A virtual power plant system and operation method for DC loads
By designing a virtual power plant system for DC load, the seamless connection between new energy and DC load is achieved, the harmonic impact of the rectifier module on the power grid and the stability of the grid connection of new energy is solved, the electricity consumption cost is reduced, and the utilization rate of new energy is improved.
Patent Information
- Application Number
- CN202211299289.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-21
- Publication Date
- 2025-08-19
- Estimated Expiration
- 2042-10-21
AI Technical Summary
In traditional DC load distribution technology, the impact of the harmonic impact of the rectifier module on the power grid cannot be ignored. The grid connection of new energy brings challenges to the stability of the power grid, and the existing technology is difficult to achieve seamless connection between new energy and DC load, resulting in high electricity consumption costs.
Design a virtual power plant system for DC load, including a new energy power generation system, a DC energy storage system, an energy control system, a three-phase rectifier bridge module and a DC power meter. Through the energy control system, the on and off of the new energy power generation system, the DC energy storage system and the DC bus connection line are monitored and controlled to achieve a seamless connection between new energy and DC load.
It realizes seamless connection between new energy and DC load, reduces power supply costs, improves the utilization rate of new energy, and optimizes power consumption strategies.
Smart Images
Figure CN115622020B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of power system control, and in particular relates to a virtual power plant system for DC loads and an operation method thereof. Background Art
[0002] Traditional DC load distribution technology simply rectifies the mains power to DC on the distribution side. While this eliminates the need for rectifier modules in most load devices and improves overall load energy efficiency, as load power consumption continues to rise, the harmonic impact of rectifier modules on the grid cannot be ignored. Furthermore, the integration of renewable energy sources poses challenges to grid stability. Directly absorbing renewable energy generation at the distribution side would facilitate the development of a new power system. In recent years, with the rapid rise of new energy and energy storage technologies, energy internet technology has matured. This emerging energy internet model requires the parallel use of multiple energy sources to achieve "multi-source complementarity," prioritizes renewable energy, and requires coordinated collaboration across all links to reduce electricity costs. Virtual power plants can optimize the scheduling of distributed power sources across multiple regions and large areas, mitigating the impact of renewable energy integration on the load side. The combination of distributed generation and consumer-side equipment provides a cleaner and more efficient new energy supply model, fostering a wave of clean, DC-based loads, facilitating seamless integration of distributed energy resources and consumer-side equipment. With the integration of a large number of renewable energy sources, optimizing the utilization of DC power has become a key component of this energy supply model. Summary of the Invention
[0003] The purpose of the present invention is to provide a virtual power plant system and operation method for DC loads, which monitors the output power of the new energy power generation system, the charge state of the DC energy storage system and the power demand of the DC load through the energy control system, and controls the on and off of the connection lines between the new energy power generation system, the DC energy storage system and the three-phase rectifier bridge module and the DC bus, thereby realizing seamless connection between the new energy power generation system and the energy storage system and the DC load.
[0004] In order to achieve the above object, the technical solution adopted by the present invention is:
[0005] The present invention provides a virtual power plant system for DC loads, which is connected between the power grid and the DC loads on the load side. The system includes: a new energy power generation system, a DC energy storage system, an energy control system, a three-phase rectifier bridge module and a DC electric energy meter;
[0006] The new energy power generation system, DC energy storage system and three-phase rectifier bridge module are all connected to the DC load on the load side through the DC bus; the new energy power generation system, DC energy storage system, three-phase rectifier bridge module and DC electric energy meter are all connected to the energy control system;
[0007] The new energy power generation system is used to supply power to the DC load on the load side;
[0008] The DC energy storage system is used to exchange energy with the DC bus;
[0009] The AC input end of the three-phase rectifier bridge module is connected to the power grid, and the three-phase rectifier bridge module is used to use the power grid to supply power to the DC load on the load side;
[0010] The DC energy meter is connected to the DC bus and the DC load, and is used to collect the power demand of the DC load;
[0011] The energy control system is used to monitor the output power of the new energy power generation system, the state of charge (SOC) of the DC energy storage system, and the DC load power demand; and to control the on / off connection between the new energy power generation system, the DC energy storage system, and the three-phase rectifier bridge module and the DC busbar connection line; the control method is:
[0012] When the output power of the renewable energy power generation system is greater than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be shut down, disconnecting the connection between the grid and the DC load; and the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be on and off according to the state of charge (SOC) of the DC energy storage system;
[0013] When the output power of the renewable energy power generation system is less than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be turned on; and according to the current real-time electricity price of the power grid, the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be turned on and off.
[0014] Furthermore, the new energy power generation system includes a photovoltaic power generation system and a wind power generation system;
[0015] The photovoltaic power generation system includes at least one photovoltaic array and a unidirectional DC / DC module; the input end of the unidirectional DC / DC module of the photovoltaic power generation system is connected to the photovoltaic array; the output end of the unidirectional DC / DC module of the photovoltaic power generation system is connected to the DC bus;
[0016] The wind power generation system includes a wind generator set and a unidirectional DC / DC module; the input end of the unidirectional DC / DC module of the wind power generation system is connected to the wind generator set; the output end of the unidirectional DC / DC module of the wind power generation system is connected to the DC bus.
[0017] Furthermore, the DC energy storage system and the new energy power generation system are both connected to the DC load via a DC switch.
[0018] Furthermore, the DC energy storage system includes at least one set of energy storage units, a bidirectional DC / DC module and an electricity meter;
[0019] The input end of the bidirectional DC / DC module is connected to the energy storage unit, and the output end of the bidirectional DC / DC module is connected to the DC bus;
[0020] The input end of the fuel meter is connected to the energy storage unit, the output end of the fuel meter is connected to the energy control system, and the fuel meter is used to measure the state of charge (SOC) of the energy storage unit.
[0021] Furthermore, the energy storage unit is a lithium battery energy storage unit.
[0022] Furthermore, the electricity meter is specifically used to:
[0023] Continuously integrate the total current flowing into / out of the energy storage unit;
[0024] The net charge obtained by integration is used as the state of charge (SOC) of the energy storage unit.
[0025] Furthermore, the energy control system includes a computing device, a power harvester and a switch controller;
[0026] The computing device is used to record the real-time electricity price of the power grid and configure the action electricity price;
[0027] The power collector is connected to the DC energy meter, the electricity meter of the DC energy storage system and the output end of the new energy power generation system, and is used to collect the load demand power, the remaining power of the energy storage unit of the DC energy storage system and the output power of the new energy power generation system;
[0028] The switch controller is connected to the unidirectional DC / DC module in the new energy power generation system, the bidirectional DC / DC module in the DC energy storage system, the three-phase rectifier bridge module and the DC switch. The switch controller is used to control the connection between the new energy power generation system, the DC energy storage system, the three-phase rectifier bridge module and the DC switch and the DC bus connection line.
[0029] Furthermore, the switch controller is specifically used to:
[0030] If the state of charge (SOC) of the DC energy storage system is less than a preset maximum threshold of the state of charge of the energy storage unit, the connection line between the new energy power generation system and the DC bus is controlled to be conductive, and the connection line between the DC energy storage system and the DC bus is controlled to be conductive;
[0031] If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be turned on, and the connection line between the DC energy storage system and the DC bus is controlled to be turned off.
[0032] Furthermore, the switch controller is specifically used to:
[0033] When the real-time electricity price of the current power grid K < K is at its minimum, if the state of charge (SOC) of the DC energy storage system is less than the preset maximum threshold of the energy storage unit's state of charge, then control the disconnection of the connection line between the new energy power generation system and the DC bus, and control the connection line between the DC energy storage system and the DC bus to conduct, and supply power to both the DC load and the energy storage unit through the power grid;
[0034] If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit's state of charge, then control the disconnection of the connection line between the new energy power generation system and the DC bus, and control the disconnection of the connection line between the DC energy storage system and the DC bus, and supply power to only the DC load through the power grid;
[0035] When the real-time electricity price of the current power grid satisfies K min< K < K max, disconnect the DC switch, supply power to the DC load through the power grid, and collect the state of charge (SOC) of the DC energy storage system. When 20% < SOC < 80%, control the DC energy storage system to connect and charge through the power grid; when SOC > 80% or SOC is less than 20%, disconnect the DC energy storage system; K min and K max are pre-configured action electricity prices;
[0036] When the real-time electricity price of the current power grid K > K max, control the DC switch to conduct. If the state of charge (SOC) of the DC energy storage system is greater than the preset minimum threshold of the energy storage unit's state of charge, then control the connection lines between the new energy power generation system and the DC energy storage system and the DC bus to conduct, and supply power to the DC load through the power grid, the new energy power generation system and the DC energy storage system simultaneously;
[0037] If the state of charge (SOC) of the DC energy storage system is less than the preset minimum threshold of the energy storage unit's state of charge, then control the connection line between the new energy power generation system and the DC bus to conduct, control the disconnection of the line between the DC energy storage system and the DC bus, and supply power to the DC load through the power grid and the new energy power generation system.
[0038] The present invention also provides an operation method for a virtual power plant system for DC loads, including:
[0039] Obtain the output power of the new energy power generation system, the state of charge (SOC) of the DC energy storage system, and the power demand of the DC load through a power collector; control the on / off of the connection lines between the new energy power generation system, the DC energy storage system, and the three-phase rectifier module and the DC bus in the following manner:
[0040] When the output power of the renewable energy power generation system is greater than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be shut down, disconnecting the connection between the grid and the DC load; and the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be on and off according to the state of charge (SOC) of the DC energy storage system;
[0041] When the output power of the renewable energy power generation system is less than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be turned on; and according to the current real-time electricity price of the power grid, the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be turned on and off.
[0042] Furthermore, the controlling of the connection between the new energy power generation system and the DC energy storage system and the DC bus according to the state of charge (SOC) of the DC energy storage system includes:
[0043] If the state of charge (SOC) of the DC energy storage system is less than a preset maximum threshold of the state of charge of the energy storage unit, the connection line between the new energy power generation system and the DC bus is controlled to be conductive, and the connection line between the DC energy storage system and the DC bus is controlled to be conductive;
[0044] If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be turned on, and the connection line between the DC energy storage system and the DC bus is controlled to be turned off.
[0045] Furthermore, when the state of charge (SOC) of the DC energy storage system is less than a preset maximum threshold of the state of charge of the energy storage unit, the photovoltaic array and wind turbine generator set of the new energy power generation system are controlled to operate in the maximum power point tracking mode, and the energy storage unit of the DC energy storage system is controlled to operate in the fluctuation smoothing mode.
[0046] Furthermore, when the state of charge (SOC) of the DC energy storage system is greater than a preset maximum threshold of the state of charge of the energy storage unit, the photovoltaic array and wind turbine generator set of the new energy power generation system are controlled to operate in a non-maximum power point tracking mode.
[0047] Furthermore, the controlling of the on / off of the connection lines between the new energy power generation system and the DC energy storage system and the DC bus according to the current real-time electricity price of the power grid includes:
[0048] When the current real-time electricity price of the power grid K < K min, if the state of charge (SOC) of the DC energy storage system is less than the preset maximum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be shut down, and the connection line between the DC energy storage system and the DC bus is controlled to be turned on, so that power is simultaneously supplied to the DC load and the energy storage unit through the power grid;
[0049] If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit's state of charge, then control the disconnection of the connection line between the new energy power generation system and the DC bus, and control the disconnection of the connection line between the DC energy storage system and the DC bus, and supply power to the DC load only through the power grid;
[0050] When the real-time electricity price of the current power grid satisfies K min< K < K max, disconnect the DC switch, supply power to the DC load through the power grid, and collect the state of charge (SOC) of the DC energy storage system. When 20% < SOC < 80%, control the DC energy storage system to connect and charge through the power grid; when SOC > 80% or SOC is less than 20%, disconnect the DC energy storage system; K min and K max are pre-configured action electricity prices;
[0051] When the real-time electricity price of the current power grid K > K max, control the DC switch to conduct. If the state of charge (SOC) of the DC energy storage system is greater than the preset minimum threshold of the energy storage unit's state of charge, then control the connection lines between the new energy power generation system and the DC energy storage system and the DC bus to conduct, and supply power to the DC load simultaneously through the power grid, the new energy power generation system and the DC energy storage system;
[0052] If the state of charge (SOC) of the DC energy storage system is less than the preset minimum threshold of the energy storage unit's state of charge, then control the connection line between the new energy power generation system and the DC bus to conduct, and control the disconnection of the line between the DC energy storage system and the DC bus, and supply power to the DC load through the power grid and the new energy power generation system.
[0053] Furthermore, the preset maximum threshold of the energy storage unit's state of charge is 80%; the preset minimum threshold of the energy storage unit's state of charge is 20%.
[0054] The beneficial effects of the present invention are as follows:
[0055] The present invention discloses a virtual power plant system and operation method for DC loads. The system monitors the output power of the new energy power generation system, the state of charge of the DC energy storage system, and the demand power of the DC load through an energy control system, and controls the on-off of the connection lines between the new energy power generation system, the DC energy storage system, and the three-phase rectifier module and the DC bus, realizing seamless connection between the new energy power generation system and the energy storage system and the DC load, saving the intermediate power conversion link, and reducing the power supply cost.
[0056] The method of the present invention formulates a power consumption strategy for DC loads through an energy control system based on the demand power of DC loads and the real-time electricity of the current power grid, improving the utilization rate of new energy and reducing the power consumption cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIG1 is a structural diagram of a virtual power plant system for DC loads provided in Example 1 of the present invention;
[0058] FIG2 is a control flow chart of a virtual power plant operation method provided in Example 2 of the present invention. DETAILED DESCRIPTION
[0059] The present invention will be further described below. The following examples are only used to more clearly illustrate the technical solution of the present invention and are not intended to limit the scope of protection of the present invention. Example
[0060] This embodiment provides a virtual power plant system for DC loads, which is connected between the power grid and the DC loads on the load side. The system includes: a new energy power generation system, a DC energy storage system, an energy control system, a three-phase rectifier bridge module and a DC power meter.
[0061] The new energy power generation system is used to supply power to the DC load on the load side;
[0062] The DC energy storage system is used to exchange energy with the DC bus;
[0063] The AC input end of the three-phase rectifier bridge module is connected to the power grid, and the DC output end is connected to the DC bus. The three-phase rectifier bridge module is used to use the power grid to supply power to the DC load on the load side;
[0064] The DC energy meter is connected to the DC bus and the DC load to collect the DC load demand power PL;
[0065] The energy control system is used to monitor the output power of the renewable energy power generation system, the state of charge of the DC energy storage system, and the power demand of the DC load; and to control the on / off connection between the renewable energy power generation system, the DC energy storage system, and the three-phase rectifier bridge module and the DC bus. The control method is:
[0066] When the output power of the renewable energy power generation system is greater than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be shut down, disconnecting the connection between the grid and the DC load; and the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be on and off according to the state of charge (SOC) of the DC energy storage system;
[0067] When the output power of the renewable energy power generation system is less than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be turned on; and according to the current real-time electricity price of the power grid, the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be turned on and off.
[0068] It should be noted that the new energy power generation system, DC energy storage system and three-phase rectifier bridge module are all connected to the DC load on the load side through a DC bus.
[0069] It should be noted that the AC input end of the three-phase rectifier bridge module is connected to the 220V power grid, and the DC output end is connected to the DC bus.
[0070] As a preferred embodiment, both the DC energy storage system and the renewable energy generation system are connected to the DC load via a DC switch. In the event of a failure or post-failure repair of the renewable energy generation system or DC energy storage system, the DC switch can be operated to disconnect the renewable energy system or DC energy storage system to ensure power safety. During normal operation, no attention is required.
[0071] As a preferred embodiment, the new energy power generation system includes a photovoltaic power generation system and a wind power generation system.
[0072] See also Figure 1 ,The photovoltaic power generation system includes one or more photovoltaic arrays and unidirectional DC / DC modules;
[0073] The wind power generation system includes a wind turbine generator set and a unidirectional DC / DC module;
[0074] The photovoltaic power generation system and the wind power generation system are both connected to the DC bus through a unidirectional DC / DC module to realize power supply to the DC load on the load side.
[0075] As a preferred embodiment, the DC energy storage system includes one or more energy storage units, a bidirectional DC / DC module and an electricity meter.
[0076] See also Figure 1 ,The energy storage unit is connected to the DC bus through a bidirectional DC / DC module, which is used for bidirectional energy exchange with the DC bus.
[0077] The input end of the fuel meter is connected to the energy storage unit, and the output end is connected to the energy control system. The fuel meter is used to measure the state of charge (SOC) of the energy storage unit.
[0078] The input end of the bidirectional DC / DC module is connected to the energy storage unit, and the output end is connected to the DC bus.
[0079] As a preferred embodiment, the energy storage unit may be a lithium battery energy storage unit.
[0080] As a preferred embodiment, the electricity meter adopts an integral measurement method, continuously integrating the total current flowing into / out of the energy storage unit, and using the net charge obtained by the integration as the remaining capacity of the energy storage unit. This method can achieve higher accuracy compared with traditional measurement methods.
[0081] As a preferred embodiment, the energy control system includes a computing device with storage function, a power harvester and a switch controller.
[0082] Computing equipment is used to record real-time electricity prices on the grid K , manually set the input action electricity price based on the electricity price and the cost of renewable energy power generation K min and K max, which in turn affects the decision-making of smart electricity consumption.
[0083] It should be noted that the action price is the price set by the virtual power plant system based on load demand and the real-time grid electricity price to determine whether to supply power from the grid or renewable energy systems. This is to select the optimal power supply method for the current situation without affecting user use.
[0084] The power collector is connected to the DC energy meter, the DC energy storage system's electricity meter, and the output end of the new energy power generation system to collect relevant data from each module, including the load demand power PL, the state of charge (SOC) of the DC energy storage system's energy storage unit, and the output power Pnew of the new energy power generation system.
[0085] To ensure the life of the energy storage unit of the DC energy storage system and the stable operation of the energy storage system, the optimal state of charge (SOC) of the lithium battery energy storage unit is usually set to 20%~80%.
[0086] The switch controller is connected to each unidirectional DC / DC module in the renewable energy power generation system, the bidirectional DC / DC module in the DC energy storage system, the three-phase rectifier bridge module and the DC switch, and is used to control the photovoltaic array and wind turbine generator set, the DC energy storage system, the three-phase rectifier bridge module and the on-off of the DC switch and the DC bus connection line in the renewable energy power generation system.
[0087] The specific control method of the switch controller is:
[0088] If the state of charge (SOC) of the DC energy storage system is less than a preset maximum threshold of the state of charge of the energy storage unit, the connection line between the new energy power generation system and the DC bus is controlled to be conductive, and the connection line between the DC energy storage system and the DC bus is controlled to be conductive;
[0089] If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be turned on, and the connection line between the DC energy storage system and the DC bus is controlled to be turned off.
[0090] When the current real-time electricity price of the power grid K < KWhen it is less than
[0091] min, if the state of charge (SOC) of the DC energy storage system is less than the preset maximum threshold of the energy storage unit's state of charge, control the disconnection of the connection line between the new energy power generation system and the DC bus, and control the connection line between the DC energy storage system and the DC bus to be turned on, and supply power to the DC load and the energy storage unit through the power grid at the same time;
[0092] When the real-time electricity price of the current power grid meets K min < K < K max, disconnect the DC switch, supply power to the DC load through the power grid, and collect the state of charge (SOC) of the DC energy storage system. When 20% < SOC < 80%, control the DC energy storage system to be connected and charge through the power grid; when SOC > 80% or SOC is less than 20%, disconnect the DC energy storage system; K min and K max are pre-configured action electricity prices;
[0093] When the real-time electricity price of the current power grid K > K max, control the DC switch to be turned on. If the state of charge (SOC) of the DC energy storage system is greater than the preset minimum threshold of the energy storage unit's state of charge, control the connection lines between the new energy power generation system and the DC energy storage system and the DC bus to be turned on, and supply power to the DC load through the power grid, the new energy power generation system and the DC energy storage system at the same time;
[0094] If the state of charge (SOC) of the DC energy storage system is less than the preset minimum threshold of the energy storage unit's state of charge, control the connection line between the new energy power generation system and the DC bus to be turned on, control the disconnection of the line between the DC energy storage system and the DC bus, and supply power to the DC load through the power grid and the new energy power generation system.
[0095] It should be noted that the input end of the unidirectional DC / DC module of the photovoltaic power generation system is connected to the photovoltaic array, and the output end is connected to the power collector and the DC bus. The photovoltaic power generation system supplies power to the DC load through the DC bus, and provides the real-time output power Ppv to the energy control system through the power collector; the input end of the unidirectional DC / DC module of the wind power generation system is connected to the wind turbine generator, and the output end is connected to the DC power collector and the DC bus. The wind power generation system supplies power to the DC load through the DC bus, and provides the real-time output power Pwn to the energy control system through the power collector. The total output power of the new energy power generation system is: Pnew = Ppv + Pwn. Embodiment
[0096] This embodiment provides an operation method for a virtual power plant facing DC loads. Based on the virtual power plant system of Embodiment 1, the operation method of this virtual power plant system includes:
[0097] Obtain the output power of the new energy power generation system, the state of charge (SOC) of the DC energy storage system, and the power demand of the DC load through a power collector, and control the on / off of the connection lines between the new energy power generation system, the DC energy storage system, and the three-phase rectifier module and the DC bus in the following manner:
[0098] When the output power of the new energy power generation system is greater than the power demand of the DC load (Pnew > PL), the control method is as follows:
[0099] a. Control the line between the three-phase rectifier module and the DC bus to be turned off, disconnecting the connection between the power grid and the DC load;
[0100] b. Control the on / off of the lines between the new energy power generation system and the DC bus and between the DC energy storage system and the DC bus according to the state of charge of the DC energy storage system.
[0101] In this embodiment, controlling the on / off of the lines between the new energy power generation system and the DC bus and between the DC energy storage system and the DC bus according to the state of charge of the DC energy storage system, the specific implementation process is as follows Figure 2 , including:
[0102] If the state of charge (SOC) of the DC energy storage system is less than the preset maximum threshold of the state of charge of the energy storage unit, control the line between the new energy power generation system and the DC bus to be turned on, and control the line between the DC energy storage system and the DC bus to be turned on;
[0103] If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the state of charge of the energy storage unit, control the line between the new energy power generation system and the DC bus to be turned on, and control the line between the DC energy storage system and the DC bus to be turned off;
[0104] As a preferred implementation manner, when the state of charge (SOC) is less than the preset maximum threshold of the state of charge of the energy storage unit, control the photovoltaic array and the wind turbine generator to operate in the maximum power point tracking mode, and control the energy storage unit of the DC energy storage system to operate in the fluctuation suppression mode to absorb the excess power of the new energy power generation system and achieve load power balance.
[0105] As a preferred implementation manner, when the state of charge (SOC) is greater than the preset maximum threshold of the state of charge of the energy storage unit, control the photovoltaic array and the wind turbine generator to operate in a non-maximum power point tracking mode.
[0106] When the output power of the new energy power generation system is less than the power demand of the DC load (Pnew < PL), the control method is as follows:
[0107] a. Control the conduction of the line between the three-phase rectifier bridge module and the DC bus to connect the power grid to the DC load.
[0108] b. Control the on / off of the lines between the new energy power generation system and the DC energy storage system and the DC bus according to the real-time electricity price of the current power grid.
[0109] In this embodiment, to control the on / off of the lines between the new energy power generation system and the DC energy storage system and the DC bus according to the real-time electricity price of the current power grid, the specific implementation process is as follows Figure 2 , including:
[0110] b1. When the real-time electricity price of the current power grid K < K is less than min, if the state of charge SOC of the DC energy storage system is less than the preset maximum threshold of the state of charge of the energy storage unit, control the line between the new energy power generation system and the DC bus to be turned off, and at the same time control the line between the DC energy storage system and the DC bus to be turned on, and supply power to the DC load and the energy storage unit through the power grid.
[0111] If the state of charge SOC of the DC energy storage system is greater than the preset maximum threshold of the state of charge of the energy storage unit, control the line between the new energy power generation system and the DC bus to be turned off, and at the same time control the line between the DC energy storage system and the DC bus to be turned off, and supply power to the DC load only through the power grid.
[0112] b2. When the real-time electricity price of the current power grid satisfies K min < K < K < max, disconnect the DC switch and supply power to the DC load through the power grid. At this time, collect the state of charge SOC of the DC energy storage system. When 20% < SOC < 80%, control the DC energy storage system to be connected and charge through the power grid. When SOC > 80% or SOC is less than 20%, disconnect the DC energy storage system.
[0113] b3. When the real-time electricity price of the current power grid K > K > max, control the DC switch to be in the conducting state. If the state of charge SOC of the DC energy storage system is greater than the preset minimum threshold of the state of charge of the energy storage unit, control the lines between the new energy power generation system and the DC energy storage system and the DC bus to be turned on, and supply power to the DC load through the power grid, the new energy power generation system and the DC energy storage system.
[0114] If the state of charge SOC of the DC energy storage system is less than the preset minimum threshold of the state of charge of the energy storage unit, control the line between the new energy power generation system and the DC bus to be turned on, and control the line between the DC energy storage system and the DC bus to be turned off, and supply power to the DC load through the power grid and the new energy power generation system.
[0115] As a preferred embodiment, the preset maximum threshold value of the energy storage unit state of charge is 80%; the preset minimum threshold value of the energy storage unit state of charge is 20%.
[0116] It should be noted that controlling the on / off of the line between the renewable energy power generation system and the DC bus refers to controlling the on / off of the line between the unidirectional DC / DC module at the output end of the photovoltaic array and the unidirectional DC / DC module at the output end of the wind turbine generator set and the DC bus through a switch controller.
[0117] It should be noted that controlling the on / off of the line between the DC energy storage system and the DC bus refers to controlling the on / off of the line between the bidirectional DC / DC module in the DC energy storage system and the DC bus through a switch controller.
[0118] It should be noted that it also includes pre-setting the action price K min and K max steps.
[0119] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.
[0120] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.
[0121] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.
[0122] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.
[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.
Claims
1. A virtual power plant system for DC loads, connected between the power grid and the DC loads on the load side, characterized in that: The system includes: a new energy power generation system, a DC energy storage system, an energy control system, a three-phase rectifier bridge module and a DC energy meter; The new energy power generation system, DC energy storage system and three-phase rectifier bridge module are all connected to the DC load on the load side through the DC bus; the new energy power generation system, DC energy storage system, three-phase rectifier bridge module and DC electric energy meter are all connected to the energy control system; The new energy power generation system is used to supply power to the DC load on the load side; The DC energy storage system is used to exchange energy with the DC bus; The AC input end of the three-phase rectifier bridge module is connected to the power grid, and the three-phase rectifier bridge module is used to use the power grid to supply power to the DC load on the load side; The DC energy meter is connected to the DC bus and the DC load, and is used to collect the power demand of the DC load; The energy control system is used to monitor the output power of the new energy power generation system, the state of charge (SOC) of the DC energy storage system, and the DC load power demand; and to control the on / off connection between the new energy power generation system, the DC energy storage system, and the three-phase rectifier bridge module and the DC busbar connection line; the control method is: When the output power of the renewable energy power generation system is greater than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be shut down, disconnecting the connection between the grid and the DC load; and the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be on and off according to the state of charge (SOC) of the DC energy storage system; When the output power of the new energy power generation system is less than the DC load demand power, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be conductive; and according to the current real-time electricity price of the power grid K , control the on-off of the connection lines between the new energy power generation system and the DC energy storage system and the DC bus; When the current real-time electricity price of the power grid K < K min, if the state of charge (SOC) of the DC energy storage system is less than the preset maximum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be shut down, and the connection line between the DC energy storage system and the DC bus is controlled to be turned on, so that power is simultaneously supplied to the DC load and the energy storage unit through the power grid; If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be shut down, and the connection line between the DC energy storage system and the DC bus is also controlled to be shut down, so that only DC loads are supplied through the grid; When the real-time electricity price of the current power grid meets K min< K < K max, disconnect the DC switch, supply power to the DC load through the power grid, and collect the state of charge SOC of the DC energy storage system. When 20% < SOC < 80%, control the DC energy storage system to connect and charge through the power grid; when SOC > 80% or SOC is less than 20%, disconnect the DC energy storage system; K min and K max are pre-configured action electricity prices; When the current real-time electricity price of the power grid K > K When the SOC of the DC energy storage system is greater than the preset minimum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system, the DC energy storage system and the DC bus is controlled to be turned on, and power is supplied to the DC load simultaneously through the power grid, the new energy power generation system and the DC energy storage system. If the state of charge (SOC) of the DC energy storage system is less than the preset minimum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be turned on, and the line between the DC energy storage system and the DC bus is controlled to be turned off, and power is supplied to the DC load through the power grid and the new energy power generation system.
2. A virtual power plant system for DC loads according to claim 1, characterized in that: The new energy power generation system includes a photovoltaic power generation system and a wind power generation system; The photovoltaic power generation system includes at least one photovoltaic array and a unidirectional DC / DC module; the input end of the unidirectional DC / DC module of the photovoltaic power generation system is connected to the photovoltaic array; the output end of the unidirectional DC / DC module of the photovoltaic power generation system is connected to the DC bus; The wind power generation system includes a wind generator set and a unidirectional DC / DC module; the input end of the unidirectional DC / DC module of the wind power generation system is connected to the wind generator set; the output end of the unidirectional DC / DC module of the wind power generation system is connected to the DC bus.
3. A virtual power plant system for DC loads according to claim 2, characterized in that: The DC energy storage system and the new energy power generation system are both connected to the DC load via a DC switch.
4. A virtual power plant system for DC loads according to claim 3, characterized in that: The DC energy storage system includes at least one set of energy storage units, a bidirectional DC / DC module and an electricity meter; The input end of the bidirectional DC / DC module is connected to the energy storage unit, and the output end of the bidirectional DC / DC module is connected to the DC bus; The input end of the fuel meter is connected to the energy storage unit, the output end of the fuel meter is connected to the energy control system, and the fuel meter is used to measure the state of charge (SOC) of the energy storage unit.
5. A virtual power plant system for DC loads according to claim 4, characterized in that: The energy storage unit is a lithium battery energy storage unit.
6. A virtual power plant system for DC loads according to claim 5, characterized in that: The electricity meter is specifically used for: Continuously integrate the total current flowing into / out of the energy storage unit; The net charge obtained by integration is used as the state of charge (SOC) of the energy storage unit.
7. A virtual power plant system for DC loads according to claim 6, characterized in that: The energy control system includes a computing device, a power harvester and a switch controller; The computing device is used to record the real-time electricity price of the power grid and configure the action electricity price; The power collector is connected to the DC energy meter, the electricity meter of the DC energy storage system and the output end of the new energy power generation system, and is used to collect the load demand power, the state of charge SOC of the energy storage unit of the DC energy storage system and the output power of the new energy power generation system; The switch controller is connected to the unidirectional DC / DC module in the new energy power generation system, the bidirectional DC / DC module in the DC energy storage system, the three-phase rectifier bridge module and the DC switch. The switch controller is used to control the connection between the new energy power generation system, the DC energy storage system, the three-phase rectifier bridge module and the DC switch and the DC bus connection line.
8. A virtual power plant system for DC loads according to claim 7, characterized in that: The switch controller is specifically used to: If the state of charge (SOC) of the DC energy storage system is less than a preset maximum threshold of the state of charge of the energy storage unit, the connection line between the new energy power generation system and the DC bus is controlled to be conductive, and the connection line between the DC energy storage system and the DC bus is controlled to be conductive; If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be turned on, and the connection line between the DC energy storage system and the DC bus is controlled to be turned off.
9. The method for operating a virtual power plant system for DC loads according to any one of claims 1 to 8, characterized in that: include: The power collector is used to obtain the output power of the renewable energy power generation system, the state of charge (SOC) of the DC energy storage system, and the required power of the DC load. The connection between the renewable energy power generation system, the DC energy storage system, and the three-phase rectifier bridge module and the DC bus is controlled as follows: When the output power of the renewable energy power generation system is greater than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be shut down, disconnecting the connection between the grid and the DC load; and the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be on and off according to the state of charge (SOC) of the DC energy storage system; When the output power of the renewable energy power generation system is less than the power demanded by the DC load, the connection line between the three-phase rectifier bridge module and the DC bus is controlled to be turned on; and according to the current real-time electricity price of the power grid, the connection line between the renewable energy power generation system and the DC energy storage system and the DC bus is controlled to be turned on and off.
10. The method for operating a virtual power plant system for DC loads according to claim 9, characterized in that: The controlling of the on / off of the connection line between the new energy power generation system and the DC energy storage system and the DC bus according to the state of charge (SOC) of the DC energy storage system includes: If the state of charge (SOC) of the DC energy storage system is less than a preset maximum threshold of the state of charge of the energy storage unit, the connection line between the new energy power generation system and the DC bus is controlled to be conductive, and the connection line between the DC energy storage system and the DC bus is controlled to be conductive; If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be turned on, and the connection line between the DC energy storage system and the DC bus is controlled to be turned off.
11. The method for operating a virtual power plant system for DC loads according to claim 10, characterized in that: When the state of charge (SOC) of the DC energy storage system is less than a preset maximum threshold of the state of charge of the energy storage unit, the photovoltaic array and wind turbine generator set of the new energy power generation system are controlled to operate in the maximum power point tracking mode, and the energy storage unit of the DC energy storage system is controlled to operate in the fluctuation smoothing mode.
12. The method for operating a virtual power plant system for DC loads according to claim 10, characterized in that: When the state of charge (SOC) of the DC energy storage system is greater than a preset maximum threshold of the state of charge of the energy storage unit, the photovoltaic array and the wind turbine generator set of the new energy power generation system are controlled to operate in a non-maximum power point tracking mode.
13. The method for operating a virtual power plant system for DC loads according to claim 9, characterized in that: The controlling of the connection between the new energy power generation system and the DC energy storage system and the DC bus according to the current real-time electricity price of the power grid includes: When the current real-time electricity price of the power grid K < K min, if the state of charge (SOC) of the DC energy storage system is less than the preset maximum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be shut down, and the connection line between the DC energy storage system and the DC bus is controlled to be turned on, so that power is simultaneously supplied to the DC load and the energy storage unit through the power grid; If the state of charge (SOC) of the DC energy storage system is greater than the preset maximum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be shut down, and the connection line between the DC energy storage system and the DC bus is also controlled to be shut down, so that only DC loads are supplied through the grid; When the real-time electricity price of the current power grid meets K min< K < K max, disconnect the DC switch, supply power to the DC load through the power grid, and collect the state of charge SOC of the DC energy storage system. When 20% < SOC < 80%, control the DC energy storage system to connect and charge through the power grid; when SOC > 80% or SOC < 20%, disconnect the DC energy storage system; K min and K max are pre-configured action electricity prices; When the current real-time electricity price of the power grid K > K When the SOC of the DC energy storage system is greater than the preset minimum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system, the DC energy storage system and the DC bus is controlled to be turned on, and power is supplied to the DC load simultaneously through the power grid, the new energy power generation system and the DC energy storage system. If the state of charge (SOC) of the DC energy storage system is less than the preset minimum threshold of the energy storage unit's state of charge, the connection line between the new energy power generation system and the DC bus is controlled to be turned on, and the line between the DC energy storage system and the DC bus is controlled to be turned off, and power is supplied to the DC load through the power grid and the new energy power generation system.
14. The method for operating a virtual power plant system for DC loads according to claim 13, characterized in that: The preset maximum threshold value of the state of charge of the energy storage unit is 80%; the preset minimum threshold value of the state of charge of the energy storage unit is 20%.