Photovoltaic installation and method of operating the installation with delayed battery connection in case of an emergency request

• US 9,716,406 B2
• Filed: 02/20/2014
• Issued: 07/25/2017
• Est. Priority Date: 08/20/2011
• Status: Active Grant

• Current Assignee: Adensis Gmbh
• Original Assignee: Adensis Gmbh
• Inventors: Beck, Bernhard
• Primary Examiner(s): Kinkead, Arnold
• Application Number:
  US14/185,265
• Publication Number:
  US 20140167505A1
• Time in Patent Office: 1,251 Days
• Field of Search: 307151, 307 29, 318106, 318480, 363102, 363 95, 323311, 700287
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/0012 Contingency detection
• CPC Class Codes: H02J 3/18 Arrangements for adjusting, eliminating or compensating reactive power in networks for adjustment of voltage H02J3/16
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/42 with automatic parallel connection when synchronisation is achieved
• CPC Class Codes: H02J 7/35 with light sensitive cells
• CPC Class Codes: H02J 9/00 Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems
• CPC Class Codes: H02M 1/20 Contact mechanisms of dynamic converters
• CPC Class Codes: H02M 7/68 by static converters
• CPC Class Codes: H02S 30/10 Frame structures
• CPC Class Codes: H02S 40/32 comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
• CPC Class Codes: H02S 40/34 comprising specially adapted electrical connection means to be structurally associated with the PV module, e.g. junction boxes
• CPC Class Codes: H02S 40/38 Energy storage means, e.g. batteries, structurally associated with PV modules
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin

Abstract

A photovoltaic system has a plurality of subsystems, each with a photovoltaic generator and an associated inverter. The inverter has a control element for setting the maximum power point of its subsystem. A battery is connectible in parallel with the photovoltaic generator. The inverters are connectible to a power grid, which is operated by a utility operator. When a control device receives an emergency signal from the utility operator indicating impending instability of the grid, the following is initiated: If the battery voltage is above the current voltage as set by the MPP control element, the battery is immediately connected to the input of the inverter while the generator remains connected to the inverter. If the battery voltage is below the current voltage the battery connection is delayed until the MPP control element has adjusted the voltage. Then the voltage is further lowered to generate a discharge current from the battery.

Claims

1. A photovoltaic installation, comprising:

a plurality of partial photovoltaic installations each including a photovoltaic generator disposed for connection to an input of an associated inverter, wherein an MPP control element for setting a maximum power point of the respective said partial photovoltaic installation connected thereto is inherent to an inverter, and each of said partial photovoltaic installations including a battery connectible in parallel to said photovoltaic generator, all of said inverters of said partial photovoltaic installations having outputs connectible to a common electrical grid operated by a grid operator;

a control device configured to initiate the following measures upon receiving from the grid operator an emergency signal on occasion of an imminent instability of the electrical grid;

i) if a battery voltage lies above a voltage currently set by said MPP control element, causing an immediate connection of the battery to the input of said inverter while at the same time maintaining a connection of said photovoltaic generator to said inverter; and

ii) if the battery voltage lies below the voltage currently set by said MPP control element, deferring a connection of the battery to the input of said inverter until said MPP control element has adjusted the voltage applied to the input to the battery voltage and, following a connection of the battery, further reducing the voltage in order to generate a discharge current from the battery.

2. The photovoltaic installation according to claim 1, wherein said control device is configured to perform the following:

if a plurality of connections of batteries have to be deferred, effecting adjustments to the maximum power point of the respective inverters in a time-staggered manner.

3. The photovoltaic installation according to claim 2, wherein said control device is configured to effect a time staggering such that power drops of two partial photovoltaic installations which result from the adjustment to the battery voltage due to leaving the maximum power point of the respective partial photovoltaic installations, do not overlap each other.

4. The photovoltaic installation according to claim 2, wherein said control device is configured to start an adjustment with the respective said partial photovoltaic installation in which a difference between the voltage associated with the current maximum power point and the battery voltage is the smallest.

5. The photovoltaic installation according to claim 1, wherein said control device is configured, if there is a partial photovoltaic installation having a battery voltage above the currently set MPP voltage, to first connect the battery thereof before starting the adjustment to the battery voltage in other said partial photovoltaic installations.

6. The photovoltaic installation according to claim 5, wherein said control device is configured simultaneously initiate the adjustment to the battery voltage in all said partial photovoltaic installations requiring adjustment.

7. The photovoltaic installation according to claim 1, which comprises partial photovoltaic installations with an unconnected photovoltaic generator wherein the battery is directly connected to the input of said inverter.

8. A photovoltaic installation, comprising:

the photovoltaic installation of claim 1 having said partial photovoltaic installations; and

a separate stand-by inverter with its own allocated battery that is adapted to be activated separately in an existing inverter to the associated battery.

9. The photovoltaic installation according to claim 2, wherein said control device is configured to start an adjustment with a respective said partial photovoltaic installation in which a currently available power is lowest.

10. A method of controlling a photovoltaic installation formed of a plurality of partial photovoltaic installations,

wherein each of the partial photovoltaic installations includes a photovoltaic generator that can be connected to an input of an inverter associated therewith, wherein a control element for setting the maximum power point of the partial photovoltaic installation connected thereto is inherent to the inverter, and wherein each partial photovoltaic installation includes a battery that can be connected in parallel to the photovoltaic generator, wherein the outputs of all inverters can be connected to a common electrical grid which is operated by a grid operator, the method comprising:

initiating the following steps with a control device if an emergency signal is received by the control device from the grid operator in the event of an imminent instability of the electrical grid;

i) immediately connecting the batteries of at least a part of the photovoltaic installations having a battery voltage above a voltage currently set by the MPP control element to the input of the associated inverter while maintaining a connection of the associated photovoltaic generator at the same time;

ii) for those partial photovoltaic installations the battery voltage of which lies below the voltage currently set by the MPP control element, deferring a connection of the battery to the input of the inverter until the MPP control element has adjusted the voltage applied to the input to the battery voltage, and, after the battery has been connected, further reducing the voltage in order to generate a discharge current from the battery.

11. The method according to claim 10, wherein step i) comprises immediately connecting all of the batteries of all photovoltaic installations having a battery voltage lying above a voltage currently set by the MPP control element to the input of the associated inverter.