PV Systems in Romania

Photovoltaic Power Systems in Romania

Introduction

The photovoltaic (PV) generation in Romania as an important source of distributed generation (DG) is just at the beginning. The conditions for support schemes of large-scale grid integration of PV systems in Romania are favorable. The legal environment for such support schemes was improved in 2015. Government support for renewable energy production is expected to decline in the next years. The legal support to encourage small-scale deployments of PV systems is still pending. If the approval process is not expedited, the market can become overheated.

This work presents some aspects of the PV systems integration in the Romanian Power System (RPS). The solar electricity potential and the Romanian support mechanisms (legal and regulatory framework for PVs in Romania), as well as the technical grid requirements for Photovoltaic Power Plants (PVPP) according to the recent grid codes are covered.

Solar Electricity Potential and Installed PV Capacity in Romania

Romania has significant PV electricity potential. In the next years, PV power generation would be an important part of the electricity production in Romania. The level of solar irradiation in Southern Romania, which covers more than half of the country’s surface, is similar to the one of countries with tradition in developing PV projects.

Romania estimated to have an important solar energy potential in Europe, by ranking on 11th place in the 30 EU countries as global yearly irradiation from horizontal and optimum angle for vertical mounting. The solar map of Romania with yearly sum of global irradiation and solar electricity potential on optimally inclined surface of PV modules is depicted below.

The total installed capacity of electricity produced from renewable energy sources (E-RES) from certified production units (wind, hydropower <10 MW, biomass and solar PV) at the end of 2016 is 4795 MW, of which 1360 MW is solar power, which is about 28% of total capacity as depicted below.

Legal and Regulatory Framework for Photovoltaic Systems in Romania

Comparing to other European states, Romania offers not only similar weather conditions, but a more attractive support scheme, as well as economic stability, very skilled technical personnel and in general a friendly business environment. Among European Economic Area (EEA) countries, Romania is one of the most promising emerging markets for PV energy investments. With the introduction of support mechanisms in the law in 2008 and the subsequent amendments in 2010, 2011, 2012, 2013, 2014 and 2015, Romanian PV energy market will significantly grow in next years.

In Romania, the PVPPs have priority access to the electric grid and there are simplified connection procedures. In Romania a compulsory quota system combined with Tradable Green Certificate (TGC) is active for the promotion of E-RES. The TGC system has been introduced with the Government Decision (GD) no. 1892/2004 of the Romanian Government (GD no. 1892/2004 was amended and supplemented by GD no. 958/2006).

The main legal framework for renewable energy sources (RES) development in Romania is the Electricity Law. The Electricity Law established ways to promote electricity produced from RES and the rights and obligations of the persons involved. The Parliament passed the Law no. 220/2008 in order to improve the promotion system of E-RES. The Law no. 220/2008 creates the legal framework for the implementation of the mechanisms to promote of E-RES. Through the adoption of the GD no. 1479/2009, the Government of Romania decided to implement the combination of compulsory quota combined with the trading of green certificate (GC) instead of the mechanism of „feed in tariffs” as promotion mechanism of E-RES.

The functioning of the GC system in Romania is depicted below. After the E-RES producers received from Romanian Energy Market Regulator (ANRE) the license to produce electric energy, they must request also from ANRE to be qualified as beneficiaries of the promotion system of GC. In order to receive GCs, the next step is the register of E-RES producers at the transmission system operator (TSO). The E-RES producers will receive monthly from TSO a number of GC according to the type of RES and to the amount of electricity provided to the electricity supplier or/and to the final consumer.

As stipulated by Law no. 220/2008, modified by Law no. 139/2010, the energy generated by E-RES producers may be provided using the national grid system or through an isolated grid system.

In Romania, the electricity produced by PV generation is also eligible for the net metering system. The net metering system is applied for less than 50% of the PVPP with power rated less than 1 MW. In addition to the GC schemes, the PV technology in Romania is supported by investment subsidies and tax incentives.

The annual change in the number of GC emitted between 2010 and 2016 are shown below.

Grid Requirements for Photovoltaic Power Plants in Romania

In Romania, the grid requirements for safe operation of both the power system and PVPP are given by ANRE. The PVPP should fully respect all technical grid requirements of Technical Transmission Grid Code and Electricity Distribution Grid (EDG) Technical Code.

The PVPP should be able to produce simultaneously active and reactive power on unlimited duration in the point of common coupling (PCC), corresponding to any conditions within the equivalent PQ diagram at frequency values ranging between 49.5÷50.5 Hz and admissible voltage. The PV inverter has to be capable to stay connected to the grid and operate continuously without time limit, at frequency values ranging between 47.5÷52 Hz, rates of frequency variation up to 1 Hz/second (s), and voltage variations in the PCC between 0.9pu and 1.1pu of the nominal voltage (Un). The PVPP and its inverters should stay in operation at voltage dips and voltage variations in the PCC on one phase or all three phases according to figure given below. The PV inverters should inject the maximum reactive current for at least 3s during the occurrence of voltage dips without exceeding the operating limits of PVPP.

The PVPP should be equipped with automatic control system of active power depending on frequency (f/P automatic control). The control system should operate according to frequency/active power response curve (power variation depending on frequency).

When the voltage in the PCC have values in the admissible range, the reactive power generated/ absorbed by the PVPP should be continuously controlled according to a power factor placed at least in the range of 0.95 capacitive and 0.95 inductive. The PVPP should provide the automatic voltage/ reactive power control in the PCC through voltage control, controlling the reactive power exchanged with the RPS and power factor control (to ensure the exchange with the power system of zero reactive power when the active power generated by PVPP is zero). The PVPP that operates under a normal operational regime of the power grid should not generate fast voltage variations higher than ±5% from the nominal voltage in the PCC. Also the islanding of PVPP is not allowed, so any PVPP should be provided with anti-islanding protection devices.

In Romania, the grid connection requirements for PVPP meet international standards. These requirements are similar to those from others European countries and are approved by the European Commission. The conditions for interconnection of RPS to the electric power system (EPS) of Europe are fulfilled and also the technical conditions for attracting new investments in this promising field are ensured.

Conclusions

As the principal conclusion, it may be stated that Romania has high potential for solar energy. The variable renewable energy of PVPP needs access to the power grid. Considering the large amount of existing and also the further developments of RES projects, particularly PV systems, the transmission grid and the distribution grid needs significant reinforcements and adaptations to intermittent renewable generation. The RPS developments and upgrades to smart grid solutions are needed in the near future to tap into the true generation potential and to ensure a healthy and safe development of grid.

Please cite my paper in your work:

I. V. Banu, M. Istrate, D. Machidon, R. Pantelimon, "Aspects of Photovoltaic Power Plant Integration in the Romanian Power System," Proceedings of the 9th International Conference on Industrial Power Engineering, CIEI 2014, Ed. Alma Mater Bacău, pp. 13-20, 2014, ISSN 2069-9905.