Patent ID: 12187149

DETAILED DESCRIPTION

FIG.4shows a balancing system10awhich also forms a charging station for an electric or hybrid vehicle. This balancing system10atypically comprises a network input11incorporating protection units12and measurement units13. The network input11can be connected to the high-voltage or medium-voltage network. For example, the network input11may be connected to two separate power cables each carrying a voltage of 20 kV. Additionally, the network input11may also include a network outlet allowing one of the two cables to pass through the network input11so as to form a balancing system through which the network passes.

The protection units12typically correspond to high-voltage or medium-voltage circuit-breakers, for example controlled circuit-breakers capable of disconnecting a current of 400 A in order to protect the balancing system10a. Preferably, the network cables enter the network input11via manual circuit-breakers allowing maintenance operations to be performed in the balancing system10a. An automatic circuit-breaker is preferably installed at the output of these manual circuit-breakers so as to cut off the current flowing through the network input11when the inrush currents inside the balancing system10aare greater than a threshold value. Thus, these protection units12are preferably coupled with measurement units13in order to detect the instants at which it is necessary to cut off the current flowing through the network input11.

These measurement units13also have the function of measuring the frequency, the voltage and the phase shift between the current and this voltage, in order to detect the active and reactive power balancing requirements of the network. Preferably, these measurement units13incorporate several energy meters: one energy meter associated with the network operator and one independent energy meter associated with the operator of the balancing system10a. These energy meters are preferably connected to a wired or wireless communication network.

Thus, the network operator can obtain information about the balancing requirements in real time using the measurements taken by the measurement units13of the balancing system10a. Similarly, the measurements taken by the independent energy meter can be transmitted to the operator of the balancing system10ato control the amount of energy injected into or withdrawn from the network.

The measurement units13transmit at least three pieces of information to a supervision unit22: a voltage measurement mU, a frequency measurement mF and a current measurement ml, the supervision unit22being configured to calculate the phase shift between the current and the voltage. Alternatively, the measurement units13may comprise means for automatically detecting the phase shift between the voltage and the current and this phase shift may be transmitted to the supervision unit22.

The primary function of the supervision unit22is to identify the network balancing requirements ΔU, ΔF, and ΔI and to fulfill these requirements based on the state of charge of the batteries17integrated in the balancing system10a. This supervision unit22can be in the form of a microcontroller or a microprocessor associated with a sequence of instructions. In addition, this supervision unit22can be remotely controlled, for example by the operator of the balancing system10ain order to update the balancing strategies or the authorizations to charge the electric or hybrid vehicles.

In order to perform the balancing or charge of an electric or hybrid vehicle, the output of the network input11is connected to a transformer21comprising three windings. The first winding is preferably delta-wired and receives the 20 kV voltage from the network. This first winding is coupled to a second winding preferably also delta-wired with a voltage lowered to 450 V.

This lowered AC voltage is connected to an inverter15, which makes it possible to transform this AC voltage into a DC voltage that supplies the set16of batteries17. Preferably, the output of the inverter15has a DC voltage level between 700 and 1000 volts.

The transformer21also has a third winding that is preferably star-connected is linked to an additional inverter23. This additional inverter receives a voltage lowered to 400 V and transforms this AC voltage into a DC voltage suitable for charging a motor vehicle, for example 50 V. Thus, the output of the additional inverter23is connected to a charging socket of an electric or hybrid vehicle24. Of course, the voltage levels at the network input11, transformer21and inverters15,23can vary without deviating from the contemplated embodiments.

In addition to these features which are essential to the embodiment described, other features may be implemented to improve the safety or the control strategies of the balancing system10a. For example,FIG.5shows probes disposed after the transformer21in order to measure power at various points in the balancing system10b. More precisely, a probe is disposed at the output of the inverter15in order to measure the power at the set of batteries Peq, i.e. after the losses associated with the transformer21and the inverter15, and a probe is disposed between the third winding of the transformer21and the additional inverter23in order to measure the power consumed Pre by the charging socket24.

To adapt the balancing strategy of the two inverters15and23, it suffices to detect a consumption or, at the very least, a presence on the charging socket24by means of a signal Ep, as shown inFIG.4. Preferably, as shown inFIG.5, the charging power requested Prrve by the charging socket24is measured by a probe disposed at the charging socket24in order to provide information to the supervision unit22.

Based on these various pieces of information transmitted to the supervision unit22, the supervision unit22can determine the strategy to be followed by the inverters15and23.

In addition to these structural features that make it possible to charge an electric or hybrid vehicle and to balance the network, the balancing system10a-10bcan incorporate conventional features of a balancing system, such as a cooling unit making it possible to cool the transformer21or the set of batteries17, an alarm, a fire protection unit, etc.

FIG.6shows an example of a method for managing the two inverters15and23implemented by the supervision unit22. In a first step50, this method measures the difference between the voltage mU, frequency mF, and current ml and nominal values to detect the reactive and/or active power injection or withdrawal requirements ΔU, ΔI, ΔF of the network. Thus, when the difference between a nominal value and a measured value mU, mF, ml exceeds a threshold value, an injection or withdrawal requirement is determined based upon this difference. The second step51aims to determine the power to be applied to the inverter15based upon the injection or withdrawal requirements Pc1and a coefficient k. These requirements Pc1are then specified in a second determination step52by taking into account the real losses at the transformer21. These real losses can be estimated by the different probes based upon the state of the inverters15and23.

The requirements Pc2obtained from step52can be applied based upon several predefined scenarios, for example:if the injection requirements ΔU, ΔF, ΔI are greater than a maximum injection power Pmax, deactivating the additional inverter23and activating the inverter15connected to the set of batteries17in order to inject the maximum injection power Pmax,if the injection requirements ΔU, ΔF, ΔI are less than a maximum injection power Pmax, deactivating the additional inverter23and activating the inverter15connected to the set of batteries17in order to inject the control power Pc1or Pc2,if the withdrawal requirements ΔU, ΔF, ΔI are less than a requested charging power Prrve at the charging socket24and the charge level of the set of batteries17is greater than a threshold value, deactivating the inverter15connected to the set of batteries17and activating the additional inverter23in order to withdraw the control power Pc1or Pc2, andif the withdrawal requirements ΔU, ΔF, ΔI are greater than a requested charging power Prrve at the charging socket24and the charge level of the set of batteries17is less than a threshold value, activating both inverters15,23until the charge level of the set of batteries17is greater than the threshold value.

The disclosed embodiments thus make it possible to obtain a balancing system10a-10bwhich makes it possible, in addition to balancing the network, to charge an electric or hybrid vehicle very rapidly since the balancing system is connected directly to the high-voltage or medium-voltage network. The disclosed embodiments thus make it possible to obtain a “rapid” charging station that is less expensive since it reuses existing components in the balancing system10a-10b, particularly at the network input11.