CN103023085A - Independent photovoltaic storage battery grouping management method - Google Patents

Abstract

The invention discloses an independent photovoltaic storage battery grouping management method, and belongs to the technical field of new energy power generation control control. The invention relates to an independent photovoltaic storage battery system, and the main components of the independent photovoltaic storage battery system comprise a photovoltaic battery, a storage battery, a power transformer, a load and the like. The independent photovoltaic storage battery grouping management method provided by the invention comprises the steps of collecting the limited photovoltaic electrical energy in a period of time to charge for a storage battery group, discharging as less as possible before the charging is full so as to enable the storage battery group to achieve a fullly charged state quickly, and circularly implementing the policy aiming at different groups. The independent photovoltaic storage battery grouping management method provided by the invention is suitable for the occasion that the photovoltaic electrical energy is continuously scant, so that each storage battery group breaks away from a long-term underfilling state, the duty-cycle operation is avoided under low charge state, and the service life of a storage battery is prolonged.

Description

Independent photovoltaic storage battery group management method

Technical field

The present invention relates to a kind of independent photovoltaic storage battery group management method, belong to generation of electricity by new energy control technology field.

Background technology

Solar energy has at random and the characteristic of being interrupted, and independent type photovoltaic power generation system will be realized the supply of electric power of continous-stable, needs to adopt necessary energy storage equipment.Storage battery has low, the easy to maintenance and efficiency for charge-discharge high of cost, and this makes it become photovoltaic generating system a kind of energy storage mode commonly used.

Simultaneously, the storage battery that in photovoltaic generating system, uses, it discharges and recharges has some new features.When storage battery is full of, mainly depend on environmental condition (intensity of illumination, ambient temperature, whether have object to block etc.) and loading demand, it is inevitable that storage battery owes to fill phenomenon, easily cause the deep discharge of storage battery during particularly in the winter time with the continuous cloudy day, and after crossing and put, storage battery also is difficult to again be full of in a short time, thereby make storage battery be in for a long time low state-of-charge (SOC), and under low SOC, recycle.

Therefore, storage battery becomes the most flimsy part in the photovoltaic system, and inappropriate accumulator cell management method will make its premature failure, causes the raising of system's displacement cost and the reduction of system reliability.

Summary of the invention

The object of the present invention is to provide a kind of independent photovoltaic storage battery group management method, maximally utilise existing photovoltaic electric energy, to be charge in batteries much more as far as possible and soon, it is broken away from be in for a long time low charged state, and avoid under low state-of-charge, recycling, thereby the useful life of prolongation storage battery.

Purpose of the present invention is achieved by the following technical programs:

A kind of independent photovoltaic storage battery group management method may further comprise the steps;

At first detect the terminal voltage V of each batteries _BatAllow charging current I with maximum _Bat, and determine the state-of-charge SOC of each batteries according to it;

Define a batteries and discharge and recharge sequential vector C (1, N), state-of-charge SOC according to batteries arranges C (1)～C (N) from low to high, C (1) batteries is in preferential charging and last discharge condition Z1, and C (N) batteries is in preferential discharge and last charged state Z2;

Management process to charge in batteries comprises:

1) detects photovoltaic array power output PV (t) and bearing power Load (t), calculate residue photovoltaic electric energy O (t), described O (t)=PV (t)-Load (t);

2) statistics state-of-charge SOC is lower than 100% batteries number L;

And according to the terminal voltage V of each batteries _BatAllow charging current I with maximum _BatDetermine that O (t) can satisfy the charging demand of a few group storage battery groups, appraise and decide chargeable batteries and count the method for M and be:

$L=0\mathrm{orO}\left(t\right)\≤0\⇒M=0---\left(1\right)$

When formula (1) was set up, namely all storage batterys all were full of (L=0) or O (t)≤0, and then M=0 stops charging;

$[O\left(t\right)-V_{\mathrm{Bat}}\left(C\left(1\right)\right)I_{\mathrm{Bat}}\left(C\left(1\right)\right)]\≤0\mathrm{andO}\left(t\right)>0\⇒M=1---\left(2\right)$

When formula (2) was set up, O (t) all was filled with batteries C (1);

$[O\left(t\right)-\underset{i=1}{\overset{M-1}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Bat}}\left(C\left(i\right)\right)I_{\mathrm{Bat}}\left(C\left(i\right)\right)]>0\mathrm{and}[O\left(t\right)-\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Bat}}\left(C\left(i\right)\right)I_{\mathrm{Bat}}\left(C\left(i\right)\right)]<0\mathrm{andO}\left(t\right)>0\&DoubleRightArrow;2\&le;M\&le;L---\left(3\right)$

When formula (3) is set up, after M-1 batteries allows charging current for charging with its maximum before the vectorial C, will remain the photovoltaic electric energy and all be filled with batteries C (M);

$[O\left(t\right)-\underset{i=1}{\overset{L}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Bat}}\left(C\left(i\right)\right)I_{\mathrm{Bat}}\left(C\left(i\right)\right)]\&GreaterEqual;0\mathrm{andO}\left(t\right)>0\&DoubleRightArrow;M=L---\left(4\right)$

When formula (4) was set up, M batteries was all with its maximum charging current for charging that allows before the vectorial C; Behind the battery charging, upgrade its SOC value;

3) if there is batteries to be full of, then this group is put into the end of vectorial C, other group sequentially moves forward;

4) otherwise get back to and calculate O (t) and appraise and decide chargeable batteries and count M, begin new circulation;

Management process to battery discharging comprises:

1) discharged by C (N) group storage battery group first;

2) drop to below 60% as its state-of-charge SOC, upgrade from low to high the C vector according to the batteries state-of-charge SOC except C (1), make batteries C (1) be in all the time the Z1 state, C (N) batteries is in the Z2 state;

3) be less than or equal to 60% as the SOC of all C (N) batteries, batteries is according to C (N), C (N-1) ..., the order of C (1) is discharged successively; The batteries discharge priority that is in the Z1 state is minimum, only have after the state-of-charge SOC of other group has dropped to minimum state-of-charge 30%, the batteries that is in the Z1 state just starts, until its state-of-charge SOC also reaches minimum state-of-charge, then stops battery discharging.

Compared with prior art, the invention has the beneficial effects as follows: use this to discharge and recharge strategy, can be when residue photovoltaic electric energy O (t) be few, concentrating is C (1) charging, makes it comparatively fast reach fully charged state, breaks away to be in for a long time low charged state; When the photovoltaic electric energy is more, after satisfying C (1) charging demand, can be other battery charging simultaneously also, take full advantage of existing photovoltaic electric energy.Before underfill, lack discharge so that be in the batteries of Z1 state during discharge as far as possible, to reach as early as possible fully charged state, avoid it under low SOC, to recycle.

Description of drawings

Fig. 1 is independent photovoltaic battery system structure chart;

Fig. 2 is independent photovoltaic charge in batteries group management method flow chart;

Fig. 3 is independent photovoltaic battery discharging group management method flow chart.

Embodiment

The invention will be further described below in conjunction with the drawings and specific embodiments.

The principle of storage battery grouping is: after determining the storage battery total capacity according to photovoltaic cell capacity and loading demand, take single group storage battery the Current Control of load discharge is divided into groups to storage battery as benchmark in the discharge rate of manufacturer's recommended, when making each batteries with its rated current discharge, can satisfy separately loading demand.Present embodiment will be divided into three groups to storage battery, when each storage battery group discharges with its rated current, can satisfy separately loading demand.

Fig. 1 is independent photovoltaic battery system structure chart of the present invention.Native system adopts dc bus structure, bus voltage V _DBBe stabilized in 220V.Photovoltaic array is sent electric energy into dc bus by MPPT maximum power point tracking (MPPT) by a booster converter, and with its output voltage stabilization at 220V.Each batteries links to each other with dc bus by independent two-way DC/DC respectively, thereby can realize the step-down control from dc bus to each batteries end, and the boosting rectifier control from each batteries end to dc bus.Photovoltaic battery management center is according to SOC of the terminal voltage of each batteries and each group of current estimation, and controls accordingly the break-make of the two-way DC/DC that links to each other with each batteries.

Define a batteries and discharge and recharge sequential vector C (1, N), state-of-charge SOC according to batteries except C (1) arranges C (2)～C (N) from low to high, C (1) batteries is in preferential charging and last discharge condition Z1, and C (N) batteries is in preferential discharge and last charged state Z2.For example C=(2,1,3) shows, the charging priority that is numbered 2 batteries is the highest, and discharge priority is minimum, and the charging priority that is numbered 3 batteries is minimum, and discharge priority is the highest.

Fig. 2 is independent photovoltaic charge in batteries group management method flow chart.During charging, at first detect the terminal voltage V that judges each batteries _BatAllow charging current I with maximum _Bat, and estimate the state-of-charge SOC of each batteries according to it, and take out the batteries that is in the Z1 state from memory cell, be assigned to C (1), the state-of-charge SOC according to storage battery group except C (1) arranges C (2)～C (N) from low to high; Then detect photovoltaic array power output PV (t) and bearing power Load (t), calculate residue photovoltaic electric energy O (t), the batteries number L of statistics SOC＜100%, and according to the terminal voltage V of each batteries _BatAllow charging current I with maximum _BatDetermine that O (t) can satisfy the charging demand of a few group storage battery groups, appraises and decides chargeable batteries and counts M.If all storage batterys all have been full of or O (t)＜=0 M=0, stop charging, otherwise to M group storage battery group charging before the C, and upgrade SOC.If there is batteries to be full of, then put it to the end of C, other group (M=2 for example that sequentially moves forward, according to C=(2,1,3), the 2nd group and the 1st group storage battery are charged simultaneously, if the 2nd group is full of, then C is updated to C=(1,3,2)), calculate O (t) and appraise and decide M otherwise get back to, begin new circulation, herein, might not be that batteries C (1) at first is full of, when photovoltaic electric energy abundance, when the SOC of batteries C (1) SOC lower and batteries C (2) was higher, then batteries C (2) might at first be full of.Use this charging strategy, can be when residue photovoltaic electric energy O (t) be few, concentrating is C (1) charging, makes it comparatively fast reach fully charged state, breaks away to be in for a long time low charged state; When the photovoltaic electric energy is more, after satisfying C (1) charging demand, can be other battery charging simultaneously also, take full advantage of existing photovoltaic electric energy.

Fig. 3 is independent photovoltaic battery discharging group management method flow chart.For avoiding frequently switching because state-of-charge SOC is close between the batteries in the discharge process, two switching points (SOC=60% and SOC=30%) are set.During discharge, at first detect the terminal voltage V of each batteries _BatAnd electric current I _Bat, and estimate the state-of-charge SOC of each batteries according to it, and take out the batteries that is in the Z1 state from memory cell, be assigned to C (1), the state-of-charge SOC according to storage battery group except C (1) arranges C (2)～C (N) from low to high; First by the discharge of C (N) group, SOC drops to 60% when its state-of-charge, upgrade from low to high the C vector according to the batteries state-of-charge SOC except C (1), make batteries C (1) be in all the time the Z1 state, C (N) batteries is in the Z2 state; When the SOC of C (N) batteries has been less than or equal to 60%, batteries is according to C (N), C (N-1) ..., the order of C (1) is discharged successively.The batteries discharge priority that is in the Z1 state is minimum, only have after the state-of-charge SOC of other group has dropped to minimum state-of-charge 30%, the batteries that is in the Z1 state just starts, until its state-of-charge SOC also reaches minimum state-of-charge, then stops battery discharging.Can so that be in batteries as far as possible few discharge before underfill of Z1 state, to reach as early as possible fully charged state, avoid it under low SOC, to recycle like this.

In addition to the implementation, the present invention can also have other execution modes, and all employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop in the protection range of requirement of the present invention.

Claims (1)

1. an independent photovoltaic storage battery group management method is characterized in that, may further comprise the steps:

At first detect the terminal voltage V of each batteries _BatAllow charging current I with maximum _Bat, and determine the state-of-charge SOC of each batteries according to it;

Define a batteries and discharge and recharge sequential vector C (1, N), state-of-charge SOC according to batteries arranges C (1)～C (N) from low to high, C (1) batteries is in preferential charging and last discharge condition Z1, and C (N) batteries is in preferential discharge and last charged state Z2;

Management process to charge in batteries comprises:

1) detects photovoltaic array power output PV (t) and bearing power Load (t), calculate residue photovoltaic electric energy O (t), described O (t)=PV (t)-Load (t);

2) statistics state-of-charge SOC is lower than 100% batteries number L;

And according to the terminal voltage V of each batteries _BatAllow charging current I with maximum _BatDetermine that O (t) can satisfy the charging demand of a few group storage battery groups, appraise and decide chargeable batteries and count the method for M and be:

$L=0\mathrm{orO}\left(t\right)\&le;0\&DoubleRightArrow;M=0---\left(1\right)$

When formula (1) was set up, namely all storage batterys all were full of (L=0) or O (t)≤0, and then M=0 stops charging;

$[O\left(t\right)-V_{\mathrm{Bat}}\left(C\left(1\right)\right)I_{\mathrm{Bat}}\left(C\left(1\right)\right)]\&le;0\mathrm{andO}\left(t\right)>0\&DoubleRightArrow;M=1---\left(2\right)$

When formula (2) was set up, O (t) all was filled with batteries C (1);

$[O\left(t\right)-\underset{i=1}{\overset{M-1}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Bat}}\left(C\left(i\right)\right)I_{\mathrm{Bat}}\left(C\left(i\right)\right)]>0\mathrm{and}[O\left(t\right)-\underset{i=1}{\overset{M}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Bat}}\left(C\left(i\right)\right)I_{\mathrm{Bat}}\left(C\left(i\right)\right)]<0\mathrm{andO}\left(t\right)>0\&DoubleRightArrow;2\&le;M\&le;L---\left(3\right)$

When formula (3) is set up, after M-1 batteries allows charging current for charging with its maximum before the vectorial C, will remain the photovoltaic electric energy and all be filled with batteries C (M);

$[O\left(t\right)-\underset{i=1}{\overset{L}{\mathrm{\&Sigma;}}}{V}_{\mathrm{Bat}}\left(C\left(i\right)\right)I_{\mathrm{Bat}}\left(C\left(i\right)\right)]\&GreaterEqual;0\mathrm{andO}\left(t\right)>0\&DoubleRightArrow;M=L---\left(4\right)$

When formula (4) was set up, M batteries was all with its maximum charging current for charging that allows before the vectorial C; Behind the battery charging, upgrade its SOC value;

3) if there is batteries to be full of, then this group is put into the end of vectorial C, other group sequentially moves forward;

4) otherwise get back to and calculate O (t) and appraise and decide chargeable batteries and count M, begin new circulation;

Management process to battery discharging comprises:

1) discharged by C (N) group storage battery group first;

2) drop to below 60% as its state-of-charge SOC, upgrade from low to high the C vector according to the batteries state-of-charge SOC except C (1), make batteries C (1) be in all the time the Z1 state, C (N) batteries is in the Z2 state;

3) be less than or equal to 60% as the SOC of all C (N) batteries, batteries is according to C (N), C (N-1) ..., the order of C (1) is discharged successively; The batteries discharge priority that is in the Z1 state is minimum, only have after the state-of-charge SOC of other group has dropped to minimum state-of-charge 30%, the batteries that is in the Z1 state just starts, until its state-of-charge SOC also reaches minimum state-of-charge, then stops battery discharging.

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