object are updated.

If 8) reach maximum iteration time T, terminate computing, return independent microgrid system design optimal solution；Otherwise iteration Number of times adds one, goes to step 3) enter next iteration.

The present invention stores independent microgrid system around wind-light-diesel, with the string in parallel of wind-driven generator number of units, photovoltaic cell in system Number and accumulator string number in parallel are optimized variable, establish consider its economy, the feature of environmental protection, renewable energy utilization rate, The objective design model of the technical-economic indexes such as power supply safety reliability.Then multi-objective problem conversion single object optimization is asked Inscribe, and method is weighed surely using paried comparison determine each sub-goal weight.Using the single-goal function after conversion as GSA algorithms adaptation Degree index, devises the capacity of the rated power and energy-storage system of distributed power source in system, and has fully ensured that independent micro-grid The economy of system and safety.

Finally illustrate, above example is only unrestricted to illustrate technical scheme, although with reference to compared with Good embodiment has been described in detail to the present invention, it will be understood by those within the art that, can be to the skill of the present invention Art scheme is modified or equivalent, and without deviating from the objective and scope of the technical program, which all should be covered in the present invention Right in the middle of.

Claims (5)

1. a kind of independent microgrid system method for designing based on universal gravitation algorithm, it is characterised in that：Comprise the steps：

Step S1, sets up the independent microgrid system model with Multi-target evaluation index；

Step S2, by the independent micro-grid system that the independent microgrid system model conversion of Multi-target evaluation index is single goal evaluation index System model；

Step S3, chooses blower fan number of units Num that may be incorporated into_wt, photovoltaic battery array string number Num in parallel_pv, accumulator string number in parallel Num_batAs optimized variable；

Step S4, determines the operation control strategy of independent microgrid system, pays the utmost attention to meet load with renewable energy power generation amount Demand, according to renewable energy power generation amount and the difference of load institute subfam. Spiraeoideae, determines the charging and discharging state and diesel oil of accumulator The start-stop of electromotor；

Step S5, is solved to independent microgrid system model using universal gravitation algorithm.

2. a kind of independent microgrid system method for designing based on universal gravitation algorithm according to claim 1, its feature exist In：The independent microgrid system model process set up with Multi-target evaluation index in step S1 is as follows：

Using Model for Multi-Objective Optimization, the optimum capacity allocation plan of each distributed power source in microgrid, energy-storage system is determined；Its tool Body scheme include four can quantitatively evaluating index：Economic index, is represented with the total net ready-made NPC in life cycle management；Ring Guarantor property index, uses carbon emission amountRepresent；Renewable energy utilization rate index, uses R_renRepresent；Microgrid security reliability index, Represented with load short of electricity rate LPSP；

Total net ready-made NPC refers to the produced net charge in life cycle management of microgrid, and which includes initial outlay cost, engineering Each several part operation expense, fuel cost and displacement cost in life-span, income part includes sale of electricity income and remanent value of equipment；Number Learning expression formula is：

$f_1\left(x\right)=\underset{i=1}{\overset{N}{\&Sigma;}}\frac{C\left(i\right)-B\left(i\right)}{{(1+r)}^i}$

In formula：X is optimized variable, engineering life-spans [year] of the N for microgrid, and r is discount rate, C (i), B (i) be respectively 1 year into Originally with income [$/year]；C (i) computing formula are as follows：

C (i)=C_I(i)+C_M(i)+C_F(i)+C_R(i)

In formula：C_I(i)、C_M(i)、C_F(i)、C_R(i) respectively 1 year initial outlay cost, operation expense, fuel cost With displacement cost；Concrete variable computing formula point row are as follows：

C_I(k)=C_Iwt+C_Ipv+C_Ibat+C_Ide+C_Iconverter+C_Icontrol

Wherein, C_Iwt、C_Ipv、C_Ibat、C_Ide、C_Iconverter、C_IcontrolRespectively wind-driven generator, photovoltaic cell, accumulator, diesel oil The cost of investment of electromotor, current transformer and microgrid management control system；

C_M(i)=C_Mwt(i)+C_Mpv(i)+C_Mbat(i)+C_Mde(i)+C_Mconverter(i)

Wherein, C_Mwt(i)、C_Mpv(i)、C_Mbat(i)、C_Mde(i)、C_MconverterI () is respectively wind-driven generator, the photovoltaic of 1 year The operation maintenance of battery, accumulator, diesel-driven generator and current transformer into；

C_F(i)=C_Fde(i)

Represent the fuel cost of the diesel-driven generator of 1 year；

C_R(i)=C_Rwt(i)+C_Rpv(i)+C_Rbat(i)+C_Rde(i)+C_Rconverter(i)

C_Rwt(i)、C_Rpv(i)、C_Rbat(i)、C_Rde(i)、C_Rconverter(i) be respectively 1 year wind-driven generator, photovoltaic cell, The displacement cost of accumulator, diesel-driven generator and current transformer；

B (i)=B_sell(i)+B_sal

In formula, B_sell(i)、B_salThe power selling income of respectively 1 year, remanent value of equipment；Remanent value of equipment is referred to During system usage cycles, the surplus value that equipment component does not also arrive service life and remains；

Carbon emission amountRefer to CO of the microgrid to environmental emission in life cycle management₂Amount, introduce discharge punishment come computing environment into This：

$f_2\left(x\right)=\underset{i=1}{\overset{i}{\&Sigma;}}\frac{p_{{\mathrm{CO}}_2}{\mathrm{\&mu;}}_{{\mathrm{CO}}_2}{v}_{diesel}\left(i\right)}{{(1+r)}^i}$

In formula：Unit CO is produced for diesel oil₂Caused punishment expenses standard [$/kg]；For Diesel Emissions coefficient [kg/ L], i.e. CO produced by mean unit diesel oil₂Amount；v_dieselI () is year diesel-fuel consumption [L] of 1 year microgrid；

Ratio of the regenerative resource annual electricity generating capacity with whole micro- source annual electricity generating capacities in independent microgrid system is defined as into renewable energy Source utilization rate R_ren；Regenerative resource energy to not utilizing in life cycle management carries out economic punishment：

$f_3\left(x\right)=\underset{i=1}{\overset{N}{\&Sigma;}}\frac{p_{un}{T}_{un}\left(i\right)}{{(1+r)}^i}$

In formula：p_unExpenses standard [] is punished caused by the regenerative resource not utilized for unit；T_un(i) for 1 year not The regenerative resource energy [kWh] for utilizing.

3. a kind of independent microgrid system method for designing based on universal gravitation algorithm according to claim 2, its feature exist In：It is the independent microgrid system model conversion of Multi-target evaluation index is micro- for the independence of single goal evaluation index in step S2 The detailed process of net system model is as follows：

Multi-objective optimization question is converted to by single-object problem using linear weighted function summation, a penalty factor σ is introduced, Specifically expression formula is：

$\min F=\underset{i=1}{\overset{3}{\&Sigma;}}{\mathrm{\&lambda;}}_i{f}_i+\mathrm{\&sigma;}$

$s.t.\left\{\begin{array}{c}\underset{i=1}{\overset{3}{\&Sigma;}}{\mathrm{\&lambda;}}_i=1,{\mathrm{\&lambda;}}_i\&GreaterEqual;0\\ \mathrm{\&sigma;}=\left\{\begin{array}{cc}0& g\left(X\right)\&le;0\\ {10}^{10}& g\left(X\right)>0\end{array}\right.\end{array}\right.$

In formula, the weight coefficient of each sub-goal weighs method determination surely using paried comparison；G (X) is drawn by load short of electricity rate LPSP for representing The constraint function for entering；LPSP is defined as the ratio for not meeting workload demand energy and total capacity requirement energy, and its value is less, power supply Security reliability is higher, is converted into constraints and is expressed as：

$LPSP=\frac{{\mathrm{\&Sigma;P}}_{load-un}}{{\mathrm{\&Sigma;P}}_{load}}\&le;\mathrm{\&lambda;}$

I.e.：

G (X)=LPSP- λ≤0

Wherein, ∑ P_load-unFor total load and energy that do not meet, ∑ P_loadFor total workload demand energy, if λ is 0.1%；

Simultaneously, it is considered to constraints below：

(1) restriction of the charged state of accumulator no more than accumulator maximum carrying capacity and minimum carrying capacity, i.e.,

SOC_min≤SOC(t)≤SOC_max

(2) within the 20% of the provided electricity of system, i.e., diesel-driven generator year generated energy accounts for

P_DG/(P_RE+P_DG)≤0.2

In formula：P_DGFor the power that diesel-driven generator is provided, P_RE=Num_pvP_pv+Num_wtP_wtFor the power that regenerative resource is provided.

4. a kind of independent microgrid system method for designing based on universal gravitation algorithm according to claim 3, its feature exist In：The detailed process of step S4 is：

According to renewable energy power generation amount and the difference of load institute subfam. Spiraeoideae, determine that the charging and discharging state and diesel oil of accumulator are sent out The start-stop of motor；

△ P (t)=P_RE(t)-P_L(t)

In formula：P_RET () represents the power in moment t by produced by regenerative resource；

P_RE(t)=Num_pvP_pv(t)+Num_wtP_wt(t)

P_LT () represents current transformer DC side power demand, calculated with equation below：

P_L(t)=P_load(t)/η_i

P_loadT () represents t load power demand, η_iRepresent the conversion efficiency of DC/AC current transformers；

When △ P (t) >=0, unnecessary capacity is to battery charging, if the electricity of accumulator reaches SOC charging upper limits, preferentially Consider input cold-storage ice making load, such as have unnecessary again, then cut-out regenerative resource；

As △ P (t)<0, unsatisfied power can be provided by diesel-driven generator or accumulator, specially：

If 1. the electric energy stored by accumulator battery can meet workload demand, by battery discharging, diesel-driven generator is closed.

P_bat(t)=△ P (t)

If 2. the electric energy stored by accumulator battery can not meet remaining workload demand, start diesel-driven generator, now electric power storage Neither discharge nor charge in pond；

P_de(t)=P_L(t)-P_RE(t)

In formula：P_deT () represents the power that diesel-driven generator need to be provided.

5. a kind of independent microgrid system method for designing based on universal gravitation algorithm according to claim 4, its feature exist In：The detailed process of step S5 is：

1) independent microgrid system topological structure to be optimized is input into, including the parameter of blower fan, photovoltaic, accumulator, diesel engine, current transformer And constraints；

2) population scale N, gravitational constant initial value G are set₀, gravitation variation coefficient α, maximum iteration time T；

3) with X=[Num_wt,Num_pv,Num_bat] for variable to be optimized, generate initial population at random, independent microgrid system is designed Single-goal function after conversionAs fitness index, population at individual fitness value is evaluated, obtain complete The initial value of office's optimal solution；

4) gravitational constant G (t) in Population Regeneration, optimum best (t), worst-case value worst (t)；

5) each mass of object M, and number Kbest (t) of regeneration function object are calculated；

6) calculating each object is attracted generation to be made a concerted effort by effect object, calculates resultant acceleration；

7) speed and the position of object are updated；

If 8) reach maximum iteration time T, terminate computing, return independent microgrid system design optimal solution；Otherwise iterationses Plus one, go to step 3) enter next iteration.