CN-121984371-A - Converter control device and control method

CN121984371ACN 121984371 ACN121984371 ACN 121984371ACN-121984371-A

Abstract

The invention discloses a converter control device and a control method, wherein the converter control device comprises a battery pack, N converters and a boosting component, the battery pack is connected with the boosting component through the N converters, the battery pack comprises N groups of batteries, at least comprises a first battery cluster and a second battery cluster, adjacent groups of batteries are connected with each other through a first relay and a second relay and are connected with each other in positive and negative mode, and a first converter connected with the first battery cluster is connected with the first battery cluster through a third relay and a fourth relay. The method has the beneficial effects that the method controls the PCS1 modulation circuit of the first converter to actively discharge the energy of the bus capacitor in an open loop state through software, so that the voltage of the first converter can be quickly reduced below a target value in a few seconds. This completely eliminates the passive latency of up to several minutes required in conventional schemes to rely on the natural bleed of capacitance.

Inventors

LEI BING
LI KAIXU
JIANG LAN
ZHOU GANG

Assignees

浙江南都能源科技有限公司
浙江南都电源动力股份有限公司

Dates

Publication Date: 20260505
Application Date: 20251223

Claims (10)

1. An inverter control device, comprising: The power supply device comprises a battery pack, N converters and a boosting assembly, wherein the battery pack is connected with the boosting assembly through the N converters; The battery pack comprises N groups of batteries, wherein the N groups of batteries at least comprise a first battery group and a second battery group, and adjacent groups of batteries are connected through a first relay and a second relay to form positive and negative poles; the first converter connected with the first battery cluster is connected with the first battery cluster through the third relay and the fourth relay; The first converter connected with the first battery cluster comprises a fifth relay, a sixth relay, a seventh relay, an eighth relay, a ninth relay, a bus capacitor and a first control modulation circuit; The third relay and the fourth relay are respectively electrically connected with the first control modulation circuit through a fifth relay and a wire, the first modulation circuit is respectively connected with the sixth relay, the seventh relay and the eighth relay through three-way inductors and respectively electrically connected with the boosting component, and the third relay and the fourth relay are respectively electrically connected with two ends of the bus capacitor through a ninth relay, a first resistor and a wire.
2. The converter control device of claim 1, wherein the boost assembly comprises a first grid-tie relay, a second grid-tie relay, and a third grid-tie relay; one end of the first grid-connected relay, one end of the second grid-connected relay and one end of the third grid-connected relay are respectively and electrically connected with the three-way inductor, the other end is connected with the power grid through a converging distribution box.
3. The converter control device of claim 2, wherein the three inductors include a first inductor, and a first inductor; the first path of inductor comprises a first inductor and a second inductor, and is connected with the first control modulation circuit and the first grid-connected relay in series; The second path of inductor comprises a third inductor and a fourth inductor, and is connected with the first control modulation circuit and the second grid-connected relay in series; The third inductor comprises a fifth inductor and a sixth inductor, and is connected with the first control modulation circuit and the third grid-connected relay in series.
4. A converter control apparatus according to claim 3, wherein, The position where the first inductor is connected with the second inductor, the position where the third inductor is connected with the fourth inductor, and the position where the fifth inductor is connected with the sixth inductor are respectively connected in a crossing way after passing through the second resistor and the first capacitor.
5. The inverter control device of claim 4 further comprising a microcontroller electrically connected to the first relay, the second relay, the third relay, the fourth relay, the fifth relay, the sixth relay, the seventh relay, the eighth relay, and the ninth relay, respectively; The microcontroller can collect voltage and current signals of three output ends of the N groups of batteries, the bus capacitor and the first control modulation circuit through the voltmeter.
6. A control method of an inverter, which is applied to an inverter control device, the method comprising: Detecting the voltage of a bus capacitor at the direct current side of a first battery cluster in response to a shutdown instruction received by a first converter from the first battery cluster to a second battery cluster or the first relay; And if the bus capacitor is judged to be required to be actively discharged, controlling an alternating current side modulation circuit required by the first converter to operate in an open loop mode, so that the electric energy stored in the bus capacitor is released to an alternating current side through the switching loss and the conduction loss of the modulation circuit, and the voltage of the bus capacitor is rapidly reduced.
7. The control method of claim 6, wherein the determining that active discharge of the bus capacitor is required comprises: When the first battery cluster needs to be switched to the second battery cluster, if the current voltage of the bus capacitor is higher than the voltage of the second battery cluster to be connected, judging that discharging is needed, and pre-charging the second battery cluster; when the first battery cluster receives a shutdown instruction, if the current voltage of the bus capacitor is higher than a preset safety voltage threshold value, the first battery cluster judges that discharging is needed.
8. The control method of claim 7, wherein the controlling the ac side modulation circuit required by the first converter to operate in an open loop manner comprises: setting an initial duty ratio for a switching tube in the modulation circuit, gradually increasing the duty ratio according to a preset step length, and enabling the modulation circuit to enter an open-loop working state in a soft start mode; switching off the third relay, the fourth relay, the fifth relay, the ninth relay, the sixth relay, the seventh relay and the eighth relay; Setting discharge enabling Dischg to be 1, controlling a first modulation circuit to set a specific range Duty ratio Duty mode according to an open loop, performing soft start according to a step length, detecting a bus capacitor voltage value in real time, and clearing discharge enabling Dischg to be 0 after the bus capacitor voltage value is reduced to be lower than a set value.
9. The control method according to claim 7, wherein, And stopping the open-loop operation of the modulation circuit when the voltage of the bus capacitor is reduced to be lower than a preset discharging completion voltage value.
10. The control method according to claim 7, wherein in a case where the first converter needs to switch a battery cluster, the method further comprises: After the active discharging is completed, closing a ninth relay to precharge the bus capacitor through a first resistor until the voltage of the ninth relay is close to the voltage of the second battery cluster; And then closing a main connection switch between the first converter and the second battery cluster to form a first relay and a second relay, and starting the first modulation circuit to perform closed-loop modulation so as to realize grid-connected operation.

Description

Converter control device and control method Technical Field The invention relates to the field of energy storage, in particular to a converter control device and a control method. Background The energy storage converter (PCS, powerConversionSystem) is used as core electric energy conversion equipment connected between the energy storage battery and the power grid and is responsible for realizing bidirectional, efficient and controllable conversion between direct current and alternating current. Because of its excellent efficiency and power quality, PCS has been widely used in various applications such as energy storage power stations, data centers, industrial and commercial energy storage. In these application scenarios, the cost effectiveness, power density and operation reliability of the system are key technical indexes, and PCS is used as a key link for energy flow, and its availability and safety directly affect the performance of the whole system. A cluster-to-management group string energy storage architecture is a solution widely used at present. In this architecture, each battery cluster (BT) is connected to the ac grid through an independent PCS unit, forming a plurality of parallel power generation units. The architecture has the advantages of flexible deployment and high fault tolerance, and when a single battery cluster or a corresponding PCS thereof fails, the whole system is not stopped. However, the existing serial-serial scheme in practice exposes a significant problem that when a certain cluster of cells (e.g., BT 1) is charged, the PCS (e.g., PCS 1) connected in series with the cluster of cells goes into an idle state, resulting in the waste of the partial power conversion capacity, which reduces the overall power density and economic benefit of the entire energy storage system. In order to improve the system utilization, it is desirable to quickly switch the idle PCS unit to other battery clusters (e.g., BT 2) that are not fully charged, so as to continue to provide charge and discharge services. The realization of the flexible switching faces a key technical obstacle that when the battery cluster BT1 is fully charged and disconnected, high-voltage charges similar to BT1 still remain on the corresponding PCS1 direct-current side bus capacitor (C1). If the PCS1 is directly switched to the battery cluster BT2 with lower voltage at this time, the capacitor cannot be precharged normally by the battery because the bus capacitor voltage is higher than the battery voltage to be accessed. If the main connecting relay is forcibly closed, the high-voltage capacitor can form instant reverse impact current to the low-voltage battery cluster, so that the safety of the battery and the stability of the system are seriously threatened. Therefore, the prior art can only passively wait for the bus capacitor to slowly discharge through the tiny leakage current of the circuit, and can start the pre-charging and grid-connection processes until the voltage of the bus capacitor naturally drops below the voltage of the target battery cluster. This waiting process is lengthy (up to several minutes) and severely affects the system response speed and handover efficiency. In addition, this technical disadvantage also introduces an important safety issue in that large capacity electrolytic capacitors are typically used inside the PCS to stabilize the DC bus voltage. After normal shutdown or fault emergency shutdown of the PCS, a large amount of electric energy stored in the capacitors is very slow in voltage drop if only natural discharge is relied on. When equipment overhaul or maintenance is needed, if technicians misjudge that the capacitor is completely discharged and uncover the cover, high-voltage electric shock is most likely to happen, and serious personal injury accidents are caused. Disclosure of Invention The invention aims to solve the technical problems in the prior art and provide a converter control device and a control method. The technical scheme is that the converter control device comprises: The power supply device comprises a battery pack, N converters and a boosting assembly, wherein the battery pack is connected with the boosting assembly through the N converters; The battery pack comprises N groups of batteries, wherein the N groups of batteries at least comprise a first battery group and a second battery group, and adjacent groups of batteries are connected through a first relay and a second relay to form positive and negative poles; the first converter connected with the first battery cluster is connected with the first battery cluster through the third relay and the fourth relay; The first converter connected with the first battery cluster comprises a fifth relay, a sixth relay, a seventh relay, an eighth relay, a ninth relay, a bus capacitor and a first control modulation circuit; The third relay and the fourth relay are respectively electrically connected with the first control modulation