Energy storage converter with switchable netting and meshing mode

Abstract

The utility model relates to energy storage converter technical field especially relates to a kind of energy storage converter with switchable follow network and network mode, including mode selection module, state machine control module, network type control module, follow network type control module and parallel off-network switching module.The utility model is based on not changing original follow network type converter hardware architecture and core software logic, is compatible with two kinds of operating mode by optimizing control strategy and state machine management, without additional hardware circuit or replacement power device, only by software configuration can support network type control, substantially reduce equipment transformation cost, compatible with the topology structure of existing follow network type converter, flexible adaptation to the demand of different power grid, mode can be switched according to power grid operating state, high-precision power control is realized under follow network mode, voltage / frequency support is provided under network mode, improve the stability of system, quickly deploy application, shorten technical iteration cycle, reduce field debugging workload.

Description

Technical Field

[0001] This utility model relates to the field of energy storage converter technology, specifically an energy storage converter with switchable grid-connected and grid-connected modes. Background Technology

[0002] As the global energy structure transitions towards low-carbon and clean energy, the proportion of renewable energy sources, such as wind and solar power, in the power system is rapidly increasing. However, renewable energy power generation is characterized by significant intermittency, volatility, and randomness, with its output power greatly affected by natural conditions (such as sunlight intensity and wind speed). For example, photovoltaic power generation outputs zero at night, and cloud cover can cause a sharp drop in power; wind power generation relies on wind speed variations, resulting in highly unpredictable output power. These characteristics lead to voltage fluctuations and frequency instability issues when a high proportion of renewable energy is integrated into the grid, seriously affecting the safe and stable operation of the power grid.

[0003] Traditional power systems primarily rely on synchronous generators to provide inertial support and frequency and voltage regulation capabilities to maintain system stability. However, with the increasing proportion of renewable energy and the integration of numerous distributed power sources into the grid via power electronic converters, the proportion of synchronous generators in the system has decreased, weakening the overall inertia and dynamic regulation capabilities of the power grid. Under fault or disturbance conditions, the system's frequency and voltage recovery speed slows down, potentially triggering cascading failures and causing widespread blackouts. Therefore, there is an urgent need for new power electronic devices and technologies to enhance the grid's inertial response capabilities and improve system stability.

[0004] Against this backdrop, grid-forming energy storage converter technology has emerged. Unlike traditional grid-following converters, grid-forming converters can simulate the operating characteristics of synchronous generators, autonomously establishing voltage and frequency, and providing virtual inertia and damping, thereby enhancing grid stability. However, existing energy storage converters typically only support a single operating mode (grid-following or grid-forming), making it difficult to adapt to the needs of different grid operating conditions. Solutions to these related technical problems have not yet been proposed. Utility Model Content

[0005] To address the problems in related technologies, this utility model proposes an energy storage converter with switchable grid-connected and grid-connected modes to overcome the aforementioned technical issues in existing related technologies. The purpose of this utility model is to achieve compatibility between the two operating modes by optimizing control strategies and state machine management without changing the original hardware architecture and core software logic of the grid-connected converter. This significantly reduces equipment modification costs, is compatible with the topology of existing grid-connected converters, reduces redundant development investment, flexibly adapts to the needs of different power grids, improves system stability, enables rapid deployment and application, shortens the technology iteration cycle, and reduces on-site commissioning workload.

[0006] To achieve the above objectives, this utility model provides the following technical solution: an energy storage converter with switchable grid-connected and grid-connected modes, comprising:

[0007] The mode selection module is used to receive manual commands in hot standby mode to select either network construction mode or network following mode.

[0008] The state machine control module is configured to trigger state transitions based on preset parameters, causing the converter to enter either grid-connected or grid-connected working state, and execute the corresponding control strategy.

[0009] The grid-type control module is used to perform pre-synchronization operations in grid-type mode. After the synchronization is stable, the AC relay is closed, and the grid voltage is established by pre-charging the AC capacitor.

[0010] The grid-following control module is used to first close the AC relay to complete the capacitor pre-charging before starting the power unit in grid-following mode.

[0011] The on-grid / off-grid switching module is used to switch between on-grid and off-grid states in network construction mode.

[0012] Preferably, the pre-synchronization operation of the network-type control module includes:

[0013] Detect the voltage amplitude, phase, and frequency on the grid side;

[0014] The converter output voltage is adjusted to match the power grid using a virtual synchronous machine algorithm.

[0015] The relay is triggered to close after continuous and stable synchronization reaches a preset time threshold.

[0016] Preferably, the following network control module includes:

[0017] The current command generation unit calculates the target current based on the AC side voltage and power command.

[0018] The closed-loop control unit controls the output current within the target current range through a PI regulator.

[0019] Preferably, the on-grid / off-grid switching module includes:

[0020] Off-grid to grid-connected unit, used to restart the pre-synchronization process when the grid is detected to have returned to normal;

[0021] The grid-connected to off-grid unit is used to disconnect AC relays in the event of a grid fault or upon receiving a manual command.

[0022] Preferably, the state machine control module includes:

[0023] The jump logic for initial state, hot standby state, network operation state, network construction operation state, and fault state;

[0024] The fault triggering unit is used to force a jump to a fault state when a fault in the power grid or device is detected in a non-initial state.

[0025] Preferably, the conditions for resolving the fault state include:

[0026] Automatically returns to hot standby status after detecting that the fault has disappeared;

[0027] Alternatively, it can return to its initial state after receiving a manual reset command.

[0028] Preferably, the offline state in the network configuration mode includes:

[0029] Virtual synchronous machine control unit, used to simulate the inertia and damping characteristics of a synchronous generator;

[0030] The voltage and frequency self-regulation unit is used to maintain stable output voltage when there is no power grid support.

[0031] Preferably, the AC relay is a solid-state relay or a mechanical contactor with zero-voltage-difference closing function.

[0032] Compared with the prior art, the beneficial effects of this utility model are:

[0033] (1) This utility model is a grid-connected and grid-connected energy storage converter. Without changing the original grid-connected converter hardware architecture and core software logic, it achieves compatibility between the two operating modes by optimizing the control strategy and state machine management. It does not require additional hardware circuits or power device replacement. It can support grid-connected control through software configuration, which greatly reduces the equipment modification cost, is compatible with the existing grid-connected converter topology, and reduces repeated development investment.

[0034] (2) This utility model is an energy storage converter that can switch between grid-connected and grid-connected modes, which can flexibly adapt to the needs of different power grids. It can manually or automatically switch modes according to the power grid operating status. In grid-connected mode, it can achieve high-precision power control, and in grid-connected mode, it can provide voltage / frequency support. It supports pre-synchronous grid connection and off-grid autonomous operation in grid-connected mode, and meets the needs of scenarios such as black start of new energy power plants and microgrid networking.

[0035] (3) This utility model is a grid-connected and grid-connected energy storage converter that can switch between grid-connected and grid-connected modes. It inherits the mature control algorithm of the original grid-connected converter, only expands the grid-connected state machine logic, reduces software complexity, improves system stability, and ensures smooth transition during mode switching through the state machine jump mechanism, avoiding equipment downtime or grid impact caused by strategy conflicts.

[0036] (4) This utility model is a grid-connected and grid-connected energy storage converter that can be switched, which can be quickly deployed and applied. It can directly upgrade the software of existing grid-connected energy storage converters without hardware modification, shorten the technology iteration cycle, and is compatible with existing power grid dispatching protocols and communication interfaces, reducing the workload of on-site debugging. Attached Figure Description

[0037] Figure 1 This is a structural block diagram of the power unit of this utility model;

[0038] Figure 2 This is a schematic diagram of the overall process of this utility model. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0040] Example

[0041] Please see Figures 1-2 This utility model proposes a technical solution for an energy storage converter with switchable grid-connected and grid-connected modes: an energy storage converter with switchable grid-connected and grid-connected modes, comprising:

[0042] The mode selection module is used to receive manual commands in hot standby mode to select either network construction mode or network following mode.

[0043] The state machine control module is configured to trigger state transitions based on preset parameters, causing the converter to enter either grid-connected or grid-connected working state, and execute the corresponding control strategy.

[0044] The grid-type control module is used to perform pre-synchronization operations in grid-type mode. After the synchronization is stable, the AC relay is closed, and the grid voltage is established by pre-charging the AC capacitor.

[0045] The grid-following control module is used to first close the AC relay to complete the capacitor pre-charging before starting the power unit in grid-following mode.

[0046] The on-grid / off-grid switching module is used to switch between on-grid and off-grid states in network construction mode.

[0047] In this embodiment, as Figure 1As shown, the left side of the power unit is the DC side, and the right side is the AC side. Different start-up strategies are adopted in different operating states. In the high-voltage hot standby process, the DC relay of the DC pre-charge circuit needs to be closed to charge the DC capacitor. After the capacitor is fully charged, the DC relay is closed again. In grid-connected mode (grid-connected control module), it can directly enter the working state. In the pre-synchronization process, the power unit can perform inverter operation to raise the AC measurement voltage to charge the AC measurement capacitor. In grid-connected mode (grid-connected control module), the AC relay of the AC measurement needs to be closed before the power unit starts running, and the AC capacitor is charged by the grid voltage.

[0048] Furthermore, the pre-synchronization operation of the network-type control module includes:

[0049] Detect the voltage amplitude, phase, and frequency on the grid side;

[0050] The converter output voltage is adjusted to match the power grid using a virtual synchronous machine algorithm.

[0051] The relay is triggered to close after continuous and stable synchronization reaches a preset time threshold.

[0052] Furthermore, the following network control module includes:

[0053] The current command generation unit calculates the target current based on the AC side voltage and power command.

[0054] The closed-loop control unit controls the output current within the target current range through a PI regulator.

[0055] Furthermore, the on-grid / off-grid handover module includes:

[0056] Off-grid to grid-connected unit, used to restart the pre-synchronization process when the grid is detected to have returned to normal;

[0057] The grid-connected to off-grid unit is used to disconnect AC relays in the event of a grid fault or upon receiving a manual command.

[0058] Furthermore, the state machine control module includes:

[0059] The jump logic for initial state, hot standby state, network operation state, network construction operation state, and fault state;

[0060] The fault triggering unit is used to force a jump to a fault state when a fault in the power grid or device is detected in a non-initial state.

[0061] Furthermore, the conditions for resolving the fault state include:

[0062] Automatically returns to hot standby status after detecting that the fault has disappeared;

[0063] Alternatively, it can return to its initial state after receiving a manual reset command.

[0064] Furthermore, the offline state in the network construction mode includes:

[0065] Virtual synchronous machine control unit, used to simulate the inertia and damping characteristics of a synchronous generator;

[0066] The voltage and frequency self-regulation unit is used to maintain stable output voltage when there is no power grid support.

[0067] Furthermore, the AC relay is a solid-state relay or a mechanical contactor with zero-voltage-difference closing function.

[0068] In this embodiment, switching losses and surges can be reduced.

[0069] This invention, without altering the existing grid-connected converter hardware architecture and core software logic, achieves compatibility between two operating modes through optimized control strategies and state machine management. It requires no additional hardware circuitry or power device replacement; grid-connected control is supported solely through software configuration, significantly reducing equipment modification costs. It is compatible with existing grid-connected converter topologies (such as two-level or three-level inverters), minimizing redundant development investment and flexibly adapting to the needs of different power grids. The mode can be manually or automatically switched according to the grid operating status. High-precision power control is achieved in grid-connected mode, while voltage / frequency is provided in grid-connected mode. It supports pre-synchronous grid connection and off-grid autonomous operation in grid-connected mode, meeting the needs of scenarios such as black start of new energy power plants and microgrid networking. It inherits the mature control algorithm of the original grid-connected converter, only extending the grid-connected state machine logic to reduce software complexity and improve system stability. The state machine jump mechanism ensures a smooth transition when switching modes, avoiding equipment downtime or grid impact caused by strategy conflicts. It can be quickly deployed and applied, and can directly upgrade the software of existing grid-connected energy storage converters without hardware modification, shortening the technology iteration cycle. It is compatible with existing grid dispatching protocols and communication interfaces, reducing the workload of on-site commissioning.

[0070] In the description of this utility model, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "other end", "upper", "side", "top", "inner", "front", "center", "both ends", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0071] In this utility model, unless otherwise explicitly specified and limited, the terms "installation", "setting", "connection", "fixing", "screw connection", etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0072] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A switchable energy storage converter for grid-connected and grid-connected modes, characterized in that, include: The mode selection module is used to receive manual commands in hot standby mode to select either network construction mode or network following mode. The state machine control module is configured to trigger state transitions based on preset parameters, causing the converter to enter either grid-connected or grid-connected working state, and execute the corresponding control strategy. The grid-type control module is used to perform pre-synchronization operations in grid-type mode. After the synchronization is stable, the AC relay is closed, and the grid voltage is established by pre-charging the AC capacitor. The grid-following control module is used to first close the AC relay to complete the capacitor pre-charging before starting the power unit in grid-following mode. The on-grid / off-grid switching module is used to switch between on-grid and off-grid states in network construction mode.

2. The energy storage converter with switchable grid-connected and grid-connected modes according to claim 1, characterized in that: The pre-synchronization operation of the network-type control module includes: Detect the voltage amplitude, phase, and frequency on the grid side; The converter output voltage is adjusted to match the power grid using a virtual synchronous machine algorithm. The relay is triggered to close after continuous and stable synchronization reaches a preset time threshold.

3. The energy storage converter with switchable grid-connected and grid-connected modes according to claim 1, characterized in that: The network-following control module includes: The current command generation unit calculates the target current based on the AC side voltage and power command. The closed-loop control unit controls the output current within the target current range through a PI regulator.

4. The energy storage converter with switchable grid-connected and grid-connected modes according to claim 1, characterized in that: The on-grid / off-grid handover module includes: Off-grid to grid-connected unit, used to restart the pre-synchronization process when the grid is detected to have returned to normal; The grid-connected to off-grid unit is used to disconnect AC relays in the event of a grid fault or upon receiving a manual command.

5. The energy storage converter with switchable grid-connected and grid-connected modes according to claim 1, characterized in that: The state machine control module includes: The jump logic for initial state, hot standby state, network operation state, network construction operation state, and fault state; The fault triggering unit is used to force a jump to a fault state when a fault in the power grid or device is detected in a non-initial state.

6. The energy storage converter with switchable grid-connected and grid-connected modes according to claim 5, characterized in that: The conditions for resolving the fault state include: Automatically returns to hot standby status after detecting that the fault has disappeared; Alternatively, it can return to its initial state after receiving a manual reset command.

7. The energy storage converter with switchable grid-connected and grid-connected modes according to claim 1, characterized in that: The offline state under the network construction mode includes: Virtual synchronous machine control unit, used to simulate the inertia and damping characteristics of a synchronous generator; The voltage and frequency self-regulation unit is used to maintain stable output voltage when there is no power grid support.

8. The energy storage converter with switchable grid-connected and grid-connected modes according to claim 1, characterized in that: The AC relay is a solid-state relay or a mechanical contactor with zero voltage difference closing function.

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