Yunt Mars PCS - grid-support inverter

What it is

The YUNT Mars PCS is a three-phase energy storage converter. It moves power between a high-voltage battery and the grid, in the two directions. The LoggerV monitors the PCS, records its data and controls it in plant control.

This page applies to the Mars-100KT, the Mars-110KT and the Mars-125KT. Their rated power is 100 kW, 110 kW and 125 kW. When you add a unit, the LoggerV reads the rated power from the unit and shows it in the device name.

How it connects

• Ethernet, Modbus TCP: connect the LoggerV to the EMS RJ45 port of the PCS. The factory IP address of the PCS is 192.168.1.174. The Add-Device wizard gives the TCP port 502. The LoggerV sends a request to the Modbus address that you enter, and adds the PCS when it replies.
• RS485, Modbus RTU: connect the LoggerV to pins 3 and 4 of the 20-pin signal terminal. At the factory, the PCS uses 9600 baud, 8 data bits, no parity and 1 stop bit. Set the LoggerV serial port to the same rate. The LoggerV sends a request to the Modbus address that you enter.

The PCS does not send its serial number. Thus, you must type the serial number when you add the PCS.

What plant control can do with it

• Battery converter: the LoggerV writes the active power setpoint each time plant control changes its request. The setpoint has steps of 0.1 kW.
• Start and stop: the LoggerV starts and stops the PCS. When it starts the PCS, it also sets the working mode. The mode is AC constant power for dispatch on the grid, AC constant voltage for an off-grid supply, or grid construction.
• Safe state on a failure: when the PCS reports a failure or an unknown state, the LoggerV sets the active and reactive power setpoints to 0.

What the platform records

• Line voltage A-B, V.
• Line voltage B-C, V.
• Line voltage C-A, V.
• Current on phase A, A.
• Current on phase B, A.
• Current on phase C, A.
• Active power, kW.
• Reactive power, kvar.
• Apparent power, kVA.
• Grid frequency, Hz.
• Power factor.
• DC voltage at the battery terminals, V.
• DC current at the battery terminals, A.
• Module temperature, °C.

Reference Documents

These open in the myPower24 library. Sign in to read them.

• YUNT Mars-100KT, 110KT and 125KT PCS module user manual V01.08
• YUNT Mars-50KT and 60KT PCS module user manual V02.04

Wiring

The Add-Device wizard makes the connection diagrams. Refer to How to add a device in myPower24.

The PCS installs in a cabinet. The power terminals are copper bars at the rear of the unit:

• Grid side: A, B, C, N and PE. Use a minimum of 50 mm² for A, B, C and N, and 16 mm² for PE.
• Battery side: DC+ and DC-. Use a minimum of 50 mm².

The signal terminal and the RJ45 ports are on the front panel. The signal terminal has 20 screw pins.

RS485 to the LoggerV

Connect the RS485 RJ45 connector of the LoggerV to the 20-pin signal terminal of the PCS.

The EMS RS485 pins have a 120 Ω termination resistor. This resistor is on at the factory.

CAN to the battery

Connect the CANBUS (3) RJ45 connector of the Solar MD battery to the 20-pin signal terminal of the PCS.

Emergency stop

• Pin 15, DI1_EPO: emergency stop input.
• Pin 19, DI_GND: ground for the digital inputs.

RJ45 ports

• EMS: Ethernet to the LoggerV.
• SYNC1 and SYNC2: the parallel sync link between PCS units.
• CONS: the vendor debug port.

Setting it up

1. Connect the cables as the generated diagram shows.
2. Add the device on the LoggerV. Refer to How to add a device in myPower24.
3. Type the serial number from the label on the unit.
4. On the Info tab, make sure that Rated Power agrees with the nameplate.
5. On the Settings tab, open Voltage/Current Protection.
6. Set the charge and discharge limits from the data of the battery manufacturer.
7. Make sure that the PCS has a connection to the LoggerV. On the Actual Data tab, Operating Mode shows a value and the AC Measurements card shows live values.

Battery communication

The Mars PCS operates with the Solar MD SS7000 series batteries. The PCS gets the battery data from the battery BMS through CAN, on pins 5 and 6. The LoggerV does not send or read this CAN data.

The PCS operates at a DC voltage from 580 V to 1000 V.

On the device page

The page has three tabs: Info, Actual Data and Settings.

• Info shows the data that the LoggerV reads when you add the PCS: Manufacturer, Device Name, Serial Number, Installed Date, Rated Power, Rated Voltage, Rated Current and Rated Frequency.
• Actual Data has these cards: System Status, AC Measurements, Power Measurements, DC Measurements, STS Status, Time & Energy, Phases, Limits and Device Date/Time.
• Settings has these groups: Basic Control, System Time Settings, DC Power Control, AC Power Control, Reactive Power Control, RS485 Communication, Voltage/Current Protection and Other Settings.

On a healthy link, System Status → Operating Mode shows one of these values: "Ready to run", "On-grid operation", "Charging operation", "Discharge operation", "Off-grid operation" or "Standby". The value "Failure" shows that the PCS has a fault.

Troubleshooting

The PCS reports these faults. Many of them reset automatically when the cause goes away.

Grid faults:

• "Grid overvoltage", "Grid undervoltage", "Grid overfrequency" and "Grid underfrequency": the grid is out of the limits of the grid code. Examine the grid voltage and frequency. Make sure that Grid Code in Other Settings is correct for the site.
• "Power grid phase sequence error": the phase sequence on the AC terminals is incorrect. Change the phase sequence on the AC side.
• "Grid not powered on", "Power grid phase loss" and "Grid voltage imbalance": examine the grid supply and the AC breaker.
• "Grid island status": the PCS found a grid outage. Make sure that the grid supplies power.
• "High penetration protection", "Low penetration protection" and "N-line overcurrent protection": the PCS reports a grid protection event. If the fault stays, speak to YUNT support.

Communication faults:

• "EMS communication failure": the PCS has no data link to the LoggerV. Examine the RS485 or Ethernet cable. Make sure that the LoggerV shows the PCS as connected.
• "BMS communication failure": the PCS has no CAN link to the battery BMS. Examine the CAN cable on pins 5 and 6.
• "STS communication failure", "Host communication failure" and "Slave communication failure": the PCS lost its link to the STS or to a parallel unit. Examine the SYNC cables and the STS cable.
• "Slave machine failure", "Host failure", "Carrier synchronization failure", "Parallel and off-grid switching command abnormal" and "STS failure": a parallel unit or the STS has a fault. Examine the fault on that unit.

DC and battery faults:

• "Battery voltage polarity reverse detection abnormal": the battery cables are on the incorrect terminals. Make sure that DC+ and DC- are correct.
• "Battery overvoltage", "Battery undervoltage" and "Abnormal battery voltage detection": the battery voltage is out of the range of the PCS. Examine the DC input voltage.
• "Battery overcurrent" and "Battery current hardware overcurrent": the battery current is too high. Examine the current limits in Voltage/Current Protection.
• "Charging termination" and "Discharge termination": the battery reached a charge or discharge limit.
• "BMS failure": the battery BMS reports a fault. Examine the battery.
• "Precharge timeout", "DC system precharge not ready" and "DC power not ready": the DC bus voltage does not increase. Examine the DC breaker. If the fault stays, speak to YUNT support.
• "Bus overvoltage", "Bus undervoltage", "Bus hardware overvoltage", "Bus short circuit", "Abnormal bus voltage detection", "Positive and negative buses unbalanced" and "Positive and negative buses unbalanced to ground": the internal DC bus has a fault. Examine the grid and the battery. If the fault stays, speak to YUNT support.

Module and power faults:

• "Module overtemperature", "Internal ambient temperature too high" and "Overtemperature load reduction": the PCS is too hot. Examine the airflow in the cabinet and the fans.
• "Internal fan failure" and "External fan failure": a fan stopped. Speak to YUNT support.
• "Module hardware overcurrent", "Module overcurrent", "Wave-by-wave current limit exceeded", "Module I2t overload" and "Grid-side module current unbalanced": the AC current is too high. Examine the load and the AC cables. If the fault stays, speak to YUNT support.
• "Filter capacitor overvoltage", "Filter capacitor undervoltage", "Power failure", "AD sampling zero drift too large" and "Debugging error": the PCS has an internal fault. Speak to YUNT support.
• "Active power too large", "Active power limit reached", "Active power adjustment output limit reached", "Reactive power adjustment output limit reached" and "Reactive power limit reached": the setpoint is more than the PCS can supply. The PCS limits its output.
• "AC and DC power mismatch" and "Large active power deviation": the output of the PCS does not agree with the setpoint. If the fault stays, speak to YUNT support.

Protection and contactor faults:

• "Emergency shutdown": the emergency stop input is open. Reset the emergency stop switch.
• "DC-to-ground insulation resistance failure", "AC to ground insulation failure", "Grid-side leakage current too large", "Leakage current sensor self-test failure" and "Leakage current zero drift sampling too large": a cable or a component has a leakage to ground. Speak to YUNT support.
• "AC lightning arrester failure" and "DC lightning arrester failure": a surge arrester in the PCS has a fault. Speak to YUNT support.
• "Precharge contactor failure", "Main contactor failure", "DC precharge contactor failure", "DC main contactor failure" and "On-grid contactor failure": a contactor does not agree with its command. Speak to YUNT support.

STS faults:

• "STS power failure", "STS fan failure", "STS emergency stop", "STS external 24 V power input abnormality" and "STS overtemperature": the STS has a hardware fault. Examine the STS.
• "STS reports PCS fault", "STS host communication fault", "Main STS fault" and "Slave STS fault": the STS has a communication fault. Examine the STS cable.
• "STS grid overvoltage", "STS grid undervoltage", "STS grid overfrequency", "STS grid underfrequency", "STS grid overcurrent" and "STS grid phase sequence error": the grid at the STS is out of its limits. Examine the grid supply.
• "STS load overvoltage", "STS load undervoltage", "STS load overfrequency", "STS load underfrequency", "STS load hardware overcurrent", "STS load overcurrent" and "STS load phase sequence error": the load side of the STS is out of its limits. Examine the load and its cables.
• "Grid-connected switch action failure", "Load switch action failure", "Grid N line switch action failure", "PCS N line switch action failure" and "N to PE switch failure": a switch in the STS does not operate. Speak to YUNT support.

If you see a fault that this page does not show, record the message and the serial number of the PCS. Then speak to support.

Who can do what

• Regular user (basic): can see the device page and change most settings. These settings include start and stop, the working mode, the system reset and the STS bypass. They also include the power settings, the charge and discharge limits, the clock and the grid code.
• Advanced user (advanced): can also change the battery overvoltage and undervoltage protection, the RS485 address and the RS485 baud rate.

A user with a higher permission can also do all the tasks of a lower permission.

Tips and gotchas

• Hardware Version and Firmware Version on the Info tab show 0. Use Software Version on the Actual Data tab to find the firmware version.
• To operate more than one PCS in parallel, refer to Configure a parallel cluster on the YUNT Mars PCS.