Application Background

Power Conversion System(PCS) is the core hub equipment of energy storage system grid connection,bear various power grid sustain functions(low or high voltage fault ride through,grid voltage peak and frequency adjustment),receive grid power dispatch,controlling battery charge & discharge power,achieve the energy bi-direction transport between storage power station and power grid.For now,PCS has been widely used in renewable energy grid connection ,distributed generation and AC-DC micro-grid,electric vehicle energy storage application,power transport and distribution,auxiliary services and other fields.

The control strategy,topology and test standard are different of PCS apply to different fields.In order to ensure the PCS healthy connect grid.hen the PCS  is applied in different fields, its control strategy, topology and test standards are not exactly the same. In order to ensure the healthy and friendly grid connected operation of the energy storage system, in the industrial actual product iteration link of "R & D production test", the R & D and test engineer should repeatedly modify the controller parameters and test conditions to test the energy storage system under a series of different working conditions, Based on the characteristics of hardware in the loop simulation, which supports the construction of arbitrary topology models and is highly accurate, using HIL simulation to test the grid connection of PCS has gradually become the mainstream trend.

MoedelingTech self developed MT 6040 real time simulation can help engineers achieve PCS HIL simulation research and test as below:

1.Various type PCS topology application research

2.PCS grid connection test and performance standard test

3.Certify New controller or control strategy performance

PCS test classical application

1.PCS test scheme of Renewable energy grid connection

With the increase of the proportion of renewable energy power generation, the problem of wind and light abandonment is becoming increasingly prominent. By construct energy storage system, the storage can participate in the grid voltage peak and frequency adjustment, stabilize the fluctuation of renewable energy, and effectively improve the quality and economic benefits of renewable energy grid connection. According to the function of the energy storage converter in the renewable energy grid connection, relying on the real-time simulation platform, not only can the energy storage converter be tested independently, but also the functionality of the energy storage system can be tested and verified based on the renewable energy grid connection architecture.

2.AC micro-grid PCS test

The energy storage system in the AC microgrid can effectively give play to the potential of distributed clean energy, reduce the impact of adverse factors such as small capacity, unstable power generation and low reliability of independent power supply, and ensure the safe operation of the power grid. It is a useful supplement to the large power grid to maximize energy, economic and environmental benefits. According to the function of the energy storage converter in the AC microgrid, relying on the real-time simulation platform, not only the standard test of the energy storage converter can be carried out independently, but also the relevant functional test verification of the energy storage system can be carried out based on the AC microgrid architecture.

Solution based on StarSim HIL

ModelingTech MT 6040 real time simulation platform carry out PCS grid connection standard test and controller functional test.Among them, the grid connection standard test mainly includes high / low voltage ride through test, grid adaptability & frequency response test, etc., and the controller functional test mainly includes fast power dispatch,frequency modulation and other functional tests; At the same time, it can also effectively avoid the  "IGBT explosion"phenomenon caused by the controller, provide a safe & low-cost test platform for enterprises.

Content of network access standard test of energy storage converter

1. High/low voltage ride through test

According to the test standards of the technical specification for energy storage converters of electrochemical energy storage systems (GB/T 34120-2017), the technical specification for the detection of energy storage converters (GB/T 34133-2017), and the technical regulations for the connection of electrochemical energy storage systems to the power grid (GB/T 36547-2018), the reaction capacity of the energy storage converters under the conditions of instantaneous voltage drop / rise under the two operation modes of charge and discharge is tested to ensure that the energy storage converters can operate continuously without being disconnected from the grid, It has high / low voltage ride through function under two operation modes of charge and discharge.

2. Grid adaptability frequency response test

According to the test standard of the technical specification for energy storage converters of electrochemical energy storage systems (GB/T 34120-2017), when the energy storage converter is connected to the voltage level of 10 (6) kV or above, it must have a certain ability to withstand the abnormal frequency of the system, so as to ensure the stable and safe operation of the energy storage converter. The test frequency range can be specifically divided into: lower than 48Hz, 48Hz-49.5Hz, 49.5Hz-50.2HZ, 50.2HZ-50.5HZ, and higher than 50.5HZ.

Content of control function test of energy storage converter

1. Fast power scheduling

The energy storage converter supports receiving the idle contact command of the intelligent network load interactive terminal to realize the MS level load switching; The energy storage converter shall be able to switch from full power charging state to full power discharging state within 100ms.

2.Primary frequency modulation

The energy storage converter shall have primary frequency modulation and primary frequency modulation online monitoring functions in the charging, discharging and zero power operation states; At the same time, ensure that the frequency acquisition error is less than 0.005HZ, and the response time should be less than 200ms.

Demo display of simulation test of energy storage system

Generally, according to the control requirements of PCs by the energy storage power station on the grid side, the energy storage converter shall be able to switch from full power charging state to full power discharging state within 100ms. Let's take this function test as an example.

The topology is as follows:

It mainly includes energy storage system, energy storage converter, circuit breaker, voltmeter and ammeter and power grid.

Real time simulation results:

After receiving the superior command, PCS can complete the switching from full power charging state (-75kw) to full power discharging state (75kW) within 100ms, with good dynamic performance.