CN105406433A - Optimal power and capacity selection method of mobile battery energy storage DC-based deicing system - Google Patents

Abstract

The invention relates to an optimal power and capacity selection method of a mobile battery energy storage DC-based deicing system. The method comprises the following steps: step S1: providing a mobile battery energy storage DC-based deicing system, wherein the DC-based deicing system comprises a battery energy storage system, a bidirectional converter, a DC/DC converter, a background monitor and switch combination; step S2, carrying out statistics on the distribution of ice regions of a power grid; step S3, calculating the current value of the DC-based deicing system in the DC-based deicing process; and step S4, calculating deicing powers, deicing capacities and optimization functions of the DC-based deicing system under three deicing modes of "1-1, 1-2", "1-1, 1-1", "1-2, 1-2, 1-2". Starting from the angle of system cost, according to the conditions of ice regions, the state grid guideline and the actual situation of lines of mountainous areas, the method can be used for putting forwards a cost optimization function by calculating the powers and capacities of the DC-based deicing system under three deicing modes, thereby providing a basis for selection of power and capacity of the mobile battery energy storage DC-based deicing system.

Description

The power of mobile battery energy storage direct current ice melting system and capacity optimum option method

Technical field

The present invention relates to ice melting system field, particularly a kind of power of mobile battery energy storage direct current ice melting system and capacity optimum option method.

Background technology

Ice disaster has serious harm to electrical network, traffic and crops etc., and the serious icing of electric line can cause its machinery and electric property sharply to decline, thus causes the generation of icing density.Although Fujian Province is located in In South China, but the north of Fujian Province, icing is had during distribution network line winter in the High aititude mountain area of Min Dong and Min Xi, very adverse influence is caused to resident's daily life and industrial and agricultural production, 2008 especially serious, strong cold air starts to invade Fujian Province from late January, continue the low temperature of more than ten day along with sleet, snow ice, icing, electrical network facilities large area is impaired, numerous electric line because of icing fall string, broken string, fall tower and forced outage, Fujian Counties of North-west Five 220kV and following system is caused to be inflicted heavy losses on, Jianning, Shaowu, gloss, Ninghua, Pucheng, Changting, Taining, Shanghai-Hangzhou, Wuyi Mountain, Deng26Ge county, Wuping (city) part small towns suffers loss in various degree, wherein with Jianning, Shaowu, gloss, Ninghua, Pucheng five counties and cities are the most serious, 35kV and following level Grid occurrence of large-area have a power failure.Carry out except ice-melt is one of important channel reducing electrical network icing calamity damage to transmission & distribution icing circuit timely and effectively, therefore can for Fujian mountain area medium-voltage line, study the medium-voltage line DC ice melting technology based on mobile battery energy storage device, propose power and the capacity optimum option method of this ice melting system.

Summary of the invention

In view of this, the object of this invention is to provide a kind of power and capacity optimum option method of mobile battery energy storage direct current ice melting system, from the angle of system cost, propose cost optimization equation, can be to choose based on the power of mobile battery energy storage direct current ice melting system and capacity provides foundation.

The present invention adopts following scheme to realize: a kind of power of mobile battery energy storage direct current ice melting system and capacity optimum option method, comprise the following steps:

Step S1: provide a mobile battery energy storage direct current ice melting system, described direct current ice melting system comprises battery energy storage system, two way convertor, DC/DC DC converter, background monitoring and switch combination; Described battery energy storage system comprises ferric phosphate lithium cell cabinet and the battery management system of parallel running, and wherein battery rack is formed by a sequence ferric phosphate lithium cell case connection in series-parallel;

Step S2: power grid ice region distribution situation is added up;

Step S3: calculate the current value of direct current ice melting system in DC ice melting process;

Step S4: calculate the ice-melt power of direct current ice melting system under " 1-1,1-2 ", " 1-1,1-1 ", " 1-2,1-2,1-2 " three kinds of ice-melting modes, ice-melt capacity and optimization method.

Further, described step S2 adds up ice formation distribution situation according to the ice covering thickness of different altitude height, specifically comprises the following steps:

Step S21: calculate standard ice thickness: the standard ice covering thickness evenly wrapped around wire by different densities, difform ice covering thickness equivalent being density 0.9g/cm3, then standard ice thickness heavily calculates by icing ice, and its computing formula is as follows:

$b_0=\sqrt{\frac{G}{0.9\mathrm{\π}L}+r^2}-r$

In formula: b ₀for standard ice thickness; G is ice weight; L is icing body length; R is wire radius;

Step S22: the height correction and the wire diameter correction that calculate standard ice thickness: answer reduction to 10m eminence by line design code requirement ice covering thickness, then shown in the following formula of altitude correction factor:

K _h＝(Z/Z ₀) ^α

Shown in the following formula of wire diameter correction factor:

With in above formula: K _hfor altitude correction factor; Z gets 10m; Z ₀for actual measurement or investigation ice coating wire suspension height; α is index, relevant with wind speed, water content and capture coefficient, if without field data time, α can value 0.22; for wire diameter correction factor; for design diameter of wire, φ≤40mm; for actual measurement or the diameter of wire investigating icing;

Step S23: calculate different reoccurrence standard ice thickness: add up respectively according to 100 year return period of 30 years, 50 years one-levels, the ice covering thickness of icing data method, CRREL modelling, the local landform of meteorological parameter Return Law one-level-meteorological effect icing Grade Model method determination different reoccurrence can be adopted;

Step S24: ice covering thickness is revised with altitude change: ice covering thickness increases with height above sea level and increases, the different reoccurrence standard ice thickness value utilizing several different altitude height to calculate, simulate the exponential formula that ice thickness changes with height above sea level, shown in following formula:

R _h＝βe ^ah

In formula: R _hfor a certain height above sea level _hon ice thickness; A and β is undetermined parameter.

Further, in described step S3, the ice melting current of direct current ice melting system in DC ice melting process adopts following formulae discovery to draw:

$I_{melt}=\sqrt{\frac{\frac{10g_{0}db+\frac{0.045g_0{D}^2}{R_{T0}+R_{T1}}(R_{T1}+0.22\frac{R_{T0}}{\lg \frac{D}{d}})\mathrm{\Δ}t}{T_{melt}}+\frac{\mathrm{\Δ}t}{R_{T0}+R_{T1}}}{R_0}}$

In formula: I _meltfor ice melting current; R ₀the resistance value of wire of one meter long when being 0 DEG C; Δ t is the difference of conductor temperature and ambient temperature; R _t0for equivalent ice sheet thermal-conduction resistance, relevant with conductive coefficient; D is the external diameter after conductor icing; D is diameter of wire; R _t1for convection current and radiological equivalent thermal resistance, relevant with wind speed; B is ice layer thickness; g ₀for the proportion of ice, get 0.9, T by glaze _meltfor the ice-melt time;

Then DC ice melting current should be chosen between minimum ice melting current and maximum ice melting current, and the computing formula wherein calculating minimum direct current ice melting current is as follows:

$I_{min}=\sqrt{\frac{\mathrm{\Δ}t}{R_0(R_{T0}+R_{T1})}};$

When heating wires makes its temperature rise to 90 DEG C, the computing formula calculating maximum DC ice melting current is as follows:

$I_{max}=\sqrt{\[7.24\left(\frac{318+0.5t_2}{1000}\right)\mathrm{\Σ}id+0.7{\left(\frac{Vd}{2}\right)}^{\frac{3}{4}}(90-t_2)\]/R_{90}}$

In formula: I _minfor minimum ice melting current; I _maxfor maximum ice melting current; t ₂for ambient temperature; V is wind speed, and its value is greater than 2m/s; Σ i is radiation coefficient.

Further, in described step S4, it is 10mm that direct current ice melting system chooses ice covering thickness, and single DC ice-melting length is 4km, circuit model is LGJ-120, ambient temperature is-4 DEG C, and wind speed is that the environment of 5m/s carries out ice-melt work, calculates the ice-melt power under described direct current ice melting system " 1-1; 1-2 ", " 1-1; 1-1 ", " 1-2,1-2,1-2 " three kinds of ice-melting modes and ice-melt capacity; Wherein " " for ice-melt power supply one enters an access way, " 1-2 " enters twice access waies for ice-melt power supply one to 1-1;

Described " 1-1,1-2 " ice-melting mode is specially: adopt two DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and another output is connected with the B phase of ac bus; One output of the 2nd DC/DC DC converter is connected with the A phase of ac bus and B phase, and another output is connected with the C phase of ac bus;

Described " 1-1,1-1 " ice-melting mode is specially: adopt two DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and another output is connected with the B phase of ac bus; One output of the 2nd DC/DC DC converter is connected with the B phase of ac bus, and another output is connected with the C phase of ac bus;

Described " 1-2,1-2,1-2 " ice-melting mode is specially: adopt three DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and B phase and the C phase of another output and ac bus are connected; One output of the 2nd DC/DC DC converter is connected with the A phase of ac bus and B phase, and another output is connected with the C phase of ac bus; One output of the 3rd DC/DC DC converter is connected with the A phase of ac bus and C phase, and another output is connected with the B phase of ac bus.

Further, under described " 1-1; 1-2 ", " 1-2,1-2,1-2 " ice-melting mode, due to the current-sharing of two-phase lines in parallel, by parallel line every road electric current close to critical current, ice-melt effect is not had substantially, then when boundary condition is constant to icing circuit in parallel, ignore the change of conductor impedance in deicing processes, choosing each ice-melt power is the rated power of DC converter:

$\left\{\begin{array}{c}{E}_{1-1,1-2}=P_r(T_{1-1}+T_{1-2})\\ E_{1-1,1-1}=2P_r{T}_{1-1,1-1}\\ E_{1-2,1-2,1-2}=3P_r{T}_{1-2,1-2,1-2}\\ 2r_0{\mathrm{lI}}_{1-1}^2=1.5r_0{\mathrm{lI}}_{1-2}^2\end{array}\right.$

In formula: E _1-1,1-2for the electricity spent by the ice-melt of " 1-1,1-2 " ice-melting mode; E _1-1,1-1for the electricity spent by the ice-melt of " 1-1,1-1 " ice-melting mode; E _1-2,1-2,1-2for the electricity spent by the ice-melt of " 1-2,1-2,1-2 " ice-melting mode; P _rfor the rated power of ice-melt DC converter, kW; I _1-1be into an ice melting current; I _1-2be into twice ice melting currents; L is line ice-melting length; r ₀for the resistance per unit length of circuit, do not consider that in deicing processes, variations in temperature is on its impact.

Further, the ice-melt voltage of described " 1-1,1-2 " ice-melting mode and ice-melt power is adopted to enter shown in following formula respectively:

U _1-1＝2r ₀lI _1-1

$P_{1-1}=2I_{1-1}^2{r}_{0}l$

In formula: U _1-1for the DC ice melting voltage under " 1-1 " ice-melt plant-grid connection mode; P _1-1for ice-melt power required under " 1-1 " ice-melt plant-grid connection mode.

Further, the cost of described direct current ice melting system is subject to the impact of battery energy storage system, two way convertor and DC/DC DC converter cost, wherein the cost of battery energy storage system depends on quantity and the price of connection in series-parallel ferric phosphate lithium cell case, can obtain shown in the ice-melt power of described direct current ice melting system and the following formula of optimization method of capacity, DC ice melting current is its constraints:

$\left\{\begin{array}{c}F=P_r\&CenterDot;f_{PCS}+P_r\&CenterDot;f_{DC-DC}+f_b\&CenterDot;\max (P_r/p1,C_1/c1)\\ P_r=P_{1-1}=2I_{1-1}^2{r}_{0}l\\ E_1=2I_{1-1}^2{r}_0{\mathrm{lT}}_{1-1}+1.5I_{1-2}^2{r}_0{\mathrm{lT}}_{1-2}\\ I_{\min }<I_{1-1},I_{1-2}<I_{\max }\end{array}\right.$

In formula: F is direct current ice melting system total cost; f _pCSfor the PCS price of unit power; f _dC-DCfor the DC-DC DC converter price of unit power; f _bfor the price of single battery case; P1 is the power of single battery case; C1 is the capacity of single battery case.

Compared with prior art, the power of a kind of mobile battery energy storage direct current ice melting system provided by the invention and capacity optimum option method, according to ice formation situation, state's net directive/guide and mountain route actual conditions, the power of the direct current ice melting system of computational analysis " 1-1; 1-2 ", " 1-1; 1-1 ", " 1-2,1-2,1-2 " three kinds of ice-melting modes and capacity requirement; From the angle of ice-melting mode and system cost, the power of DC ice melting and capacity are optimized, propose based on the cost optimization equation of the medium-voltage line ice melting system of mobile energy storage device, can be to choose based on the power of the direct current ice melting system of mobile battery energy storage device and capacity provides foundation.

Accompanying drawing explanation

Fig. 1 is mobile battery energy storage direct current ice melting system structure chart of the present invention.

Fig. 2 is wire deicing processes schematic diagram of the present invention.

Fig. 3 (a) is the DC converter wiring schematic diagram of the present invention " 1-1,1-2 " ice-melting mode.

Fig. 3 (b) is the DC converter wiring schematic diagram of the present invention " 1-1,1-1 " ice-melting mode.

Fig. 3 (c) is the DC converter wiring schematic diagram of the present invention " 1-2,1-2,1-2 " ice-melting mode.

Fig. 4 is the graph of a relation of power and ice-melt capacity under the different ice-melting mode of the present invention.

Fig. 5 is the graph of a relation of ice-melt time and ice-melt power under the different ice-melting mode of the present invention.

Fig. 6 (a) is ice melting current of the present invention, voltage and ice-melt time chart.

Fig. 6 (b) is ice-melt power of the present invention, capacity and ice-melt time chart.

Fig. 7 is present system cost and rated power graph of a relation.

Fig. 8 is method flow schematic diagram of the present invention.

Embodiment

Below in conjunction with drawings and Examples, the present invention will be further described.

The present embodiment, for In Fujian Province, provides a kind of power and capacity optimum option method of mobile battery energy storage direct current ice melting system, as shown in Figure 8, comprises the following steps:

Step S1: provide a mobile battery energy storage direct current ice melting system, described direct current ice melting system comprises battery energy storage system, two way convertor, DC/DC DC converter, background monitoring and switch combination; Described battery energy storage system comprises ferric phosphate lithium cell cabinet and the battery management system of parallel running, and wherein battery rack is formed by a sequence ferric phosphate lithium cell case connection in series-parallel;

Step S2: power grid ice region distribution situation is added up;

Step S3: calculate the current value of direct current ice melting system in DC ice melting process;

Step S4: calculate the ice-melt power of direct current ice melting system under " 1-1,1-2 ", " 1-1,1-1 ", " 1-2,1-2,1-2 " three kinds of ice-melting modes, ice-melt capacity and optimization method.

In the present embodiment, the medium-voltage line direct current ice melting system based on mobile battery energy storage device is made up of battery energy storage system, two way convertor, DC converter, background monitoring and switch combination, is all integrated into mobile railway carriage.One or the parallel running of many Mobile energy storage devices complete ice-melt work, the concrete composition structure of system as shown in Figure 1, battery energy storage system forms primarily of the ferric phosphate lithium cell cabinet of parallel running and battery management system, wherein battery rack is formed by a sequence ferric phosphate lithium cell case connection in series-parallel, and two way convertor and DC converter are respectively and exchange discharge and recharge and DC ice melting interface.

In the present embodiment, Fujian is located in south China, latitude is lower, the probability of ice and snow low temperature is little relatively, the sight ice station of laying is also little, the height above sea level on In Western Fujian Province and middle part two large mountain ranges is higher, along with electrical network electric line increasing in high altitude localities, also there will be more serious icing disaster, from all previous ice damage situation, ice damage region mainly concentrates on region, the northwestward, Fujian Province, the most serious disaster-stricken point mainly concentrates on and Jiangxi adjacent area in this region, height above sea level Longyan more than 500 meters, region, the northwestward, Nan Ping icing disaster is more serious, Sanming City northwestward region icing disaster of height above sea level more than 300 meters is more serious, the ice-covering-proof design and reconstruction work that the statistical analysis that ice formation, Fujian Province distributes can be electric line provides important reference frame.

In the present embodiment, power grid ice region Statistic Analysis in Fujian Province's is according to comprising: Fujian weather bureau observation data, electric wire freeze observation station observation data and the standard ice thickness according to glaze, rime matching; Different altitude height ice covering thickness fitting formula; Ice damage and operation of power networks experience; Terrain data etc.The concrete steps of statistical analysis are as follows:

(1) standard ice thickness is calculated.In order to make the whole province's icing zone plotting unified and standardization, need be the standard ice covering thickness evenly wrapped around wire of density 0.9g/cm3 by different densities, difform ice covering thickness equivalent.The standard ice thickness of each icing observation station heavily calculates by icing ice, and its computing formula is such as formula shown in (1):

$b_0=\sqrt{\frac{G}{0.9\mathrm{\&pi;}L}+r^2}-r---\left(1\right)$

In formula: b ₀for standard ice thickness, mm; G is ice weight, g; L is icing body length, m; R is wire radius, mm.

(2) height of standard ice thickness, wire diameter correction.Icing size and wind speed, air moisture content are in close relations.Wind speed, the water content of differing heights have difference.Increase in near-earth air layer wind speed with altitude, wind speed is larger, wire catch water droplet, crystal just the more, icing is just larger.China's line design code requirement ice covering thickness answers reduction to 10m eminence, and altitude correction factor is as shown in formula (2).Wire diameter correction factor should be determined according to field data analysis, unsurveyed area carry out wire diameter correction by correction factor formula (3) Suo Shi:

K _h＝(Z/Z ₀) ^α(2)

In formula: K _hfor altitude correction factor; Z gets 10m; Z ₀for actual measurement or investigation ice coating wire suspension height, m; α is index, relevant with wind speed, water content and capture coefficient, and during without field data, α can value 0.22; for wire diameter correction factor; for design diameter of wire, mm, φ≤40mm; for actual measurement or the diameter of wire investigating icing, mm.

(3) different reoccurrence standard ice thickness calculates.The distribution of ice formation, Fujian Province was generally added up respectively according to 30,50,100 year return period.According to various places actual conditions, the ice covering thickness of the method determination different reoccurrence such as icing data method, CRREL modelling, the meteorological parameter Return Law, local landform-meteorological effect icing Grade Model method can be adopted.

(4) ice covering thickness is with the correction of altitude change.Increase because ice covering thickness increases with height above sea level, wire icing is in Beneath Clouds height, its condensation number is with highly exponentially Changing Pattern, therefore the different reoccurrence standard ice thickness value of several different altitude height weather station is utilized, simulate the exponential formula that ice thickness changes with height above sea level, as shown in formula (4):

R _h＝βe ^ah(4)

In formula: R _hfor the ice thickness on a certain height above sea level h; A and β is undetermined parameter.

Distinguish as shown in Table 1 and Table 2 according to the ice formation distribution situation that above-mentioned ice formation distribution statistics division methods obtains under Central Southern Fujian Province and northern territory different altitude height.As can be seen from the table, Fujian Province's ice covering thickness is obvious with height above sea level change, and comparatively southern is serious for northern territory icing situation.

Ice formation, Mountainous Area of North, table 1 Fujian distribution situation (to the north of in the of 26 ° 30 ')

Ice formation, mountain range, table 2 Middle and southern part of Fujian province distribution situation (on the south in the of 26 ° 30 ')

In the present embodiment, due to urban and rural power grids disparate development, In Fujian Rural Areas Power grid structure, electrical network equipment and technical merit, power supply quality are starkly lower than urban distribution network.MV distribution systems generally adopts built on stilts wiring, segmentation, contact ratio lower.Line conductor cross section is less than normal, and the 10kV circuit wire diameter of the whole province's rural power grids 36% is less than 95mm2, and the medium-voltage line wire diameter of 20% is between 95mm2 to 150mm2.Rural power grids medium-voltage line radius of electricity supply is long, wherein the whole province 10kV circuit average length 12.8km, and the ability that equipment is withstood natural calamities is lower.

The division of the power supply area standard of power distribution network is mainly divided into A, B, C, D tetra-class by " State Grid Corporation of China " 12 " distribution network planning (engineering philosophy) instruction ".C class power supply area mainly refers to the industry of the outer suburbs, the rural area of population Relatively centralized and ground village, the rural area based on agricultural industry, and its load density is between 1 ~ 6MW/km2.Main consideration herein at least can carry out ice-melt to the backbone total length in the radius of electricity supply in C class area, and the radius of electricity supply of C class area medium-voltage line is generally no more than 4km, and trunk overhead wire gets LGJ120.

At present, be applied to the most frequently used method of power network line ice-melt and surely belong to the ice-melt of direct current thermodynamics.According to many researchs of deicing processes, deicing processes is broadly divided into following 2 stages: the first stage is the ice-melt when cylinder is wrapped up completely by ice; In second stage, cylinder upper surface breaks ice cylinder and ice is come off.When ice sheet upper surface summit and wire upper surface apexes contact, the now deadweight of ice will be greater than and the shear stress of the ice sheet contacted with conductive line surfaces, and comes off from wire.Ice-melt detailed process as shown in Figure 2.

The Joule heat that in DC ice melting process, electric current produces mainly acts on: ice is dissolved into the latent heat of phase change of water, heat needed for Ice Temperature rises and the convection current on ice sheet surface and heat loss through radiation, according to this heat balance relation, the dynamic factors such as the heat conduction of correspondence, convection current and heat loss through radiation can be converted to equivalent thermal resistance, adopt the DC ice melting current computing formula of state's net Q/GDW716-2012 " transmission line electric current de-icing technology directive/guide ", shown in (5):

$I_{melt}=\sqrt{\frac{\frac{10g_{0}db+\frac{0.045g_0{D}^2}{R_{T0}+R_{T1}}(R_{T1}+0.22\frac{R_{T0}}{1g\frac{D}{d}})\mathrm{\&Delta;}t}{T_{melt}}+\frac{\mathrm{\&Delta;}t}{R_{T0}+R_{T1}}}{R_0}}---\left(5\right)$

In formula: I _meltfor ice melting current (peace); R ₀for DEG C time wire resistance per unit length (Europe/rice); Δ t is the difference (degree Celsius) of conductor temperature and ambient temperature; R _t0for equivalent ice sheet thermal-conduction resistance (degree centimetre/watt), relevant with conductive coefficient; D is the external diameter (centimetre) after conductor icing; D is diameter of wire (centimetre); R _t1for convection current and radiological equivalent thermal resistance (degree centimetre/watt), relevant with wind speed; B is ice layer thickness; g ₀for the proportion of ice, generally get 0.9, T by glaze _meltfor the ice-melt time.

From formula (5), under same boundary condition, it is less that the ice-melt deadline gets, and wire ice melting current requires larger, but the energy that ice-melt expends is less, and therefore each ice-melt power should get the maximum of rating of set.Meanwhile, wire ice melting current should be chosen between minimum ice melting current and maximum ice melting current, and this is also the selection range of ice melting current.Defining minimum ice melting current is: its Joule heat produced all by the convection current radiant transfer of ice sheet in air, computing formula is as shown in formula (6); Defining maximum ice melting current is: heating wires makes its temperature rise to the ice melting current of 90 DEG C, and its computing formula is such as formula [10-11] (7) Suo Shi.

$I_{min}=\sqrt{\frac{\mathrm{\&Delta;}t}{R_0(R_{T0}+R_{T1})}}---\left(6\right)$

$I_{max}=\sqrt{\&lsqb;7.24\left(\frac{318+0.5t_2}{1000}\right)\mathrm{\&Sigma;}id+0.7{\left(\frac{Vd}{2}\right)}^{\frac{3}{4}}(90-t_2)\&rsqb;/R_{90}}---\left(7\right)$

In formula: I _minfor minimum ice melting current; I _maxfor maximum ice melting current; t ₂for ambient temperature; V is wind speed, and its value is greater than 2m/s; Σ i is radiation coefficient.

In the present embodiment, the height above sea level of the power supply area that mountain area, Fujian Province is extended by middle pressure network frame is mostly at below 1000m, according to Fujian Province's transmission and distribution network icing situation analysis in 2008, the comparatively extreme ice covering thickness of medium-voltage line mainly concentrates on about 10mm, be roughly the 50 years chances in Middle and southern part of Fujian province and northern height above sea level 500m to 900m ice formation, this is also that 50 years chances match with ice damage in 2008.Consider herein to possess based on the direct current ice melting system of mobile battery energy storage device under comparatively extreme icing condition to meet the ice melting capability of C class power supply area for medium-voltage line, choosing ice covering thickness is 10mm, single DC ice-melting length is 4km, circuit model is LGJ-120, ambient temperature is-4 DEG C, and wind speed is 5m/s.Based on these conditions, calculate ice melting current and the ice-melt capacity under " 1-1,1-2 ", " 1-1,1-1 ", " 1-2,1-2,1-2 " three kinds of ice-melting modes.

As shown in Fig. 3 (a), described " 1-1; 1-2 " ice-melting mode is specially: adopt two DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and another output is connected with the B phase of ac bus; One output of the 2nd DC/DC DC converter is connected with the A phase of ac bus and B phase, and another output is connected with the C phase of ac bus;

As shown in Fig. 3 (b), described " 1-1; 1-1 " ice-melting mode is specially: adopt two DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and another output is connected with the B phase of ac bus; One output of the 2nd DC/DC DC converter is connected with the B phase of ac bus, and another output is connected with the C phase of ac bus;

As shown in Fig. 3 (c), described " 1-2; 1-2; 1-2 " ice-melting mode is specially: adopt three DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and B phase and the C phase of another output and ac bus are connected; One output of the 2nd DC/DC DC converter is connected with the A phase of ac bus and B phase, and another output is connected with the C phase of ac bus; One output of the 3rd DC/DC DC converter is connected with the A phase of ac bus and C phase, and another output is connected with the B phase of ac bus.

In the present embodiment, for " 1-1 (ice-melt power supply one enters a tieback and enters); 1-2 (ice-melt power supply one enters two tiebacks and enters) ", " 1-2; 1-2; 1-2 " mode, due to the current-sharing of two-phase lines in parallel, by parallel line every road electric current close to critical current, ice-melt effect is not had substantially to icing circuit in parallel.When boundary condition is constant, ignore the change of conductor impedance in deicing processes, choosing each ice-melt power is the rated power of device:

$\left\{\begin{array}{c}{E}_{1-1,1-2}=P_r(T_{1-1}+T_{1-2})\\ E_{1-1,1-1}=2P_r{T}_{1-1,1-1}\\ E_{1-2,1-2,1-2}=3P_r{T}_{1-2,1-2,1-2}\\ 2r_0{\mathrm{lI}}_{1-1}^2=1.5r_0{\mathrm{lI}}_{1-2}^2\end{array}\right.---\left(8\right)$

In formula: E _1-1,1-2for the electricity spent by the ice-melt of " 1-1,1-2 " mode, kWh; E _1-1,1-1for the electricity spent by the ice-melt of " 1-1,1-1 " mode, kWh; E _1-2,1-2,1-2for the electricity spent by the ice-melt of " 1-2,1-2,1-2 " mode, kWh; P _rfor the rated power of ice-melt DC converter, kW; I _1-1be into an ice melting current, A; I _1-2be into twice ice melting currents, A; L is line ice-melting length, km; r ₀for the resistance per unit length of circuit, Ω/m, does not consider that in deicing processes, variations in temperature is on its impact herein.

As shown in Figure 4, be that the rated power of system carries out ice-melt to circuit when choosing ice-melt power at every turn, and when rated power is greater than 146.59kW, total electricity that under " 1-1,1-2 " mode, ice-melt consumes is minimum.Again as shown in Figure 5, when ice-melt power is less than 146.59kW, the ice-melt time that under " 1-1 " mode, ice-melt consumes is greater than 2.31 hours, the ice-melt time that under " 1-2 " mode, ice-melt consumes need be greater than 1.16 hours, namely ice-melt total time 3.47 hours are greater than under " 1-1; 1-2 " ice-melting mode, ice-melt total time 3.48 hours are greater than under " 1-2; 1-2; 1-2 " ice-melting mode, both all greatly exceed the regulation for the ice-melt time in " transmission line electric current de-icing technology directive/guide ", and it is excessive to expend electricity.Therefore, in order to carry out effective deicing to transmission line in official hour, and make total electricity of consuming in deicing processes minimum, therefore the present embodiment adopts the DC ice melting mode of " 1-1,1-2 ".

In order to meet the requirement of ice-melt voltage and power, the VD of ice melting system and power designs should with the value under " 1-1 " ice-melt plant-grid connection mode for normative references.Adopt the ice-melt voltage of " 1-1,1-2 " ice-melting mode and ice-melt power such as formula shown in (11) and (12):

U _1-1＝2r ₀lI _1-1(11)

$P_{1-1}=2I_{1-1}^2{r}_{0}l---\left(12\right)$

In formula: U _1-1for the DC ice melting voltage (V) under " 1-1 " ice-melt plant-grid connection mode; P _1-1for ice-melt power (kW) required under " 1-1 " ice-melt plant-grid connection mode.

According to the line parameter circuit value of above-mentioned selected C class service area, environmental parameter and ice-melting mode, calculate ice melting current, ice-melt voltage, ice-melt power and the graph of a relation of ice-melt capacity and ice-melt time as shown in Figure 6.

In the present embodiment, from the consideration of ice melting system cost angle, relative with the cost of container body fixing based on the background monitoring of the medium-voltage line direct current ice melting system of energy storage device, switch combination, the principal element of influential system cost is the cost of energy-storage system, two way convertor and DC converter.In order to make rational use of resources, need power and the capacity of this cover system of optimum option, making the minimization of cost of system, the power of simultaneity factor and the selection of capacity also will be limited by the DC ice melting demand under boundary condition.Consider that influential system cost principal element is the cost of energy-storage system, two way convertor and DC converter, the cost of energy-storage system depends on quantity and the price of connection in series-parallel ferric phosphate lithium cell case, can obtain the optimization method of system power and capacity as shown in formula (13), DC ice melting current is its constraints:

$\left\{\begin{array}{c}F=P_r\&CenterDot;f_{PCS}+P_r\&CenterDot;f_{DC-DC}+f_b\&CenterDot;\max (P_r/p1,C_1/c1)\\ P_r=P_{1-1}=2I_{1-1}^2{r}_{0}l\\ E_1=2I_{1-1}^2{r}_0{\mathrm{lT}}_{1-1}+1.5I_{1-2}^2{\mathrm{lT}}_{1-2}\\ I_{\min }<I_{1-1},I_{1-2}<I_{\max }\end{array}\right.---\left(13\right)$

In formula: F is direct current ice melting system total cost, ten thousand yuan/kW; f _pCSfor the PCS price of unit power, ten thousand yuan/kW; f _dC-DCfor the DC-DC DC converter price of unit power, ten thousand yuan/kW; f _bfor the price of single battery case, ten thousand yuan/; P1 is the power of single battery case, kW; C1 is the capacity of single battery case, kWh.

From Fig. 6 (a) and Fig. 6 (b), power, the energy storage system capacity of direct current ice melting system are contrary with the variation tendency of ice-melt time, then the optimal value that there is an ice-melt power and ice-melt capacity makes ice melting system total cost in formula (13) minimum.Choosing ice covering thickness is 10mm, and line length is 4km, and circuit model is LGJ-120, ambient temperature is-4 DEG C, wind speed is 5m/s is boundary condition, and calculate at the ice melting system power demand allowed within the scope of DC ice melting current and capacity, all the other ice melting system parameters are as shown in table 3.

Table 3 ice melting system cost parameter

By calculating the total cost of ice melting system and the relation of ice-melt time as shown in Figure 7, as seen from the figure, this existence of system synthesis minimum value.The corresponding ice-melt parameter of system cost is as shown in table 3, as seen from table, when under " 1-1 " mode, the ice-melt time is 1.43 hours, the ice-melt time is 0.819 hour under " 1-2 " mode, ice-melt voltage is 549.40V under " 1-1 " mode, the rated power of direct current ice melting system is 176.67kW, capacity is 397.32kWh, the lowest cost of direct current ice melting system.

The corresponding ice-melt parameter of table 4 ice melting system cost

In the present embodiment, cross due to energy storage system discharges and deeply can damage battery, reduction system useful life, preliminary consideration is under above-mentioned boundary condition, energy-storage system completes the ice-melt of mesolow three-phase line, and SOC also has the pre-allowance of 20%, and system effectiveness is 90%, when corresponding above-mentioned capacity is 397.32kWh, the capacity of energy-storage system is 576.6kWh.Ferric phosphate lithium cell case includes 3 and the cells of 12 strings, and the rated voltage of cell, capacity and lower voltage limit are respectively 3.2V, 66Ah and 2.5V, and the maximum discharge current of cell is 180A.

Therefore, choose 72 battery cases, every 18 battery cases series connection is placed in battery rack, 4 battery racks are connected in parallel to the battery rack DC bus shown in Fig. 1, busbar voltage lower limit is 540V, and corresponding ice-melt power is the discharging current of the cell of 176.67kW is 27.3A, and monomer discharging current can not be out-of-limit.Now, the capacity of energy-storage system is 547.4kWh, and under above-mentioned boundary condition, energy-storage system completes the ice-melt of mesolow three-phase line, and SOC residue 19%, can not cause electric discharge excessively dark, meet Optimized System Design requirement.

In sum, the present embodiment proposes the direct current ice melting system based on mobile battery energy storage device, introduces good fortune Jian Sheng ice formation distribution statistical method; According to ice formation situation, state's net directive/guide and mountain route actual conditions, the power of the direct current ice melting system of computational analysis three kinds of ice-melting modes and capacity requirement.From the angle of system cost, propose cost optimization equation, can be to choose based on the power of the direct current ice melting system of mobile battery energy storage device and capacity provides foundation.

The foregoing is only preferred embodiment of the present invention, all equalizations done according to the present patent application the scope of the claims change and modify, and all should belong to covering scope of the present invention.

Claims (7)

1. the power of mobile battery energy storage direct current ice melting system and a capacity optimum option method, is characterized in that: comprise the following steps:

Step S1: provide a mobile battery energy storage direct current ice melting system, described direct current ice melting system comprises battery energy storage system, two way convertor, DC/DC DC converter, background monitoring and switch combination; Described battery energy storage system comprises ferric phosphate lithium cell cabinet and the battery management system of parallel running, and wherein battery rack is formed by a sequence ferric phosphate lithium cell case connection in series-parallel;

Step S2: power grid ice region distribution situation is added up;

Step S3: calculate the current value of direct current ice melting system in DC ice melting process;

Step S4: calculate the ice-melt power of direct current ice melting system under " 1-1,1-2 ", " 1-1,1-1 ", " 1-2,1-2,1-2 " three kinds of ice-melting modes, ice-melt capacity and optimization method.

2. the power of a kind of mobile battery energy storage direct current ice melting system according to claim 1 and capacity optimum option method, it is characterized in that: described step S2 adds up ice formation distribution situation according to the ice covering thickness of different altitude height, specifically comprises the following steps:

Step S21: calculate standard ice thickness: the standard ice covering thickness evenly wrapped around wire by different densities, difform ice covering thickness equivalent being density 0.9g/cm3, then standard ice thickness heavily calculates by icing ice, and its computing formula is as follows:

$b_0=\sqrt{\frac{G}{0.9\mathrm{\&pi;}L}+r^2}-r$

In formula: b ₀for standard ice thickness; G is ice weight; L is icing body length; R is wire radius;

Step S22: the height correction and the wire diameter correction that calculate standard ice thickness: answer reduction to 10m eminence by line design code requirement ice covering thickness, then shown in the following formula of altitude correction factor:

K _h＝(Z/Z ₀) ^α

Shown in the following formula of wire diameter correction factor:

With in above formula: K _hfor altitude correction factor; Z gets 10m; Z ₀for actual measurement or investigation ice coating wire suspension height; α is index, relevant with wind speed, water content and capture coefficient, if without field data time, α can value 0.22; for wire diameter correction factor; for design diameter of wire, φ≤40mm; for actual measurement or the diameter of wire investigating icing;

Step S23: calculate different reoccurrence standard ice thickness: add up respectively according to 100 year return period of 30 years, 50 years one-levels, the ice covering thickness of icing data method, CRREL modelling, the local landform of meteorological parameter Return Law one-level-meteorological effect icing Grade Model method determination different reoccurrence can be adopted;

Step S24: ice covering thickness is revised with altitude change: ice covering thickness increases with height above sea level and increases, the different reoccurrence standard ice thickness value utilizing several different altitude height to calculate, simulate the exponential formula that ice thickness changes with height above sea level, shown in following formula:

R _h＝βe ^ah

In formula: R _hfor the ice thickness on a certain height above sea level h; A and β is undetermined parameter.

3. the power of a kind of mobile battery energy storage direct current ice melting system according to claim 1 and capacity optimum option method, it is characterized in that: in described step S3, the ice melting current of direct current ice melting system in DC ice melting process adopts following formulae discovery to draw:

$I_{melt}=\sqrt{\frac{\frac{10g_{0}db+\frac{0.045g_0{D}^2}{R_{T0}+R_{T1}}\left(R_{T1}+0.22\frac{R_{T0}}{\lg \frac{D}{d}}\right)\mathrm{\&Delta;}t}{T_{melt}}+\frac{\mathrm{\&Delta;}t}{R_{T0}+R_{T1}}}{R_0}}$

In formula: I _meltfor ice melting current; R ₀the resistance value of wire of one meter long when being 0 DEG C; Δ t is the difference of conductor temperature and ambient temperature; R _t0for equivalent ice sheet thermal-conduction resistance, relevant with conductive coefficient; D is the external diameter after conductor icing; D is diameter of wire; R _t1for convection current and radiological equivalent thermal resistance, relevant with wind speed; B is ice layer thickness; g ₀for the proportion of ice, get 0.9, T by glaze _meltfor the ice-melt time;

Then DC ice melting current should be chosen between minimum ice melting current and maximum ice melting current, and the computing formula wherein calculating minimum direct current ice melting current is as follows:

$I_{min}=\sqrt{\frac{\mathrm{\&Delta;}t}{R_0(R_{T0}+R_{T1})}};$

When heating wires makes its temperature rise to 90 DEG C, the computing formula calculating maximum DC ice melting current is as follows:

$I_{max}=\sqrt{\&lsqb;7.24\left(\frac{318+0.5t_2}{1000}\right)\mathrm{\&Sigma;}id+0.7{\left(\frac{Vd}{2}\right)}^{\frac{3}{4}}(90-t_2)\&rsqb;/R_{90}}$

In formula: I _minfor minimum ice melting current; I _maxfor maximum ice melting current; t ₂for ambient temperature; V is wind speed, and its value is greater than 2m/s; Σ i is radiation coefficient.

4. the power of a kind of mobile battery energy storage direct current ice melting system according to claim 1 and capacity optimum option method, it is characterized in that: in described step S4, it is 10mm that direct current ice melting system chooses ice covering thickness, single DC ice-melting length is 4km, circuit model is LGJ-120, ambient temperature is-4 DEG C, wind speed is that the environment of 5m/s carries out ice-melt work, calculate the ice-melt power under described direct current ice melting system " 1-1; 1-2 ", " 1-1; 1-1 ", " 1-2,1-2,1-2 " three kinds of ice-melting modes and ice-melt capacity; Wherein " " for ice-melt power supply one enters an access way, " 1-2 " enters twice access waies for ice-melt power supply one to 1-1;

Described " 1-1,1-2 " ice-melting mode is specially: adopt two DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and another output is connected with the B phase of ac bus; One output of the 2nd DC/DC DC converter is connected with the A phase of ac bus and B phase, and another output is connected with the C phase of ac bus;

Described " 1-1,1-1 " ice-melting mode is specially: adopt two DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and another output is connected with the B phase of ac bus; One output of the 2nd DC/DC DC converter is connected with the B phase of ac bus, and another output is connected with the C phase of ac bus;

Described " 1-2,1-2,1-2 " ice-melting mode is specially: adopt three DC/DC DC converter to carry out ice-melt, wherein an output of a DC/DC DC converter is connected with the A phase of ac bus, and B phase and the C phase of another output and ac bus are connected; One output of the 2nd DC/DC DC converter is connected with the A phase of ac bus and B phase, and another output is connected with the C phase of ac bus; One output of the 3rd DC/DC DC converter is connected with the A phase of ac bus and C phase, and another output is connected with the B phase of ac bus.

5. the power of a kind of mobile battery energy storage direct current ice melting system according to claim 4 and capacity optimum option method, is characterized in that:

Under described " 1-1; 1-2 ", " 1-2; 1-2; 1-2 " ice-melting mode, due to the current-sharing of two-phase lines in parallel, by parallel line every road electric current close to critical current, ice-melt effect is not had substantially to icing circuit in parallel, then when boundary condition is constant, ignore the change of conductor impedance in deicing processes, choosing each ice-melt power is the rated power of DC converter:

$\left\{\begin{array}{c}{E}_{1-1,1-2}=P_r\left(T_{1-1}+T_{1-2}\right)\\ E_{1-1,1-1}=2P_r{T}_{1-1,1-1}\\ E_{1-2,1-2,1-2}=3P_r{T}_{1-2,1-2,1-2}\\ 2r_0{\mathrm{lI}}_{1-1}^2=1.5r_0{\mathrm{lI}}_{1-2}^2\end{array}\right.$

In formula: E _1-1,1-2for the electricity spent by the ice-melt of " 1-1,1-2 " ice-melting mode; E _1-1,1-1for the electricity spent by the ice-melt of " 1-1,1-1 " ice-melting mode; E _1-2,1-2,1-2for the electricity spent by the ice-melt of " 1-2,1-2,1-2 " ice-melting mode; P _rfor the rated power of ice-melt DC converter, kW; I _1-1be into an ice melting current; I _1-2be into twice ice melting currents; L is line ice-melting length; r ₀for the resistance per unit length of circuit, do not consider that in deicing processes, variations in temperature is on its impact.

6. the power of a kind of mobile battery energy storage direct current ice melting system according to claim 4 and capacity optimum option method, is characterized in that:

The ice-melt voltage of described " 1-1,1-2 " ice-melting mode and ice-melt power is adopted to enter shown in following formula respectively:

U _1-1＝2r ₀lI _1-1

$P_{1-1}=2I_{1-1}^2{r}_{0}l$

In formula: U _1-1for the DC ice melting voltage under " 1-1 " ice-melt plant-grid connection mode; P _1-1for ice-melt power required under " 1-1 " ice-melt plant-grid connection mode.

7. the power of a kind of mobile battery energy storage direct current ice melting system according to claim 4 and capacity optimum option method, it is characterized in that: the cost of described direct current ice melting system is subject to the impact of battery energy storage system, two way convertor and DC/DC DC converter cost, wherein the cost of battery energy storage system depends on quantity and the price of connection in series-parallel ferric phosphate lithium cell case, the optimization method that can obtain the ice-melt power of described direct current ice melting system and capacity is as follows, and DC ice melting current is its constraints:

$\left\{\begin{array}{c}F=P_r\&CenterDot;f_{PCS}+P_r\&CenterDot;f_{DC-DC}+f_b\&CenterDot;\max \left(P_r/p1,C_1/c1\right)\\ P_r=P_{1-1}=2I_{1-1}^2{r}_{0}l\\ E_1=2I_{1-1}^2{r}_0{\mathrm{lT}}_{1-1}+1.5I_{1-2}^2{r}_0{\mathrm{lT}}_{1-2}\\ I_{\min }<I_{1-1},I_{1-2}<I_{\max }\end{array}\right.$

In formula: F is direct current ice melting system total cost; f _pCSfor the PCS price of unit power; f _dC-DCfor the DC-DC DC converter price of unit power; f _bfor the price of single battery case; P1 is the power of single battery case; C1 is the capacity of single battery case.