An energy storage system for frequency modulation and peak shaving of a combined heat and power unit

Abstract

The utility model discloses a kind of energy storage systems for frequency modulation, peak shaving of combined heat and power unit, including fire line L1, fire line L2, fire line L3, zero line N, energy storage device and control protection system, the fire line L1, fire line L2 and fire line L3 are sequentially connected with alternating current circuit breaker, grid-connected contactor, harmonic suppression device, bidirectional energy storage converter, DC switch, converter and energy storage device, and the both ends of grid-connected contactor fire line L1, fire line L2 and fire line L3 are respectively provided with alternating voltage detection device, and alternating voltage detection device is connected with control protection system electric signal.The energy storage system for frequency modulation, peak shaving of combined heat and power unit, by fire line L1, fire line L2 and fire line L3 sequentially connected with alternating current circuit breaker, grid-connected contactor, harmonic suppression device, bidirectional energy storage converter, DC switch, converter and energy storage device access control protection system, can detect the energy storage dynamic in real time, and system operation is stable.

Description

Technical Field

[0001] This utility model relates to the field of electrical energy storage technology, specifically an energy storage system for frequency regulation and peak shaving of combined heat and power units. Background Technology

[0002] Energy storage systems are an important component of the six major stages of power production: "collection-generation-transmission-distribution-consumption-storage". Introducing energy storage technology into the power system enables effective demand-side management, reduces peak-valley load differences, and not only allows for more efficient use of power equipment and lowers power supply costs, but also promotes the application of renewable energy. It also serves as a means to improve system stability, adjust frequency, and compensate for load fluctuations. The energy storage converter is a core component of energy storage technology. As the interface between the power grid and the energy storage device, it is suitable for applications requiring dynamic energy storage. When there is a power surplus, it stores the energy; when there is a power shortage, it inverts the stored energy and outputs it to the grid. Furthermore, it can serve as the main power source to support the operation of microgrids, thus playing a significant role in the construction of smart grids. Utility Model Content

[0003] The purpose of this invention is to provide an energy storage system for frequency regulation and peak shaving of combined heat and power units, so as to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, this utility model provides the following technical solution: An energy storage system for frequency regulation and peak shaving in a combined heat and power (CHP) unit includes a live wire L1, a live wire L2, a live wire L3, a neutral wire N, an energy storage device, and a control and protection system. An AC circuit breaker, a grid-connected contactor, a harmonic suppression device, a bidirectional energy storage converter, a DC switch, a converter, and an energy storage device are sequentially connected to the live wires L1, L2, and L3. AC voltage detection devices are respectively installed on the live wires L1, L2, and L3 at both ends of the grid-connected contactor, and the AC voltage detection devices are electrically connected to the control and protection system.

[0005] As a further embodiment of this utility model: the harmonic suppression device is a filter, and AC current detection devices are respectively installed on the live wires L1, L2, and L3 between the filter and the converter. The AC current detection devices are connected to the control and protection system via electrical signals.

[0006] As a further embodiment of this utility model: the harmonic suppression device is an isolation transformer integrated reactor, and AC current detection devices are respectively installed on the live wires L1, L2, and L3 between the isolation transformer integrated reactor and the grid-connected contactor. The AC current detection devices are connected to the control and protection system electrical signals.

[0007] As a further improvement of this utility model: the two outputs of the converter are equipped with a DC voltage detection device and a DC current detection device, and both the DC voltage detection device and the DC current detection device are connected to the electrical signals of the control and protection system.

[0008] As a further improvement of this utility model: the isolated transformer integrated reactor outputs a neutral line N as a grounding line, and the AC voltage detection device is electrically connected to the neutral line N to detect the voltage of the neutral line N and transmit it to the control and protection system.

[0009] As a further embodiment of this utility model: the DC switch is provided with a parallel DC output switch, and the DC output switch is provided with a resistor. During the energy storage process, the DC switch is closed and the DC output switch is opened. During the energy storage process, the DC switch is opened and the DC output switch is closed.

[0010] As a further improvement of this utility model, an isolation drive is provided between the bidirectional energy storage converter and the control and protection system.

[0011] As a further improvement of this invention: the energy storage device is equipped with a battery management system and connected to a control and protection system.

[0012] Compared with the prior art, the beneficial effects of this utility model are: This energy storage system, used for frequency regulation and peak shaving of cogeneration units, connects to the control and protection system via AC circuit breakers, grid-connected contactors, harmonic suppression devices, bidirectional energy storage converters, DC switches, converters, and energy storage devices in sequence on live wires L1, L2, and L3. It can monitor the dynamics of energy storage and release in real time, and the system operates stably. Attached Figure Description

[0013] Figure 1 This is a block diagram of the main circuit of a non-isolated converter for a storage system used in frequency regulation and peak shaving of a combined heat and power unit. Figure 2 This is a block diagram of the main circuit of an isolated converter in an energy storage system used for frequency regulation and peak shaving in a combined heat and power unit. Figure 3 This is a schematic diagram of a communication system for the control and protection system in an energy storage system used for frequency regulation and peak shaving in a combined heat and power unit. Detailed Implementation

[0014] Example 1 Please see Figure 1 and 3In this embodiment of the utility model, an energy storage system for frequency regulation and peak shaving of a combined heat and power unit includes live wires L1, L2, L3, neutral wire N, an energy storage device, and a control and protection system. An AC circuit breaker, a grid-connected contactor, a harmonic suppression device, a bidirectional energy storage converter, a DC switch, a converter, and the energy storage device are sequentially connected to live wires L1, L2, and L3. AC voltage detection devices are respectively installed on the live wires L1, L2, and L3 at both ends of the grid-connected contactor. The AC voltage detection devices are electrically connected to the control and protection system. The bidirectional energy storage converter is a PCS-9567 energy storage converter with the structure shown below. Figure 1 As shown, a bidirectional converter topology is adopted, which can realize bidirectional power flow for charging and discharging. In this structure, when the energy storage device is charging, the converter operates in rectifier mode, converting the AC power on the system side into DC power and storing the energy in the energy storage device. When discharging, the converter operates in inverter mode, converting the energy released by the energy storage device from DC to AC to feed back to the external system. The AC output harmonic suppression device, together with the software settings in the control system, can meet the requirements for harmonic suppression. The AC switch and AC grid-connected contactor can realize the grid-connected control function. The output section of the converter is connected to a step-up transformer so that its voltage matches the voltage of the parallel AC network, and at the same time, it plays a role in electrically isolating the energy storage system from the external system.

[0015] In a preferred embodiment, the harmonic suppression device is a filter. AC current detection devices are installed on the live wires L1, L2, and L3 between the filter and the converter. The AC current detection devices are connected to the control and protection system via electrical signals. The filter is an advanced LC filter, which is a passive filter circuit based on a combination of inductor (L) and capacitor (C). By utilizing the high impedance characteristics of inductor to high-frequency signals and the low impedance characteristics of capacitor to high-frequency signals, it achieves selective passage or suppression of specific frequency components, thereby performing frequency filtering on the signal.

[0016] In a preferred embodiment, the two outputs of the converter are equipped with DC voltage detection devices and DC current detection devices, both of which are electrically connected to the control and protection system. The isolation transformer integrated reactor outputs a neutral line N as a grounding line. The AC voltage detection device is electrically connected to the neutral line N to detect the voltage of the neutral line N and transmit it to the control and protection system. The energy storage device is equipped with a battery management system and is connected to the control and protection system. It can communicate with the BMS in real time to obtain battery status information and can operate in different charging and discharging modes according to BMS monitoring data and external charging and discharging commands. It can realize the purpose of converting the DC of the energy storage battery to AC for grid connection or converting AC power to DC to charge the battery. At the same time, the device can monitor the operating conditions of the entire energy storage converter system and can operate correctly and reliably under fault conditions such as overvoltage, overcurrent, and BMS protection signals.

[0017] In a preferred embodiment, the DC switch is equipped with a parallel DC output switch, which has a resistor. During the energy storage process, the DC switch is closed and the DC output switch is open. During the energy storage process, the DC switch is open and the DC output switch is closed. The inverter converts AC power to DC power and stores energy in the energy storage device. During the discharge process, the current is released through the circuit of the DC output switch. When the inverter is turned on, its internal capacitor will charge rapidly, which may generate a surge current far exceeding the normal operating current. This current may burn out the switching components or damage the battery. The series resistor can suppress the fluctuation of current and voltage during the start-up. After the capacitor is fully charged, the resistor is short-circuited through the relay without affecting normal operation.

[0018] In a preferred embodiment, an isolation drive is provided between the bidirectional energy storage converter and the control and protection system. The core function of the isolation drive is to achieve electrical isolation between the input and output terminals, while accurately transmitting drive signals, protecting the control circuit and improving system stability.

[0019] The control and protection system supports RS485 and Ethernet communication for EMS, and supports multiple communication protocols including IEC-60780-103, IEC-61850, Modbus, etc. The PCS-9567 control device supports high-speed fiber optic communication with the upper-level coordinating controller and supports the GOOSE protocol. It can work with the upper-level coordinating controller to form a high-speed control network and realize fast control functions.

[0020] The control and protection system can communicate with the Battery Management System (BMS) to monitor the status information of the energy storage battery in real time. It can also provide alarms and fault protection based on the battery status, thus ensuring the safe operation of the battery. Communication supports protocols such as CAN, Modbus TCP, and Modbus RTU. By default, it uses the Modbus TCP protocol with a network interface to communicate with the BMS. This method features fast communication speed and high stability. If the RS485 serial port Modbus RTU protocol is required for communication, a Modbus gateway (optional) is needed to convert between Modbus TCP and Modbus RTU.

[0021] This Modbus protocol gateway includes an Ethernet port and a serial port that supports RS-232, RS-422, and RS-485 communication. It can automatically switch between Modbus TCP (Ethernet) and Modbus ASCII / RTU (serial) protocols without additional programming or work.

[0022] Example 2 Please see Figure 2 and 3 In this embodiment of the utility model, an energy storage system for frequency regulation and peak shaving of a combined heat and power unit includes live wires L1, L2, L3, neutral wire N, an energy storage device, and a control and protection system. An AC circuit breaker, a grid-connected contactor, a harmonic suppression device, a bidirectional energy storage converter, a DC switch, a converter, and the energy storage device are sequentially connected to live wires L1, L2, and L3. AC voltage detection devices are respectively installed on the live wires L1, L2, and L3 at both ends of the grid-connected contactor. The AC voltage detection devices are electrically connected to the control and protection system. The bidirectional energy storage converter is a PCS-9567 energy storage converter with the structure shown below. Figure 2 As shown, a bidirectional converter topology is adopted, which can realize bidirectional power flow for charging and discharging. In this structure, when the energy storage device is charging, the converter operates in rectifier mode, converting the AC power on the system side into DC power and storing the energy in the energy storage device. When discharging, the converter operates in inverter mode, converting the energy released by the energy storage device from DC to AC to feed back to the external system. The AC output harmonic suppression device, together with the software settings in the control system, can meet the requirements for harmonic suppression. The AC switch and AC grid-connected contactor can realize the grid-connected control function. The output section of the converter is connected to a step-up transformer so that its voltage matches the voltage of the parallel AC network, and at the same time, it plays a role in electrically isolating the energy storage system from the external system.

[0023] In a preferred embodiment, the harmonic suppression device is an isolation transformer integrated reactor. AC current detection devices are installed on the live wires L1, L2, and L3 between the isolation transformer integrated reactor and the grid-connected contactor. The AC current detection devices are connected to the control and protection system electrical signals. The "isolation + shielding" function of the isolation transformer works in conjunction with the "frequency selective impedance" function of the reactor to filter grid noise for common-mode interference, differential-mode interference, and specific frequency harmonics.

[0024] In a preferred embodiment, the two outputs of the converter are equipped with a DC voltage detection device and a DC current detection device, and both the DC voltage detection device and the DC current detection device are connected to the electrical signals of the control and protection system.

[0025] In a preferred embodiment, the isolation transformer integrated reactor outputs a neutral line N as a grounding line, and the AC voltage detection device is electrically connected to the neutral line N to detect the voltage of the neutral line N and transmit it to the control and protection system.

[0026] In a preferred embodiment, the DC switch is provided with a parallel DC output switch, and the DC output switch is provided with a resistor. During the energy storage process, the DC switch is closed and the DC output switch is opened. During the energy storage process, the DC switch is opened and the DC output switch is closed.

[0027] In a preferred embodiment, an isolation drive is provided between the bidirectional energy storage converter and the control and protection system.

[0028] In a preferred embodiment, the energy storage device is equipped with a battery management system and connected to a control and protection system.

[0029] It should be noted that all the above embodiments belong to the same utility model concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0030] The embodiments described above merely illustrate the implementation of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. An energy storage system for frequency regulation and peak shaving in a combined heat and power (CHP) unit, comprising a live wire L1, a live wire L2, a live wire L3, a neutral wire N, an energy storage device, and a control and protection system, characterized in that, An AC circuit breaker, a grid-connected contactor, a harmonic suppression device, a bidirectional energy storage converter, a DC switch, a converter, and an energy storage device are sequentially connected to the live wires L1, L2, and L3. An AC voltage detection device is installed on each of the live wires L1, L2, and L3 at both ends of the grid-connected contactor. The AC voltage detection device is connected to the electrical signal of the control and protection system.

2. The energy storage system for frequency regulation and peak shaving of a combined heat and power unit according to claim 1, characterized in that, The harmonic suppression device is a filter. AC current detection devices are installed on the live wires L1, L2, and L3 between the filter and the converter. The AC current detection devices are connected to the control and protection system via electrical signals.

3. The energy storage system for frequency regulation and peak shaving of a combined heat and power unit according to claim 1, characterized in that, The harmonic suppression device is an isolation transformer integrated reactor. AC current detection devices are installed on the live wires L1, L2, and L3 between the isolation transformer integrated reactor and the grid-connected contactor. The AC current detection devices are connected to the control and protection system electrical signals.

4. The energy storage system for frequency regulation and peak shaving of a combined heat and power unit according to claim 2 or 3, characterized in that, The converter has a DC voltage detection device and a DC current detection device installed on its two outputs, and both the DC voltage detection device and the DC current detection device are connected to the electrical signals of the control and protection system.

5. The energy storage system for frequency regulation and peak shaving of a combined heat and power unit according to claim 3, characterized in that, The isolation transformer integrated reactor outputs a neutral line N as a grounding line. The AC voltage detection device is electrically connected to the neutral line N to detect the voltage of the neutral line N and transmit it to the control and protection system.

6. The energy storage system for frequency regulation and peak shaving of a combined heat and power unit according to claim 1, characterized in that, The DC switch is equipped with a parallel DC output switch, which has a resistor. During the energy storage process, the DC switch is closed and the DC output switch is open. During the energy storage process, the DC switch is open and the DC output switch is closed.

7. The energy storage system for frequency regulation and peak shaving of a combined heat and power unit according to claim 1, characterized in that, An isolation drive is provided between the bidirectional energy storage converter and the control and protection system.

8. The energy storage system for frequency regulation and peak shaving of a combined heat and power unit according to claim 1, characterized in that, The energy storage device is equipped with a battery management system and connected to a control and protection system.

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