CN105162148A - Energy storage system - Google Patents

Abstract

The invention relates to an energy storage system, which comprises a plurality of basic units, wherein each basic unit is provided with an energy conversion system and a battery pack; each battery pack is connected with each energy conversions system; an alternating-current side of each energy conversions system is accessed into an alternating-current power network through an isolation transformer; the battery packs of all basic units utilize energy-based energy storage lithium iron phosphate batteries; or the battery packs of a few of basic units utilize energy-based energy storage lithium iron phosphate batteries; and the battery packs of the other basic units utilize power-based energy storage lithium titanate batteries. The energy storage system has a grid-connected operation mode, can achieve the operation functions of peak regulation control, frequency regulation control and reactive voltage control, and fully takes respective advantages of different energy storage elements; and the investment cost and the operation cost are effectively reduced.

Description

A kind of energy-storage system

Technical field

The present invention relates to power domain, particularly a kind of energy-storage system.

Background technology

Common energy storage device can be divided into power-type and energy type.It is large that the former has power density, the advantages such as fast response time, but energy density is less, as ultracapacitor, superconducting energy storage, flywheel energy storage etc.; It is large that the latter has energy density, but power response is unsuitable for frequent discharge and recharge more slowly, as storage battery and pumped storage etc.Due to the restriction of above-mentioned shortcoming, the energy storage device of single kind is often difficult to the requirement meeting distributed power generation and microgrid, therefore, in conjunction with two or more energy storage composition mixed energy storage system, can give full play to two kinds of technical complementarity of energy storage device.Hybrid energy-storing technology to have the power-type energy storage of fast response characteristic cycle period life-span length and to have the energy type energy storage conbined usage of Large Copacity energy storage characteristic, cooperation control, to play the strong point of various energy storage technology to greatest extent, improves the technology economy advantage of energy-storage system.

Summary of the invention

The object of the present invention is to provide a kind of energy-storage system, possess the pattern of being incorporated into the power networks, the operation function of peak regulation control, frequency modulation control, reactive power/voltage control can be realized, give full play to the respective advantage of different energy-storage travelling wave tube, effectively reduce investment, operating cost.

In order to achieve the above object, technical scheme of the present invention is to provide a kind of energy-storage system, wherein comprises:

Multiple elementary cell; The battery pack that each elementary cell is provided with energy conversion system and is attached thereto, the AC of described energy conversion system is by isolating transformer incoming transport electrical network;

Wherein, the battery pack of all elementary cells is all the battery of energy type energy storage; Or the battery pack of some of them elementary cell uses the battery of energy type energy storage, the battery pack of other elementary cells to use the battery of power-type energy storage.

Preferably, the battery of described energy type energy storage is ferric phosphate lithium cell;

The battery of described power-type energy storage is lithium titanate battery.

Preferably, in the energy-storage system of 2MWh, four elementary cells are provided with; Each elementary cell is provided with the energy conversion system of 500kW, and 500kW × 1h battery pack corresponding with it uses ferric phosphate lithium cell.

Preferably, in the energy-storage system of 2MWh, four elementary cells are provided with; Each elementary cell is provided with the energy conversion system of 500kW;

500kW × 3h battery pack that one of them elementary cell is arranged uses ferric phosphate lithium cell, and 500kW × 0.333h battery pack that its excess-three elementary cell is arranged uses lithium titanate battery.

Preferably, described energy-storage system is provided with battery management system, and it communicates with each energy conversion system respectively by CAN, carries out monitoring and protection to each self-corresponding battery pack of described energy conversion system.

Preferably, described energy-storage system is provided with background monitoring system, and it, by gateway, is monitored the energy conversion system in described battery management system and each elementary cell.

Preferably, described energy-storage system and wind energy turbine set distributed power source form micro-grid system, and by low-pass filtering, the reference power calculating lithium titanate battery and ferric phosphate lithium cell is respectively:

$P_{TL\_ref}=-\frac{T_{TL}\·S}{1+T_{TL}\·S}{P}_T$

$P_{LL\_ref}=-\frac{T_{LL}\·S}{(1+T_{TL}\·S)(1+T_{LL}\·S)}{P}_T$

Wherein, TL represents lithium titanate battery, LL represents ferric phosphate lithium cell, time constant T _tL, T _lL; What wind energy turbine set distributed power source was total exert oneself P _t.

Energy-storage system of the present invention, its advantage is:

Utilize LiFePO4 energy-storage system to have the long-time charge-discharge characteristic of high-energy, meet the peak regulating function demand of system long period;

Utilize power-type lithium titanate battery energy-storage system to have high-power high power charging-discharging characteristic, meet system frequency modulation in short-term or determine functional requirement.

Mixed energy storage system provided by the invention, have the feature of high power density, high-energy-density, high cycle life concurrently, the power adopting separately ferric phosphate lithium cell energy storage to cause can be avoided to exceed the quata to configure, can avoid again adopting separately the cost caused by lithium titanate battery energy storage to increase, effectively reduce the cost of investment of energy-storage system.

Accompanying drawing explanation

Fig. 1 is with the theory diagram of the 2MWh energy-storage system of ferric phosphate lithium cell structure in the present invention;

Fig. 2 is with the theory diagram of the 2MWh energy-storage system of LiFePO4+lithium titanate battery structure in the present invention;

Fig. 3 is the schematic diagram of the micro-grid system that wind energy turbine set and hybrid energy-storing are formed.

Embodiment

Energy-storage system provided by the invention is a kind of 2MWh battery energy storage system, and two schemes can be adopted to realize.

As shown in Figure 1, in the energy-storage system of scheme one, battery system all adopts ferric phosphate lithium cell.Wherein, be provided with 4 PCS (energy conversion system) and each self-corresponding ferric phosphate lithium cell 10 thereof, there is the long-time charge-discharge characteristic of high-energy, the peak regulating function demand of system long period can be met.

Energy-storage system is with 500kW × 1h for elementary cell, and each unit inside is that the PCS of 1 500kW and the battery pack connected respectively with it and battery management system (BMS) are formed, and the AC of PCS is by isolating transformer incoming transport electrical network; The 2MWh energy-storage system described in this programme is formed by 4 cover unit.

Battery management system is communicated with PCS by CAN, realizes the monitoring to battery and protection; Battery management system is communicated with background monitoring system by Ethernet, realizes uploading and monitoring of a large amount of non-real-time data.Configuration monitoring system is a set of, and this supervisory control system realizes the monitoring to PCS and battery management system in each elementary cell by gateway.

As shown in Figure 2, in the energy-storage system of scheme two, battery system adopts the battery energy storage of two types, comprises the power type battery system (as lithium titanate battery system) of 500kWh, and the energy-type cells system of 1.5MWh (as LiFePO4 energy-storage system).

Power type battery energy-storage system is provided with 3 PCS and each self-corresponding power type battery 30 thereof, has high-power high power charging-discharging characteristic, can meet system frequency modulation in short-term or stabilization function demand; The LiFePO4 energy-storage system of energy type is made up of 1 PCS and corresponding ferric phosphate lithium cell 20, has the long-time charge-discharge characteristic of high-energy, can meet the peak regulating function demand of system long period.

Power type battery energy-storage system with 500W × 0.333h for elementary cell, LiFePO4 energy-storage system with 500kW × 3h for elementary cell, each elementary cell is inner to be made up of 1 500kWPCS and the respective battery group be attached thereto respectively and battery management system, and the AC of PCS is by isolating transformer incoming transport electrical network; 3+1 cover unit forms the 2MWh energy-storage system described in this programme.

Battery management system is communicated with PCS by CAN, realizes the monitoring to battery and protection; Battery management system is communicated with background monitoring system by Ethernet, realizes uploading and monitoring of a large amount of non-real-time data.Configuration monitoring system is a set of, monitors by the monitoring of gateway realization to PCS device and battery management system in each elementary cell.

From the respective advantage giving full play to different energy-storage travelling wave tube in this programme, the angle of reduction investment, operating cost is set out, and formulates coordination control strategy rule and is:

1) power density is large, the lithium titanate battery had extended cycle life follows the principle of preferential discharge, serve as " power buffer " simultaneously, for stabilizing spike and fluctuating toward renaturation wind power, thus reduce the coupling capacity of storage battery, avoid storage battery to carry out small-power, super rate charge-discharge, increasing storage battery service life, reduce investment, operating cost;

2) ferric phosphate lithium cell that energy density is large is the main energy sources in system, for stabilizing the long-term steady-state fluctuation of wind power, and regulates lithium titanate battery state-of-charge in real time, to respond the lower secondary undulation of wind power in time.

By implementing above-mentioned coordination control strategy, whole energy-storage system is made to have the feature of high power density, high-energy-density, high cycle life concurrently, the power adopting separately ferric phosphate lithium cell energy storage to cause can be avoided to exceed the quata to configure, can avoid again adopting separately the cost caused by lithium titanate battery energy storage to increase, effectively reduce the cost of investment of energy-storage system.

For the micro-grid system be made up of wind energy turbine set and hybrid energy-storing shown in Fig. 3, energy storage discharge power is just, charge power is negative, and the variable relation in Fig. 3 is as follows:

P _E＝P _line-P _w

Wherein: P _efor energy storage power output; P _linefor grid-connected dominant eigenvalues; P _wfor wind power output power.

When the micro-grid connection of upper figure is run, for reducing the batch (-type) distributed power sources such as wind-powered electricity generation to the impact of distribution network electric energy quality, smoothing to grid-connected interconnection power output.Lithium titanate battery power density is large, has extended cycle life, for stabilizing spike and fluctuating toward renaturation wind power; The little energy density of ferric phosphate lithium cell power density is large, is used for the little but component that amplitude is larger of compensated waving frequency.

According to the capacity that Fig. 3 configures in conjunction with the grid-connected power fluctuation requirement of distributed power source and hybrid energy-storing, can determine that lithium titanate battery and ferric phosphate lithium cell need the vibration frequency section stabilized respectively, thus determine the time constant that low-pass filtering is corresponding, obtain respective power output reference value.

The reference power that can obtain lithium titanate battery and ferric phosphate lithium cell is respectively:

$P_{TL\_ref}=-\frac{T_{TL}\·S}{1+T_{TL}\·S}{P}_T$

$P_{LL\_ref}=-\frac{T_{LL}\·S}{(1+T_{TL}\·S)(1+T_{LL}\·S)}{P}_T$

Above-mentioned TL represents lithium titanate battery, LL represents ferric phosphate lithium cell, time constant T _tL, T _lL; P _tfor total the exerting oneself of distributed power source.Reference power low-pass filtering obtained, as the reference value of energy-storage system power limitation control, can reach the control effects of flat volatility.

Although content of the present invention has done detailed introduction by above preferred embodiment, will be appreciated that above-mentioned description should not be considered to limitation of the present invention.After those skilled in the art have read foregoing, for multiple amendment of the present invention and substitute will be all apparent.Therefore, protection scope of the present invention should be limited to the appended claims.

Claims (7)

1. an energy-storage system, is characterized in that, comprises:

Multiple elementary cell; The battery pack that each elementary cell is provided with energy conversion system and is attached thereto, the AC of described energy conversion system is by isolating transformer incoming transport electrical network;

Wherein, the battery pack of all elementary cells is all the battery of energy type energy storage; Or the battery pack of some of them elementary cell uses the battery of energy type energy storage, the battery pack of other elementary cells to use the battery of power-type energy storage.

2. energy-storage system as claimed in claim 1, is characterized in that,

The battery of described energy type energy storage is ferric phosphate lithium cell;

The battery of described power-type energy storage is lithium titanate battery.

3. energy-storage system as claimed in claim 1, is characterized in that,

Four elementary cells are provided with in the energy-storage system of 2MWh; Each elementary cell is provided with the energy conversion system of 500kW, and 500kW × 1h battery pack corresponding with it uses ferric phosphate lithium cell.

4. energy-storage system as claimed in claim 1, is characterized in that,

Four elementary cells are provided with in the energy-storage system of 2MWh; Each elementary cell is provided with the energy conversion system of 500kW;

500kW × 3h battery pack that one of them elementary cell is arranged uses ferric phosphate lithium cell, and 500kW × 0.333h battery pack that its excess-three elementary cell is arranged uses lithium titanate battery.

5. the energy-storage system as described in claim 3 or 4, is characterized in that,

Described energy-storage system is provided with battery management system, and it communicates with each energy conversion system respectively by CAN, carries out monitoring and protection to each self-corresponding battery pack of described energy conversion system.

6. energy-storage system as claimed in claim 5, is characterized in that,

Described energy-storage system is provided with background monitoring system, and it, by gateway, is monitored the energy conversion system in described battery management system and each elementary cell.

7. energy-storage system as claimed in claim 1, is characterized in that,

Described energy-storage system and wind energy turbine set distributed power source form micro-grid system, and by low-pass filtering, the reference power calculating lithium titanate battery and ferric phosphate lithium cell is respectively:

$P_{TL\_ref}=-\frac{T_{TL}\·S}{1+T_{TL}\·S}{P}_T$

$P_{LL\_ref}=-\frac{T_{LL}\·S}{(1+T_{TL}\·S)(1+T_{LL}\·S)}{P}_T$

Wherein, TL represents lithium titanate battery, LL represents ferric phosphate lithium cell, time constant T _tL, T _lL; What wind energy turbine set distributed power source was total exert oneself P _t.