Utility-scale PV Power Plant Control PPC Cooperate with EMS(Part I)

Author: Yuyao

2022-10-10 14:11

Photovoltaic + energy storage will become the mainstream mode for the development of photovoltaic power stations in the future. The regulation and control of energy storage system is also a technical core in the future. The control of energy storage involves the coordinated work of active regulation of PPC on power grid side and EMS control and management on PCS side of energy storage.

1  PPC Control Strategy

The PPC control target is to control the active power on the grid of the photovoltaic power station, to monitor the change of active power and adjustable active power inside the photovoltaic power station in real time, and to get the final adjustment instruction after the substation has restricted the change rate of the adjustment instruction by dispatching the down regulation instruction or the plan curve.Then, according to the set principle, the active power allocation among clusters is made to respond to the control target quickly and accurately with the minimum adjustment frequency.

1.1、Control Mode (Active power command acquisition method)

Remote control power limit mode: execute the active command issued by the dispatch center (PPC master station), which is smaller than the current maximum active power of the photovoltaic power station. The active power includes the inverters which can generate the maximum active power and the stored energy which can generate the maximum active power.

Remote control free power generation mode: use 120% of rated active capacity as active command of photovoltaic power station, and remote control inverters and energy storage or remote control inverters only.

Plan curve mode: execute active plan curve issued by dispatch center or local engineer station.

Manual mode: Active instructions manually set by operators of photovoltaic power stations at local engineer stations are executed.

1.2、Active Power Change rate limit

The active power instructions are processed according to the restriction requirements of 1-minute and10-minute changes of the power network. The active power of the photovoltaic power station's grid-connected points is restricted by the rate of change, so that they can meet the restriction of 1-minute and 10-minute changes of the power network requirements.

1.3、Active power distribution between inverters and storage clusters

For photovoltaic power stations with multiple inverters and storage groups, the active power allocation between groups supports two allocation modes, which are set by a fixed value "active power allocation mode".

Equal scale method: The distribution is based on the proportion of the power generation capacity of the inverters and the energy storage groups.

Manual proportional method: The active power allocation ratio is assigned to each cluster set at a fixed value.

Compensation method: according to the instructions, the inverter generates power first, and the insufficient part is compensated by storage energy.

2、PPC Commissioning Steps

System Commissioning Steps

 

3、PPC Test

3.1 Local open loop test

Objective: to verify whether the power optimization control sub station can correctly allocate active power commands to the photovoltaic power station cluster.

Mode: input the active power control function when the working mode is commissioning, set different target active power and different 1-minute variation, observe and record the active power command allocated by the power optimization control substation to the photovoltaic power station cluster.

3.2 Local closed loop test

Objective: to verify whether the power optimization control sub station can correctly allocate active power command to the photovoltaic power station cluster, adjust the photovoltaic station and set the node power as the set target active power value.

Mode: put the active power control function into operation under the operating mode, set different target active power and different 1-minute and 10 minute changes, observe and record the active power command allocated by the power optimization control sub station to the photovoltaic power station cluster and the regulation effect.

3.3 Remote closed loop test

Objective: to verify whether the dispatching master station can effectively control the active power of the photovoltaic power station;

Mode: put the active power control function into operation under the operating mode, observe and record the active power command issued by the dispatching master station to the power optimization control sub station, the response of the photovoltaic power station cluster and the actual active power generated by the photovoltaic station;

According to the actual situation of each site, it is also necessary to test the switching of various control modes by the dispatcher, and observe and record whether the display of the screen control mode is consistent with the display feedback state of the master station during the switching process.

Test record of remote switching active power control mode:

 

Please click here to read Part II of this article.

 

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