The Most Easily Overlooked Basic Issues in Energy Storage System Projects

Energy storage system is a complex project. Inadequate requirements, design and management in the early stage of the project have led to frequent changes in the later stage, affecting the overall rationality of the system. Listed below are some common problems.

In-cluster fuse. Usually, the fuse of the battery cluster is arranged in the high-voltage box outside the cluster. When a short circuit occurs inside the battery cluster, the short-circuit overcurrent protection device outside the battery cluster cannot be activated in time, causing accidents such as battery fire. Adding an in-cluster fuse on the basis of the original solution, located in the middle of the battery cluster, can effectively reduce the blind area that cannot be protected when a short circuit occurs in the battery cluster. Improve the safety of the group end maintenance operation.

Battery capacity configuration. In high-rate charge and discharge applications, such as frequency modulation applications, the system dispatch control is based on power as the control target, while the battery characteristics are based on current. When the battery voltage is lower than a certain value, the power remains unchanged, and the current will exceed the design charge and discharge rate of the battery cell. When the battery is lower than the nominal voltage, in order to prevent the battery charge and discharge current from being too large, the current value needs to be limited. When the battery voltage is greater than the nominal voltage, the internal resistance increases, the efficiency decreases, and the heat generation is large when the battery voltage is high, so the current value needs to be limited to work.

Control system dual redundant backup. The control part of the energy storage frequency modulation system adopts a dual redundant design scheme. When a problem occurs in the system, it automatically switches to the backup server to run, ensuring the long-term stable and reliable operation of the frequency modulation system.

Balance between AGC frequency modulation benefits and battery loss costs. Taking China's AGC frequency modulation as an example, the benefits come from the compensation obtained by increasing the Kp index after adding the energy storage system. The energy storage system can increase the regulation rate, regulation accuracy, and reduce the response time. Each adjustment will cause the life loss of the battery system, that is, the adjustment cost. It is necessary to balance the adjustment cost and adjustment compensation to maximize the benefits. In addition, combined with the frequency modulation assessment mechanism, the output is reduced in the non-assessment interval to reduce battery loss.

Fault recording. After a system or equipment failure occurs on site, it is necessary to analyze the possible cause of the failure based on the fault event record, and the fault waveform can more accurately analyze the cause at the time, but now the fault is often difficult to reproduce, which makes it difficult to completely solve the problem. Moreover, the oscilloscope is relatively expensive and inconvenient to carry. When a fault occurs, the waveform shapes of certain predetermined waveforms before and after the fault are recorded to facilitate analysis of the cause of the fault.